TommiM

iTrader: (19)

Not my idea but from being a previous mr2 turbo owner I still read on that forum every now and again. They have a long thread discussing the pros and cons of eliminating the bpv altogether. Apparantly it frees up tq and makes the turbo spool faster due to the fact that your keeping the air in the charge pipes. They go on to say to back up their findings by saying how the all trac celica with the a/w intercooler setup rolled off the line with NO bpv as compared to the mr2 variant 3sgte which did. They also commented on how an old mazda manual stated that it offered its bpv in its rx7 for "emissions" and "noise reduction".
After comments about people asking about surge damage, one person commented about how their are two types of surge, compressor surge which is bad, and the second, when you let off the throttle. The second one he said isnt bad for the turbo..
SO this is just what I read. I think since they are starting to get limited in aftermarket parts for their engines they tend to think outside the box a lot more than we need to. They definately dont have as many vendors as we do. Thats the only thing I can think of.
What do you guys think of it? Im not actually considering it but wanted to hear what the evo world thinks of it.

heel2toe

iTrader: (41)

With no first hand experience, I can only provide my instinctive thoughts to get this topic rolling. I could see the transient response between shifts being improved considering the charged air never leaves the system. In terms of actual spoolup, I dont understand how it could possibly improve unless the BPV was leaking in the first place. I also believe that by eliminating it drive ability will suffer and it will also have negative affects on the turbo itself.

Iowa999

iTrader: (1)

Not relieving the pressure between the turbo and the throttle body is probably the single worst thing you can do for "spool up." Well, a 1" downpipe might be worse, so I guess that was more of my characteristic hyperbole. Wonder if the MR2 folks do that, too. (That one was more of my sarcasm.)

94AWDcoupe

iTrader: (125)

dont believe everything you read.
eliminating your BPV will destroy the thrust bearing in the turbo in short order.

leaking BVP at low boost helps spool turbo. leaking IC pipes are know to over spin turbo.

put your hand in front of hair drier and fan will slow down. remove hand and fan spins free. your engine offers that same resistance to turbo . I have my greddy type S valves setup to spool turbo quicker. I hear them leak at low boost ~10-15psi. after which they lock down and stay leak free to 35psi +. I have swapped in stock 9 valve and watched fast spool take a hit.

I have seen drag cars with large turbos use two blow off valves. One ecu controlled to open and spool turbo quick, the second to operate as normal bypass.

211Ratsbud

iTrader: (1)

My dads purpose built 450hp 3071 powered snowmobile uses a bov during launch control to regulate boost down to 5-10 psi while on two step, then when you let go of the little red button all hell breaks loose in a "timely fashion" < which is a computer controlled wastegate timer which ramps boost based on mS and not RPM/speed. (due to CVT) With out bleeding off boost via bov the boost level climbs above and beyond accepted levels: where it doesnt make sense to open wastegate because youre not moving yet long ramble.. but I wouldnt remove the bpv or bov to gain torque.. Id definately remove any friend who told me to though!

b16a2delsol

iTrader: (1)

There is an aussie company that makes a special bov that relieves just enough charge pipe pressure to prevent turbo surge while keeping the pipes still partially charged.

This would be a good idea for those who like the feel of the pre charged pipes. I will try and find the site.