flash68

I bought a road race car with an LS2 in it and not much documentation (but from a reputable local former road racer).

What I do know:

LS2
ARE 2 stage dry sump system
L92 carb intake
Holley carb

Unknown:

Cubic inches (was thought to be 4" stroker)
Compression (he ran it on 112 leaded, so I will too - no cats, no O2 sensors)
head work (probably something done to it)
cam specs (not stock, not a monster)

So.... I believe it is NOT a 4" stroker based on the 6600 rpm hp peak and the relatively low corresponding torque number.

Dynojet dyno...... 9" rear and a Jerico WC4 trans.

I am not unhappy with the results. Just curious about more info. I am thinking it's more like a stock stroke crank --- anyone agree?

Thoughts?

Thanks

Z28SteveA4

iTrader: (16)

It could still be a mild stroker with that rpm and hp. The cam and head combo is what’s going to carry the rpms higher. If it’s a mild cam then 6600 is right where I would expect it to peak. What transmission is in the car? Auto or manual?

flash68

Ok, so maybe a mild stroker, sure.. but you doubting the 4" stroke thing too?

Trans is a dog ring Jerico WC4 4 speed. Road Race trans.

Thanks

Mike@Diablosport

iTrader: (2)

IMO too strong to be a 6.0 with heads/cam.
That intake will make the torque curve look different than most similar setups with composite long runner intake, so tough to say.
My guess is non optimized 408, down on torque for whatever reason, plus the 9"....

flash68

Good info. Thanks Mike.

flash68

Also, on same dyno last year on my stock LS3 with only a medium sized cam (didn't have specs - estimating here) and throttle body and a tune, made 465 whp and 437 wtq. That car has an 8.8 rear though.

See attached. Just a little surprised I guess.... or maybe the LS3 is really that superior over an LS2 with more work and cubes......

Mavn

iTrader: (3)

It's a 408 for sure .

flash68

Found out what the heads are on this LS2..... and now I think I am even more disappointed or perplexed why it only made 472 wheel hp. Maybe the cam is mismatched.

The heads are WCCH stage 3 L92's...... that's a pretty bad *** head!

http://www.proheads.com/WCCH_L92.html

G Atsma

How big a carb? Maybe too small?

flash68

Not sure. I just called ProSystems to see if they could pull up the specs on it... I need to get the 5 digit number off the carb and call them back.

G Atsma

You don't say or know the cam spec- I would find that out, along with which carb you are using. One or the other, or both are choking your power potential. I doubt it's the heads. WCCH is usually good stuff!

jlangley

iTrader: (8)

If it is a stock stroke Ls2 those numbers might be about right considering the fact that it's just dyno numbers.

I think a stock Ls2 bottom end with nice heads and a medium cam should be in the 475 wheel neighborhood.

flash68

I am afraid I don't have the cam specs... and short of pulling it out I am not sure we can get that info.

I will have the carb info soon when I call Pro Systems back after Thanksgiving. The heads do seem bad ***.... and only intended for engines over 400" which further makes me believe this is a 4" stroker as I was told.

WCCH also confirmed today that the chamber us 75cc. So maybe the compression is not ideal. I dunno.

I am pretty sure now that it is a 4" stroker as the previous owner recalled.... he just didn't have receipts or much for records. Was built many years ago. But he is a trustworthy guy and the rest of the car is legit.

jlangley

iTrader: (8)

Based on this Information I think you are correct. Seems unlikely anyone would put those heads on a stock Ls2 bottom end.

Unfortunately I think your results are in line with my previous comment. Decent for a 364 not so good for a 400+ with high end heads

flash68

Yeah. Once I confirm the carb info, the last key piece is really the cam I suppose.....

flash68

Pro Systems says the carb is a 780 cfm road race carb and is good for up to 560-570 hp apparently...... like they didn't expect to make any more than 560-570 hp? hmmmm weird

G Atsma

Just being conservative.

Darth_V8r

iTrader: (4)

Did previous owner class race? That's almost like running a restrictor...

flash68

Perhaps

Sorry - missed your reply. He did class race and was very good but they were all unlimited hp / weight classes.... NASA AIX, etc.

gnx7

iTrader: (28)

Couldn't you pull a spark plug and measure how far down it goes to calculate stroke somehow?
Have you done a leakdown or compression test in all cylinders? Confirmed what spark plugs are in it... and maybe change them out?

That torque seems low even for a 402ci motor. My LS7 427 with mild exhaust porting on the heads, stock LS7 intake, 1 7/8" long tubes, 11.25:1 compression, and older LS7 grind 243/256 .650" lift QM600 cam made 522rwhp/472rwtq on a Dynojet, T56, steel flywheel clutch/twin disc, 8.8" IRS out back. 3.73's with a 335/30/18 tire.