Can someone tell me about a BPV, nad what it does? Also a Good One?
02-06-2001, 12:14 PM
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Re: Can someone tell me about a BPV, nad what it does? Also a Good One?
A bypass valve prevents air from backing up once you let off the throttle. If the air backs up it causes a lot of stress on the turbo, so instead the BPV releases the air. The difference between a BPV and a BOV(blow off valve) is that a BPV recirculates the air back in to the intake before the turbo. This helps to keep the turbo spooled and that way when you are back on the throttle, the air pressure is already there. A BOV releases the air out in to the atmosphere. This causes the air pressure to not be there when your back on the throttle so there might be a little bit of lag and you might run rich becaues your computer is applying fuel as if the pressure were still there. This doesn't apply for all cars, just one's that have air sensor setups like Audi's.
I know you didn't ask about BOV's but I just though I'd include a little info on them too. As for a good BPV, I have no idea cause I am running the stock one. Why do you need a BPV?
Someone correct me if I am wrong or left something out.
I know you didn't ask about BOV's but I just though I'd include a little info on them too. As for a good BPV, I have no idea cause I am running the stock one. Why do you need a BPV?
Someone correct me if I am wrong or left something out.
02-06-2001, 12:59 PM
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No HP, just insurance....if you need it
Hiya,
Dusty is on the money, so you have to ask yourself, does what he described give you horsepower. Well, no. It mearly bleeds off EXCESS pressure (off throttle) back into the intake tract (read here less air=less power, but you are off-throttle). It's main purpose is to protect the turbo from overpressure.
Some argue that in high boost applications the spring rate on the factory unit may not be sufficient to fufil its function (hangs open, etc.) and they use replacement units available from vendors such as Turbo5.
There is no HP with this mod. Some do the BOV on Japanese imports with turbos/add-on turbos because these engines do not use an air-mass sensor (at least the Hondas and Mazdas) and it makes that neat (as they see it) phhhhhhfffftttt sound when they shift.
Hope this helps.
Cheers!
Michael
Dusty is on the money, so you have to ask yourself, does what he described give you horsepower. Well, no. It mearly bleeds off EXCESS pressure (off throttle) back into the intake tract (read here less air=less power, but you are off-throttle). It's main purpose is to protect the turbo from overpressure.
Some argue that in high boost applications the spring rate on the factory unit may not be sufficient to fufil its function (hangs open, etc.) and they use replacement units available from vendors such as Turbo5.
There is no HP with this mod. Some do the BOV on Japanese imports with turbos/add-on turbos because these engines do not use an air-mass sensor (at least the Hondas and Mazdas) and it makes that neat (as they see it) phhhhhhfffftttt sound when they shift.
Hope this helps.
Cheers!
Michael
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02-06-2001, 02:14 PM
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Spring rate Schming rate..the Bosch rubber diaphragm is crap and has been for 10 years and many fail
scary thing is that about 3 2.7t owners have R&R'ed their stock DV's in the last week and found one or both, stuck closed!!
they had a small enough tear to keep the vacuum from pulling the diaphragm up,
BUT not big enough to vent boost, other than into the vacuum hose...yikes!!
A brand new Bosch valve and a Forge or Bailey..etc will apear identical...
The difference is that the aftermarket pistons don't degrad like the Bosch POS diaphragm does
simple keep buying/Warrantying, new ones and hope they fail by opening and not sticking shut.
or get a better quality aftermarket Valve once
BTW all Bosch DV's that I have seen, have a rubber seal at the edge
they had a small enough tear to keep the vacuum from pulling the diaphragm up,
BUT not big enough to vent boost, other than into the vacuum hose...yikes!!
A brand new Bosch valve and a Forge or Bailey..etc will apear identical...
The difference is that the aftermarket pistons don't degrad like the Bosch POS diaphragm does
simple keep buying/Warrantying, new ones and hope they fail by opening and not sticking shut.
or get a better quality aftermarket Valve once
BTW all Bosch DV's that I have seen, have a rubber seal at the edge
