Stock engine basics

[Danpa]

I have always been amazed at the amount of horsepower Stock Eliminator racers have been able to extract from their cars. I would think that the engines must be extremely efficient, squeezing the last bit of hp from every drop of fuel.
My question is, what do you guys do to the engines to make them run so strong on seemingly mundane parts?
I realize some basics like fully balanced rotating assembly and cc' ing the heads would help, but what else?
I'd like to apply some of the things to my street engine when I rebuild it.

Thanks,

Dan

[X-TECH MAN]

Originally Posted by Danpa

I have always been amazed at the amount of horsepower Stock Eliminator racers have been able to extract from their cars. I would think that the engines must be extremely efficient, squeezing the last bit of hp from every drop of fuel.
My question is, what do you guys do to the engines to make them run so strong on seemingly mundane parts?
I realize some basics like fully balanced rotating assembly and cc' ing the heads would help, but what else?
I'd like to apply some of the things to my street engine when I rebuild it.

Thanks,

Dan

I know you are looking for a somewhat honest answer here but I will leave that for another to answer. A lot of the combos are....shall we say "Enhanced" to the limit and in a lot of cases beyond. They would make a poor STREET engine. The cams are way to radical, the spring pressures are way to high and the piston rings would not seal for very long in everyday street use. Not to mention the operating range (RPM's) they are twisted to with 5.13-5:38 and up rear gearing. You would not be happy with this type of rear gearing in an everyday street car. Its a combination of precision machine work, careful assembly, and picking the right combo to begin with. On the street you are stuck with pump gas (no lead) and lower compression ratio's. Use a stroker kit for your brand of engine and go for torque to run on todays junk gas and you will be happier for it. If you want to fool your buddies just make the engine "LOOK" stock on the outside.

[Gary Smith]

Originally Posted by Danpa

I have always been amazed at the amount of horsepower Stock Eliminator racers have been able to extract from their cars. I would think that the engines must be extremely efficient, squeezing the last bit of hp from every drop of fuel.
My question is, what do you guys do to the engines to make them run so strong on seemingly mundane parts?
I realize some basics like fully balanced rotating assembly and cc' ing the heads would help, but what else?
I'd like to apply some of the things to my street engine when I rebuild it.

Thanks,

Dan

Very valid and good question. Probably the most important is NEVER overlook details. The factories have so many imperfections in some of the smallest areas where improvements can yield some surprising results. Also, remember the car itself. There are many areas where you can improve performance in suspension, weight transfer, and hp robbing rotating weight.

I was talking to another racer yesterday about the very same subject. Too many racers looking to go fast fail to look at the most basic areas. I'm sure there will be others that chime in on this subject and should offer some interesting answers.

[jmcarter]

X-TECH MAN is right on, for the street it's hard to beat stroker motors that remain pump gas friendly. Correct clearances, file your ring end gaps, etc. are essential and let a good shop bore/hone your block. Also, given the tighter convertors (you do NOT want a "stocker" convertor on the street any more than you want 5:13's) cam selection is absolutely critical. Don't catalog shop, talk to one of the reputable cam makers and tailor the cam to your combo. Finally, get all the weight out of your car that's practical, it pays dividends in every area of car performance.

P.S. Crate motors are a pretty good deal but again selection is key and cubic inches rule. If you decide to go crate motor then start a new thread soliciting feedback, there is a wealth of knowledge on this forum. Also helpful to indicate your current car/motor. Every make has it's own following.

[Gary Smith]

Originally Posted by X-TECH MAN

I know you are looking for a somewhat honest answer here but I will leave that for another to answer. A lot of the combos are....shall we say "Enhanced" to the limit and in a lot of cases beyond. They would make a poor STREET engine. The cams are way to radical, the spring pressures are way to high and the piston rings would not seal for very long in everyday street use. Not to mention the operating range (RPM's) they are twisted to with 5.13-5:38 and up rear gearing. You would not be happy with this type of rear gearing in an everyday street car. Its a combination of precision machine work, careful assembly, and picking the right combo to begin with. On the street you are stuck with pump gas (no lead) and lower compression ratio's. Use a stroker kit for your brand of engine and go for torque to run on todays junk gas and you will be happier for it. If you want to fool your buddies just make the engine "LOOK" stock on the outside.

I think what he's looking for is how to apply some Stock Eliminator technology to a street engine, not building a class motor for the street per-se. There are a lot of good practices to get in the habit of doing when prepping a motor. Many are no nonsense basics that are often overlooked. When I was in tech school 30 years ago we took a tired Olds 350 that was burning coolant and oil past the rings and guides. While other students completed rebuilds on their projects much quicker than my group, we simply took the time to ensure everything was matched, head cc's were the same, proper clearances, tightly sealed chambers, etc. The result was a tire frying engine that certainly produced more power than it did from the factory, with no aftermarket parts whatsoever.

[Alan Roehrich]

What few people understand is that most Stock Eliminator cars are not fast just because of the engine. It's the entire car, and all the tuning and work that goes with it. The engine is important, don't get me wrong.

Most people can't take around 600HP in a 3300# car and run 9.90 with it in good air.

[Danpa]

Thanks so much for the responses! I feel I understand the class a little better now, much more going on behind the scenes than I realized. There is definately a lot more to it than a common weekend bracket car.

Some of the things that I'm planning for my motor are;

1.) balance the rotating assembly
2.) cc the heads
3.) port the heads, working to improve flow and velocity instead of just hogging out the ports.
4.) keeping the stock size valves or maybe a slight increase, again for velocity.
5.) 3 angle valve job
6.) match port everything
7.) keeping the stock carb (maybe??? don't know yet)
8.) headers, small tube
9.) stock compression

Just trying to make it the most efficient, make decent power without killing gas mileage.

What do you think? Am I on the right track? Missing anything obvious?

A few questions, though.

Does an increase in overlap work the same as higher lift on the cam. If it does, I guess you guys are limited on your lift, so you acomplish the same thing with overlap. Am I kind of right or COMPLETELY wrong?
Also, does an increase benefit torque or top end?

Again, thanks for everybodys patience with a new guy.

Dan

[Larry Hill]

Dan you can do all of your list and pick up power, remember hard smart work is what it takes. OR.....................

You can do what Mr. Bill did and get Shelby to change all the spec. 20 years later.

Most S/SS racers work very hard to use the power they make to turn the wheels.

[Alan Roehrich]

Dan,
Stock cams not only have a lot more duration and overlap than you'd want, but also a lot more aggressive lobe profile than you'd want in a street flat tappet cam.

Attention to detail is what makes Stock engines run.

Honestly, using a set of aftermarket heads with modern ports and combustion chambers will get you years ahead of what we're working with to make these older heaps go fast. The same thing with pistons, more efficient dish/dome profiles, better skirts, and better ring packages will be a lot cheaper and work better than what we run.

What you need to take away from the typical Stock program is the attention to detail and the blueprinting that allows us to make the most of the limited stuff we have. The use of torque plates, the perfect hone finish, the blueprinted locations of the deck, the main bearing bores, the lifter bores, the cylinder bores, and the exacting tolerances and clearances.

[Richard Grant]

Good answer, Alan