2008's Top Advanced Engine Building Posts

2008's Top Advanced Engine Building Posts
By Don Terrill (c) - www.RacingSecrets.com

Engine Masters, advance curve
Engine Masters, tuning priorities
Adjustable LCA
Airflow dynamics and how it applies to porting
Exhaust system surface finish
carburetor isolation, Engine Masters
3,4,5 angle valve job, what to blend and what not to blend
Why 90 degree Bobweight is 100% and 50%
Engine overbalancing
Inlet to exaust ratio flow
what do you consider a turbulent intake port?
lean burn engine
cylinder head flow, possibly too much
valve train harmonics
Header lengths
351C Head flow
Wet flow video discussion
GT40P heads
Mass Air Flow
camshaft questions, Engine Masters
DTS vs. Superflow
Flow bench accuracy
Intake Plenums vs Individual Runner intakes
Intake seat venturi? Blow out the bowl?
Nitro in a Diesel Injector
Theoretical Exhaust Velocity
E85 as Race Fuel
intake port shape
Flow Data for SBC
What rules would you LIKE to see for the EMC?
Flow coefficient versus pulse strength.
Cd of F1 engines and the rpm limiting factor
Burning rates

Recession Proof Horsepower

Recession Proof Horsepower
By Don Terrill (c) - www.RacingSecrets.com

Does the news media have you all wigged out about the economy? Are you looking to cut costs, but still need your racing fix? Well, you can't race for free, but you sure can be smart about how and where you spend your money.

Build Affordable Horsepower:

• Only Build What You Need - The vast majority of racers will build their engine with more horsepower than required. Instead, think about how much power you need and then find the most affordable (and reliable) way to get there.
• Engine Size - If there are no restrictions on engine size, build one large enough so you don't have to put it on meltdown to make power. 400" with a flat tappet cam may be better than 350" with a roller.
• Power-Adders - Throwing reliability out the window, power-adders (nitrous, blowers, etc) can add a lot of bang for the buck. It's hard to beat the HP per Dollar of Nitrous Oxide -- in fact it's impossible.
• Airflow - Have a bunch of rules? Forced to make your horsepower the old fashioned way? Don't waste a penny on titanium rods or other nonsense. Put your money where it counts, in airflow improvements.

Build Reliable Horsepower:

The last thing you need is a blown engine when money is tight. Here are a few tips to help out with engine longevity.

• RPM - There's no bigger killer of engines than too much RPM. Don't spin the engine any harder than required to be competitive. You won't have to give up any performance if you build/tune the engine to work down low.
  
• Compression - The main problem here is the increased risk of detonation as you raise compression ratio. The lower the compression the better, but learning how to read spark plugs will help keep you out of trouble no matter what the compression.
  
• Valvetrain - If you can only afford to build the engine once, then this is no time for any aggressive valve motion. Leave the camshafts with quick ramps and a ton of lift to the rich folks. Get more air into the engine through airflow improvements, not by wilder cam lobe profiles.
  

As for financial success in this economy, I don't see anything more important than protecting your ability to earn, and one of the best ways to do that is by furthering your education -- Make yourself more valuable to the marketplace.

The same goes for your racing success, there's no better bang for the buck than educating yourself. Dummies will never find themselves in the winner's circle very often.

10 Early Season Performance Tips

10 Early Season Performance Tips
By Don Terrill (c) - www.RacingSecrets.com

It's your first time out this year and you're not happy with the results - Your car feels short on power. At this point most racers will go on a witch hunt to find the one item causing the entire shortfall. Rarely is this the case, more often it's 10 little things adding up to one big problem. Here are 10 I see over and over:

(1) Ignition Timing
Some engines are very touchy to ignition timing - I've seen 2 degrees too little cost 10hp or more and 2 degrees too much cost over 30 hp. An engine or chassis dyno is the best way to find the sweet spot. If that's not an option, learn how to read spark plugs.

(2) Air/Fuel Mixture
If you're still running out of the box jetting on your carburetor, odds are it's fat and costing you power. You can't blame the carb manufacturers for wanting to play it safe and avoid a mass of angry customers who race at sea level in 40 degree (f) weather. Learning how to read plugs is critical to getting it right, but most applications can benefit from going leaner.

(3) Gasoline Mix
I can't even remember the last time I ran gas straight out of the drum/pump. The trick is getting as much oxygen content in the gas as possible with just enough octane to stay out of detonation. Less than max compression engines have the most to gain from getting the fuel mix just right. If you're brave enough and the rules allow it, you can try some of the additives meant to boost oxygen. Depending on the amount oxygen added, you may need to re-jet.

(4) Forced Air
This is not the time to consider a blower or turbo charger, but what about a hood scoop or cowl? For a forward facing hood scoop make sure it's high enough to catch the positive pressure coming off the front of the car. A rear facing cowl hood makes it a lot tougher to find and capture that positive pressure - testing with a manometer will help. With either setup, make sure you've got a tight fitting air pan or your efforts will be for naught. Also, if the car slows down when you seal the air pan, your scoop/cowl is in the wrong spot.

(5) Cold Air
You can easily find 10 hp for every 10 degrees (f) lower you can make the air going into the engine. A hood scoop or cowl is best, but if you're forced to pull air from under the hood, there are still some things you can do: (1) Create a "Cold Air Kit" that pulls air from in front and to the side of the radiator. (2) Paint the top of your hood white to stop the sun from adding to the problem.

(6) Oil Volume
On a wet sump engine you lose approximately 10 hp for each additional quart of oil you run, so stop letting oil pan manufacturers dictate how much oil you run - nobody needs 12 quarts of oil. On a dry sump engine the oil level in the pan is controlled by the scavenge side of the pump, so to keep the level as low as possible consider more stages and bigger hoses.

(7) Oil Pressure
You can lose as much as 5 hp for each additional 10 psi of oil pressure you run. You lower it at your own risk, but I've seen engines making over 700 hp run fine on less than 40 psi. For dry sump engines it's an easy adjustment, for wet you'll have to decide if it's worth the effort.

(8) Oil Type & Weight
The debate was over a long time ago - synthetic oils do free up power - You can expect 5 to 10 horsepower when switching from mineral based oils. Weight should be matched to rod/main bearing clearance and the temperature the oil runs at - the more the clearance or the higher the temperature, the "thicker" the oil required.

(9) Shift Points
It cost nothing to make sure you're shifting at the right rpm. If you have dyno numbers, try a fuzz over peak power and test from there. Of course you can always use your internal dyno - our ability to feel g-force - It's crude, but better than nothing. Here's a clue: If you feel pushed back in the seat immediately after a shift, you were late - which is a lot worse than being early.

(10) Gear Ratio
Ignoring traction or longevity issues, the majority of cars don't have enough gear ratio. Drag racing and short track stock cars should top out well over peak power. Big track stock cars or any type of racing where you spend a lot of time at one rpm should hang closer to peak power.

Building Your Own Headers - Part 3

Building Your Own Headers - Part 3
By O'Darrell Poole (c)

In our first two articles (1) (2) we discussed the characteristics of a properly designed and tuned header. In this month's article we will discuss some theory on the gas flow in a tube and also the difference between mandrel bent and welded headers.

