Recirculate?...or Blow off loud?

bytemee495 · Jan 23rd, 2005, 02:22 AM

ok...now my best friends uncle owns a porscha which he has twin turbo'd and he went with a set up that recirculates the turbo out through the exhaust, as opposed to using a blow off valve. I wanna keep the car like a sleeper. (It's not exactly a show car right now...a few rust patches and so on) so I'd like to eliminate the sound of the blow off if I can help it. That'd be kinda cool! is it possible? How's the whole blow off thing work? gmmie some feedback

cozzmo · Jan 23rd, 2005, 03:12 AM

Blow off valves are designed to reduce stress on the turbo when the throttle is closed by releasing the boost. When you pull your foot off hte throttle, this creates Vacuum instead of boost and allows the blow off valve to vent the pressure built up between the turbo compressor housing and the intake.
This boost SHOULD be re-circulated back into the inlet pipe AFTER the airflow meter but BEFORE the turbo or else there's a high chance you can suffer from a "pop" on every gear change and/or a highly rich mixture between gear changes due to metered air being vented atmospherically and not entering the engine as expected. (assuming stock setup for computer etc etc).

You can get recirculating blow off valves that should be quiet, the stock bosch type BOV's are usually pretty quiet unless you're running extra boost, also having a Pod filter will increase the noise heard from the blow off valve.

TheVodKA · Jan 23rd, 2005, 05:19 AM

if you really don't care about looks and just want performance (I assume you're not gonna run above 22 psi) you should use a 1G DSM BPV. You can find one in a junkyard on the cheap and they're tough as nails.

**chimmike** · Jan 23rd, 2005, 03:36 PM

Like I said before, you REALLY need to read and research how turbo cars work.

I recommend this book:

Maximum Boost by Corky Bell. Buy it. Read it. Live it.