Wastegate setting??

[lilskyline240]

well after fixing all my boost leaks, installing my Nismo FPR, and finally gettin the car timed correctly my rb still only make 5psi of boost. After thinking about it this turbo is from a vg30det for australia that i got from a guy on zilvia. Larger wheel and exhaust housing than the stock rb25 turbo. Im wondering if the stock wastegate on the turbo is only set at 5psi? So i went and pressure checked my motor like i would to check for boost leaks but this time i was seeing what PSI the wastegate would open. Its starting to open at like 4psi. Im guessing that means the wastegate has a 5psi spring possibly?

anyone wanna chime in on this

[240z4u]

Sounds like a 5 psi gate.

Evan

[lilskyline240]

thats what i was thinking man. i figured it would start opening at around 6psi if it was a 7psi gate

[WhatsADSM]

Sounds like a small WG spring.. Yea they start to crack open usually 1-2psi before the set point. Also as a side note the general rule of thumb is about 2x the wastegate spring pressure is going to be controllable with a MBC, but above that you *might* find that the boost wants to oscillate.

[lilskyline240]

yeah i know that. im still on motor break in right now so i dont really want anything over 10psi anyways. i just wanna get it to the stock 7psi setting for breakin right now. It feels like a dog at 5

[Joe]

make a manual boost controller

i used one for years and never had a problem

http://www.geocities.com/chmwatson/FAQs/mbc.html

[mello88]

To the OP, sounds like a 5psi spring on the WG. Can you swap your WG actuator over from the 25 turbo (7psi)? FYI the 20 turbo uses a 10psi WGA if you're looking for a little more without running a MBC/EBC...

Sounds like a small WG spring.. Yea they start to crack open usually 1-2psi before the set point. Also as a side note the general rule of thumb is about 2x the wastegate spring pressure is going to be controllable with a MBC, but above that you *might* find that the boost wants to oscillate.

Interesting post so I'ma threadjack a lil.. I have a HKS external gate on my manifold with a 5psi spring. I'm planning to run 12-14psi (t3/t04e) and would rather not replace the spring if I don't have to... Will it have stable boost with an EBC and 5psi spring? Or should I definitely find a stiffer replacement spring to run with the EBC? I don't believe in MBCs and never going to run one on my car.

[lilskyline240]

ive never had a problem with MBC's working for me but have seen many people who have EBC's have a ton of problems with them

[WhatsADSM]

To the OP, sounds like a 5psi spring on the WG. Can you swap your WG actuator over from the 25 turbo (7psi)? FYI the 20 turbo uses a 10psi WGA if you're looking for a little more without running a MBC/EBC...

Interesting post so I'ma threadjack a lil.. I have a HKS external gate on my manifold with a 5psi spring. I'm planning to run 12-14psi (t3/t04e) and would rather not replace the spring if I don't have to... Will it have stable boost with an EBC and 5psi spring? Or should I definitely find a stiffer replacement spring to run with the EBC? I don't believe in MBCs and never going to run one on my car.

It actually depends on a lot on the dynamics of the engine, turbo size, BC, and wastegate as they are all part of the "control loop".... hence the 2x thing is just a rule of thumb.

Personally I would replace the spring to something like a .5 bar or .8bar or something, that way you can be confident about your boost control.... especially considering the relatively cheap cost of the spring.

However with that said you can always give it a shot and you *may* be able to control it, it will just depend on your particular setup. Just take it slow on the EBC duty cycle once you get over ~10psi.

[lilskyline240]

im running an internal wastegate so i cant swap out the spring. i need to find a rb20 wastegate

[240z4u]

I am running a rock solid 20psi on a MBC thanks to this guy ^^

Works way better then my failing greddy profec A

[lilskyline240]

thats the exact same boost controller i always use evan. works great and only costs like 10 bucks to make