I got a question thats been plagueing me nd Ive tried almost everything.
Quick setup:
D16y8 built bottom end
SRP pistons, Eagle rods, ARP studs
Stock head
2.5 Dp and exhaust
Hondata
550 injectors
t3/t4 .50/.48 (not sure on the trim)
15 psi, 245whp 202ftq
My goal was 300+!
So obviously, just turn up the boost right? Well, the boost will not go past 15psi!!! I have a turbosmart MBC and a 10.153 Tial wastegate spring. Ive tried everything. No boost leak anywhere, no exhaust leaks anywhere. I have posted this and got some ideas, like take the vacuum lines completly off the wastegate, tried that, still 15psi. I havent put a bigger spring in yet, but some people say that this wont matter. Do you think a bigger spring will raise the boost in my situation or is something else wrong.
Maybe the trim on the turbo is wrong, because I aint got a clue what it is!

 

What color is the markings on the spring itself?

The options are:
small yellow
small red
small blue
small green
big yellow
big red
big blue
big green

Might as well double check that to ensure that you have the spring you think you do. My guess is that the spring is what is holding you back. It's not stiff enough to keep the wastegate closed past 15 psi.

 

if you have a 10psi spring you should be able to make 20 psi of boost,, i made 267 hp nd 197ftq on the y8 with stock internals on 9 psi, with a turbonetics t3/t4 60 trim, I would check to see of you have a boost leak somewhere, also how is your boost controller hooked up? what rpm do you start to spool and what rpm do you hit max boost?

 

but if he's running a mbc that should hold the boost past 15psi before it hits the wastegate spring. maybe the spring in the mbc doesn't support more than that? i know my mbc holds more than that. actually it minimally holds 11psi lol.
also what map sensor are you using?

 

Agreed. That's why I think he should check the spring to be sure it's what he thinks it is.

 

I dont have any boost leaks anywhere, I made a tester, pressurized the system, and fixed a couple small leaks. I hit full boost about 4800-5000. It gets to 15 fast then just stops flat and holds. I actually took the MBC off the wastegate port and ran nothing on the wastegate (experimenting!) and still only 15 psi. However I dont remeber if I heard the wastegate open then. But I know it is opening with the MBC hooked up to side port. And the MBC is hooked up right. I had several guys that know alot about turbos and have made 400-700whp and they dont know either. I am gonna try to take the air filter off and run an open Dp. and see what happens.

 

CHECK THE SPRING! :uhhok:

 

if you take the spring out you will not boost, check the spring man

 

I will probably just buy a 14.5 psi spring and try it. I know that if you dont have anything in the wastegate it wont boost, thats how I broke-in the motor,. Im just trying to narrow down all options. Now im leaning toward not a stiff enough spring in the wastegate.

 

:a:

Good for you. Odd that I mentioned exactly that three days ago. :a: