602 GM Crate vs. Built Engine

[IMCADW]

IMCA Made a clarification in the newsletter last year about crankshafts being lightened.

Yeah, I've seen some weird stuff in tech. My gas ported stuff never had a problem passing. It makes you wonder.

[rustbucket79]

If you build an engine outside the rules and win, what was the challenge? More importantly, most every oval track rule book I've read states something like "within the spirit of the rules" and building a cheating engine is a complete contradiction of that rule.

Does anyone ever stop and think that the crate engine stronghold might not have ever happened if everyone had followed the rulebook rather than building these exotic engines for budget classes?

Our local rules are even stricter than what's been posted, and there's no cheating because the engine is thoroughly inspected, assembled, and sealed with 2 track techs.

[Brian W]

In every form of racing, there are two types of racers... those that have been caught cheating and those that have not!!
everybody cheats to some extent... thats what we call the grey area. If your not pushing the rules your getting beat because the guy that just passed you is pushing the rules, somewhere, on some part of the car. And that's a good thing, other wise we would still be racing model T engines or horses for that matter..!

If the track techs seal the engines then somebody will just make there own seals... and around and around we go. Look at NASCAR teams get caught cheating all the time, and NASCAR has a really strict tech inspection. A strict tech inspection takes alot of very smart Tech inspectors and costs alot of $$. Guess what, there is still stuff running on the track every Sunday that is not legal, and has not been caught... yet. No dirt track can police the cars like that, so that just opens the door a little more.

[raceman14]

OK, just so I get it straight...The engine the post is about is an IMCA engine built -v- 602 chevy.
When I looked at the rules it stated the built engine could run a 4412 where did the Rochester come in at ???

I also asked about testing the 602 with at least a 650hp 4bbl cause I know they can make 375-400RWHP in a dirt car with a 2" spacer and good headers. That number is down about 50-75RWHP to a good GM604 crate, and they are down about 50HP to a decent 4412 2bbl built engine around here.

Did you ever say what the lobe separation and installed Intake CL was on the cam???

I would say rather than argue what parts cost and the weight of a crankshaft if it is 45# or 50# that would not contribute significantly to the HP output as much as a proper camshaft, carb combination and proper fuel selection for the acceleration rate of the engine.

Fuel selection to an engine is as important as tire selection to a chassis... get the combination right and you can pick up 1/2 to 1 sec. easily.

My first question to any engine, carb, cam, chassis dyno customer is What are your fuel rules and what fuel do you run ??? It is the basis for all other testing and modifications.

I just did a carb and distributor + treated stock GM Valve Springsfor a guy in NY and his fuel is Environment Friendly VP98 for a GM 602 Crate. Switching from Sunoco 100 Unleaded made that combination almost -57HP just swapping fuel for initial baselilne runs. The car was not lean or rich it just was not burning the new VP98 just right. I first started working with the distributor and the timing curve, when and how fast it came in. It took 6 pulls @$15ea to pick up 11RWHP. Now the engine was starting to come to life but was showing some signs of early detonation via the Katech Block Knock sensors which are Ultrasonic micro sensors that pick up noise in the water thru the freeze plugs.

Retarding the timing back from 36* to 34* gained power, dropping to 32* lost so I stopped at 33*. Next I went to the fuel curve as it was now time to hit that and I went lean to start and engine did not like it even though it was showing rich. Took about 12 pulls to get the carb right and changed jets a couple times, power valves, and accelerator squiters and picked up 21RWHP. Changed the plugs to a slower burn retracted tip and picked up +9rwhp and called it a day. At the end of the day I installed a new set of springs on my mule engine as they had about 500 pulls on the old ones and they needed re-treating and that netted 16RWHP and +400rpms on the top end of the pull to 6700rpms.

Shipped the parts out Next day air today and he should be at practice on Thursday with new stuff in his car. Total cost on that program was about $850 including the shipping = about $15 per HP. Does it cost a lot??? I am not sure, how and where would he have ever found +57RWHP using his stock parts. He did not have to buy a new carb or dizzy, he just had to get his old stuff re-programmed to the new fuel. He sent the stuff to me this year because I did the same thing for him last year when he switched from Sunoco 110 Leaded to the Sunoco 100 Unleaded. Many tracks are changing for insurance and environmental reasons as leaded fuel contaminates the Air & the water table and EPA and insurance companies are into the "green" changes in racing cause NASCAR is doing it.

