OBSSSD

The car is my father's daily driven Z28 - here's all the information:

2002 Z28 - 5,000 miles on the car at time of dyno
M6 transmission
Stock 10-bolt w/ 3.42's
OEM SLP airlid
Free Ram Air mod
ASP Pulley
Jantzer Stage II ported TB
Kooks 1-3/4" race style coated longtubes
Lane's true duals with x-pipe
G5X-3 cam
Patriot LS6 style heads w/ 59cc chambers (11.5:1 CR)

The car ran 423rwhp/389rwtq on the best of 3 dyno pulls at RPM Motorsports in the Dallas, Texas area. Obviously I tuned the car myself with LS1 Edit. The A/F is dead flat @ 13.0:1 from 2K-7K. The timing was set at 30 degrees through that entire range. No detonation or knock retard whatsoever at any time during any pull. Everything was run 100% as the car is driven on the street. The only change was that the tires were inflated to 30 psi (315/35-17 Nitto DR's on chrome 17x11 ZR1's) instead of leaving them at 18 like the car is driven on the street.

Just to make sure there was no exhaust restriction the exhaust was unbolted at the collectors and run on the dyno - and the car actually lost a little power. There was no short belt, electric water pump or any other stuff that might inflate the dyno. The car is in perfect mechanical condition and is a total street car - driven 100% as a daily driver. Overall I was disappointed in the results from the heads. I figure just bolting up unported 6.0L castings with a bump to 11.5 CR should yield 25rwhp easy. Before I make my final judgements though - I'm going to tune the 3 other cars we just put these heads on - and then the verdict will be in

The car feels good though and as a frame of reference - it ran 340/358 through stock manifolds @ 2,000 miles before the headers, duals, pulley, heads, and cam added. Also, an LS1 C5 M6 car with CNC cylinder heads and a little smaller cam ran 440rwhp on the same dyno a couple weeks ago with basically the identical mods except the heads/cam. That was with ported LS1 heads though so 450rwhp should be there with a well ported set of LS6 or LS6 style heads with an 11.5:1 CR.

I will have Wade @ RPM post the dyno graph up Monday - but I can assure you that every "t" was crossed and every "i" was dotted. Nothing was missed and the tune was perfect. For better or worse this is all 100% legit


Chris

VINCE

iTrader: (1)

You must be mistaken. Are U sure that was not 463rwhp? Is it valve float?

SPANKY LS1

iTrader: (24)

That is too low, especially for a 2002 car with a M6 and a 10 bolt. You should have gained more than 83hp/31tq with all of the stuff you added since the 340/358 dyno. Maybe the tuning can be tweaked? Somethings not right, IMO.

maddboost

iTrader: (11)

I thought the 59cc chambers gave you a 11:1 compression.

onyxxtreme

iTrader: (4)

is it something other than a dynojet?
a dynomite would make a 450hp car show a good bit less, but they're supposedly more accurate

LG Motorsports

Hi Chris,

The only thing that I can see is the "free ram air" mod. On a dyno with no air flowing, you are taking in hot radiator air which is usually worth some but not this much. The dynojet is correcting for room air but the engine is seeing hot 200* air.

I would have thought that the patriot heads would be worth more.

LG

TApimp

iTrader: (1)

what injectors are you running?

whats the duty cycle on them right now?

-Joseph-

iTrader: (12)

I just installed the same heads on a car (01 WS6) that had our 231/237 and did 409rwhp before heads with just the cam. With absolutely no other changes other than heads being swapped it did 439rwhp. It will probably do 445rwhp with some addn tuning.

The car before that did 445rwhp with those heads and a slightly bigger camshaft in a 01 C5.

Since these were done in the same timeframe as yours, I really doubt the heads are the problem. FWIW our dyno is usually 5 rwhp lower than others from what our customers say when comparing to previous dyno pulls.

CamM

Isn't the OEM SLP lid marginally better than a stock lid and you could see better gains with another aftermarket lid?

DG Gordon

I believe those heads with stock pistons only yeild about 11.1 comp. I have those same heads.

