mike13

iTrader: (27)

383 (stroked LS1) ported 317's 224/230cam
TC76 .96A/R

Motor only builds 11-12lbs boost, is the TC76 out of breathe? On my LS1 with ported heads it built 14+lbs of boost.

elias_799

iTrader: (8)

what wastegate spring you got in there ?

you have a boost controller ?

mike13

iTrader: (27)

Yes Tial wastegate I installed a combination of spare springs so I have a 20lb combination and my electronic boost controller is set at the max of 90% duty cycle. I wanted to make sure backpressure wasn't opening the wastegate.

spools fine just tops out at 11-12lbs. Took all the cold side piping and intercooler apart to check for leaks.

JAX04

iTrader: (17)

what size charge pipe are you running?

black98ws6ta

iTrader: (77)

Most maxxed out turbos I have worked with would spike a higher boost at first and drop in the upper rpm's. If you have a slower spooling set-up it may not act the same.

If you are worried about the back pressure opening the gate just put the reference to the gate on the top port only. That will give you max boost the turbo can supply and insure the gate is not opening. Just make sure you keep a close eye on it in case it does make more boost.

mike13

iTrader: (27)

rearmount 2 1/4" under the car and 3" & 3 1/2" from intercooler to intake.

kbracing96

iTrader: (25)

Being rear mounted, you probable just don't have enough heat/energy left in the exhaust to power the turbo to make more boost. Do you have all the hot piping header wrapped to retain the heat/energy? That would be my guess...

MUSTANGBRKR02

iTrader: (91)

Motor is going to build less boost because it is bigger.

But the 76 is probably small for the 383. I'm going to be running a TC-78 on a 370 and will probably be maxing it out.

Did you change springs or anything in the wastegate?

mike13

iTrader: (27)

Yes it's wrapped, my thinking is there is plenty of energy because reading the different threads the TC76 is considered a small turbo for this combination.

mike13

iTrader: (27)

Yes 20lb spring combination. Trying to word this correctly, when researching your turbo did you find information that would have you believe that a TC76 would not be able to provide enough capacity?

mike13

iTrader: (27)

This is some info from a datalog before I went speed density this was with 8lbs boost breaking in the motor. When I was datalogging my concern was to let out of the throttle when the maf maxed out that's why the odd rpm/tps%

73 degree iat
5100rpm
83% tps
64lbs/min maf reading
65% injector duty on 60lb'ers (69@58 psi)
10.5afr W/100% methanol injection.
no knock retard

MUSTANGBRKR02

iTrader: (91)

Just using the compressor map and the airflow per second needed i forget the formula off the top of my head.

Yellowsierra

iTrader: (7)

I bet the TC76 will go higher. Switch the hose on the wastegate to the top port instead of the side port. That will force the wastegate to stay shut. That will tell you exactly how much the turbo will push! Trust me! I accidently hooked the hose up backwards on the wastegate and found out how much boost the TC78 would do on my forged LS1... 20+ PSI ! haha This was on a remote turbo setup

mike13

iTrader: (27)

The wastegate isn't opening 20lb spring with the boost controller set 90% duty cycle will hold boost to 35-40lbs

mike13

iTrader: (27)

OK I emailed Turbonetics and Robert who is the administrator for the forum for Turbonetics owners forum emailed me back. He thinks I've maxed the turbo.

"The Hurricane units are essentially exteremely large compressors in smaller housings. That compressor housing limits what is normally an 860 CHP compressor wheel to about 700 CHP. It's mean for vehicles that need to stuff a compresor that large into almost no room."

I'm not sure what to think, I've seen people get more but when talking with Robert he made it sound like what I'm seeing is normal. He said a 383 with ported heads&cam is to much motor for a TC76, he thought my backpressure should be pretty high.