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ok - Im not sure about the factory boost control setup on the 33 gtst but on a 34 gtt there are 2 restrictors in place, if you remove either 1 of them or both, power will drop significantly - you can feel the difference [boost gauge used to verify too].

Plumbing in a pneumatic [bleed] valve to introduce MORE restriction results in a boost increase [again boost gauge used to verify but more power is evident by feel]...Its not rocket science ~ Aussie Home Loans

ZOOM magazine documented the removal of a restrictor but it applied to the GTR only which has a different setup and does cause a boost increase...when removed.

Also 21st Century Performance, Julian Edgar documents this "mod".

pp 179: By inserting a restriction on the compressor side of the T-piece, the bleed needs to flow only a small amount of air to make a large difference to the pressure seen by the wastegate diaphragm
ok - Im not sure about the factory boost control setup on the 33 gtst but on a 34 gtt there are 2 restrictors in place, if you remove either 1 of them or both, power will drop significantly - you can feel the difference [boost gauge used to verify too].

NismoR34 is referring to the hose with yellow stripe going into the boost control solenoid.I can back that up because I was there too.After removing the restrictors boost gauge indicated LESS boost then previously.

Hey NismoR34,Long time no see!

This is a touchy subject isn't it!!! From my knowledge GTR's have a restrictor and not GTS-T's, as I've previously owned a GTS-T.

I don't want to get into this argument but after reading HPI GT-R special edition no.2 (see below) I removed my restrictor and yes I received a very stable 14.5PSI.

I have scanned page 33 from this magazine if anyone is interested. BTW I'm not saying that magazines are gospel or anything but this info is from a pretty reputable workshop.

People have to realise that this mod is POSSIBLY ONLY WORKS on GTR,even though both GTR and GTST have restritors.If your car doesnt have a restrictor,the hose was probably changed to a normal one at some stage BEFORE you bought the car.

Whats so hard to understand?

  • 3 weeks later...

Well, I took the restrictor out of the pipe that leads from the intake tubing to the t piece and noticed no difference. I put it back in again, as I read in an article about an S15 (HPI i think) that the restrictor makes the boost 'ramp up' quicker. They also soldered up the restrictor and redrilled it smaller...apparently this gives a better result. This car was running an electronic boost control.

The restrictor does exist on the R33 gtst. I found it on mine and my 'line is 100% stock. Attached is a pic looking into the hose.

However, removing it had absolute NO positive effect on boost. I tried replacing the restrictor with a Festo neumatic flow control valve and found that as I CLOSED the valved, boost seemed to come on stronger at first (more spike). However, the result was unsatisfactory and I didn't go further because I was worried that I might blow the turbo if I inadvertently closed it completlely. I now have the Festo valve placed in parallel with the factory solenoid and the result is somewhat satisfactory.

Just another pic to explain why the restrictor actually helps to increase boost with the setup on an R33 gtst. Also, when the solenoid is closed (ie. no bleed), the restrictor provides a wastegate pressure delay and thus allowing boost to build up more quickly than if it were not there. The last diagram is a guess on why removing (a different) restrictor increases boost on the GTR, because of its different location. Please correct me if I'm wrong.

Cheers.

dont you get defected for bleed valves???

Originally posted by wasted

don't even consider, such a stupid modification as this. as rev210 said, you will gain NO more boost, i'd bet this guy has damaged his own car, and just wants to see it happen to others. if you want more boost just go and buy a bleed valve ~$100.

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