raceman14 wrote: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.
IMCADW wrote: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.