Boost Restrictor

[markc32]

on stock boost gauge with restrictor removed....whats the reading at full boost? i hve never boosted it full with restrictor out...

with restrictor on i only made 525mmhg/.7bar......

[Gordoskin]

I might be wrong but I've been told it runs at 1 bar

[Skym]

Without boost restrictor 0.9-1bar (13.23psi-14.7psi). Varies from car to car.

I hear the stock boost restrictor diameter is perfect for boost control. As far as I know, boost level is adjusted by ECU (boost duty maps). Some say it isn't. But as far as I know, S15, R33 25T, etc run similar boost restrictor / solenoid setup and boost level is controlled by ECU.

[RedGTR]

With the restrictor out, you will get just around one bar of boost. And it will reach the 7 on the gauge.

[archaeic_bloke]

wow can't believe how many of you don't know the facts...

its like one of the first things you learn (well i did anyways)....



- your ECU has no possible way of controlling boost, only timing, ignition and fuel...
- if you pull the boost restrictor the only thing left to limit the boost is actuator pressure from the turbos.. which are typically set for 1 bar pressure.. thats where you get the "1 bar " from... BUT... if the actuators are faulty, or not in top shape... you'll get over boosting or under boosting... and more commonly you'll get boost spikes
- boost spikes kill turbos with ceramic wheels... cause they come on hard and quick and are not controlled.

id like to back up what skym said though... by far the best way is to drill the oem soelnoid.. its the most acurate and least dangerous.


thats pretty much it.


i have a question though for those of you that pulled the restrictor out... did you connect the 2 lines together? or just block them off?

[RedGTR]

You must connect them as far as I know.

[sarazinj]

ok so i have a question, i am putting an rb26 into my r33, and only have vaccuum lines going from compressor housing to wastegate actuator, issues?

[natetheguy]

i have the restrictor out on my gtr now for 10,000km and the car has just over 100k kms and i have had no problems. I have also tested to see how much boost i get with an aftermarket guage and I peak to .95 bar and spike to 1 bar.

regarding if the ecu controls the boost, I think it does and I'll explain why.

when I took the gtr on hwy 1 through the mountains in BC this summer the car got really hot and I think that the engine got hot enough to put the car in either safe mode or it was running off a knock map because I could only boost to 0.5 bar untill I had turned the engine off and back on again.

also if you look at the rb26 vacuum diagram in the gtr manual it clearly states it has a "turbo pressure control solenoid" so it has to be 'controlled' by something.

[RedGTR]

indeed, nathaniel.

[sarazinj]

hmm, is that what the yellow sensor is on the intake manifold? because mine broke off during shipping of my motor