FPR + Boost = Busted FPR

[Wicked]

My buddy Steven has just added a Procharger to his 87 GT. He had my old Aeromotive FPR on it and after the blower install and seeing some boost he started experiencing a extreme rich condition to the point it would not run without throttling it. I told him to check the vacuum lines to the AFPR and FMU to see if maybe the diaphragms had busted. Sure enough that's what happened. It was a good guess but I've never actually seen it before this.

Is this common? Is there a AFPR that is better suited for boosted applications?

Thanks.

[QWKSNKE]

How much boost was he running? I don't think that it is very common. Could had something to do with age but I wouldn't have thought that particular line would throw out enough positive air to actually burst the diaphragm.

[Wicked]

How much boost was he running? I don't think that it is very common. Could had something to do with age but I wouldn't have thought that particular line would throw out enough positive air to actually burst the diaphragm.

Well pressure is pressure, so size of the line won't matter.

He made a pull to 6000rpm or so. He has a 9 psi pulley installed and only saw 7 psi I think, this is an HCI car. He has a voucher for a 11 psi pulley that he will install before taking it to the dyno, should be good for at least 9psi.

He said it even ran fine after that at least for a few miles, so maybe it was more age related and not boost. I bought the AFPR in about 99 or so, so its a few years old.

[Sendero]

Well pressure is pressure, so size of the line won't matter.


But volume will...

[QWKSNKE]

But volume will...


exactly

[Wicked]

:nono:

Size of the diaphragm is the only thing that will dictate what kind of force is being caused by the vacuum. Volume is not an issue considering there is no real flow rate. When you pull a vacuum on your FPR, the air or lack thereof is static under a constant vacuum.

Nathan, haven't you had physics? :jester:

[slvrbullit]

The failure was more likely to age than Boost. A 6yo piece of rubber the has been exposed to gas all its life wont last forever. I am on my 2nd AFPR on my car, one was a paxton and the other is still in use which is an aeromotive.

[Italian LX]

Well pressure is pressure, so size of the line won't matter...
Yes it does... a larger line will allow it to reach that pressure a lot quicker. If line size doesn't matter, maybe you could change all your intake tubing to 1" in order to save space. :booty:


Maybe you should go back and take physics again, Brad. :P

[Wicked]

Yes it does... a larger line will allow it to reach that pressure a lot quicker. If line size doesn't matter, maybe you could change all your intake tubing to 1" in order to save space. :booty:


Maybe you should go back and take physics again, Brad. :P

That's what I figured too Tommy.

Brian, you're wrong. A vacuum line and intake hose are two different things. A vacuum line is small for quick response, large flow volume is not needed. A larger vacuum line would take longer time to reach boost or vacuum and therefore would delay the necessary tune changes.

My intake hose is big because large flow volume is needed.

[93Cobra#2771]

Even stock FPR can/do go bad over time, with or without boost. Just one of those things...