Rb20 Manual Boost Controller

[Luke HCR32]

I bought my 1992 R32 GTS-T with a manual boost control already fitted between the compressor housing and wastegate actuator tucked under the turbo.

The controller doesn't seem to be in effect at the moment as the car is only running 7 psi (factory turbo), the time has come where I would like to increase the boost slightly however the position of the controlelr is extremely inconvenient.

I would like to extend the amount of hose between the housing and wastegate so that I can put the controller in a more accessible location but I have been told it will cause boost spikes.

How much can I extend this hose without causing significant boost spikes if I were to run 10psi.

Would boost spiking to say 12psi be harmful to my turbo?

[KiwiRS4T]

Just get rid of the controller. You should have a 10psi spring in the actuator so just run the pipe direct and you should get 10psi more or less.

[Luke HCR32]

Wouldn't that put the set up back to the factory configuration which still gives around 7 psi? The controller is aftermarket, I think it's branded GBH and is just a blue anodized knob with an alan bolt adjuster in it's center.

[zebra]

standard rb20 is 10psi

[GTSBoy]

It may be running 7 psi if someone has put an R33 turbo on there I suppose.

To answer the question directly, yes, just extend it. An extra bit of hose to bring the controller up behind the shock tower won't cause you any grief. And, for what it's worth, you can run 14 or 15 psi on an RB20 with no real motor/ECU related problems provided your fuel pump is up to scratch and you probably should have a good intercooler and exhaust (just to make sure that things are flowing freely and not causing too much heat). The only problem is that the old ceramic turbos are known to die faster/more frequently when running at higher boosts. So, if you want to turn it up to 12 psi, that's actually a reasonably safe level to run at - with the unknowable extra risk of the turbo cacking itself. And the risk with that is that they sometimes kill the motor when they go.

I have been running a stock 1993 RB20 turbo at 14+psi for nearly 10 years and >100000km and it is still going fine.

[Luke HCR32]

I have a 300 by 600 aluminium tube and fin front mount, bosch in tank 040 and 3 inch dump to 3 inch exhaust.

I am pretty sure it's an RB20 turbo as I have bought a second hand RB20 turbo to replace it as it shits oil and they look the same to me, how can i tell the difference between the two easily?

I would consider turning the boost up to 12 pound if it is considered safe, for some reason I was under the impression that standard RB20 turbo pressure was 7 pound. I did calculate what my boost gauge peaks at to be roughly 7 pound, maybe i stuffed up.

[Luke HCR32]

Why would the presence of a controller give me less boost rather than more?

[Luke HCR32]

Is there a difference between a standard gts-t and an m-spec turbo? I've heard people talk about m-spec turbos before but I'm not sure if they were a myth.

[GTSBoy]

10 psi is it (for RB20s).

It could have an R33 actuator on it even if the turbo is RB20. People take RB20 actuators for RB25s all the time. It doesn't matter too much. A gated boost controller on a 7psi actuator won't be much worse than on a 10 psi actuator. (assuming you really have 7psi happening).

And there is no way that a boost controller can make a 10psi actuator yield 7psi. So either different actuator, or something else is wrong. If something else is wrong, then you really need to find and fix before boosting it up, lest you blow something up.

Edited October 9, 2011 by GTSBoy

[Luke HCR32]

I think I stuffed up my units, my factory gauge does peak at approximately 500mmHg (Approx 10psi) from memory. I think I used kg/cm^2 by accident, and I'm supposed to be an engineer!

I've heard of people experiencing boost above 10psi with 3 inch setups, not sure if I have anything more than 10 psi but it might just be that my gauge isn't accurate enough to tell me.

I reckon i will go with extending the hose and setting boost to 12psi with my controller, want to allow for spikes and don't really want to risk the turbo at 14 psi at this stage.

I do have a secondary boost gauge in my drivers side air vent, problem is it's hard to see down below the steering wheel and I think it reads in kPa or bars (can't check as I'm away from home), so i have nothing to read psi directly (which is what I'm most comfortable with).

[Rolls]

You can get as high as 13psi with no boost controller on an rb20, free flowing exhaust, free flowing intake will easily spike up to 13psi and bleed back to 9psi by redline.

In fact all the rb20s with 3" exhausts I've had have run about 13psi with a huge pod, fmic and 3" exhaust.

Just putting the bleed valve on with the lowest setting can cause spiking if you are already running 10psi on the tiny stock turbo, make the hosing as short as possible otherwise you will risk not being able to run less than 15psi.

I had a turboshit bleed valve that wouldn't run less than 15psi with f**k all hose on it, so be careful. If you want more power just get an rb25 turbo, you won't really make much more running it at 13psi over 10psi.

Edited October 11, 2011 by Rolls

[Luke HCR32]

I've just had a proper look at the controller today and it seems that it is not a ball and spring type valve, rather just a needle that is screwed in and out to restrict access to a bypass port, does this make a difference?

[GTScotT]

My vacuum lines run from just before my throttle all the way over to my actuator, on my SR20. Its quite a distance, probably close to two meters total.

Works perfectly find and have done a few like that in the past. No spike issues.

[GTSBoy]

I've just had a proper look at the controller today and it seems that it is not a ball and spring type valve, rather just a needle that is screwed in and out to restrict access to a bypass port, does this make a difference?

Most manual boost controllers are essentially nothing more than a needle valve that controls how much boost is bled off through a vent. The better ones add the ball and spring on top of that so that they are gated (ie they do not pass any pressure signal to the actuator until they reach some minimum threshold boost - this is to reduce wastegate creep).

If yours is not even gated, piss it off in favour of something decent.

I built the Autospeed boost controller many years ago and am still using it. Consists of a pneumatics pressure regulator, a pneumatics relief valve (both Norgren 1/4" stuff) and a one way valve. Is located on hoses that run about 600mm from comp cover and back to actuator, just up behind the passenger's shock tower. Rock solid boost control and nicely adjustable - not that I ever adjust it. But the best adjustability is not just to the overall boost level but to the threshold before which it opens up, courtesy of the adjustable relief valve. Cheap at the time I built it (~$100) and at least as good, if not better than any of the simple gated boost controllers. Just a bit more bulky, and more work to build and fit.

You could build the same for similar money today, or buy one of the many and various gated manual controllers for <$100 easy.

[zebra]

or buy a turbo-tech one off ebay for $30

[Rolls]

stop being a pussy and just run infinite boost, all the cool kids do it, just remove the line entirely

[Luke HCR32]

Yeah was just looking at the Turbotech, might email the guy after I get this set up running and see how shit it is

[Luke HCR32]

A non gated controller shouldn't creep any more than the stock setup should it?

[Rolls]

A non gated controller shouldn't creep any more than the stock setup should it?

If the hoses are really long it could.

[Luke HCR32]

Nah I've kept the hoses quite short, might have it running tonight