I'll give you guys a little background on the motor, turbo, etc to help you get an idea of the problem we are having.

D16Z6
8.5:1 Pistons
Eagle Rods
ARP Headstuds
Stock Head
Apexi Turbo Kit
Internal Wastegate (5 psi)
Stock Apexi downpipe
2.5 in. Exhaust
TurboXS High Performance Boost Controller - Set to 15 psi

The problem we are having is getting the car to hold boost. I've included a datalogging graph below to help show what I'm talking about.

The boost slowly falls off after it hits 15 psi. We've checked and are pretty sure there aren't any boost leaks. I've only got one other idea.
The stock wastegate can't handle that much psi even with a boost controller. Some people have said you can double the stock internal wastegate psi before you start having problems. I can get the boost controller for hold 10 psi.

Does anyone have any other ideas? Let me know if you need any other information!!!

Thanks for any info/help!

-P

 

its probably just the turbo cant keep up with the airflow requirements of the motor

 

ya i think trying to more than double what the stock wastegate is pre-set to will cause that problem........just keep it under 15psi and you should be ok.....or change your pre-set wastegate setting.

 

Sounds like tiny turbo syndrome.
I know, I have it to.

 

Its probably that wastegate.

 

anybody have any ideas?

 

It's probably a small turbo like the one in the Greddy kit and you're pushing it out of its efficiency range with 15psi.

 

It's the internal wastegate actuator. The wastegate is being blown open at higher exhaust pressures.

A stiffer wastegate spring will solve that problem.

 

time to go externaal wg

 

Sounds just like my 14b problems (although i was also getting massive spiking on the unported internal). I went with an audi 5000 external gate grafted onto my HF manifold... that in combination with stiffer spring and an EBC fixed my issues.

 

Hf manifold + external gate is the way to go