We installed the waste gate that came with my kit, and then the manual controller. In second gear I saw 13# of boost and let off. My question is why is the boost so high if the MBC is turned all the way down..?

 

It depends. Some aftermarket wastegates have stiff springs that won't open until you reach a certain pressure. If you have one of these, the boost controller won't be able to lower the boost to below that.

Sometimes you can have another sort of trouble - the wastegate doesn't flow enough to actually limit boost. This usually only happens on a too-small turbo or wastegate.

 

You need to find the lowest psi rated spring and go from there. The bigger the turbo the bigger the wastegate you will need to run low boost.

 

I was told that the waste gate (part a HP kit) came with an 8-9# spring. I assumed that if i wanted more boost than I'd just crank up the MBC...... Is it possible that I have something hooked up wrong and should I bypass the MBC..???

 

TTT

 

you should try just the wg with no boost controller. I have a tial 38mm wg with a .5 spring and it gets to around 7.5. I put a boost controller on and it went to 11 but looked to go higher. I took it off so I don't break anything

 

cause the .5 spirng is a .5 bar = 7.5lbs +/-...

 

Do not mean to raise up an old thread here but this raises a question for me.... My whole Kit came with one BOV and both turbos having waste gates on them and a MBC... I know that I need to run the BOV and waste gates but the MBC?? I thought that was the purpose of the waste gates was to limit boost. From what I've been reading on this fabulous forum LOL is that I can run just the BOV and the waste gates on the turbos. Which is what I prefer, due to this being a toy\street machine I don't see the need to control the boost to that extent. what's your opinions?

 

Only install the MBC if you want more boost than what you get by just running spring pressure on the gates.

 

Ok got it. Thank you!

 

Think of the MBC as another way to tune the gates, totally up to the you if you want one or not.

 

avoid manual boost controllers at all costs.

If you want boost control, get a powerful electronic boost controller, or at least a well known unit.
My favorite 'cheapest best' is Greddy Profec-B Spec-II

It has a start boost function, which keeps the gate from seeing any pressure until some set number, which is very helpful.
Gate springs have a 'cracking' pressure, which is when they begin to open way before the final set boost is reached. This slows down the turbo spool. It can be dramatic at higher boost pressure with stiffer spring rates. Thus the 'start boost' allows the gate to stay fully closed during the time when it would normally be cracking open and slowing down your turbo spool.

 

Ok awesome! I’ll look into that, I appreciate the advice.