Can I Lower Boost?

[Barrellboy]

My rb20 r32 I bought a while back has a highflowed rb25 turbo and a turbosmart boost controller when I turn the Mbc right down it doesn't lower the boost at all my buddy said its because the actuator might have been modified when the turbo was highflowed at per4manz? Is there anything I can do to turn down the boost other than buying a different actuator?

[Sklyn]

nope. can't run less than actuator pressure. well you could adjust the preload possibly but little change really.

How much are you running, and how much do you want?

Lowering the boost may require retuning depending on your set up.

replacing the actuator is pretty easy and cheap.

Edited December 14, 2013 by Sklyn

[Barrellboy]

How do you adjust the preload? It's running 16psi then tapers to 14. I bought it even though though it's not tuned, they have had it running like this with the highflow for 4 years and no problems but It runs a little bit rich and I think I can hear it pinging a tad under boost at high rpm so I wanted to lower the boost to maybe 10ish untill I got it tuned? It has a fmic and cat back but no fuel management or ecu

[Sklyn]

I'd remove the Mbc and just run actuator pressure, at least to see exactly what that offers. also eliminates any effect from the Mbc.

(actually I do just run this)

The stock ecu can't really handle a highflow so it is struggling, which is whats causing your problems. You need to replace the ecu or nistune it.

(i could be a little wrong as I don't have a 32, but assuming similar to 33)

running rich is good, how rich is it? sometimes in this case it runs too lean or not at all..

[Barrellboy]

I took the Mbc off when I put it over the pits a month ago and when I hit boost with out the Mbc attached it boosted too damn high I don't think I had any loose lines. So I put the Mbc back on and it's ok. It runs just a little bit rich like when I come on boost a bit of black smoke spews out the exhaust. How do I even go about getting it nistuned, I dont know where to start. But I know before I get it tuned it needs bigger fuel pump and a 3 inch down and dump pipe.

[Blackkers]

rich is better than lean when untuned but mate if you can hear it pinging I'd be pulling the CAS back a couple degrees until you get to a tuner; don't blow the motor

[R_34]

It's odd that when you removed the MBC you got more boost.

Are you sure that there was no leaks between the actuator and the pressure source when you removed it ?

Can you take pics of the actuator ?

Where the pressure is taken to feed the actuator ?

+1 with blackkers.

If you don't find a way to remove boost, retarding CAS will do the job. But performance and fuel economy will suffer, and you'll have to set the CAS again before getting any tune.

[Sklyn]

best advice for right now: a little less right foot! better safe than sorry.. there 'should' be no problem without the Mbc.

and yes, pics may help. pics are always welcome here =)