Tube Bending
So that a piece of tubing can be bent and maintain consistent wall thickness as well as cross sectional area a mandrel type bender is used. When headers are made with mandrel bent tubing that use 1 piece of tubing per primary cylinder, bend radius is limited to 1 � times the tubing diameter. In designing a header of this type and merging multiple primary tubes into one collector variations in tubing length are inevitable. Due to limited room and available radiuses header design must be compromised and a under performing header is the usual outcome. Some will disagree and say "when I installed my set of brand X headers to replace my stock manifolds my performance increased and � mile et and mph improved." Unfortunately what had really happened is that the stock design manifold was produced for mass production and was designed to meet many different operating conditions and its not performance, so that bolting almost anything to the head to replace the stock manifolds will produce more power because of reduced restriction. You will also find for example in a small block Chevy that a poorly designed header of unequal length primary tubes will produce fouled plugs usually in the front and rear cylinders and nicely tuned centre cylinders. This is because the tubing in the middle cylinders is pretty close to the properly tuned length for the conditions of the engine and the front and rear cylinders are to long and to short (in tubing length ) and cause exhaust to be forced back into the cylinders (inert gas) mixed with fresh gas and a misfire results. I would never recommend using unequal length or one piece primary headers on ANY ENGINE EVER!!! The potential to damage your engine is far more expensive than buying a set of headers that are properly sized and tuned for your engine. Now while custom made headers or welded headers are much more expensive than the ones we have just discussed the advantages are well worth it. Custom made or welded headers will still use mandrel bent tubing but because they can be cut and rewelded at any spot and position necessary the lengths and design of the header will not be compromised. Although welded headers are sometimes extremely difficult to build because the primaries may have to snake their way through and around each other to achieve equal length primaries the performance gains are well worth the effort and at plug check time all the cylinders will be burning the same. I image my e-mail box will be full of comments from those who will say that the welds cause gas flow problems because of the weld intrusion into the primary pipe.

Gas Flow in Pipes
When gas or a liquid travels down a pipe there is what is called a gradient of flow. This means that the gas or liquid in the centre or middle of the pipe moves faster and speed diminishes as it gets closer to the outer wall of the tube and is actually almost no movement on the wall itself. As an example take a walk to the nearest quick running stream in your area. Notice out in the centre of the stream that the current is carrying the water quiet quickly now walk to the edge of the stream and notice the water at the shore line it's barely moving!! This is the same way that a header tube works. The gas in the centre of the primary pipe is traveling extremely fast (1,700ft/sec) but at the tubing wall is almost at a stand still therefore while a poor weld and gobs of weld protruding into the primary pipe from a weld will adversely affect gas flow, a properly cleaned and applied weld fillet with proper penetration will have no effect on gas flow.

Remember we welcome your questions on intake and exhaust systems as well as any comments you may have. Stay tuned for more articles on intake and exhaust systems in upcoming articles.

O'Darrell Poole
Autocraft Dynamic Design Inc.
E-mail: autocraftdynamicdesign@live.ca

Building your Own Headers - Part 2

Building your Own Headers - Part 2
By O'Darrell Poole (c)

As we discussed in our first column the design characteristics of our headers fall into 4 distinct categories. To recap they are as follows

1) Primary Pipe Diameter
2) Primary pipe Length
3) Collector Diameter
4) Collector Length

While the diameter and the length of both the primary and collector pipes are of extreme importance there are other very important factors in header design. We will discuss 3 necessary elements.

1) Cylinder Head to header primary pipe entrance
Maintaining gas flow velocity is vital in proper exhaust scavenging. If your header flange is causing a partial blockage (by way of size or shape) turbulence will be step up at the time when velocities are at its highest therefore turbulence will be at its highest. If your header flange opening is to large gas velocities are slowed down and will effect the timing of the negative pressure pulse used to promote scavenging and cause the pulse to come well after TDC. To ensure proper flow from cylinder head to primary pipe use a header flange shaped to match your head (square, circle, rectangle) and merge it into your primary pipe. Using a header flange with short starter tubes that transition from your square (cyl head port) to your primary pipe ( curcular) is common practice.

2) Primary Pipe to Collector Merging
Maintaining gas velocities into and beyond the collector merge point is sometimes overlooked. The collector is not only the spot where the primary tubes merge into one but must also promote smooth transition from primary pipes to our collector pipe. The method used by some is to weld the centre section together with a small piece of metal to help reduce the dead zone left when for example four pipes meet. Another method is to bring the edges of the pipes together in the centre to form a cross where by eliminating all together the dead zone and welding them together. I prefer the ladder method as it promotes smooth transition with no dead zone.

3) True Equal Length Headers
Apparently equal length headers to some does not mean primary pipe length's that are the same length to every cylinder. We have seen headers primary pipe length vary from cylinder to cylinder by as much as 15". Our internal combustion engine is nothing more than a air pump that we put extensive time into making all the internals the same. Examples are compression ratio's, cylinder head volume, intake tract length, and camshaft lift and durations. Now no one would ever think of putting 8 different pistons in a engine or having cylinder head volumes differ by 25% or have a camshaft ground with 8 different profiles, so why would we put 8 different lengths of pipe on the exhaust side of our engine. Utilizing sound wave and pressure wave technology in our exhaust system is free power and once you have gone through the task of determining proper primary pipe length for your header and then not taking advantage of that imformation is just silly. Design your header for your RPM range then use that length on all cylinders and get equal power from all cylinders.

Stay tuned for more information on designing and building your own headers in up coming columns. We welcome your intake and exhaust system questions!!!! Contact us at autocraftdynamicdesign@live.ca O'Darrell Poole

Last Minute Power

Last Minute Power
By Don Terrill (c) - www.RacingSecrets.com

Ok, you're almost finished with your new engine - all the machine work is done and you're ready to assemble. But, you're starting to worry about power - it won't be enough. Now what?

Well, this is no time to fiddle with cubic inches, compression or new cylinder heads, but there are still things you can do to help power that won't require starting from scratch.

Camshaft
If you've got enough piston-to-valve clearance (measure it, don't assume) and you're not sure about your cam choice, maybe it's time to sell it and try again. For more power focus on picking the right intake duration and then getting as much lift as possible for that duration. Make sure the valve springs (and your maintenance schedule) can handle the increased stress from a more aggressive lobe design.

Rocker Arms
More intake rocker ratio can be a real help - especially if you think the cam is a fuzz short on duration. In addition to the warnings above, make sure the increased rocker ratio won't create clearance problems between the side of the pushrods and cylinder head. A rough estimate for the piston-to-valve clearance lost with a 0.1 increase in rocker ratio is 0.1 x lobe lift @ TDC (a spec listed by most cam companies).

Intake Manifold
Not a ton of power to be found here, but an easy swap. If your manifold was designed 40 years ago (many were), you may want to look at some of the newer offerings. Also, don't get all caught up in having a perfect gasket match - As long as the manifold port is smaller, but not radically smaller, than that of the cylinder head, you'll be fine. Don't believe me? Back to back it on the dyno.

Carb Spacer
Most applications will benefit (max power) from having the tallest carb spacer the hood will allow. Try a 4-hole spacer nicely blended into an open - It doesn't work on all applications, but it works more often than not.

Carburetor
If your carburetor still has a choke tower on it, you're leaving at least 1ohp on the table. Upgrade to a newer high flow model or modify the one you've got - which is not that hard. http://racingsecrets.com/holley_carburetors.shtml

Headers
Not that cheap anymore, but a simple bolt on. If your headers are the wrong tube diameter, replace them. If you think you've got the right tube diameter, then cut off the collectors and get a set of merge models - they do work. Buy the slip on models if you want to do some tube length testing by adding extensions between the header and collector, or if you want to try different collectors down the road.

Oil Pan
Wet or dry sump, anything you can do to get the oil away from the crankshaft will help free up horsepower. In fact, it's impossible, from a power standpoint, to get the oil pan too big or too deep. And when you're done, don't defeat the whole purpose by adding more oil to the pan.

