Stock R33 GTR Turbos Max Spring Pressure

[LiBRiUMz]

Hey guys,

I have a pair of stock rebuilt R33 GTR turbos with steel wheels (I'm planning on going to a single turbo precision 6266 setup next year; so no twin upgrade recommendations); I'm curious about the internal wastegate spring pressure on stock turbos? I am planning on running about 1.4-1.5bar on these rebuilt turbos until I get all of my single turbo bits and wondering if i'd need to size up the springs? Would I also need to drill out the oil supply a bit? Has anyone done this before and have any recommendations?

I heard the springs max out at about 15psi; just wanted some clarification on how to proceed before I put the turbos back into the car for the summer.

Thanks guys!

Edited March 11, 2021 by LiBRiUMz

[BK]

Stock 33GTR wastegate actuators are 14psi. Want more, run boost controller as you won't be replacing the actuator springs on the stock sealed units.

Don't stuff around with your oil feeds either.

[joshuaho96]

10 hours ago, BK said:

Stock 33GTR wastegate actuators are 14psi. Want more, run boost controller as you won't be replacing the actuator springs on the stock sealed units.

Don't stuff around with your oil feeds either.

Isn't the OEM boost spec somewhere around 0.85 kg/cm^2? That's with a constant wastegate solenoid duty cycle so there's no way it's that high.

[BK]

Come on bro, I thought you knew about stuff with these cars.

2 hours ago, joshuaho96 said:

Isn't the OEM boost spec somewhere around 0.85 kg/cm^2? That's with a constant wastegate solenoid duty cycle so there's no way it's that high.

14psi direct to actuators, As in run lines directly to the actuators. Flick the solenoid line restrictor olive out and see what happens - 14 - 15psi.

[Duncan]

interesting. R32 workshop manual says the actuator starts opening under direct pressure at 0.8 bar / 12 psi (EN-24)

[BK]

Flick the olive restrictor from out of a 32 or 33 solenoid feed and see what boost you get.

It will be 14-15psi, 1 bar if you will. It is common knowledge that the standard actuators are approx 1 bar.

If you really want to get technical they will be more than 14psi with just a regulated air compressor feed as they will not be fully open until at least 16psi as there is no exhaust pressure acting against them to keep them closed.

This is from real world testing by the way, not whatever the manual implies.

He has a 33 GTR. No restrictor it will be 14-15psi boost on actuator pressure.

I can't actually believe this is a debate.

[GTSBoy]

1 hour ago, BK said:

I can't actually believe this is a debate.

Especially considering that this has been generally known since the mid 90s.

[joshuaho96]

13 hours ago, BK said:

Come on bro, I thought you knew about stuff with these cars.

14psi direct to actuators, As in run lines directly to the actuators. Flick the solenoid line restrictor olive out and see what happens - 14 - 15psi.

I thought the boost solenoid is needed, as well as removing the boost restrictor to get to 1 bar of boost. I have a hard time reading the vacuum line diagram but isn't this just a normal 2 port boost setup where disconnecting the boost solenoid gives you wastegate spring pressure? I thought you need to have everything connected and functioning with the boost restrictor removed to see 1 bar of boost.

Edited March 12, 2021 by joshuaho96

[BK]

17 hours ago, Duncan said:

interesting. R32 workshop manual says the actuator starts opening under direct pressure at 0.8 bar / 12 psi (EN-24)

Yes correct, starts opening.

[LiBRiUMz]

Thanks for all of the helpful responses guys.

When setting up a wastegate, is the rule of thumb to have it set to within 5psi of the boost you're running? For example, if i'm running 23psi, should I set the spring preload to 18psi? I may just talk to my tuner and see what he recommends since it's a pain in the ass to access low mount twins lol

[GTSBoy]

Depends on how well it controls. Bleeding a 5psi actuator up to 15 psi would probably not work as nicely as bleeding a 15 psi actuator up to 25. But different kit will always work differently. Try it and see. Change it if it's not good.

[Murray_Calavera]

A good rule of thumb is with a 3 port mac valve, you can double your base spring pressure. 

So with a 1 bar wastegate spring, if you max out your boost controller you should get around 2 bar of boost.