GQ_Style
01-16-2004, 04:51 AM
I've been reading and reading through the archives and I think I finally understand why even though the Vortech/PD S/C kits use the same identical Bosch ByPass Valve as the AA Rotrex S/C kit, the Vortech/PD kits' BPV seems to be virtually quiet whereas the AA Rotrex kit's BPV seems rather, ahem, loud.
The V/PD S/C kits usually have much shorter plumbing due to not having an intercooler/aftercooler. Even with an aftercooler, the plumbing is much shorter than with an intercooler setup. The BPV almost always attaches directly from one pipe to another with no excess tubing except what is needed to connect the ends together, usually about 2 inches. The air goes from the compressed side and travels about 4 inches to the inlet side.
The AA Rotrex S/C kit has a much more lengthy plumbing system due to the front mount ic. The BPV actually vents back to the intake via a connector tube that is at least 2 feet long. I think this tube and all the free space that this air gets to rush through is causing the additonal sound of whosh or loud sshhhhhhh. Additionally, since the system is larger, there is more compressed air (volume) venting out back around the system.
I've listened to another local guy with a RMS S/C that was using a GFB Hybrid BOV, and honestly, my stock Bosch BPV was a tad louder on my AA S/C system. The same Bosch BPV on his RMS S/C kit was totally quiet (according to the other guy) and sounded nothing like what it does on my car with the AA S/C kit. My AA S/C would give a loud "whoosh", his RMS S/C would give a noticeable but definitely more subtle "shhhhhhh".
And yes I've checked, I am holding boost fine. My BPV is not torn or leaking. My Bosch BPV is operating, it appears, as it would and should. I've considered getting a Hybrid BOV but now that I see that my stock BPV is already louder than the aftermarket ones, I probably will spend my money elsewhere.
Also, I think I understand why the BOV, venting to atmosphere, is bad for a S/C car. You'll run rich the instant that metered air escapes from the closed system. Your car ECU will compensate by leaning out your overall mixture, skewing your a/f toward lean. This lean condition will cause problems in the long run.
Boy, all this research just to NOT buy something and stick with what the kit came with. Hope this helps someone else thinking the same thing as me.
The V/PD S/C kits usually have much shorter plumbing due to not having an intercooler/aftercooler. Even with an aftercooler, the plumbing is much shorter than with an intercooler setup. The BPV almost always attaches directly from one pipe to another with no excess tubing except what is needed to connect the ends together, usually about 2 inches. The air goes from the compressed side and travels about 4 inches to the inlet side.
The AA Rotrex S/C kit has a much more lengthy plumbing system due to the front mount ic. The BPV actually vents back to the intake via a connector tube that is at least 2 feet long. I think this tube and all the free space that this air gets to rush through is causing the additonal sound of whosh or loud sshhhhhhh. Additionally, since the system is larger, there is more compressed air (volume) venting out back around the system.
I've listened to another local guy with a RMS S/C that was using a GFB Hybrid BOV, and honestly, my stock Bosch BPV was a tad louder on my AA S/C system. The same Bosch BPV on his RMS S/C kit was totally quiet (according to the other guy) and sounded nothing like what it does on my car with the AA S/C kit. My AA S/C would give a loud "whoosh", his RMS S/C would give a noticeable but definitely more subtle "shhhhhhh".
And yes I've checked, I am holding boost fine. My BPV is not torn or leaking. My Bosch BPV is operating, it appears, as it would and should. I've considered getting a Hybrid BOV but now that I see that my stock BPV is already louder than the aftermarket ones, I probably will spend my money elsewhere.
Also, I think I understand why the BOV, venting to atmosphere, is bad for a S/C car. You'll run rich the instant that metered air escapes from the closed system. Your car ECU will compensate by leaning out your overall mixture, skewing your a/f toward lean. This lean condition will cause problems in the long run.
Boy, all this research just to NOT buy something and stick with what the kit came with. Hope this helps someone else thinking the same thing as me.