2007's Top Engine Building Posts

2007's Top Engine Building Posts
By Don Terrill (c) - www.RacingSecrets.com

Fatal Mistakes....
Indexing spark plugs ??
Micrometer choices????
old school vs modern, can it be done
PUMP GAS
When does a firing order swap on a SBC become an advantage??
Cam profile in relation to airflow curve
Interesting flat tappet pre break-in treatment.
power pulses and rpm
Rotating weight.....crankshaft....bobweight
intake port screens?
I specialize in Filtration and would like to share so info:
valve to piston clearance
700+hp N.A. Ford engine ideas, budget.
Suggestions please...600hp sbc buildup
horsepower increase w/ dry sump and vacuum pump
Valve Size
I.E ratio for heavy nitrous 565
KB hypers & timing
squirter pullover,,dominators
Let's talk assembly lube
Holley Carburetor Emulsion
What is the most effective windage tray for a SBC?
TQ vs. HP which is more important. . .
The great torque/HP debate
Bearing damage analysis
race oil
Singh Groove testing redux and CFD for groove positioning.
carbs and fouled plugs on the street big solid roller cam...
Camshaft profile design - hard on parts?
k&n stub stack
Standard Vs High Volume Oil Pump Pressure.
Diagnosing hurt motor
balancing holes ?
Weirdest engine rattle ever, BBC454. Help!
Minimum quench in BBC?
Square Headers??
too much compression vs. cam timing, what happens?
Has anyone here done any testing on mufflers
Suggestions for "pullover"
Oxygenated Fuel??
Does MSD make power?
Why does this car burn my eyeballs right out of my face??
Squeezing more HP out of a 434
Question about repeated bearing failure
1000HP SBC in the Making
How much vacuum does an intake port really see?
Would like to find 70 hp from my 582
Solid vrs roller cam on a street motor
Where does power come from?
Pump gas BBC street motor
Pushrod Deflection
head flow vs cam choice
Why are carbs still use in racing if F.I. is so much better
Intake/Exhaust ratio
HP - RATE - Actual Performance
high lift flow backing up
compression ratio limit
Quench v.s. Squish?
Help analyze port design, pictures within...
cfm gain to horsepower gain correlation
Port Velocity vs RPM Range
Port Area Curve
intersting head design
Cam Gurus, Question about Dynamic Compression
% Mixture burned/crank angle
Valve shrouding - myth or fact?
Detonation starts on intake side of chamber. True?

Choosing the Best Cylinder Heads

Choosing the Best Cylinder Heads
By Don Terrill (c) - www.RacingSecrets.com

What needs to be decided and in what order:

1. Head Design - It's been a long time since factory 23 degree Chevy heads were your best choice. If cost and rules won't stop you, get wild.
   
2. Port Size - Manufacturers only advertise the Intake Port volume (cc), but the critical dimension is the area at the short turn - which is mainly dictated by the engine size & RPM.
   
3. Material - Cast Iron or Aluminum? Unless the rules specify, I wouldn't mess with cast iron - aluminum is lighter, better at shedding heat and easier to fix.
   
4. Manufacture - If multiple companies make heads that will work with your application, go with the one that has the best reputation for good castings - core shift, porosity, machining, etc.
   

Questions that need to be answered:

1. Engine Size - The bigger the engine, the more port area it will need.
   
2. RPM - Equally as important as engine size is RPM - the higher the RPM, the more port area required.
   
3. Application - Is it a 6 speed drag car the operates in a 1,500 RPM range or is it a stock car that runs on a track with tight corners, dictating a 4,000 RPM range?
   

In a nut shell: First focus on getting the best port area (at the short turn) for your application and then on getting the most airflow through that area.

Building Your Own Headers

Building Your Own Headers
By O'Darrell Poole (c)

Over the years I have had many people ask me about building their own headers. Specifically what size and length of the primary tubes as well as the size and length of our collectors. In this article we will discuss the 4 most important design aspects of headers as well as explain some important points to remember. As stated there are 4 important aspects in proper headers design. They are in order of importance:

1) Primary Pipe Size:
The size of the primary pipe is the number #1 mistake we see in self designed as well as aftermarket headers. The size of the primary pipe should be the same diameter as the cylinder head valve throat, not the valve but the throat. Exhaust system effectiveness depends largely on maintaining gas velocities from the time the exhaust valve opens to the time it is deposited to the atmosphere. If for example your primary pipe size is to large (often the case because many believe bigger is better) and your exhaust valve throat diameter is one tubing size smaller than your primary tube size you have changed your gas velocity by roughly 20%. This change is gas velocity will affect the scavenging properties of your header because the pressure pulses (negative pressure) used to scavenge the cylinders will now come later in the exhaust stroke or even after the exhaust valve is closed.

2) Primary Pipe Length:
Determining the proper primary tubing length is extremely important to the timing of the pressure pulses used in scavenging the cylinders and ensuring fresh charge. If your primary pipe length is to short the pressure pulses may reverse so quickly that you may actually be forcing exhaust residue back into the cylinders. If your primary pipe length is to long then the pressure pulses will have no effect on scavenging because that negative pressure that we desire at TDC will happen well after TDC.

3) Collector Diameter:
Many believe and commit the same error here as they do with primary tube size. That is that bigger is better. The fact is that the collector has a bigger job that just merging the 4 or 3 pipes into 1 although this is one of its functions it also provides secondary scavenging characteristics for our headers. When the exhaust valve opens and sends spent exhaust gas down our primary tube and merges into our collector the pipe size difference between the primary and the collector causes a pressure wave reflection sending a negative pressure back up our primary pipe and assisting scavenging the pressure wave continues on past the primary pipe and into the collector when it emerges from the collector again it sends another wave reflection back up the primary pipe behind the first reflection and thus prolonging the scavenging effects and ensuring clean fresh charge is digested into our cylinders. Improper diameter will slow down exhaust gas velocities and thus delay the start of this secondary scavenging wave.

4) Collector Length:
Proper collector length is important in timing the secondary scavenging characteristics of our header. If the first 3 factors are correct the incorrect collector length (short) will cause our secondary reflection to be timed to close to the primary reflection and may allow for pressure to rise above atmospheric over TDC. If the length is to long then our secondary reflection may be too late in the stroke to be effective in assisting scavenging.

These are just a few of the important characteristic of effective exhaust system design a tuning. Stay tuned for more info on intake and exhaust systems in my future articles. We welcome your questions!!


O'Darrell Poole
Autocraft Dynamic Design Inc.
autocraftdynamicdesign@live.ca

AVOID Catastrophic Engine Failure

AVOID Catastrophic Engine Failure
By Don Terrill (c) - www.RacingSecrets.com

Have you ever noticed there are racers who have engine failures, one right after another? Then on the other hand, there are racers who never have any trouble, ever? Do you think it's luck?

Not hardly!

Here's how to be a member of group two:

(1) Mock-Up
I'm amazed how few people test fit engine parts before assembly. Getting home-assemblers to do it is like pulling teeth. For a freshen-up with just rings and bearings, a mock-up is probably not mandatory, but when assembling parts that have not been together before, a mock-up is required - at least once and maybe twice.

(2) Handle Every Part
When I say handle, I don't mean only once on a part's way to final assembly. I mean to handle every part multiple times and to actually look at the part. The next level of protection is to have multiple people look at each part.

(3) Measure Everything
And I mean E-V-E-R-Y-T-H-I-N-G. I've helped some friends assemble their own engines and it drives them crazy when I tell them what needs to be checked - one even went to the point of lying about what had, and had not, been checked. I quickly removed my name from that project.

(4) Trust No One
Picking up on the last point - don't trust that your parts were made correctly, machined correctly, assembled correctly or even cleaned correctly - no matter what they say - you'll be the one on the hook if it blows up.

Want to know the real key to keeping an engine together?
Take more time, a lot more time, to assemble it.

FYI - The photo above is a Ferrera valve that was caught during a freshen-up.

Airflow and Overlap

Airflow and Overlap
By Don Terrill (c) - www.RacingSecrets.com

"I pick up the .300, .400, .500 numbers and the car goes 1 tenth quicker!!!!!!!!!!! and the experts say no!"

I received this email from a racer who has spent his entire adult life trying to prove that mid-lift flow is the most important.

What I want to know is who is he arguing with? Who ever said picking up mid flow doesn't help?

The only lifts where you can MAYBE have too much flow is any lift where both valves are open at the same time - overlap.

My problem has been people saying the reason they focus on the mid numbers is because the valve spends more time there - it has to go through those lifts twice they say.

Sounds good, but when you do the math it's not true - it may go through there twice, but it doesn't spend much time there because it's the fastest part of the lobe.

