# Blow Off Valve Q.



## Nismotune86 (Jul 23, 2005)

Hey guys, how’s it going? I'm looking into getting a BOV. I was thinking Greddy or TurboXS. What is your opinion?


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## Zen31ZR (Mar 24, 2004)

Look amongst the stickies at the top of this page. One of our guys has done this already. You'll see the size and what in all was involved to install it. Personally, the TurboXS is huge, you might want to go with the Greddy Type-S, which is more expensive but a lot smaller.


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## asleepz (Feb 24, 2004)

Yeah I have a picture of my BOV next to a ruler just to show how massive this thing is... Of course they say it'll hold about anything you throw at it. The initial prototype was tested up to 60 PSI and each one after that is rated at 30PSI.


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## Jason Lange (Aug 22, 2005)

Go with a greddy type-s, it sounds the best in my opinion and it doesn't ake up alot of room.


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## AZ-ZBum (Nov 21, 2004)

my opinion is BOV's are ricer crap. unless you have a MAP sensor with an aftermarket ECU, a BOV is not a great idea.


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## asleepz (Feb 24, 2004)

If you recirculate it like your supposed to, there are no problems.

Of course, I haven't gotten around to it yet.


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## AZ-ZBum (Nov 21, 2004)

Even then, they have that rich period and tend to blow fireballs. Which, if that's what you're going for, have at it.


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## Zen31ZR (Mar 24, 2004)

Shouldn't run rich at all if they are recirced properly. That's why factory turbo cars use them, they have to be emissions compliant. That means no running rich. Otherwise, most factory cars with their comparatively low boost probably wouldn't use them at all. The Z31 was one of the last turbo cars to _not_ have a BOV.


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## asleepz (Feb 24, 2004)

AZ-ZBum said:


> Even then, they have that rich period and tend to blow fireballs. Which, if that's what you're going for, have at it.



LOL, go ahead and explain this one oh mighty one..


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## Zen31ZR (Mar 24, 2004)

asleepz said:


> LOL, go ahead and explain this one oh mighty one..


The only car I was aware of that blew fireballs even when running properly were the RX7s..... But they run omg rich anyway, one reason they all but disappeared with the appearance of OBD-2. And one reason the RX-8 is not turbo. It could never hope to pass emissions in turbo trim.


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## AZ-ZBum (Nov 21, 2004)

Ken's 450hp Z had a recirculating BOV. And he would shoot fireballs.

Just because the air recirculates into the intake, doesn't mean there isn't air going through the MAF. And since any large amount of air going through the MAF makes the ECU think there is more air, it makes the ECU dump more fuel. But alas, your throttle is closed, so a ton of raw fuel gets dumped into the cylinders. So much fuel that it is impossible for it to all burn off. And thus, it goes into the exhaust. Where it can ignite and shoot fireballs.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> Ken's 450hp Z had a recirculating BOV. And he would shoot fireballs.
> 
> Just because the air recirculates into the intake, doesn't mean there isn't air going through the MAF. And since any large amount of air going through the MAF makes the ECU think there is more air, it makes the ECU dump more fuel. But alas, your throttle is closed, so a ton of raw fuel gets dumped into the cylinders. So much fuel that it is impossible for it to all burn off. And thus, it goes into the exhaust. Where it can ignite and shoot fireballs.


So explain to me why most factory turbo cars with BOVs don't shoot fireballs. I'd say something on his car wasn't working right. Probably the closed-throttle switch. When the ECU sees the throttle is closed, it's supposed to ignore any air still coming in through the MAF, that's being sucked in by the turbo still spinning. Otherwise all cars would run rich when the throttle is closed suddenly. But, surprisingly, they don't.  The air in the intake track, between the MAF and the throttle plates, has already been measured by the MAF but the ECU knows due to the throttle switch being closed that _that_ air is not inside the engine. So it won't dump the extra fuel. Like I said, that's if everything was working right. If this guy is running an improperly programmed standalone ECU, or a JWT unit, well, that's part of the problem right there..........


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## AZ-ZBum (Nov 21, 2004)

Zen31ZR said:


> I'd say something on his car wasn't working right.


Yeah. 450rwhp on a car that came from the factory with 200fhp. That's what it's called. I guess 2.5 times the factory HP will do that to ya.


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## Zen31ZR (Mar 24, 2004)

AZ-ZBum said:


> Yeah. 450rwhp on a car that came from the factory with 200fhp. That's what it's called. I guess 2.5 times the factory HP will do that to ya.


Hmmm, my '92 Eclipse was putting down 400 Hp on the stock engine and ECU, and I had no such issues. I guess you can blame it on the older technology if you want to, I'd blame it on inattention to detail.


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