Just my way of doing things for the last 25 years.

[Brian W]

OK, just so I get it straight...The engine the post is about is an IMCA engine built -v- 602 chevy.
When I looked at the rules it stated the built engine could run a 4412 where did the Rochester come in at ???

I also asked about testing the 602 with at least a 650hp 4bbl cause I know they can make 375-400RWHP in a dirt car with a 2" spacer and good headers. That number is down about 50-75RWHP to a good GM604 crate, and they are down about 50HP to a decent 4412 2bbl built engine around here.

Did you ever say what the lobe separation and installed Intake CL was on the cam???

I would say rather than argue what parts cost and the weight of a crankshaft if it is 45# or 50# that would not contribute significantly to the HP output as much as a proper camshaft, carb combination and proper fuel selection for the acceleration rate of the engine.

Fuel selection to an engine is as important as tire selection to a chassis... get the combination right and you can pick up 1/2 to 1 sec. easily.

My first question to any engine, carb, cam, chassis dyno customer is What are your fuel rules and what fuel do you run ??? It is the basis for all other testing and modifications.

I just did a carb and distributor + treated stock GM Valve Springsfor a guy in NY and his fuel is Environment Friendly VP98 for a GM 602 Crate. Switching from Sunoco 100 Unleaded made that combination almost -57HP just swapping fuel for initial baselilne runs. The car was not lean or rich it just was not burning the new VP98 just right. I first started working with the distributor and the timing curve, when and how fast it came in. It took 6 pulls @$15ea to pick up 11RWHP. Now the engine was starting to come to life but was showing some signs of early detonation via the Katech Block Knock sensors which are Ultrasonic micro sensors that pick up noise in the water thru the freeze plugs.

Retarding the timing back from 36* to 34* gained power, dropping to 32* lost so I stopped at 33*. Next I went to the fuel curve as it was now time to hit that and I went lean to start and engine did not like it even though it was showing rich. Took about 12 pulls to get the carb right and changed jets a couple times, power valves, and accelerator squiters and picked up 21RWHP. Changed the plugs to a slower burn retracted tip and picked up +9rwhp and called it a day. At the end of the day I installed a new set of springs on my mule engine as they had about 500 pulls on the old ones and they needed re-treating and that netted 16RWHP and +400rpms on the top end of the pull to 6700rpms.

Shipped the parts out Next day air today and he should be at practice on Thursday with new stuff in his car. Total cost on that program was about $850 including the shipping = about $15 per HP. Does it cost a lot??? I am not sure, how and where would he have ever found +57RWHP using his stock parts. He did not have to buy a new carb or dizzy, he just had to get his old stuff re-programmed to the new fuel. He sent the stuff to me this year because I did the same thing for him last year when he switched from Sunoco 110 Leaded to the Sunoco 100 Unleaded. Many tracks are changing for insurance and environmental reasons as leaded fuel contaminates the Air & the water table and EPA and insurance companies are into the "green" changes in racing cause NASCAR is doing it.

Just my way of doing things for the last 25 years.

Sorry for the confusion, guess I should have started my own post. My testing was done on a IMCA hobby stock engine, the OP was about a different IMCA class that has about the same engine rules except for carb and exhaust. I just posted my info because I thought it might help someone...
The lobe sep on the shelf cam I ran was 106 and was installed @ 102 ICL. Even though I know there is a better cam combo to run, I put this cam in this engine because it is probably the most common cam most "home" engine builders use in engines running in the IMCA hobby stock class. And thats kinda what I was trying to prove, along with testing some bolt on parts that should be the same no matter what combo you run. (I.E. Ex manifolds and different pipe sizes)
If you don't wanna do it right...then buy a crate!

[IMCADW]

Doing it right doesn't involve expensive parts. It involves the right part selection.

Your results are helpful, but would like to see the same engine with a different camshaft and a 4412 on it.

