Electronic Boost Controller

[Lextreme II]

Hey Gang,

Anyone know if there is an electronic boost control unit that is capable of controlling two different boost. For example, i would like to run 25 psi on the twin turbo system and I would like to have the exhaust bypass wastegate open between 12-15 psi

 

[cribbj]

Many of us from the Supra crowd abandoned the EBC's and went to simple ball & spring type manual boost controllers. I run a simple Norgren pressure regulator type boost controller on my '94 which still has the stock twins. This was described in detail by Julian Edgar of Autospeed a few years back and it works very well and is dead reliable. You might want to consider using a version of these MBC's in your project, as we've found them to be as good as, and sometimes better than the EBC's.

You could buy & install 2-3 of these MBC's for half the cost of an EBC, and the only thing you would sacrifice would be cockpit adjustability.
John

 

[Lextreme II]

John,

MBC is Manual Boost Controller right? I have problem with it. This damn thing is either 0 boost or all boost. Its all or none type of control.

 

[cribbj]

David, the MBC functions nearly the same as an EBC in that it keeps the wastegate closed until a certain pressure, then it opens and tries to control that pressure. The turbo spools up normally, and only when the boost exceeds the setting on the MBC does it open the WG. In fact, the WG does start creeping open early, because the MBC is actually a proportional device. Some people don't like this, so they've put an adjustable pressure check valve in series with the MBC (Julian Edgar did this). But IMHO the MBC is definitely not a 0 or 100% boost device. Have you tried one?

John

 

[Lextreme II]

Yes, i have one and not too please with it. I have been playing around with the setting, but dont seen to get the setting i wanted. With less then 1/16th of the turn, the boost is like night and day. Stock wastegate (10 psi) or over 17 psi.

 

[cribbj]

Hmm, maybe as someone else suggested, your WG could be too small for the system, and it's not able to control well and you're seeing boost creep? Also, we've found that smaller turbo's are actually harder to control boost than large ones, because more exhaust needs to be bypassed to the WG to keep the little suckers under control. So the WG is constantly stroking - I've seen this with the little T61 that's on my '97 Supra, whereas the guys with the T70's and bigger don't have this problem.

Also, maybe it's the configuration of your MBC - some guys connect it directly inline between the turbo compressor and the WG, so, in theory anyway, this line is "blocked" until the MBC opens up. Others connect it via a bleeder tee, and this results in a smoother operation, but it "wastes" boost pressure.

Don't give up on it yet; many of us who had expensive EBC's before, now prefer the set & forget advantages of the MBC. Even some of the guys with the standalone AEM ECU are still using MBC's for their boost control!

John

 

[R-Jay]

end of the day, i always liked to have boost control at the flick of a switch (or press of a button)...... never liked mbc's due to boost creep and spikes.... after my first few attempts, i gave up and just went with an AVCR... pricey, but did the job quite nicely with a few options to play with....