Hi guys. I have a ‘96 T/A LT1 M6 that has been out of commision for about 2 years - it's a long story. Anyway, it is up and running now and I am not getting the power that I thought it would have. I am taking it to a dyno next week, but my ***-o-meter tells me it is making less than it was with 360/380 rw when it was a heads and cam car. Here are some details:

Motor:
OBD I w/ Fastchips & House of Speed tuning, on Patterson Motorsports built 396 corvette block-4 bolt mains stroker with:
All forged drivetrain- Callies crank, Eagle rods, Clevite bearings & JE Pistons. About 12:1 cr.
CC Extreme Energy cam,
GTP stage II heads & ported intake
Comp cams stud girdle kit & AFR hydra rev kit
Bullet proof Comp cams valve train
SVO 30# injectors
Extreme duty timing chain
Hooker ceramic coated (Paul Barry Motorsports) long tubes with Mufflex off road Y pipe & SLP dual/dual catback
58mm AS&M TB
160 deg Thermostat
WS6 factory hood w/ SLP airbox kit & K&N Filter
MSD 6AL & Timing retard
Taylor 10mm wires.
NGK's
Ed Wright program with local tuning

Suspension & Drivetrain:
Strange 12 bolt with 3.73 gears.
SFC;s, STB, LCA's & adjustable panhard bar, Spohn street version torque arm

This is by no means everything, but should give you a good idea of what I have to make this decision. I don't have the cam specs handy but I would really appreciate any suggestions as to why I may not be getting the power out of it I think it should (I have been estimating 4230/430rwhp) and what cam to consider in case I narrow it down to that - or tuning specs or whatever you can offer. I would really, really appreciate anything at this point.

I will get back with dyno numbers as soon as I can as well.

Thanks in advance for anything you can offer
Mark

 

ttt

I could really use some advice guys. Or steer me to some 396 guys that have gone through this or something!

 

Find out what cam is in it . Alot of guys build these big inch strokers and don't put enough head or cam in them. They get the illusion of power when it smokes the tires off idle.. but find that it isnt too hot when it's out of breath by 5k.

You've got mail order tuning? Hope not.

 

thats true. some people have small cms in their strokers and it defeats the purpose IMO...

And yea, did u get a dyno tune??

 

Well thanks for that guys, I appreciate your input. But I assure you that the cam is not too small and I do not have mail order tuning nor have I been to the dyno yet (read my message!).

I am afraid I moved and just can't put my hands on the file with the cam details. Just going by the details provided, can you recommend a cam? I will compare it to the specs on the one installed in due course.

Many thanks

 

Well your post said something about an ed wright program with local tweaking.. but no mention of actually dyno tuning (otherwise you'd have #'s for us, no?).

Your heads probably peak in the 250's, which is a bit low for a hot 350.. if theyre LT1's that is. I'm not sure what cam you're running but I'd run somethning like the 236/242-112 or gm847 as an absolute minimum with that if emissions arent a concern.

Dunno, figure out what ya already have & we can be of more help

 

I have always figured it like this. Most "bigger" cams make alot of ther power up top, in the high RPM range, well a 396 has a larger rotating mass, and does not generally spin as high as say a 355. So if you were to have a 396 that doesn't have a really high redline, wouldn' it be better to get a cam that makes its power a little lower down the power band?Does this ake snse to anyone else, or am I missing something.

 

Maybe you should get your heads flowed and get a custom ground cam to match them.

 

Without getting into it really, for what it's worth, 355/383/396... you have 7000rpm to play with if you're using the stock PCM. I wouldn't leave power on the table

 

Well Skarodom... I know... I know... I felt dumb enough not remembering my cam specs, don't rub it in!

But you are correct in that I have not done a dyno tune yet. The Fastchips was just a staring place on the OBD I with just some simple laptop updates to smooth out the Ed Wright stuff. I have an appointment at the dyno on Monday and should come back with some numbers thereafter.

However, I know that the head flow should be roughly 275-280 at .600 lift and 210-212 on the exhaust and it is not a 350 - it is a 396. So whether I know the specs or not... is this enough information to recommend a very streetable cam?

and p.s. my shiftlight is set for 6800 with rev limiter pill in the msd at 7 grand

 

Skroat..why did you jump your price up $400!! That totaly ruined my plans of getting my heads ported by you for Graduation!!! Now it is $200 out of my reach!! AAAHHH!!!!!

 

Wasn't trying to rub it in . I also know what they "should" flow, just saying what I've seen in the past - 252-260 peak & poor E/I ratio. I wasn't saying you had a 350, I meant that even on a 350 it wasnt enough, much less a 396. Even something like the cams I mentioned should be extremely driveable in that setup IMO.

Strap it down, I wouldn't worry about it til then

Good luck,

-Phil

 

Well I may have to pull the top end off to fix that infernal rattle anyway - it's either valve clatter or a loose hydra rev or stuf girdle kit. I might just go ahead and take the heads off and have them independently checked then.