Bov vs recirculated

[Papaown]

I've heard from many people that venting to the atmosphere you'll lose pressure and will need to build it up again, resulting in a slower run, and that having an recirculating one is much better. Does anyone have any before and after track times, to see how much slower it is? The r32 I'm looking at currently has the hks ssqv and I'm wondering if I should put a recirculating kit on it. Thanks.

[JD74]

I've heard from many people that venting to the atmosphere you'll lose pressure and will need to build it up again, resulting in a slower run

(When Venting to Atmosphere) It's not so much a matter of pressure loss, but rather 'already-metered air' loss resulting in RICH smoky shifts (when running MAFs anyways).

[ARC240]

(When Venting to Atmosphere) It's not so much a matter of pressure loss, but rather 'already-metered air' loss resulting in RICH smoky shifts (when running MAFs anyways).

JD's got it right. Venting BOV to atmosphere without an ECU setup to calculate air loss of a vented BOV setup is most likely going to cause the engine to stall/hunt very low. It's a pain in the ass when it revs low and stalls on idle and at a light, I'd rather get a proper ECU or just recirc them. Up to you though.

[Papaown]

Is there any way to not run rich with the atmospheric bov that is already on the car?

[JD74]

Is there any way to not run rich with the atmospheric bov that is already on the car?

Yes. Run an ECU with MAP sensor rather than MAFs......

[Papaown]

Thanks, is there any way to delete this post now lol?

[GTR-Dad]

No need to delete. Others will have the same question in the future.

Those skilled with the search button will find your thread, read, and learn.

Dan

[tokes]

There are a few ways to get around it... You can compensate in the tune for the meter'ed air blowing off by telling the motor to run leaner when it's decelling and going back to idle.

We tweaked with some settings on a friends Silvia with a CA18 and Nistune and it works great with an atmospheric BOV. I'm going to try venting my stock bypass valves when I get my car running again, and see if I can't tune around it with nistune.

[mcfly]

Never had an issue venting any rb to atmosphere on a stock ecu. If the car is running good it is not an issue.

[Skym]

Setting BOV harder (releases less air) is another way to help in reducing this problem. But might get flutter (compressor surge).

I can see that running engine leaner is another way to compensate for the air being vented to atmosphere that MAF has already measured, but doesn't reach engine.

HKS EIDS -

http://www.hksusa.com/products/?id=2175

Or moving MAF away from front of turbo with equal diameter intake pipe that helps to reduce reversion. Reversion is air going in the opposite direction and upsetting AFM voltage which is converted to load via MAF table (software) on ECU. The result is ECU thinks there's more load, so lands on the richer load cells on fuelmap. Reversion is created by turbo slowing down.

Interesting article -

http://autospeed.com/cms/title_The-Zero-Cost-Recirculating-BOV/A_1878/article.html