If you look at upper lifts, the valve actually has to slow down, stop and change directions, which takes a lot of time.

Rule of Thumb:
Any increase in air flow, efficiently obtained, after overlap is good. Efficiently means highest cfm/sq.in. of port area.

Popular Racing Threads from the Past

Popular Racing Threads from the Past
By Don Terrill - www.RacingSecrets.com

Quench "flame channels" in piston vs. head quench
Port Vanes?
HONING procedure
DYNO Tails
two ring piston experience?
Valve/Rocker/Pushrod Geometry
Area under the curve
Guys I need some advise on bearings
How to tell if headers are too small?
Discussion: "Porting by Numbers" Darin Morgan
Widmer Terms
Merged Carb Spacers
Before/After grooved head pictures
Combustion Flame Speed
Squish ratio?
vein on the shortside of intake ports
If you could do anything to a cyl head?
pre-ignition / detonation(post ignition)
what do you guys think of this?
what do you guys think of this? Part II
wondering if there is a minimum port velocity
Exhaust back pressure power loss?
Valve angles
"well kept porting secret"
Calculating IFR/air bleed size on a Holley (long)
>100%VE
Funky airfoil in this intake bowl
Wideband Tuning for Carbureted Drag Racing
Larry's Soft Head
I wish Engine Masters would post BSFC numbers too
Experience With "Balanced Cams?"
pump gas/low compression/ high hp
Importance of Valve Events
help with switching to 0-30w oil
Flowing ports.....maybe we have it all wrong
Crank Twist: How Much?
fps question......

Crankshaft Torsion and Dampers

Crankshaft Torsion and Dampers
By William C. Sisco - Retired Damper Engineer from Metaldyne Inc.

Table of Contents:

1. Torsion - the hidden problem with the crank system – and why it needs a damper
2. Damper characteristics
3. Crank Variables
4. Other Rotating Group Parts
5. The damper – crank nose connection
6. Damper vs. Engine Application
7. Aftermarket R & D
8. Crankshaft bending vibration
9. The bottom line for the man on the street for aftermarket dampers
10. Testing and Validation

Download Complete Article (.pdf)

photo by apengineering

Racing Kool-Aid

Racing Kool-Aid
By Don Terrill (c) - www.RacingSecrets.com

Kool-Aid Drinkers - The term was coined in 1978 when 913 members of the People's Temple cult committed mass suicide on the direction of one man - Jim Jones. Today the term is used to describe anyone so committed to a position that they senselessly ignore the facts or any other viewpoint.

Areas where racers tend to drink the Kool-Aid:

(1) Coatings must be applied to every engine component - I hate to break it to you, but there are winning engines out there today that don't have a single coated component.

(2) Low component weight is crucial to making power - Yep, it's a move in the right direction, but the "weight" given to this variable is insane. There are much better areas to put your money to work.

(3) Rods and Pistons must balanced to a milligram - This is an easy one to knock down - Think about the carbon on top of pistons and oil clinging to parts during engine operation. How do you take into account for these variables?

(4) Grinding a crank makes it weaker - Actually, if the crank grinder knows what he's doing, he can actually make a crank stronger by increasing the corner radius while grinding the journals down.

(5) Spark Plug indexing is critical to making power - Anyone believing this needs to seriously look at the accuracy of their testing methods.

(6) Too much spring pressure breaks valves - The cam lobe design is what dictates how hard the valve impacts the valve seat, not spring pressure. Without enough spring pressure the valvetrain will not follow the lobe's closing ramp design and thus will increase the valve's impact speed.

(7) If an engine likes tight lash it needs more cam duration - Nope, it's quite possible the tighter lash decreased the intake valve closing bounce which in turn increased the engine's dynamic compression ratio.

(8) Grout will stiffen cylinder walls and seal leaks - The performance improvement of grout comes from how it changes the engine's cooling characteristics, not cylinder wall stiffening. As for grout's sealing ability, it has none.

(9) Lower viscosity oil makes more power - Not if you don't match it with a proper bearing clearance and oil temp.

The moral of the article? QUESTION EVERYTHING.

Horsepower Loss & what to do about it.

Horsepower Loss & what to do about it
by Don Terrill (c) - www.RacingSecrets.com

A large percentage of the energy in each gallon of gas is lost to friction and heat.

So, instead of looking at how to increase power, let's look at what's reducing it.

Frictional Losses

• Pistons - Optimization of the skirt design for your application can help minimize piston to cylinder wall friction, but if it comes at the expense of lost ring stability and sealing, it may not be worth it.
  
• Piston Rings - This area of friction has been beat to death by engine builders. Focus on the oil ring, it has the most room for improvement with the lowest risk. You can also work with the second ring, but you're flirting with disaster if you mess with the top ring.
  
• Bearings - First make sure you've got the correct bearing clearance for the oil you're using. Then you can look at risky stuff like journal diameter and bearing width.
  

For any of these frictional losses, the use of the correct weight synthetic oil will always help.

Heat Losses

• Combustion - Focus on optimizing your camshaft timing. This will put the heat from combustion to work moving the piston and not just passing out the exhaust system.
  

Aerodynamic Losses

• Crankshaft - We've all heard of knife-edging to make the counterweights more aerodynamic, but you can also cut down the counterweight diameter or even thin the counterweights. The use of heavy metal for balancing will allow more latitude for modification.
  
• Oiling System - Making items that swing inside the oil pan more aerodynamic may help slightly, but nothing beats just keeping the oil away from the engine components in the first place - A deeper oil pan, a dry-sump system, etc.
  

Pumping Losses

• Induction System - Improving the airflow of the induction system not only helps fill the cylinder, it lowers the amount of work required to pull in the air-fuel mixture.
  
• Compression - Turn your engine over by hand and you'll get the idea of the amount of work required to compress the air-fuel mixture. You could lower this with static compression and cam timing, but most of the time you'd lose more power than it would be worth.
  
• Exhaust System - Improving the efficiency of the exhaust system helps remove non-combustible gases from the chamber, but it also lowers the amount of work required to remove those gases.
  

Say What?

If you were going to design a rocket to go to the moon, you'd focus on the amount of thrust required to break the Earth's atmosphere, right? But why not look at what's keeping the rocket from going there without any help? Gravity, what if you could turn it off?

What crazy questions should racers be asking?

photo by lorentey

Choosing the Correct Headers

Choosing the Correct Headers
By Don Terrill (c) - www.RacingSecrets.com

Choosing the right Headers has as much to do with making more power as it does with where that power happens - at what RPM.

What needs to be decided and in what order:

1. Primary Diameter
2. Collector Diameter
3. Primary Length

Questions that need to be answered:

1. Engine Size - More cubic inches = more cfm required.
   
2. RPM - More rpm = more cfm required.
3. Application - For your type of racing, where do you want the power band?

Power Band Tuning: (general rules)

1. Larger primary diameter moves power band up, smaller down.
2. Larger collector diameter moves power band up, smaller down.
3. Longer primary length moves power band down, shorter up.
   

Industry Myth: You must have equal length primaries. This myth has been around for decades and is alive and well today. One of the major goals of equal length headers is to equally space exhaust pulses at the collector. The problem is the engine firing order is not taken into account. Let's look at the small block chevy.

Chevy Firing Order: 18436572
Gap between firings = 90',90',90',90',90',90',90' Crank Rotation

Now let's look at how the driver's side header sees the pulses.

Driver's Header Firing Order: 1357
Gap between firings = 270',180',90',180' Crank Rotation

Do you see the problem?

Do you still think every application needs equal length Headers?

Biggest header mistake: Leaky Header Gaskets - it's not just annoying, it can kill a noticeable amount of power.

Big Power - Focus where it matters

Big Power - Focus where it matters
By Don Terrill (c) - www.RacingSecrets.com

When trying to make more power, it's very easy to waste a bunch of time on things that don't matter. The following lists will help to focus your time and money - Do these first and then consider other areas. Rules may limit some of your options, but these are the biggies.

