I bought a turboXs mbc (the cheap one rated to like 10-12 psi) and was gonna but it on my recently reman. I am running the full turbo racing beat exhaust, rb fcd, K&N drop in and boost is quite healthy. I had a factory speced 13b turbo just installed and I know now that along with a fual pump rewire and my wideband and boost gauge I still need to keep my boost at or under10 (12lbs max).

with that said. I was told that the turboXs mbc WONT LIMIT THE BOOST. that MBC's only elevate boost. Why is that.? BTW. the waste gate is ported.

How can I keep my boost in thaqt safe range without having to dig into the engine again.

thanks guys

jared

 

boost cannot be lowered with a boost controler. if you run 12psi off the wastegate then you cant run any lower than 12psi. the only way to drop the boost levels is to port the wastegate. then if your boost lowers enough, you can raise it back up to whatever you want.

 

no, porting your wastegate is NOT the only way to limit boost. Place restrictions in your exhaust/intake (mainly intake) and you'll see a bit of lowering of boost

 

for all those that cant read

 

thanks dudes, I think the MBC doesnt limit since once it opens say at 12 lbs. it can still keep boosting (it only open the pathway then). Just b/c its not opening until 12 lbs that would mean that to limit boost. you would need to dump the wastegate like, fully, in order to keep it there right.

do you think?

 

the MBC doesn't limit the boost necessarily.. BUT if you've got a stock controlled turbo (say, a Series 5) that has the Duty Solenoid Valve, you can ditch that sucker in favor of the MBC, which allows you to go from the stock (mechanical) setting of the wastegate spring of 5.5psi (all TurboII's are mechanically sprung at 5.5psi), up to whatever amount the boost controller will let you set it at.

If you set it at 6 psi, then (in theory) the wastegate won't see pressure until 6 psi, then it'll see just enough to keep it running @ only 6 psi, assuming the wastegate CAN KEEP UP. However, if you had the stock Duty Solenoid Valve, it would boost to 5.5 and want to open, the ECU would use the DSV to bleed off some pressure to the wastegate signal line, and it would run up to the stock boost level of something around 8 psi. That's the only way you can really "limit" boost on a TurboII that I know of. You can't lower it beyond 5.5psi, and as long as the wastegate can keep up, you CAN keep it at 5.5 all day if you want.

 

thanks guys

jared


hey Barwick, what is the logo on you sig, greek or something?

 

If you need it I can give you details on how I HUGELY ported my WG using a exhaust valve as a new "door"

 

that would be sweet dude

jared