Has anyone installed a manual boost controller onto their Evo? If so, where did you tap in to do the install? Any pics would be helpful. Thanks.

 

There's a vacuum line that runs to the turbo wastegate housing its what controls the boost pressure, you just put the controller somwhere inline. A boost controller really only acts as a restriction in the line, the more its restricted, the higher the boost level (within mechanical limits of the Wastegate and the turbo/engine that is)

BTW, Did anyone determine if that 19psi dropping to 16.5 psi on the turbo have any relationship with the Blowoff valve leaking at about 16psi?

Also, does the boost controller keep boost steady? Or does it just move the window where the boost falls off to a RPM range much higher so its not within the engines operating range?

 

I just read something in another thread about a grommet mod which just confused the hell out of me.. Because it goes contrary to what I was told about how the wastegate actuator worked.. Does the boost controller replace this component?? or does it work in concert with it?? If it does, then in theory you could only reduce boost by restricting it more.. But what I gathered from other posts was by introducing a small restriction, it could allow the actuator to open the wastegate later, therefore increasing boost.. Can someone clarify this a bit? I'd hate to give out wrong information to anyone..

On second thought, does that component act as a restriction in order to place a consistent 'pressure' to eliminate spiking and unstable boost levels??

 

There are probably tons of good tech articles out there, but I don't know where they are off hand.

In the olden days, MBCs were "bleeder" type valves that bled off air to increase the boost levels... some even used vacumn tees in line as a cheap and effective way to raise boost levels. A bad MBC many people used were fish tank/aquarium valves and MANY people blew up their engines using them.

On the 2g DSMs, there was this mod on the stock BCS that you could remove part of the inner sleeve of the nipple, basically increase the diameter of the nipple, and it would raise the boost about 1 psi or so. Not sure if this is possible with the EVO BCS.

New style MBCs are ball and spring which help regulate boost spikes etc... basically they bleed off a certain amount of air that fools the waste gate into staying closed until a pre-set boost level is reached at which the waste gate will open and regulate the boost from going any higher.

Out of all the boost controllers I have had (electronic and manual), this one is by far my favorite AND it also happens to be very well priced. www.joepmbc.com

HTH

 

There is a lot of good information regarding this and other subjects at www.lancerregister.com.
Cheers,

 

Wow.. That joe's stuff is pretty cool, I was impressed with the E-MBC hybrid.. Simplicity of a MBC, with the ability to adjust inside the car.. and cheap, I may just have to get one.. I just picked up the Hallman, it looks nicer and its anodized black so its easier to hide in an inconspicous location. But I haven't installed it yet.

 

Highly doubt it's the BOV. Almost all turbocharged cars drop off boost like that. It doesnt mean the turbo is slowing down at all, it means the vacuum (negative) pressure in the engine is offsetting the boost more and more as the RPMs go up. So, if you run 20psi to redline......the turbo is actually spinning faster at redline than at 3500 to provide the 20psi. Are you having the dropoff problem with your MBC too?

I have no doubt though that a new BOV will give you more stable boost pressure. The plastic valves arent that good.

Rob

 

Don't know yet.. Haven't installed it.. I was more curious about how it allowed the dropoff in stock form.

 

Go to Road Race Engineering site for tech articles. They have a lot of stuff there.

 

In the past my experience with turbos was the boost was restricted by the exhaust system, manifold or whatnot, and the Wastegate would kick in fairly close to those levels, so you rarely could go higher without upgrading the exhaust and intake first.. (Anyone remember the Turbo 89 Isuzu Impulse, Lotus tuned suspension?? I loved that car, but nobody made anything for it at the time but it was rear drive, and it was quick for what it was back then)

 

Why does everyone round the 18.4 PSI to 19 PSI? According to Mitsubishi the max PSI is 18.4 @ 3500 and drops down after that.

Reference:

http://ryan.nebraska.edu/EVO2.avi @ 11:00

 

Actually I dunno.. Although my gauge reads 19.. Rounding error?? Mine peaks at 19 quickly, and falls off to about 16.5 really quickly..

 

Using the JoeP MBC, mine runs up to 20 psi, then ramps down to 18 at redline. When I changed to the complete Buschur 3" exhaust I had to pull more boost, as it had gone to 22 psi due to the freer flow. So I dialed it back to my daily use 20.

 

If I am not mistaken, doesn't the Evo 8 from factory was designed and made so that it would peak boost at 18-19 psi and then drop to 16 psi. With a MBC you can stop it from dropping to 16 psi because you remove the control the computer had over the boost levels.

 

I would believe you are right becuase the controller takes the place of the seleniod and you disconnect it...at least thats what I did.