No BOV?

[whitetsi95]

I was just thinking. What would happen if you did not have a BOV/ Rec. Valve? Like if the piping was solid. Would it way over pressurize the IC Piping? The intake manifold? Does anyone have any insite to this? Or ever thought about it as well?

 

[TSIMonsteR]

Depends. You could get away with it in an auto drag car, but on a street car (5spd, or auto) everytime you let off the gas, the throttle plate would close sending the air rocketing back towards the compressor. For a street car, you would ultimately be risking damaging your turbo.

 

[whitetsi95]

Let say your running 20+ psi you don't think it would do any damage to the throttle plate?

 

[spoonman]

20+ psi would probably not damage the throttle plate but the pressure from the turbo still compressing could force open the throttle plate open. The only turbo systems that do not use BOV's are the STS turbo systems and they are only running 8 psi.

 

[whitetsi95]

So if it was to force the plate open it would then inturn make it as if the throttle was stock?

 

[interex]

If it forced the throttle plate open it would be just as if you pressed in the pedal. Could be dangerous. Could surge into a building, sign, car, person.... "lawsuit"

 

[tkelly27]

What? Throttle plate? No, it can't blow open the throttle plate. The throttle plate has equal pressure distribution on both sides, it's not going to rotate.

It can cause compressor surge, which can damage your turbo. The late 80's to early 90's dodge cars with the intercooled 2.2l engine did not come with a BOV, except in rare cases. Rarely do these turbos fail, however they are only pushing 10-13psi in stock trim. The more boost you push the more damage surge can do.

Bottom line, you can do it, it's not recommended. When you start getting the puff puff puff sound when you lift the pedal, know your turbos life is being shortened by an unknown amount.

 

[Marcus92]

Your going to compressor surge like hell, A buddy and I once trashed an old Probe GT turbo, made a solid pipe from the turbo directly to the TB bypassing the intercooler and not running a BOV and beat the shit out of it at 20PSI, I really dont think you risk forcing the butterfly open, rather creating alot of backspin on your turbo, especially since its going to take the path of least resistance its going to go wherever possible meaning back into your turbo and out the inlet

 

[whitetsi95]

So no one thinks it could blow the IC piping off with 15 or more psi?

 

[tkelly27]

Yeah, you probably could blow the IC piping off, but that's less likely than the pressure surge that will for sure happen.

 

[booostedGSX]

I'm quite curious why you would not want to run a blowoff valve? It helps lengthen the life of your turbo.

 

[whitetsi95]

But even with not being on the gas(like between shifts) the is still exhaust pressure, which would be turning the turbo in one direction. So it would still be building pressure.

 

[booostedGSX]

It's not building boost though... I still haven't figured out why you do not want to run a blowoff valve. It will prevent you a headache in the future.

 

[Blindsey]

If you do this you are a complete idiot. After upgrading to a front mount i didn't run a BOV for about a week. After that week say good bye to the turbo. i was running 22lbs. There is no cons of running a blow off valve. If you like buying a new turbo every couple off weeks then go ahead and run without it. Other wise don't try and reinvent the wheel. Do what is proven and run a BOV

 

[marcmsj]

So no one thinks it could blow the IC piping off with 15 or more psi?

I think you're missing the whole point. The issue with not having a blow-off won't have to do with your throttle plate or intercooler piping but rather on the turbo side. As other have stated, compressor surge will be extremely high which would cause air to rush back through the compressor wheel, very possibly causing turbo damage with time as well as experience a bigger turbo lag in between shifts.

With that said, it's a very bad idea to not have a fully functional blow-off valve.

But even with not being on the gas(like between shifts) the is still exhaust pressure, which would be turning the turbo in one direction. So it would still be building pressure.

Incorrect. When the throttle is closed, no exhaust gases are produced, therefore no exhaust pressure is driving the turbo, it is still spinning only due to inertia.

 

[whitetsi95]

I don't want to run one. I was just wondering. I have been at work for a while and was bored. Just wondering what would happen.

:EDIT: I ment to say I am running one.

 

[whitetsi95]

Incorrect. When the throttle is closed, no exhaust gases are produced, therefore no exhaust pressure is driving the turbo, it is still spinning only due to inertia.

But when you let off the throttle wouldn't it bring the engine down to an idle? Which would still have exhaust going through the turbo.

 

[Blindsey]

This conversation is pointless.......

 

[marcmsj]

But when you let off the throttle wouldn't it bring the engine down to an idle? Which would still have exhaust going through the turbo.

Yes, but not under deceleration. And at idle, the turbo is spinning but not creating boost. Either way, what's the point you're trying to make? The blow-off valve is closed at idle

 

[marcmsj]

I don't want to run one.

Then don't, but you've been warned of the consequences. You'll be listening to your turbo flutter in between shifts, that flutter sound is your turbo cursing your mother.

 

[Blindsey]

aaaaand done. Don't run one. let us know when your turbo blows.

 

[DSMunknown]

These types of threads just make me giggle on the inside.

 

[TSIMonsteR]

There is a lot of misinformation in this thread.

First of all, if a car is cranked, exhaust gases are being produced. Under idle, accel, or decel, doesn't matter.

Even with a blowoff valve, when the throttle plate closes, the air is going to still rush towards it and hit it. That is what actually sends the air back to the turbo. The bov will divert this air to the air or back to the intake preventing it from reaching the compressor.

--------------------------------------------------------------------------------------------------------------

End of thread

 

[Burnett03]

Like stated above, alot of mis-information in here. If you don't know what you are talking about don't post. When the throttle plate closes the boost/pressure has no where to go, if you don't have a BOV it would go back towards the turbo and surge it causing damage such has broken shaft, broken fins, etc. The bov releases the pressure built up when the throttle plate closes so it doesn't slam back into the compressor wheel.

 

[rarson]

Lots of older cars used to come without BOVs, but these were almost all low-boost systems. Porsche used to use pop-off valves on some of their cars, too, which would open at a certain PSI to prevent overboosting (a very inefficient way to control boost, but a good failsafe for potential wastegate problems). Still, even on those old cars I would retrofit a BOV if I were driving it, since it's not much trouble or cost and can't hurt reliability. It just seems silly to be thinking about running without a BOV, but I get the feeling that the OP is just curious as to what would actually happen in a high-boost situation if there wasn't a valve there. BOV's are too cheap not to use.