under powered?

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Sep 22, 2008 | 10:42 PM

hawk584

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From: earth

under powered?

http://i33.photobucket.com/albums/d7...awk584/001.jpg

i've been wondering for a little while now...

forged 385ci LT1 w/stock intake manifold & TB, LEP custom turbo cam
9:1 compression
t67 STS 10psi
intercooled
tuned by pcm4less( whom i dont have any issues with i think they did an awesome job)

Sep 22, 2008 | 10:56 PM

borninatransam

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From: GSO

What kind of cam? And I don't doubt Alvin's tuning abilities but if this tune wasn't done on the road or at least on a dyno it's just not the same.

Sep 22, 2008 | 11:00 PM

hawk584

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From: earth

i was asked not to give out the cam specs and I'd like to respect his wishes. it's only be tuned once so maybe it could be in need of a touch up tune and added boost? i just find it odd that i'm only putting down about 50 more hp's then an all motor 385... maybe he played it safe for the first tune and amount of boost to let the newly built motor break in

Last edited by hawk584; Sep 22, 2008 at 11:08 PM.

Sep 22, 2008 | 11:31 PM

calongo_SS

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From: Victoria, TX

Looks like it falls off really early and falls off hard. It's peaking @ 4700 rpms???? Maybe you're floating the valves? I don't know enough about it to tell, maybe some one else will chime in.

Sep 22, 2008 | 11:40 PM

Zombie

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From: Las Vegas

If the boost isn't dropping off after it peaks, it looks like it could be valve float, what is the spring pressure?

Sep 22, 2008 | 11:52 PM

borninatransam

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From: GSO

If the motor was built correctly the only break it needs is a couple heat cycles. Was this done on or off the dyno? If it was bench top tuned then I don't see where you could be hitting the tune spot on. Again not doubting the abilities of the tuner it's just from my experience dyno or street tuning is the only way to get the car where it needs to be. Where are you located? I'm sure there's at least one tuner close to where you live.

Sep 22, 2008 | 11:52 PM

RW99

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From: Castro Valley, CA

Your turbo almost looks like a centrifugal blower by its dyno sheet. Where's the boost? In order to troubleshoot your problem, please list as much supporting info as possible. Include your A/R on the T67, and tell us about the boost trace for these pulls. Is this a new install? Or a retune? Isn't a T67 almost too small for 385 ci? I would think that it's way off of its "happy zone" on the compressor map at 10 psi for that many cubes...

I run a front-mount T67 0.96 A/R on a 346 at 11 psi and that's pretty much its limit.