602 GM Crate vs. Built Engine

[dirtracr5]

20hp 25tq will be my guess.

i'd also like to see the averages also between the 2 cams. what rpm range do you pull in?

[Brian W]

The last race, the driver said 4300-5900. Track was abnormally super dry slick...and had to run the bottom. Usually though its 4700-6300 give or take a bit each way on both the high and low depending on track conditions and such.

Avg HP from 4000-6200 is 274. Avg Tq is 287 with the Ex manifolds and 2.5" pipes

[rick7343]

The last race, the driver said 4300-5900. Track was abnormally super dry slick...and had to run the bottom. Usually though its 4700-6300 give or take a bit each way on both the high and low depending on track conditions and such.

Avg HP from 4000-6200 is 274. Avg Tq is 287 with the Ex manifolds and 2.5" pipes

Have you done any exhaust manifold testing?

We can only run 2 1/4... I would like to see some tests with the LT1 roadmaster/caprice manifolds... we can't use ramhorns...

[Brian W]

I have did some dyno testing and a bunch of flowbench testing on all types of ex manifolds. I have not tested the LT1 manifolds yet on the dyno due to lack of time but I do have a set that will be tested the next time we have a suitable engine on the dyno... have a 700hp 360 ASCS on right now and am guessing it wouldn't like the manifolds!!

[Brian W]

If anybody would like to see, here is a pic of a IMCA spec head intake runner cross section.

[rick7343]

What is the spec head?
We are allowed junky World Products #043600 A or B, Casting # 1052 or old stock heads with 1.94 and 1.5 valves.. no vortec or angle plugs...

My current engine has 920's on it ,ut I am going to try a set of 041's if I can get the compression down... Engine came with the car and needs freshened anyway...

ANybody got any piston suggestions?

[raceman14]

Rick,
What are your piston rules, most times the ring pak and honing process is where the power is made.

[rick7343]

We don't have much of a piston rule for some reason... no domes.. cast of forged, 2 or 4 relief...

What do you propose?

"Maximum over bore of 0.060” allowed. No aluminum block, rods or water pumps. (Ford and Chrysler water pumps exempt) engines must use factory specs for bore, stroke and rod length of engines used. (ie: 350 Chevy - 3.48” stroke x 4” bore x 5.7” rod length. No aluminum or fluid dampers, only standard O.E.M.) Steel elastomer type harmonic balancers permitted. Stock cast cranks only. Must retain O.E.M. original numbers. No stroker kits, no knife edging or chamfering.

Pistons - No dome pistons. 2 or 4 eyebrows cast or forged piston allowed.


Rods – no lightweight rods will be permitted. Aftermarket OE replacement rods allowed, as long as they are the same weight and design as stock. No reworking permitted. No form of traction control devices will be allowed. Any devices will be confiscated. No dry sump systems allowed. Reworked oil pans allowed. Econo racing pan allowed. An inspection hole is mandatory. No evacuation systems allowed."

[ratsass]

With 9 to 1 comp, a smog head and 500 2bbl I don't think you beat a vortec headed 9.5 to 1 4bbl hyd roller cammed engine.The open cam is your only advantage and if I understand correctly that is limited to a solid flat tappet.You can only go so big with the cam before low compression kills any advantage it can give you.You can keep going bigger and pick up numbers on the dyno but will lose drivability off the corners.That being said I'm a glutton for punishment and would try to find 487 heads stuff in a big cam and gear the piss out of it.
If you are on dirt being able to turn higher rpm has some advantages 1.easier to set the car in the corner by burping the throttle from engine braking
2.tourque is multiplied by gear ratio so even if actual output is lower than the crate by not having a chip the deeper gear you can run may well result in more tourque at the tires.3. since most passing is done off the corner you can gear it to come off hard to the flag stand and let it,s toungue hang out from there to turn entry you can't do that with a 6200 chip.

The 602 crate has a hydraulic flat tappet cam .435/.460 lift, 212/222 @ .050, not a roller cam and the C/R is 9.1-1.

[ratsass]

100% legal motor straight from GM at the end of last season went 376hp and 404tq uncorrected. 400/430 with correction.

You need to have your dyno checked.
We've dyno a bunch of them striaght from GM, and they have a hard time making 350 corrected, and the dynos in this area are not known for being on the low side.

Mike; I'm new to these threads and have to agree with you. I have a small engine building shop in Saskatoon, Canada and am also the Street Stock tech advisor for our track; Autoclearing Motor Speedway. It's a 3/8 mile banked asphalt track with 7/9/11 degrees banking. Anyways, i built an econo style engine, 9.2-1 flat top max,, Comp XE268, Holley 4412(no mods allowed), GM 920 heads 1.94/1.5 to compare it to a new 602. We are restricted with pump gas, cast exhaust. So i dynoed both engines on a Stuska dyno. Results were comparable; my built made 327 HP and 371 torque, 602 was 325 HP and 371 torque, but the 602 started making torque 1000 rpm sooner, which really helps them out of the corner. The built is allowed a Weiand 8150 or Ed 7101. The cam you mention in a later thread Part # M72352-106
244/244@.050"
.352"/.352" Lobe Lift
106 LSA Why so much duration and would it help in our situation? The Comp i used is 227/231@ .050. Also, I get mixed opinions on using split lift/duration vs straight for circle track.

[CamKing]

The M72352-106 is a solid lifter cam, and is designed for tracks where you come off the corner at 4,000rpm or above.