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BOV/Wastegate


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I am new to turbo'ed cars but I finally bought an 84 turbo. I read a ton of awesome info on the sticky's but I still am curious about BOV's. What are the gains and losses of an upgraded one. Do I even have one on a bone stock vg30et?

 

I also am curious about the wastegate idea. I get that it bypasses the turbine or what-not, but what does that do for the engine?

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Ahh, ok, so can I add a BOV? Would there be any point and what do they do? Do I have a stock wastegate and if so at what PSI will it open at? I'm sure there is a thread for this but whats the most PSI I can pull out of the stock t3?

You can. I don't see much point. A recirc valve would be much better in all respects.

I've never seen your car but if your car is bonestock as you say it is then you have a stock wg. It's been a long time since I had a stock turbo but IIRC the wg is set to somewhere between 6 and 7psi. And your POV or emergency relief valve I think it's called, will vent at about 8.5psi.

I'd really rather not advise you on safe maximum boost level for a stock z31. I ran 10 to 12psi for several years w/ my 85t. Spiked to 17psi once or twice accidentally with no apparent ill effects. Others have seriously damaged their motors at lower boost levels. I believe the z31 t3 is way past it's useful limit at around 15psi. And w/o an intercooler and more fuel to match the higher boost...very risky to the health of your motor.

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Ok, sorry, that was really confusing, what your saying is that I should just leave everything how it is to be safe? I don't think I will mess with this car, I will do it with my next one.

No I'm not telling you not to modify your car. Modification is what this board is about. What I'm telling you is to be careful with your modifications. Some things you just can't do until you have other modifications. If you raise the boost up past the point of what the stock fuel system is capable of then you have an air/fuel ratio problem. Too much air, not enough fuel. That's called running lean. That can be a very bad thing ;)

A BOV really isn't going to do any serious damage to your car but every time your BOV vents your motor is going to run very rich for an instant. Probably the worst that could happen is your catalyst won't last as long as it would normally. I think most people (nobody on this board of course ;) ) want a BOV for the sound rather than to prevent compressor surge and whatnot.

A recirc valve puts the air back into the intake. Much better for a car w/ a MAF sensor. I don't think you really need one right now but it's your car and you should do what you want.

You definitely do not need an external wg though. And if you install a better exhaust then turning the boost up to 10 or 12psi is most likely not going to cause any harm.

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Ahh, I see. Ya I am currently debating between 2.5 inch turbo back or 3 inch, and stainless or aluminized. At the same time I will be adding MSA's K&N intake.

If the weather there doesn't call for salting the roads in the winter then aluminized will be fine. 2.5" is ok but 3" would give you some headroom. You don't need the MSA kit if you mean the "performance air induction". A generic K&N cone filter...re-0810 for example and a 6" length of 3" diameter aluminum or stainless pipe would probably be half the cost of the MSA thing.

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