Blow Off Valve

[saleen]

Is it hard to fit/exchange a BOV? Don't they just screw in? If so, just keep the original one in the boot with the tool required and no probs.................

[Guest Race Rubber]

In "some" cases (probably most) a BOV upgrade is purely for the RICE factor, however......

A BOV is used for the simple purpose of venting excess pressurised air on closed throttle. This reduces lag & improves throttle response. It also prevents the pressurised air from being forced back through the compressor & slowing it down (hence the BOV reducing lag) Without a BOV a closed throttle gives pressurised intake air no other path but back through the compressor causing it to slow right down. Ultimately putting a huge load on it!

The factory BOV is designed for factory boost pressures & airflow levels, plus some level of engineering tolerance. If you start raising boost levels & airflow (larger turbo, more efficient intercooler/intake/exhaust etc...) then the factory BOV "may" struggle to cope.

1. The factory BOV can leak as it isn't strong enough to hold closed under raised boost, or increased airflow. With no form of adjustability, short of modifying the stock item, aftermarket is the only option.

2. It may not leak but is no longer able to vent the "total" intake charge & therefore allows some air to return back through the compressor, causing compressor surge.

It's the latter reason I upgraded the BOV on my R33 Skyline.

So in short, if the factory valve isn't leaking (you'll know if it is!!!) & isn't causing compressor surge (fluttering sound) the only reason to replace it is looks/sound.

I Get the fluttery sound now and my XR6T is totallty stock.

So does that mean that the standard Bosch BOV is not up to the job.

What else do I need to do to reduce/eliminate compressor surge????

[Guest mrmods]

no ppl bovs dont void warranty

[richdave]

no ppl bovs dont void warranty

with all due respect, how can you make this claim? Do you work for FOMOCO?

[CJF077]

no ppl bovs dont void warranty

yes would be interesting to know.. ive heard on the contrary.. from people who work for FOMOCO.

[Guest driftin]

They are very likely to void certain aspects of your warranty, given that they

will make your XR6T run rich and dump fuel between gears.

Adam

[Goose]

Hey guys,

Spoke to a guy who work at a performance shop specialising in turbo imports, he's got plenty of experience, and drives a 750HP Supra.

I asked him about the fluttery sounds, he said that any Big Single turbo will make this noise, and it doesn't reflect the effectivness of the Blow Off Valve.

[Guest JESMAL]

I used to get the fluttery sound, or what I like to call...THE CHIRPING NOISE.

That was when I didn't have a BOV for my AUXR6T. That's like what previous posters have said, it's the air bouncing back and forth the blades...I had a BOSCH BOV fitted, apparently that's the only one around in the market that is silent as a mouse coz it feeds the output back into the air filter piping...

Now that the BOSCH BOV has been fitted, all I get is a straight flush (very slight noise) which is hell lots better than the chirping noise.

Dunno if the XR6T actually came with one fitted as standard but I sure know that if you ask anyone (insurance companies), they'll tell you that fitting a BOV is illegal :o NOW WTF IS THAT? :o

[richdave]

Today I heard for the first time, that flutter sound of a BOV in action. It was on a non stock WRX. IMO the driver must have been that guy Wayne Kerr, 'cause IMO it sounded silly.

[Uwish]

If you want the Phhhhhhhssssssssssssttttttttttt noise then get a GFB Mach1

as you also get the wastegate/turbo flutter.

With the MAP sensor motor, Your ECU will NOT be able to detect the

difference.

AFM are the Big problem for Full Atmo BOVs.

As it relies on the return of the are.

Map Sensors are great, and when the ECU is cracked

you'll get a nice power hike as the MAP Sensor motors are easier

to Modify.

My S15 had the Flutter with the GFB MAch1.