The Engine:

1. Power-Adders - Considered by many as the easy way out, but you can't deny the results of nitrous oxide, blowers and turbo chargers. In fact, HP per Dollar, nothing beats nitrous. I know many racers will have too much pride to consider power adders, but there's still no doubt their position for this list.
   
2. Engine size - Unless there was some really good reason, why would anyone build a 289 Ford, 327 Chevy or 396 Chevy? With the current price of aftermarket stroker crankshafts, there's no excuse for not building big.
   
3. Intake & Exhaust - Like the cliche' goes, an engine is just an air pump. So, anything we can do to increase the amount of air entering and leaving the cylinder is going to increase power. Follow the air path - hood, air cleaner, carb, intake, heads, headers, mufflers and tailpipes.
   
4. Compression - The need for better fuel and added load on engine components make this no free lunch, but there's no doubt the power potential of increased static compression.
   
5. Valve Events - The right camshaft and rocker ratios will maximize the amount of air that is compressed before combustion. Valve timing is half the equation in calculating dynamic compression (static compression and valve timing).
   

Now that you've got the power, don't waste it.

The Car:

1. Weight - Nothing lightens the load quicker than actually lightening the load. If rules permit, or there are no rules, why not choose the lightest car possible? You can also trim weight from your current car - start at the front of the vehicle and work your way back.
   
2. Hook - It doesn't matter if you're stock car racing or drag racing, all the horsepower in the world is worthless if you can't hook it.
   
3. Gear ratios - Every engine has an optimal rpm range - torque converters, transmissions and rear gear ratios can all be adjusted to keep an engine in that range.
   

So, if you're starting from scratch, why not build the biggest engine, put it in the lightest car and then bolt on your power-adder of choice?

Picking the Right Carburetor

Picking the Right Carburetor
By Don Terrill (c) - www.RacingSecrets.com

Comparing carburetors by their manufacturer's cfm ratings is the number one mistake racers make when picking a carburetor. In the old days it was easy - Holley was the only game in town. Today, with more competition has come more methods for rating carburetor air flow - It has become very hard to compare apples to apples.

I recommend that you don't even look at CFM numbers.

What needs to be decided and in what order:

1. Air Flow Path Dimensions - Venturi and Throttle Plate diameters
   
2. Type/Series - 4150, 4500 (Dominator), etc
   
3. Manufacturer - Holley, Barry Grant, etc
   
4. Linkage Style - Progressive, vacuum, 1:1, etc
   
5. Booster Style - Down Leg, Annular Discharge, etc

Number one on that list is by far the most important decision you will make.

Questions that need to be answered:

1. Engine Size - More cubic inches = more cfm (size) required.
   
2. RPM - More rpm = more cfm (size) required.
3. Application - Racing on limited tires and need to kill some lowend? Try a larger carburetor. Got'er hooked and need some more lowend? You got it, try a smaller carb.
   

Never, and I mean never: Loan or get rid of a good carburetor. They all have their own personality and some are just better than others.

7 Steps to Fuel Pump Care

FUEL PUMPS: HOW TO AVOID THE BLUNDERS THAT DESTROY THEM
Text & Images by Sam Moore

Today's most popular flow-through-style fuel pumps for performance vehicles are designed to support up to 750 horsepower. Though equipped with close-tolerance Gerotor-style gears (eccentric gears--one operating inside another like that of an oil pump) and an electric motor that's rated for continuous-duty, flow-through-style fuel pumps need to be installed and operated correctly to be reliable. To become thoroughly acquainted with their needs, here are the vital clues to keep your "Flow-through" pumping.

1- Flow-through-style fuel pumps are designed for use with unleaded and leaded gasoline. They cannot function with methanol.

2- Although the electric motor is cooled by fuel flowing around it, installing a heat sink in the system is advantageous because it dissipates heat. An 8" heat sink can reduce fuel temperatures by up to 90-degrees Fahrenheit. Consequently, fuel that's delivered to the engine is cooler and the pump is protected from the higher temperatures.

3- Always mount the pump close to the fuel tank or fuel cell on a solid frame member and position it level with or below the tank outlet. Never mount the pump in the driver's compartment or near moving parts or close to the exhaust or a rear differential. Do not allow the pump motor housing to make contact with any metal component of the vehicle.

4- From the fuel pump to the fuel cell or tank, use a minimum of -10 AN (5/8" bore) fuel hose. Connecting this hose to the existing fuel tank or cell may require rework: involving either the installation of a bulkhead fitting in the fuel tank to connect to the -10 hose or, better, the installation of a welded-in fuel tank sump complete with fittings. From the fuel pump to the EFI Bypass (fuel pressure regulator), use -8 (1/2" bore) fuel hose. Install a -6 (3/8" bore) return hose from the EFI Bypass to the fuel tank/cell. The internal fuel-return pipe (inside the fuel tank or cell) must also be of -6 dimensions and terminate at the bottom of the fuel cell in the front region of the tank. Under no circumstances should returning fuel be discharged above the fuel level. Discharging pressurized fuel into the cell above the fuel level will aerate the fuel and damage the pump. The openings of the 3/8" bore return pipe (inlet) and the 5/8" bore supply pipe (outlet), both of which reside inside the tank, should be positioned as far apart as possible to prevent aerated, hot fuel from entering the supply line. To vent the fuel tank or cell to atmosphere, use a -8 hose or equivalent with a minimum bore of 1/2". Install a small vent filter on the vent hose and terminate it such that it can neither become blocked with debris nor open to the ingress of water. Failure to adequately vent the fuel system will damage the pump. Route the fuel hoses such that they avoid all heat sources including the exhaust and rear differential.

5- A fuel pump, in common with other electrical accessories, performs best when provided with adequate voltage. Use 12-gauge wire to connect the battery to the relay; the relay to the pump, incorporating a fuse in the circuit to protect the pump from overload; and from the pump to ground. The pump MUST be grounded to a good chassis connection with a minimum of 12-gauge wire. Use an 18-gauge wire to activate the relay. All wiring circuits must be fused. Before making electrical connections, disconnect the battery.

6- When installing a new flow-through-style pump, fill the fuel tank and ensure that fuel is present at the inlet port of the pump before attempting to operate it. If the pump does not deliver fuel within 20 seconds, STOP and prime it: operating the pump in a dry condition will damage it. Before driving the vehicle, check the fuel pressure at the regulator with the engine running. Employ a dampened non-liquid-filled gauge. Liquid-filled gauges are affected by heat; consequently, their readings can be unreliable. Make certain that all fuel system components are leak-free before using your system.

7- Maintain the system by checking the fuel filter periodically. Also, check the braided steel lines occasionally by squeezing them with your hands as they can deteriorate from the inside. Checking fuel lines for soft spots can often identify internal degradation before lack of flow or pressure or the presence of debris in the system spells trouble.

www.BarryGrant.com

Thermal Mapping Engine Compartments

Thermal Mapping Engine Compartments
By Ron Severtson (c) 2006

Thermal mapping of engine compartments is critical to extending life of electrical and electronic components. Drop the temperature of these components by just twenty degrees Fahrenheit and you double their life. High underhood temperatures during races may present performance issues which disappear after the race. Let's take a closer look under our hoods for answers.

Carmakers spend much time and money locating underhood components for best longevity. Racers may ignore this when installing new parts and this can result in hard to diagnose failures. Intermittent problems may come and go as components heat cycle. Engine performance falls off. Critical time is wasted chasing hard to find causes.

An infrared, non-contact thermometer, can be used to check temperatures of specific underhood components. Heat crayons are available to check temperatures from one hundred degrees Fahrenheit to well over two thousand degrees Fahrenheit. Small stick-on paper dots responding to specific temperatures can also prove useful. Powerful, computer driven CFD temperature programs are just now entering the marketplace.

Underhood components must be checked under the highest temperatures they experience. For street driven vehicles drive for at least one hour under varying conditions. Race vehicles should be checked when underhood temperatures are at their highest. Dirt, mud, oil, and grease all affect underhood temperatures and should be considered in the equation.

