Is It Natural For Boost To Drop ~1psi With Ebc? Stock Turbo

[Andi]

Hey all,

I've recently installed my ProfecB2 EBC and have tuned it myself and was just wondering if it was normal for stock turbos to drop approximately 1psi towards redline even with the EBC? Or have I not tuned it properly? I've spent abit of time doing the tuning and have played around alot with the settings.

My mods are: turboback exhaust (split dump, hiflow cat, 3.5' trust catback), ss intake pipe, fmic with 2.5 piping, profecb2, bosch 040.

Should I spend some money and get it proerly tuned on a dyno by a professional or is this natural?

Cheers,

Andy

[fr0st]

1psi aint right... There is no way it should be able to even get to 1psi.

I'd say your missing a few fins off your exhaust turbine or you have one massive vacuum leak.

[Andi]

Sorry I think you mis-understood my post. I meant it would drop 1psi as in from 12psi to about 11psi & from 9psi to about 8psi towards redline.

[Cubes]

Some R32's drop boost some dont. The majority do but I have a feeling it has a little to do with the exhaust.

Mine has always dropped boost to approx 12.5psi regardless if I dialed in 13psi or 16psi.

At the time the tuner told me the only way to stop it dropping boost was to fit up a decent ebc that learns the boost curve and forces it to hold boost.

I bought a Blitz SBC-id. It had the usual manual mode where you enter a duty cycle and gain value. That mode would drop boost.

Auto mode you simply entered a gain value and then a boost pressure, the ebc would then slowly increase boost over 2-3 full throttle idle to redline rpm pulls. It held boost perfectly.

I cant remember what made me fiddle but I elongated hte actuators bolt up holes so that I could essentially adjust the actuator, tighter or looser.

Without an EBC or any form of boost control I was able to adjust to any boost level I liked and best of all it held boost to redline.

So I sold the ebc.

[Andi]

Thats quite a drop Cubes, mines only dropping 1psi so I'm not sure if it could be a problem with my settings or its natural as the turbo/wastegate actuaor is 8 years old.

Anybody else have any inputs?

[Sydneykid]

My first guess for the 12 psi to 11 psi would be that the standard turbo is running out of airflow, so it can't hold the boost.

The 9 to 8 would indicate otherwise, so my second guess would be a plumbing problem. Check the vacuum lines and keep them as short as possible, make sure that there are no leaks.

cheers

[Cubes]

Sk,

I've ran an R34 actuator and had the same.. Boost would drop to ~1.5psi over the actuators rated pressure. I forget what that was now but none the less I do remember that was the case.

I've always suspected a dump pipe issue in my case as the 3" pipe wasn't correctly stretched over the flange.. The top meets up but the bottom won't stretch well enough resulting in a ~10-15mm raise in a v shape in front of the turbine wheel.

[Andi]

Perhaps it IS normal for boost to drop abit then. Maybe I should jump on the dyno to see what the boost curve is like on a graph.

Cubes, when playing with teh actuator did you notice any poorer performance using that method as opposed to EBC? i.e. did boost come on slower or anyting like that?

Anybody else with an RB turbo notice their boost dropping?

[Cubes]

It felt like a bleeder, the ebc was sharper in how boost came on.

[bubba]

My boost drops from ~14psi to ~11psi but I too think that has something to do with my exhaust.. it came with a split dump and a 3" catback but a stock front pipe and standard cat 0.o will be getting a full split dump/front in one and a hiflo cat soon enough so we'll see if that makes any difference. Otherwise the 33 turbo will go on sooner.