I've got a home depot mbc and I wanted to use it to spool up my turbo faster. I've got an internal wastegate set at 8 psi. But I want it to reach that faster. So I'm going to use the mbc, however, how do I set it to be lower than the wastegate?

Should I just keep turning it tighter and tighter until it boost's more than the 8 psi, then turn it back?

I was just wondering how others did this.

 

you cant go lower than the value of the sping in the wastegate.

 

Yes, I realize that. But I'd just like to use the mbc to keep the wastegate closed for a longer period of time, so it doesn't leak exhuast that could be used to spool the turbo. Thus creating a faster spool up to what my wategate is set at.

 

Well I would think whatever the lowest possible setting on the manual controller you could have... as long as the mbc does in fact work and does not leak boost or spike....

I prefer the Turbo XS over the do it yourself mbc...

Just my .02 cents.

 

the wastegate will stay SHUT until that boost is reached, then it will open... The only thing that the MBC will do is UP the boost...

 

I read this to several times on this board. I searched for hours and never found a definitive answer regarding this topic...

 

Sorry, i think i know what you are asking about now. I think you can only do this when you are trying to boost above the spring rate of the wastegate. you can keep the wastegate closed all the way and then open when the desired boost is reached. But with the stock spring rate, the door will stay closed till it is reached. hopefully this makes sense.

 

Can someone clarify that then.

Does the wastegate stay 100% shut until the desired boost is reached, and then it opens.

Or does it creap open....let's say you've got a wastegate that is set for 10 psi. At 8 psi, would wastegate start to open so that by 10 psi it will be fully open?

 

Many wastegates will open gradually near the preset boost level to prevent overboosting. This is what fuzzy logic boost controllers try to prevent. With fuzzy logic, the boost controller actually learns the boost curve of the combonation. Then, it calculates how late it can wait to open the wastegate without overboosting. This helps very little on spool time, but it's a step in the right direction. The only problem with fuzzy logic boost controllers is that anytime the setup is changed, they should be reprogrammed and they are sometimes tough to calibrate. Another advantage is that when it's set for 1 bar (example), it will run 1 bar regardless of temp or other factors, where many other boost controllers will run a few more psi when it's cold and a few less when it's hot.

 

So does a boost controller help with keeping the wastegate closed until the desired boost?

I thought that it would. But it seems like everyone thinks that a boost controller is only used to increase boost.

Is anyone using a mbc to speed up spool time?

 

Run an adjustible pressure relief valve before your MBC.

You can use it to control creep along with spike.

 

I have experineced first hand faster spool with an mbc and I know plenty of others have too. Some wastegates seem to be worse than others at starting to open early so the gains may be application specific but all wastegates will start to open before they are at their set level. You were correct in your first post the only way to get it right would be to turn it up until the boost slightly raises then turn it back slightly.