Components which have failed or are running hot must be located to a cooler place. This may involve moving them outside of the engine compartment if rules allow. You need to consider the possibility of other adjacent parts running hot after you move a component. Heat sinks can be also be used to control excessive component temperature.

I use graphing paper to record underhood temperatures by assigning an inch value to each square, which corresponds to the size of the engine compartment. Let's say our engine compartment is forty five inches long and sixty inches wide. Making each square equal to three inches wide by three inches high our example would be twenty squares wide by fifteen squares long. Using a ruler and a contrasting pencil I outline this space on the graph paper. A tape measure is used to map positions of underhood components with respect to the graph paper. Respective components are drawn in very close to their relative positions in the engine compartment. Copies are made and used to record underhood component temperatures with precision.

Thermal mapping saves money and increases your chances of finishing races. Try this technique and you just may find yourself winning more races!

Pic by Idle Type

Measuring Rocker Rollout

Measuring Rocker Rollout
By Bill Jones (c)2006 - No Reprint

Here is how I measure rocker rollout.
--------------------------------------------------------------
-The one part that slips onto the top of the valve is like a "C" washer with a vertical stand of about 1-1/4" in height brazed at a 90 degree angle to the washer.

-After it is brazed I machine it so that the roller tip can push against one side and the horizontal dial indicator is centered directly out from the crown of the roller wheel.

-the vertically mounted dial indicator tip presses down with a light spring to sort of hold the C washer stand from tipping backwards as the roller tip moves to an open position where the vertical indicator tip then tries to tip the C washer stand over backwards.

-It takes a little help by hand to hold the C washer stand in place when you start approaching about .700" lift and continue up to an inch in lift.
---------------------------------------------------------------------------------
-this C washer stand is fairly complex to get it to fit in there and to get the indicator pressures to hold it in place---a little hard to get it machined nice and smooth etc.
----------------------------------------------------------------------------------
-the long bar was bolted to the valve cover rail---then the head was installed on my mill---tilted to the get the exhaust valve straight up---then I machined a slot to allow a mounting place for the dual dial indicator mount and a mounting hole was drilled and tapped.

-this was done four places so that all cylinders can be checked.

-After figuring out he mount and fabricating the mount and the C washer stand---getting to where I could actually check the exhaust----I then did the same procedure to get mounting positions on the long square bar for the intake.

-Then I had to make an intermediate attachment extension so I could use the same dual indicator mount to check the intake.
--------------------------------------------------------------------------------
-an example of what this shows me is:

1-I ran the valve open to 1.000" lift and recorded the roller tip roll starting with the horizontal dial indicator at zero with .100" preload----and with the vertical dial indicator at zero with 1.020" preload to measure the valve lift.

2-I opened the valve in .100" increments to 1.000" and checked and recorded the roll out and roll back in which started at zero and rolled out a maximum of about .093".

3-here is a chart of the results----all numbers are OUT from zero lift unless noted with a - sign

valve ---roll out/in---
lift---------int--------exh
.000"-----.000"-----.000"
.100"-----.031"-----.031"
.200"-----.054"-----.054"
.300"-----.071"-----.073"
.400"-----.083"-----.085"
.500"-----.089"-----.091"
.600"-----.090"-----.093"
.700"-----.080"-----.079"
.800"-----.050"-----.051"
.900"-----.028"-----.031"
1.000"----.002-"----.005"

4-This is with a light valve spring holding the valve closed and operating the rocker by hand---no shims were under the rocker stands.

5-Application will be using about a maximum net lift of .940" (raceready---after valve lash) on the intake and about .918" on the exhaust.

-cam is to be .520" intake lobe lift and .510" exhaust lobe lift with 1.85 rockers on both.

-The .940 x .918 lift numbers do NOT account for any lost of lift due to the elasticity of the metals.

6-Now that the tool is built I can get serious and measure the REAL rollout and get it adjusted with rocker stand shims with the racing valve springs installed.

Bill's other articles

Carburetor Entry Epoxy

Carburetor Entry Epoxy
By Bill Jones (c)2006 - No Reprint

780 carburetor epoxied to help the air get into the throats.
---------------------------------------------------------
-Photo shows an angle drilled hole that intersects the air filter stud hole---this is drilled clear thru with a .265" drill bit----and the air filter stud is tapped way deep so that the air filter stud can be used to close off the angled hole.

-This allows an alterative method of getting some extra idle air without having to open the throttles or drill holes in the blades.

-The setscrew that's in the air filter stud hole is just to show how the lower sectionof the threads are to be closed off.
--------------------------------------------------------------
-the downleg boosters have the center holes enlarged and the underside of the booster has been machined with a step.

-JB Weld epoxy is applied at the booster to main body joint to help secure the boosters which have been swedged from the meter block side.
--------------------------------------------------------------------
-The original slanted top vent stacks have been discarded----then the holes have been reamed to 5/16" all the way down into the rectangular intersecting vent.

-The bottom of the vent tubes shown are slotted and split so that the bottom 3/16" can be spread apart and locked within that rectangle vent cavity---so that there is NO possibility of the vent stacks ever coming out and down thru an engine.
--------------------------------------------------------------------
-I flowtested this carburetor during a series of modifications as follows:

TEST# / CFM
1- 687.9------initial test on a 2" open hole spacer, no airfilter, no choke blade or shaft but still had the choke horn.

2- 701.0-------only change was to a 2" tall 4 hole spacer with bottom blended to reduce turbulence.
691.8 -same with a new 4" x 14" K&N on a dropped base with a normal chrome lid.
662.9-same but exchanged to a dirty 3" x 14" K&N---1-9/16" from top of element to the carbs gasket circle.

(all subsequent tests shown below are based off the three sections of the #2 test but with each new modification)

3- 702.6-------removed the choke horn
697.9 -4" K&N
684.4-dirty 3" K&N filter.

4- 714.6-------installed correct length button head screws.
712.0 -4" K&N
692.9-dirty 3x14 filter.

5- 736.3-------epoxy the top area as show inb the photos.
719.9 -4" K&N
707.2-dirty 3" K&N

6- 752.8--------machine just the primary throttle shaft to .085" thick with correct length screws and fluff & buff the bores
736.7 -4" K&N
720.2-dirty 3" K&N

7- 755.2--------smooth up the secondary SHAFT and throttle bore slightly, no filter.

8- 761.2--------epoxy two corner areas of the secondary throttle bores that were for PCV use.

9- 774.0--------blend the 4 throttle bores of the main carburetor body, remove the casting lines at venturis & polish.

10- 779.7--------final-assembled race ready with careful attention at the main body to baseplate gasket.
771.3 -4" K&N
750.9-dirty 3" K&N

11. 68.4--------changed back to the 2" tall open hole spacer used in test #1
754.5 -4" K&N
739.0-dirty 3" K&N

-flowtesting the carburetor naked and with the two different filters shows that airfilters definetly cost flow---and that there is airflow to be had with attention to details.

Bill's other articles

FAILURE ANALYSIS

FAILURE ANALYSIS
By Keith Morganstein
www.maxeffortengines.com

A Failure Analysis program helps you determine why things fail and how to prevent them from happening again. The eight step program outlined below is borrowed from the diesel and earthmoving industry. This type of "closed loop failure analysis program" has been a key to success in a very tough working environment. The science behind this program is rock solid and can be easily implemented by racing teams and engine builders.

These are the steps to the program:

Step 1) Identify the problem - identify the failed components and observable symptoms. This may include unusual wear, fractures or deformed parts. Noises, odors, colors etc...

Step 2) Gather facts - examine everything carefully including all related and connected parts or components. AVOID PRECONCEIVED IDEAS about the failure. JUST COLLECT THE FACTS. Determine type of fracture (i.e. brittle, ductile) or type of wear etc... Use available resources to identify the type of fracture or wear to avoid guessing.

