EVO 8 with BOV Question

[luckym85]

Does any one have a BOV on there EVO? If so which one and is it 100% atmosphere or not? Tannks

[Tso]

all Evo's come with a BYPASS valve.

a BLOW OFF VALVE is terrible for the car. the system is designed to run closed, not open when you let off the throttle.

by using a blow off, you cause the car to run rich as well as back fire. as well as other brain problems.

the only time you should be using a blow off is if the engine has been designed to run with it. from you question, i gather you have not built an evo engine to run as such.

if chirping is what you want, you need to use an external waste gate.

this is what WRC cars and the like have, and that is why you hear the turbine chirp.

[luckym85]

The EVO has an external wastgate. A wastegate only controlls the ammount of psi it holds before it slowly leeks so you don't blow up your engine. I have heard people use 100 atmosp. and not have any problems. You can get a BOV and then re-circulate it and it won't be bad for the car at all.

[luckym85]

Also a by-pass valve is the same thing as a BOV but it just re-circluates the the turbo pressure.

From your response i gather that you don't know what you are talking about and also have not bulit a EVO engine.

[luckym85]

And what do you mean by chirping? Do you mean the sounds when you shift in your car with a BOV on? More like a psssssstt than a chirp.

[Tso]

first off... i've a few GR. A Evos.

second.. you don't know what you are saying.


a bypass and blow off are two completely different things.

bypass bypasses the air, and sends it back into the system (correct).

a blow off sends the pressure out of the system, leaving the engine running rich (bad).

and external wastegate does an extreme amount of chirping. the Evo comes with one of sorts, but nothing spectacular that will chirp.


if you really want a blow off, get a 50/50. that way, the engine will not run rich, and the brain can still deal with it.

[phatdex]

U are all spazs.
U can get a blow off valve that lets the compressed air go to atmosphere and that is the psht noise u hear, or u can get a blow off valve that returns the air to the engine. If u get an atmospheric blow off valve it stuffs the stock computer up as the AF meter has decided how much fuel to pump in the engine based on how much air has gone in. If the air never makes it to the engine the fuel doesnt get burnt and goes out the exhaust making a pop and a flame.
All turbo cars have stock blow off valves that recirculate the air. When boosting ur car the stock BOV cannot take the pressure of a done up engine and will leak boost under throttle, therefore u need a aftermarket one.
Those noises u hear on the WRC cars is not the wastegate, it is the fact that the WRC cars have NO BOV at all. BOV's were originally made by SAAB to quieten a turbo car as luxury cars cant make noise.
If u ever do new pipes for ur turbo car and install no BOV u will get these noises, ppl call it pidgeon call etc etc.

An EVO, like all stock turbo cars has an internal wastegate. This means it is part of the turbo.
When u get a big turbo u need an external wastegate because an internal one cannot flow enuff exhaust gas and most big turbos dont have wastegates.
An external wastegate if not plumbed back to the exhaust just sounds like raw exhaust noise with no muffler (Ie VERY LOUD!)
My friend has an R32 GTR with T-78 and a non plumbed back external wastegate. Bloody Fucking loud when he is on full boost!

[Moppie]

Another small point about the EVOs

The 7 and 8 use an anti lag system that recirculates boost inside the inlet and turbo houseing to keep the turbo spinning.
Fitting an after market wastegate/BOV can mess with this system, and actualy create lag.
(the US EVO uses mostly EVO 6 running gear, but may or may not use turbo and inlet designs from the EVO 7 and 8)

You only really need to ever replace one if as mentioned above the stock boost levels are to great, or the orginal one is to small and its putting back pressure on the turbo slowing it down off boost and creating lag as it has to spin back up again.
On any of the new Japanese turbos this is not a problem, and you should only mess with the wastegate/BOV is your doing something major to the rest of the intake/turbo/exhaust system.

[Tso]

if your bypass is really leaking, all you need to do is flip it round.

this way the diaphram is being forced shut instead of trying to keep shut.

even though it is illegal for Gr. N, this is a very common thing. and it works well.

[Tso]

BTW....
early turbo audis had no bypass.

so not ALL come with one

[luckym85]

First: If you can make a BOV in to a re-circulating BOV that will do the same thing as a by-pass valve would you call it a by-pass valve? Didn't think so. You did know that you can make a re-circulating BOV?

Second: Not all blow off valves run a car rich... I have a VR4 and it has an 100% atmosp. BOV and it runs fine.

Third: What is this chirping you are talking about? A wastgate leeks boost when the PSI gets to high IT DOES NOT CHIRP. The chirping or psssst soud you hear is the sond of the BOV when you shift and let up on the throttle. The wastegate is the thing you attach your boost controller to to get more boost out of your turbo. The wastegate makes NO sound. If you don't believe me look at the following link....

http://www.aieonline.com/54/cat54.htm?

Know your stuff before you ramble off and can't back it up.

[luckym85]

TSo How old are you? You don't have your b-day down? You can drive right? Can you go to rate R or PG-13 movies?

[luckym85]

Tso you would think that if you have many EVO you would list them down where it asks what you drive? That is if you can drive and do have a car.

[phatdex]

wastegates make noise, they let raw exhaust be released before the turbo, the can be plumbed back to the exhaust or can run straight out to atmosphere, the ones that run to atmosphere are so loud it aint funny, for a road car u would want to run it back into the exhaust. My friends T78 GTR runs to atmoshere.

[phatdex]

Moppie, ever since the EVo4 the EVOS's have had an anti-lag feature to homologate them to the WRC car as it uses this, but as far as I know they are not connected due to the fact anti-lag is 1. Very Loud!!!
2. has explosions of fire coming from the exhaust
and 3. decreases the life of the turbo.
It is actually petrol being ignited within the turbo!