CamaroSS_2002

iTrader: (4)

Just a counterpoint. I have the free-ram air mod, when I was last at speedtek, they have a big port-a-cool air conditioner fan blowing right into the car. With EFILIVE my intake air temp was pegged at 75F when it was like 85F that day.

I dunno if RPM has one of those or not.

LS1derfull

I agree, i worked compression out to same 11.1 to 1, providing stock type head gasket of near .060" is used. Using Fel Pro Race head gasket of .042" thickness is great way to boost compression without machine work, i have 11.2 to 1 with 62cc comb. chambers!

WS6snake-eater

Did you flycut the pistons with that setup, or even check your clearance?

KGSloan

FWIW, one of my buddies put his 2002 SS on the dyno (had the slp air lid) and it put down about 320. then, on the next run, we put on a direct flo lid and the car picked up 14 rwhp over the slp lid. just a thought you might try if you're looking for some of that extra hp

Ryan02SS

iTrader: (3)

Are we talking the SLP lid for $99 or the Blackwing lid that came with the 345HP SLP package? I really don't think that is the problem as I am making 400 rwhp well really 399 lol with the blackwing lid that supposedly doesn't flwo well with a baby 224 cam on stock heads. Although if Direct Flow or TSP send me a free lid I would gladly do some back to back dyno runs with my setup.

Beast96Z

iTrader: (21)

The car with just the cam should be making about that much power. Something seems to have gone ary. The last car with that set-up did 445 through a 12-bolt and a A4 and he is legit, he lives right down the road from me. I'd start looking for problems.

OBSSSD

The car doesn't have the cheap piece of junk SLP aftermarket airlid. It has the high dollar OEM approved $299 lid that came with the dual/dual exhaust on my Firehawk. I will put on a Direct Flo lid and redyno the car to see if there is any substantial difference. This lid is supposed to flow as well as any lid out there but you never know so I'll be happy to change it out to see what happens.

As for the air intake temperature due to the FRA on the car - I did freeze frames with a GM Tech 2 tool for each and every run to check the L-trims, spark, KR, air intake temp, etc... It showed 80 degrees so I don't believe that is the issue here. There really isn't any potential exhaust or intake restriction IMO but I'll do the lid swap as that seems to be the only possible issue.

The injectors are the stock LS6 ones and based upon all the data I've seen on this car that isn't even remotely an issue. The Ltrims are locking at 0 immediately upon acceleration on the street and dyno and the car has never once showed anything other than a full 30 degrees timing on the street and dyno with multiple beatings being successively applied to the car. The A/F was dead perfect at 13.0:1 as you'll see when the graph is posted so the tuning isn't even potentially a problem.

As far as the compression ratio I'm going based upon what I've been told so if it is really only 11.0:1 it should be marketed as such IMO. I'm not trying to bash anyone here because Terry has been great to deal with. It's just that CNC'd heads should be consistent from one set to the next so until I get the other cars done we're working on I'm not making final judgements. I'm a little suprised myself because I figured the combo was good for 440rwhp no problem

Guess I'll have to get the lid swapped to the Direct Flo and redyno to see what happens. If that produces little to no change I don't see what else could be wrong. The motor has perfect compression and ran hard bone stock so there were no reasons not to expect the best case scenario here

Chris

Louis

iTrader: (7)

What LSA was your cam on, and Did you : Check valve drop, and/or flycut?

LG Motorsports

There is another problem here, and it is not a minor problem. If you doubt the cam, then come on over and we will switch it out with another one for you.

If you doubt the heads, then take one and flow it with a manifold on, and see what the numbers are.

It is just a machine, and it abides by the same laws of physics as every other engine.

Hope you get it worked out Chris

Just my .02

WS6snake-eater

G2 that was the same ?'s that I had. I have this same combo and I am installing it tomorrow. Everyone I've talked to says that the pistons are probably going to need flycutting (112 lsa). If this is the case, and he has having some serious geometry problems, it would explain the low numbers.