Step 3) Collect and record the facts - Be accurate, record everything, take photos, write down measurements, and review service records. Document everything.

Step 4) Think logically and identify all the events of the failure - Relate the facts to the events of the failure.

Step 5) Identify the most probable ROOT CAUSE of the problem - By ESTABLISHING A TIMELINE OF THE EVENTS, using the concept of "good to bad", establish this timeline of events. Some events may overlap. When all events are correctly laid out on the timeline, you will see the sequence with one event leading to another. From cause to failure.

Step 6) Communicate with the responsible party - This will help with corrective action and may reveal important circumstances affecting it.

Step 7) Make repairs as directed - Use your timeline analysis to repair the root cause of the problem and to prevent the problem from recurring.

Step 8) Follow up - Set a schedule for follow up to be sure your corrective action fixed the problem.

Picking the Right Camshaft

Picking the Right Camshaft
By Don Terrill (c)2006

What needs to be decided and in what order:

1. Lobe Family - This is a group of lobes that have similar open/close ramps, but different durations. I truly believe the smartest thing Comp Cams every did was publish lobe specs in the back of their catalog - it instantly made me a fan.
   
2. Intake Duration - If I had never run a Spin-Tron this would be my number one. Get intake duration and lobe family correct and you're 90% there.
   
3. Exhaust Duration - This maybe number three on the list, but is actually a long way from the importance of the first two.
   
4. Lobe Separation - Take every lobe separation you've ever seen run with your application, place them on a dart board, close your eyes and throw. That's how relatively important this spec is.

Before I continue I want to talk about something I've noticed on most message boards - whenever someone mentions that something is not important, they are immediately hammered with "Yes it is!!!" Don't let these people stop you from practicing the 80/20 principle.

Questions that need to be answered:

• Engine Size - Use to pick durations.
  
• RPM Range - Use to pick durations.
  
• Rocker Ratio - Use to pick lobe family and durations.
  
• Valvetrain Weight - Use to pick lobe family.
• Valve Springs - Use to pick lobe family.
• Exhaust Flow - Use to finalize exhaust duration
  

Questions that only need to be answered when you're trying to look smart:

• Cylinder Heads
• Runner CCs
• Intake Manifold
• Compression
• Valve Size
• Header Size
• And on and on and on...

That fact is, even if you're trying to set a nation record, those questions don't need to be answered. Dyno and track testing will be the only way to get the perfect cam. The goal is to get in the ballpark and adjust from there.

And finally, the following question only needs to be answered when you're trying to look stupid:

• Tire Size - If you don't find this funny, you haven't called many cam companies.
  

Want to send off a nasty email about how wrong I am? Well, first read this and then write your own article.

The Secret to Airflow

The Secret to Airflow
Luke Wickman - Performance Cylinder Head Specialist
Staab Machine Inc.

Know your opponent. A common misconception people have, is that air flows like water. Sort of, but not quite. Imagine if you will, that the air molecule is like a tiny ball bearing. It rolls over smooth surfaces, skips over gaps, and bounces when it hits a wall. Now imagine billions of these tiny bastards. They don't just flow in one direction at one speed, they fill in the inconsistancies in your port and slow or come to a stop, while the air with less resistance flows over it. Often this air will be pushed up higher in the port and skip over the quick turn, only effectively utilizing part of the valve. The key to maximizing the potential of a port, is to straighten the air out so that the velocity is even on all 360 degrees of the valve face. On some ports this is easier than others. I build heads for diesel pulling tractors, and they all have swirl ports. Do you want to talk about pulling your hair out? They are the most difficult heads to master, but I have a trick. I don't like to give away my secrets, but I'll give you a clue, you have to tilt the port in the direction of the swirl. Porting is an artform. It's like sculpting with a die grinder. 80% of people can do it, but the results are ummm.... not guaranteed. 15% spent enough time doing it to produce professional results, and then there are the final 5% of us that can actually SEE the airflow. See the resistance, and produce masterpieces that outflow the competition and win championships. A great cylinder head is a compilation of many factors. Ports that not only flow, but flow at a proper precentage of split between the intake and exhaust to optimize the amount of lift and duration possible with your cam. Valves that are lightweight, and springs that produce an amount of pressure capable of closing your valves without floating them at the RPM range your power band lives at. Then a valve job of exacting tolerances so it survive, and you have a winning head combination.

Baseline Power

Baseline Power
By Don Terrill (c)2006

At the core of every racer is a deep desire to constantly improve performance. This desire, while responsible for many successes, can also lead to unnecessary failures.

Sometimes the application just doesn't call for the most power - In that case, fall back on what you know works:

• YOUR baseline Combination
• YOUR baseline Camshaft
• YOUR baseline Cylinder Head
• YOUR baseline Carburetor
• YOUR baseline Tuneup

I know what you're going to say, if I don't try new things, how will I ever make more power? Well, for many/most applications you don't need more power, for example:

• Bracket Racing - There are advantages to leaving last and chasing, but in the end, it's the driver with the best package that wins, and that has nothing to do with how fast the car is.
  
• Short Track Stock Car Racing - The majority of local stock cars have more power than they'll ever need - Read my article on getting back to the throttle.
  

These two applications combine to make up 90% of engines built.

I did some port work for a bracket guy recently - on a combination I hadn't work on in years. I did the port work and then talked him into letting me pick out the cam. I selected a cam that has been around for decades - a cam that has worked in everything I've put it in. Everything I know about cams tells me I can do better, but the majority of times I veered away from it, I lost power. After running all season the engine finally made it to the dyno - It beat expectations.

I'm a real believer in combinations. Like I've always said, there are a 1,000 ways to make (x) horsepower, choose one - Choose one YOU know works.

If you haven't been at it long enough to have baselines, keep at it, you will. And remember, sometimes we just need to leave a good thing alone.

Think I'm out to lunch? Fine, write your own article

The Engine Building Davinci Code

The Engine Building Davinci Code
By Don Terrill (c)2005

It's there, written into every sanctioning body rule book, clues to the Holy Grail of horsepower. The clues are not encoded or hidden, they are in plain sight - you just need to ask the right questions:

1. Why did they feel the need to write this rule?
2. What did a racer do to prompt this rule change?
3. How can I "legally" apply this to my form of racing?

Here's an excerpt from the Formula 1 rule book - look for the clues.

• 5.1.5 Only reciprocating poppet valves are permitted.
• 5.1.5 The sealing interface between the moving valve component and the stationary engine component must be circular.
• 5.6.1 Variable geometry inlet systems are not permitted.
• 5.6.2 Variable geometry exhaust systems are not permitted.
• 5.8.1 Ignition is only permitted by means of a single ignition coil and single spark plug per cylinder. The use of plasma, laser or other high frequency ignition techniques is forbidden.
• 5.8.2 Only conventional spark plugs that function by high tension electrical discharge across an exposed gap are permitted.
• 5.9 Engine actuators : With the following exceptions hydraulic, pneumatic or electronic actuation is forbidden : a) Electronic solenoids uniquely for the control of engine fluids ; b) Components providing controlled pressure air for a pneumatic valve system ; c) A single actuator to operate the throttle system of the engine.
• 5.10 With the exception of electrical fuel pumps engine auxiliaries must be mechanically driven directly from the engine with a fixed speed ratio to the crankshaft.
• 5.11.1 Other than injection of fuel for the normal purpose of combustion in the engine, any device, system, procedure, construction or design the purpose or effect of which is any decrease in the temperature of the engine intake air is forbidden.
• 5.11.2 Other than engine sump breather gases and fuel for the normal purpose of combustion in the engine, the spraying of any substance into the engine intake air is forbidden.

I recommend you read every motorsports rule book you get your hands on, and not just sanctioning bodies you plan on running, but every form of racing.

Don't Blame the Rod Bolt

Don't Blame the Rod Bolt
By Don Terrill (c)2005

I feel sorry for the poor little rod bolt - it's been wrongly accused of failure more than any other part in the engine.

