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I'll start off with mods:

RB20DET

R33 S1 Turbo (R32 actuator)

JJR FMIC

GFB Stealth FX BOV

POD

When I was running my standard R32 turbo, FMIC and POD, on my boost gauge it would read 10psi with standard BOV. Once I fitted the GFB one, boost rose to 12psi all the way to redline.

Now that I have fitted the R33 turbo with R32 acuator (no boost controller whatsoever) boost under full load at about 5-6000rpm hits a peak of 15psi.

I've tee'd the acuator hose into the hose that comes off the crossover pipe to the bov. It's about 30cm long and I've got a feeling this might be a cause rather then the standard r32 acuator as it wasn't a problem before??

Cheers.

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he has already said what causes it..

it's the extra long hose to the actuator.

if it was a short hose from the actuator to say the comp cover like the stock R32 turbo or even to the intercooler pipe near the turbo, boost will be around 11-12psi as per stock setup.

now go get a remap of the stock ECU.

I think CEFFIE on these forums should do this for a living.

he know's the RB20 well and can get some decent numbers form them.

free plug for CEFFIE

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it's not the culprit. Like I said, I have 120 cm of vac line between my actuator and the boost source. Runs 11 psi day in day out

We posted at almost the same time..

I think it has something to do with my BOV because checked clearances of the acuator before fitment. I'm going to put stock BOV on and see what reading i get.

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Definitely nothing to do with bov.

Everything to do with boost control. That being the boost source, actuator, the flapper and the dump. My bets are on the jjr dump fouling with the wastegate slightly.

The rb20 turbo's are known for falling over at high rev's; they drop boost.

The rb25 turbo's are just that little bit bigger on the compressor side so they require better wastegate flow to keep boost under wraps.

A bloke only the other week had the same issue with his split dump. It wasn't until he removed the dump that he realised the dump was indeed preventing the wastegate from opening fully.

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If you read my previous post, i dummy fitted the r33 turbo with r32 acuator to the dump prior to installation and it didnt foul.

I even ran the dump on the standard rb20 turbo with rb20 acuator without and problems. Held 12psi the hole time.

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If you read my previous post, i dummy fitted the r33 turbo with r32 acuator to the dump prior to installation and it didnt foul.

I even ran the dump on the standard rb20 turbo with rb20 acuator without and problems. Held 12psi the hole time.

You said checked the clearances of the actuator. The actuator is not the wastegate :D

With regards to the rb20 turbo; smaller compressor; they are known for falling over at high rpm so its unlikely you would see it overboosting easily.

The rb25 turbo on the other hand is different kettle of fish, flowing more air making more power more air has to be bypassed.

I really think you should go back and have another look at the dump/wastegate.

Wire the wastegate completely open and see if it still makes boost up top.

Obviously it will be as laggy as shiet but up over 5500-6000rpm you will see it making some boost; how much boost 15psi? 6psi? If it still makes the 15psi then its 10000000% the dump fouling the wastegate. Even slightly fouling can cause problems.

Long runs of hose to the actuator creates issues with boost spike.

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Wire the wastegate completely open and see if it still makes boost up top.

Obviously it will be as laggy as shiet but up over 5500-6000rpm you will see it making some boost; how much boost 15psi? 6psi?

Ok I'll check this this arvo/tonight. Can I disconnect the actuator pipe and wire the flap open? Should I then see the regulated 10-12psi at 5-6000 rpm?

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