EvoByDarwin

iTrader: (12)

Well even before I got it tuned, I knew the car wasnt making near the power it should. Heres the mod list:

2002 Corvette Z06 block
Eagle 393 CI forged 4340 crankshaft
Eagle 4340 forged H-Beam rods
Block is clearanced for .700 lift camshaft
Ross racing pistons
Compression ration is 11.2:1
Ported and polished W2W LS6 oil pump

LS6 intake manifold
SLP lid K&N filter
Z06 85 mm MAF
28# injectors
255 Walbro in tank pump

Ported and polished 6.0 liter heads cast number 317
Heads flowed 329 @ .600 lift
Comp Type R lifters
Comp springs
Comp TI retainers
Comp Cams 228/230 571/573 112 LSA camshaft
Ferrea 2.02 1.60 valves
Heads are fully worked

Pacesetter Coated Long tube headers
3" y pipe
Center mount exhaust from SLP
No cats

Now these mods arent verified except for the obvious as the car had these mods on when purchased. I do know it has the 317 cast heads, and a cam due to the idle. Also the car has a slight (lifter??) tick once the car is warm and ran for a while.

I know this is the equivalent of asking someone to find a needle in a hay stack, and the lack of power could be due to a number of things. However, with all the knowledge here on these forms, I figured you guys could point me in a few directions on what to look for/do.

I dont have a scanner but the car made 406rwhp@6000 and 382rwtq@4900 with a 350rwtq from 3500rpms on. The tune is 12.8 AFR with 26* up top.

Any insight you guys can provide is GREATLY appreciated!

juicedSS

iTrader: (18)

that looks like a pretty small cam for that size motor

EvoByDarwin

iTrader: (12)

I surely agree, but how much would you think its leaving on the table to a more proper sized cam?

WOT

iTrader: (1)

maybe i missed it somewhere, but was it an a4 or m6 tranny?

some is definately being left on the table just from the small cam.

Rick@Synergy

iTrader: (5)

That cam is not going to limit him to power much. It should work fine. First thing that comes to mind is how crazy you are for trying to run stock injectors. I can tell you those are most likley going to hold you back as well as with a tune. Dont expect anything until you are tuned. So without you scanning the car, I would say you cant give anyone enough details to what your problem could be.

Rick

EvoByDarwin

iTrader: (12)

My car is dyno tuned with HPTuners, to a 12.8 afr with 28* max timing. I know the stock injectors are borderline, Ive already ordered a set of 42lb (large I know, but leave room for growth).

I have a scan of the car with some part throttle driving and a 3rd gear WOT pull, not sure how to host it, but would be more than happy to if you would like to look.

BTW the car is a M6 with a stock 10 bolt (about the most effiecient F-body drivetrain )

ty_ty13

iTrader: (42)

see what it runs...

EvoByDarwin

iTrader: (12)

I have, with a 1.85 60' it went a 7.96@90.87 mph. Not bad I dont think, but lacking compared to the mods to say the least.

ty_ty13

iTrader: (42)

with your MPH you should be hitting 7.50's atleast in the 8th.... but that is probably a little to do with the 60' and driving.

you may not be as far off as you think.....

it is lacking a little.... id think with your mods you be close to 7.0x on a good weather day.... mabey a little to do with the tune....

you'll get it... keep searching!

EvoByDarwin

iTrader: (12)

Those times are on 275-35-18 BFG KDW's. Little hard to hook.

This car is tuned perfectly as far as I can see. The timing is at 28* and a perfect 12.8 afr, unless there's something in HPTuners that me/my tuner is overlooking, I'd say the tune is pretty well set.

BTW, the dyno numbers were from a DynoJet and SAE.

Tony Mamo @ AFR

iTrader: (13)

If you ever have the chance down the road have the heads independently flow tested....you might have less flow and more port volume than you think. You wouldn't be the first guy searching for power based on airflow figures you thought you had. If they flow the number (or close), thats great, a big piece of the puzzle is now no longer a question, but if you find out they barely crack 300 CFM, have weak low and midlift flow, and the intake port is pushing 240+ cc's, you might have found a potential problem with your set-up.

By the way....I have no idea who ported your heads so lets not turn this post into anything silly. The bottom line is that cylinder heads play a huge role in power production....if you've covered most of the other bases and have NOT independently checked the heads, it would be a logical place to look if you were trying to find some missing power and performance in ANY combination.

Good luck soughting it out....

Tony M.

EvoByDarwin

iTrader: (12)

I dont have any idea who ported my heads so no poo flinging fest from this camp. (Even if I did know, thats not my style). Im going to buy a cam in the near future and when I install it, I'll pull the heads and get them on a bench.

One other question, say these heads were infact garbage. Whould there be any type of ported factory cast head that would be a good choice with my shortblock? Im not looking to break any records, and I dont care about dyno numbers, just want a good running car.

niphilli

Can you post the graph? Could you be having valve foat issues? Lifter problems? Seems like I saw some issues with the comp R lifters a while back...Why did you change the lifters?

EvoByDarwin

iTrader: (12)

I dont have a scanner right now, try to get to one later tonight. What would be the symptoms of valve float? The graph is pretty smooth, other than that I dont know.

I didnt put the Comp R lifters in, they were there when I purchsed the car. Ive also read some bad things about the Comp R lifters, Ill do a seach and see what seemed to be the problem with them.

EvoByDarwin

iTrader: (12)

Ok, just read a thread that basically said that the Comp R's are very sensitive to preload. Giving that my car has a "lifter tick" once it gets warm, that's def something to look into.

Also, what other lifters are on the market that would be a good choice for my motor besides the Comp R's?

There again, I really appreciate the info guys, its already helping!!

EvoByDarwin

iTrader: (12)

Here's the dyno sheet

xfactor_pitbulls

iTrader: (16)

The 317 heads flowing 329 with a 2.02 valve would be great. On a 3.9 bore that is really strong. I would bet that they dont get quite that high though. In that respect, if indeed they dont flow what you think, the smaller cam is limiting the amount of actual A/F volume you are getting into the CC. What is the exhaust side flowing? What size headers? I saw that A/F was around 12.8, but what was the duty on the injectors? Did you see what the MAP sensor data said? Sounds like you are missing some serious Air and Fuel. I would bet the heads dont flow what you think, there are some tuning issues present, injectors are limiting you, cam could be bigger, and LS6 intake is holding some back too. You arent running a small exhaust port with 1 3/4" headers are you?

Brandon

niphilli

Graph looks pretty good, does not look like float. Cam peaks about where it should for a 393??

EvoByDarwin

iTrader: (12)

Lots of information here, Ill answer from top to bottom.

I have no idea what these heads flow, nor do I know who ported them. So your more than likely right on the flow numbers.

Dont have a flow sheet so Im not sure of the exhaust side flow numbers.

Im not sure of the duty on the injectors, however if someone could point out how to convert MS time of the injectors into cycle duty %.

I dont have a log of the actually dyno pull, but I have one that I recorded on the street later that night. After reviewing that log, Im seeing 99kPa at 3500rpm with it dropping down to 95kPa at redline.

And yes, the headers on the car are Pacesetters which, if I understand correctly, are only made in 1 3/4".

xfactor_pitbulls

iTrader: (16)

You know even with the things I pointed out something is wrong tuning wise..... Has to be. VE tables in line? Fuel system really does some inferior for a setup like this. I just dont see how you are not getting lean. Someone more qualified than me needs to step in here. Just for ***** and giggles have you run a compression test? Checked all the plug wires and coils?

Brandon

Brandon