My eyes roll back into my head every time I hear; "Blew up my engine last weekend - broke a rod bolt." Then they go on about rumors of a bad batch of rod bolts and how they hope to get the rod manufacture to pay for their engine.

Forget about bolts breaking for no reason - it doesn't happen.

Here are the reasons:

1. Spun bearings - which starts a chain of events that lead to bolt breakage.
   
2. Improperly torqued rod bolts
   

No one tip can be given to stop spun bearings, but to stop improperly torqued rod bolts is easy and requires only one thing - A rod bolt stretch gauge. Here's how to use it. Stretch method:

1. Install the rod cap and snug both bolts/nuts
2. Completely loosen one bolt/nut - must spin freely
3. Check length of bolt with gauge
   
4. Torque to manufacturer's spec
5. Recheck length of bolt
6. Tighten bolt/nut until desired stretch is reached

You may ask, why use a torque wrench for step number 4? One; it's a great little test to see how short on stretch you'd be had you used the torque wrench only, and two; it can be used to see if bolts have been stretched too many times - If torquing the bolts to the manufacturer's spec yields a stretch greater than specified, you may have a problem. I usually see bolts 30-40 percent short on stretch when torqued to the manufacturer's spec. Typically bolts require .006" of stretch, but only obtain .004" when fastened with a torque wrench - no matter what lube is used.

Do you have any idea how much clamping force is lost with just .002" less stretch? A ton.

So, the next time you see a broken rod bolt, don't call the rod manufacturer, ask who torqued the bolt.

Engine assembly tips:
http://racingsecrets.com/racing_engines.shtml
http://speedtalk.com/engine_building_dvd.html

10 Power Plays

10 Power Plays
By Don Terrill (c)2005

1) Mix fuel - At the very least you should test cutting your race fuel with unleaded (pump or race). At the most, well, things can get pretty scary.

2) Flush with cold water - Old, old, old drag race tip that still works today. There's predictable power in having the top of the engine cold and the bottom hot. So, hot lap the car a few times and then ice it with cold water - works every time.

3) Ice intake manifold - Take it one step further, place ice bags on the intake manifold before the run.

4) Drain a quart of oil - Another one of those tips that works every time, well, right up to the point where the engine blows up. Just kidding. The fact is; 99% of engines are running with too much oil. Test it one day at the track - make a couple passes, drain a quart of oil and try it again. Yep, works every time.

5) Cut the rear-end gear lube with trans fluid - Mix it 50/50. This won't help gear longevity, but hey, it will give you more opportunities to test different ratios. Want to really push it, only run the rear with one quart of lube.

6) Use synthetic lubes - Everyone knows the engine oil, but what about the trans, rear-end and wheel bearings?

7) Heat lubes - Even synthetic lubes can benefit from some extra heat. Though you can get some heat by just driving the car, the amount of heat needed usually requires some electrical help.

8) Cool induction air - We all know how important the weather is to engine performance, especially the temperature, but there are other ways to lower the air temp being fed to the engine. You can try a hood scoop, cowl hood or cold air kit. Even something like the color of the hood can effect under hood air temperature.

9) Pressurize induction air - Some of the same things that can cool the air can also pressurize it. If you're using a hood scoop, make sure it seals perfectly to the carb.

10) More launch rpm - Doesn't always work, but many cars can benefit from putting your foot in the throttle on the starting line. If it doesn't work, you may want to look at your power curve or suspension.

Back to the Throttle

Back to the Throttle
By Don Terrill (c)2005

"I can build more power than you can hook."
---Stock Car Engine Builder

"Nope, I can hook anything you can build."
---Car Owner, Driver & Crew Chief

I've had this exchange at least a dozen times. How often have I been successful at convincing them to build less? Never. How often were they right to build more? Never. Maybe it's just the short tracks here in Michigan, but building too much power for these tracks is easy.

How do I know? I ask the driver one question; "At what point on the track are you at full throttle?" When I hear; "The Flagstand" I know they have WAY TOO MUCH power.

Maybe it's just my drag racing roots, but to me it looks like the first one back to the throttle wins. In the end, I guess it's who has the most usable power, or maybe who knows how to use their power the best.

What is usable power? Not one single horsepower more than the track can handle at any given point on the track. Now, if the driver were a computer he could easily have perfect throttle position at all times. For a human this is impossible, and the more over-powered the engine becomes, the slower the driver will be.

Building usable power: To me it's all about building less power at low rpm and more up top.

• Less cubic inches - Everything being the same, less cubes means less power, but more importantly, a power curve that moves up.
  
• Bigger/Better heads - Better heads typically make the majority of their extra power up stairs. For example; The Chevy SB2 head will move the torque peak up 500-600 rpm when compared to 18 degree head - which is no slouch.
  
• Bigger/Better intakes - Not as dramatic as cylinder heads, but still a move in the right direction. In fact, I think the intake is a great tuning aid for short track racing.
  
• More camshaft - By more I mean more duration. This will soften the engine down low and help it breath up stairs. Perfect!
  
• Less compression - Typically more compression means more power everywhere, but if the increased compression comes in the form of a big dome, it may help more at low rpm than high. Not what we want.
  
• Bigger/Shorter headers - Can act the same as an intake manifold change. Another nice tuning aid.
  

A combination I'd like to see racers try: 300 cubic inches with SB2 heads and 9 to 1 compression.

What I see built too often: 377 (or more) cubes, 23 degree heads and 13.5 to 1 compression.

A good combo that is being used today: 355 cubic inches, 18 degree heads and 9 to 1 compression. Not bad, but if they would step up to the better heads they would see a dramatic shift in their torque curves - one for the better.

Of course, none of this advice is needed if you're running a sophisticated traction control system. In that case, the driver is a computer. That's for another article though.

Starting a New Engine

Starting a New Engine
By Don Terrill (c)2005

Nothing is more nerve-racking than starting an engine for the first time. Here are some tips and reminders for getting it right:

Prime the oil pump - It's best to do it right before startup, but anything is better than nothing - even if you just pull the coil wire and crank it (assuming you're not breaking-in a flat tappet cam).

Set the lash - I recommend setting the lash on the tight side for startup. Given the low rpm it probably doesn't matter, but it is a move in the right direction.

Set the distributor - This is where many racers have problems. Here are two methods I use:

• Rotor location - Turn the crank to 30+ degrees before TDC on the compression stroke of cylinder number one and install the distributor so the rotor points to number one plug wire on the cap. For more accuracy, consider any mechanical/vacuum advance the distributor may add at startup, and which edge of the rotor tip actually does the firing - usually it's the trailing.
  
• Spark - The method above should work like a charm, but for a little more assurance you can pull the number one plug wire off at the spark plug, loosen the distributor so it moves easily, install a spare plug in the end of the wire, ground the plug by putting the threads or ground strap in contact with grounded metal on the car, turn the ignition on and then quickly turn the distributor back and forth with your hand to find the exact point where the spark happens.
  

Crank extra timing in it - Everyone wants to be safe when they start a new engine, which leads many to starting with little or no ignition advance - which leads to hot exhaust valves and glowing headers. Don't be afraid to run more than normal - with little or no load, or rpm; nothing bad can happen.

Double check the plug wires - Want a sure way to set your hair on fire? Just mess up the plug wires and put your face over the carb as the engine is cranked. If that doesn't sound like fun, give the wires one last look-over right before startup.

Use a known carburetor - This is no time to be trouble-shooting a carburetor. If you have any trouble getting the engine to start, you can rule out the carb since you used one of known quality.

Check fluids - Not many people miss the oil, but I have seen the aftermath of engines run without coolant - not pretty.

Funny observation: Have you ever noticed how many people show up to watch a new engine being started? I swear, men have a sixth sense that tells them when someone is about to start an engine, and they show up in mass. I've joked I was going to set up a grandstand and start charging for admission. Is it me or have you noticed the same thing? My advice: Don't tell anyone when you plan on starting your engine. Let the peanut-gallery go to the theatre where they belong.

Tips for tuning after start up...