Wastegate bov ??

Whats the difference between the waste gate and the bov, they both seem to expel air when throttle is released.

The wastegates control the flow of exhaust gasses through the turbos.

A BOV releases excess pressure from the compressed air forced into the engine via the turbos. Once you lift off the accelerator the thottle body closes but the turbos are still trying to force more air into the engine momentarily. This air needs to go somewhere, else it can cause the turbos to stall.

Whats the difference between the waste gate and the bov, they both seem to expel air when throttle is released.

The wastegate is on the exhaust side of the turbo system, it regulates the exhaust gasses to the turbo. The blow off valve is on the compressor/intake side of the turbo, it releases air in the intake when the throttle is closed.

See ful explanations here:

http://www.streetracersonline.com/articles/turbo/wastegate.php

http://www.streetracersonline.com/articles/turbo/bov.php

The wg limits the boost a turbo makes by directing (some) exhaust gas away from the turbine wheel so that the turbo stops making (so much) boost.

A bov doesn't stop boost being produced it just releases it. When triggered by the vacuum caused when the throttle is closed it opens and releases the boost pressure that has already been made by the turbo and is in the pipework between the compressor and the throttle.

Edit;

Bugger - too slow

Thanks for the replies guys

Mark

So why do you get wastegate chatter when you lift off?

So why do you get wastegate chatter when you lift off?

Yeah , If I rev mine hard (with the bonnet open) when I release there is a whoosh in the air box which I was told is the wastegate chatter.

With the car stopped

So why do you get wastegate chatter when you lift off?

as far as I was aware it's not actually noise from the wastegates but rather some of the compressed air flowing back over the turbos, this is why you can hear it through the air filter at partial lift off or where there isn't enough boost pressure to open the BOV.

So why do you get wastegate chatter when you lift off?

Its not the wastegate, if its chattering on lift off you're getting turbo stall caused by the BOV not releasing enough of the compressed air from the intake. This is FAR more common on single conversions.

Interesting...... So the "pidgeon" noise is the turbo but so is the chattering noise???

Every day's a school day. Why is it called wastegate chatter?

Its not the wastegate, if its chattering on lift off you're getting turbo stall caused by the BOV not releasing enough of the compressed air from the intake. This is FAR more common on single conversions.

I used to get alot of chatter in the airbox when I didnt have a bov on at all , std or other wise. I have now fitted a std bov.

Every day's a school day. Why is it called wastegate chatter?

Misinformation I guess

a quick question that i hope is related to this.....

I've read about "screamer" pipes - but get a bit confused - a screamer pipe is a pipe coming from the wastegate, and being vented to atmos, yes?

Or is it actually put back in the exhaust before the cats?

I've read somewhere that screamer pipes are very loud, and are also illegal for road use? Is this correct, or just in the US?

Thanks

a screamer pipe is a pipe coming from the wastegate, and being vented to atmos, yes?

Yes.

a quick question that i hope is related to this.....

 

I've read about "screamer" pipes - but get a bit confused - a screamer pipe is a pipe coming from the wastegate, and being vented to atmos, yes?

Or is it actually put back in the exhaust before the cats?

 

I've read somewhere that screamer pipes are very loud, and are also illegal for road use? Is this correct, or just in the US?

 

Thanks

ya can do ever with them mate and yes there legal , only if there to loud will the fuzz be on your case about it ,

Yes.

so why the need for a pipe - and whats at the end of it? What does the pipe actually DO?

Does it just make the noise LOUDER?

EDIT: And some people seem to have 2 BOV's fitted??? Am I seeing this right? For example, an SSQV, and another BOV?

Why the need for 2?

so why the need for a pipe - and whats at the end of it? What does the pipe actually DO?

Does it just make the noise LOUDER?

The standard wastegate in the supra allows any "excess" exhaust gas to be released back into the exhaust, bypassing the turbos. A screamer pipe (which I don't know if you can even get for a supra) releases this gas to atmosphere instead, effectively an unsilenced exhaust pipe in your engine bay.

it,s hot exhaust gas coming out + flames so you need to vent it out the way , yes all exturnal wastgates need a scremer pipe

yes all exturnal wastgates need a scremer pipe

An external wastegate can also be plumbed back into the down pipe too.

I'm going to see how my screamer pipe sounds, if it's excessively noisey then I'll get mine plumbed back.

so where does a screamer vent TO, if it was vented to atmos?

By this i mean where in the engine bay is the pipe run to, and is it simply a pipe with no filter/silencer on the end?

I suppose if someone knew of a picture of one somewhere, on the net, that would help explain it to me

http://img90.imageshack.us/img90/2994/cimg0004ur0.jpg

http://img225.imageshack.us/img225/4657/cimg0002gv8.jpg

Here are a couple of pics of my kit, the screamer pipe is the small black pipe, this fits on the wastegate. It is basically just an open pipe that exhaust the excess gasses into the engine bay next to the downpipe, which is the reason why they are so loud.

I may look at adding a flexi pipe section onto the end of mine, so it plumbs the wastegate back into the downpipe if it is too loud.

thanks nic - thats fantastic

Helps explain to me what it looks like, and where it goes:- just what i needed!