Bov

[syborg tt]

Or you could mount it on the intercooler

[Blown353]

Originally Posted by syborg tt

Or you could mount it on the intercooler

Marty, he's running twin intercoolers (so he'd still need 2) and by his description I don't think there is any commonality between all the piping until right at the throttle body entrance.

[syborg tt]

Originally Posted by Blown353

Marty, he's running twin intercoolers (so he'd still need 2) and by his description I don't think there is any commonality between all the piping until right at the throttle body entrance.

Opps - I missed that post.

[JND]

Thanks Guys, i think i like the crossover tube with one BOV, i could place it on the bottom side of the pipes, it would not be the first thing you see looking at the engine. Also i had some concerns about setting up a dual BOV, how do you get them both to pop at the same time. I would think it would be a pain in the butt to dial them in properly without the car on a dyno.

Thanks Joe

[speedshopmike]

most oem setups do not use blowoff valves.
there are a ton on the market, including some real monsters from ati procharger and vortech.
they're much less critical in a turbo app then a centrifugal blower app as turbo rpm rapidly falls off with throttle while blower boost is tied to rpm.
if you need nay help or advice feel free to contact me at my shop.
hi marty,
what ya been up to?
i'm gonna sell off my syclone soon...it's been parked 3 years now, kinda lost interest.
-mike
rockville speed & custom
estd. 1972
301-279-0070

[Blown353]

Originally Posted by speedshopmike

most oem setups do not use blowoff valves.

Most OEM cars use MAF-based PCM's and thus use recirculating blowoffs so metered air is not lost (unlike aftermarket dump to atmosphere setups)... turbo cars from Volvo, Subaru, Mitsubishi, Saab, Audi, VW, etc, all use recirculating type blowoff valves. I can't think of any OEM turbo application that didn't use a blowoff valve of some sort except for mid 80's Buick Grand Nationals and some other 80's stuff. Any 90s and up factory turbo car I have ever worked on or checked out all used a bypass/blowoff valve of some sort.

If the OEM's could save a few bucks and skip the blowoff valve, believe me, the beancounters would axe them... so the engineers have a good reason to put them there.

[speedshopmike]

some of the many many examples of domestics without bov's include the syclone/typhoon, svo mustang, turbo coupe, merkur, all the dodge products using 2.2/2.5's, the 1.8 turbo gm sohc cars, 2nd-gen turbo trans am, 3rd gen turbo trans ams, etc.
not arguing their usefulness, just their necessity on mild turbo applications.
to this day, even on low-boost Vortech/similiar centrifugal blower kits, a BOV is not included.
it is part of higher boost kits and kit upgrades to high-boost.
on maf vehicles, the recirculating bov's create driveability issues when not oem-engineered due to maf backflow.
when i changed my procharged mustang to externally vented double bov's the driveability went from unacceptable to almost oem-like, as an example.
a new company, abaco, has released a brilliant digital maf that can be digitally filtered to ignore backflow, among other neat features.

compressor surge simply isn't a critical issue on small, responsive turbos set for low boost with typical oem short intake tracts.
any serious turbo effort should incorporate them.
any serious centrifugal effort should use as many, as large as possible, units as possible.
lastly, euro cars gravitated toward them because they, regardless of turbo app, reduce lag between part-throttle shifts.
auto trans vehicles don't have this particular issue.