[dirtracr5]

i think parts like l/w pistons, rods and crank as light as legal all help. it may not show up on the dyno but it will on the track if the motor will rev faster. 4lbs off the crank may not sound like alot but at 6500rpm or so i bet there is a big difference. now if you can get that custom crank to have some shorted c/w's and keep them from splashing oil even better yet! we saw a 30hp gain at 6000rpm on a 406 with a 350 carb dropping the oil level from the recommended 8qts down to 6.5qts. 320hp vs 350hp. it all adds up.

[IMCADW]

Yes lighter is always better, but at what cost? Remember when everyone argued a 421 was better than a 355 with the 350 carb.

[Brian W]

4412 is doable as I have one of those, built by SMI. Will also be ordering a custom ground cam for the next engine. However I don't think there is 100 hp on the table... on this dyno anyhow. The engine that I posted the results for was put together as a race engine should be. .039 PTH clearance, bearing clearances set right, cam degreed in, chambers in heads CC matched as close as I could get them...ect. I am not the sharpest crayon in the box, but I'm no dummy either, I am outta ideas oh how to come up with an extra 100HP and keep it anywhere close to legal. After I quit racing IMCA, I ran at a few different tracks that had more open rules, called them outlaw hobbys, we still had to run EX manifolds and a cast iron intake and a Rochester carb, but unlimited CID and comp. I had a 410 sbc that had ported pro topline vortech heads with Ti valves and good springs, ported bowtie intake, good bottom end... 14.5 to 1 comp, custom ground cam, fully ported EX manifolds and mandrel bent two into one pipe setup, a wayyy not legal for IMCA carb...ect. I can't remember for sure but I don't think it was over 350 -370 peak HP, could be wrong as its been a while, made a sh%$load more TQ though, like 470 or so. I flat dominated every track I went to with that engine. I either won or was in the top four every single night, unless I broke/ had tire go down. Maybe our dyno is tight? I am not sure and I don't really care about the numbers... All I care about is that I gain, and win races!! And have been doing both for several years. And as for a legal or even legalish IMCA hobby engine beating the 410 outlaw engine in HP... not gonna happen with any cam.

[IMCADW]

Your race engine will pick up at least 75 horse with the proper cam and a 4412. Doesn't matter what you've matched inside the engine, if your off on cam its a turd.

Let me clarify the 421 vs 355, that was an IMCA stock car engine. You are right about the dyno, as long as you see gains that's what matters.

[Brian W]

Your race engine will pick up at least 75 horse with the proper cam and a 4412. Doesn't matter what you've matched inside the engine, if your off on cam its a turd.

Let me clarify the 421 vs 355, that was an IMCA stock car engine. You are right about the dyno, as long as you see gains that's what matters.

And getting rid of the EX manifolds and going to headers then yeah I agree with that.

[IMCADW]

So your around 375 horse.... maybe 400... Should keep up with a 375 horse crate?

[raceman14]

Brian where does your 421" engine enter into the equation? Is it legal against 602 and 350 Built engine??? I agree with your premise that torque is the key asset to that engine and it provides a greater amount of thrust and better instantaneous acceleration. Oval track racers need to develop some drag racing knowledge in how important the 60' time is to accelerating the race car.

Your other engine build is great now that I know it is for the division below. It should be pretty competitive as it is pretty close on power to the engines in the class above.

I am working to get some 487x heads to get to the flow bench. The work there is not that complicated as you can usually get 15-20 cfm on the valve job and selecting the right valves for the port, and then if you are allowed to de-shroud the intake valve 1/8" to 1/4" past the seat you can pick up another 5-10 cfm.

I know all of you guys are chronic about rotating weight in an engine but making a 1# change in a wheel is like the crank losing 10# or more. You have to calculate the rotational inertia on the parts to determine the importance of the part.

[IMCADW]

I'm not chronic about rotating weight

So, anyone else have anything to add? We've established that a 2bbl built engine should be able to meet or exceed the 4bbl 602 Crate option, if built correctly.

[MidgetMotorsports07]

I think you are all crazy lol. But on that note I will say that spending the time on the heads and cam will gain you the most power. I almost never worry abuot rotating weight. To me that is more of a perk than a necessity. We'll see in a couple weeks if we can all keep up or not. Dyno numbers are for bragging rights. Winning races is what really matters.