Can to big of a blow off valve be bad ?

[panel]

Hey guys , just wondering if you had a BOV in lets say 50mm instead of a 25mm. Would the 50mm cause problems etc ? This would be comparing same size engines , PSI / boost , HP etc.

[buguy]

That's a good question. Not something i had thought about before. I would think it wouldn't matter much if it was too big. Only if it was too small. All it would do being too big is let the air escape more quickly. Which i would think would be a good thing? That is provided the spring pressure was equal between the two.

[nbuscemi]

Running an oversized BOV will be fine. It may add a few milliseconds of lag between shifts but I doubt it would be noticeable. Most important thing here is that boost gets vented on throttle lift. My first iteration of turbocharging my 1600cc ran a BOV I acquired that was intended for a 500-700 HP setup (Turbosmart Raceport) and it worked just fine.

-Nick-

[Coyotemutt]

I've read BOVs help reduce turbo lag between shifts and can sometimes help lengthen the service life of a turbo but otherwise aren't necessary.

Does that fit other's experience? I haven't bothered fitting one to my setup.

[buguy]

I'd say that's true. Without a BOV, when you close the throttle, it acts like an air brake on your turbo. Slows down the impellers. Going from 100,000 rpms on the impeller to zero over and over is hard on them too.

[Chip Birks]

I've read BOVs help reduce turbo lag between shifts and can sometimes help lengthen the service life of a turbo but otherwise aren't necessary.

Does that fit other's experience? I haven't bothered fitting one to my setup.

Those are true things. So if not lifting on shifts and if you have turbo sponsors, then I wouldn't fit one. But for $300 for a nice one, it's pretty cheap insurance to protect my $1000+ turbo.

[Coyotemutt]

But for $300 for a nice one, it's pretty cheap insurance to protect my $1000+ turbo.

$300 is about double what it would cost to replace the turbo I have. Which was handed to me for free... That's the only good thing that came from my mom dating a subaru mechanic! Hahahah!