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Old 01-12-2001, 11:17 AM   #1
Scooby Newbie
Member#: 3546
Join Date: Jan 2001
Talking New WRX Questions..

I am very interested in purchasing the new WRX, but is anyone else worried that the car is boosting a heavy 14psi for such a small engine? I am kind of worried about long term reliability. Oh, does anyone know what a blowoff valve does? Does it increase performance, or is it purely for listening pleasure? Thanks.
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Old 01-12-2001, 11:35 AM   #2
Thumbs up

14psi on a 2liter is nothing new. They have been doing it in japan for a looooong time. Its all in how strong the engine is built. You can build a reliable 450hp 2.0L with the right parts/tuning.

About the blow off valve (BOV). A little turbo tech: you hit the gas, exaust flows out of the head through the turbo, the turbo spins and makes boost, the boost flows through the throttle body and the engine makes power. when you let off the gas, the turbo is still making boost, even when the butterfly is closed... and the air has nowhere to go. that puts alot of stress on the turbo. The BOV opens up when you let off the gas to release the pressure in the pipes. It closes again when you step on the gas and the whole process starts over.

hope that helps,
Old 01-12-2001, 02:47 PM   #3
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Join Date: Sep 1999
Location: Elmer, NJ USA
2011 BMW 535i
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The amount of boost you can safely run really has nothing to do with the BOV (maybe I misunderstood the point, even tho I re-read it a few times). The BOV is there to prevent compressor surge (air bouncing off the closed throttle plate and hitting back into the compressor blades), which in turn can help keep the turbo spooled between shifts. Some turbo cars never came with BOV, such as some Grand Nationals, etc.

Subaru now says the WRX will have 13.7psi of boost in the US. This is not that much, and the 2.0L motor can handle much more if tuned properly. They have the same 60K mile drivetrain warranty on the WRX as all other Subarus, so the stress is really minimal.


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Old 01-12-2001, 02:56 PM   #4
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Location: The LBC, CA, USA
2001 Cr-V


-and to clarify, exhaust gases come out of the cylinder into the headers/"Up-[pipe"(?) which spins the propeller side of the turbo, connected by a shaft, to the other turbine wheel, whose spinning pressurizes the intake manifold. The intercooler, if there is one, is usually the last thing before the throttle body.
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Old 01-13-2001, 01:10 AM   #5
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Chapter/Region: BAIC
Location: Kingstowne, Va. USA
2k RSish


I'll simply add my 2 cents here...

When I was in Okinawa I had a roommate with an MR2 Turbo, and one hell of a tuned one at that. He said we are all just scared here in the states. A good BOV will allow you to run un-godly pressures with little to no threat. Of course the rest of the engine needs help to fire that pressure, but the intake tract is more than protected with a good BOV...

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Old 01-13-2001, 01:32 AM   #6
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NUFF said
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