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**SLEEPER** · 20-03-2008, 08:21 AM

A screamer pipe gives absolutely no benefit other than a noise to frighten old ladies etc

It is on the "exhaust" side of the turbos - The exhaust which is diverted through the wastegate to drive the tubo vanes (and thus produce the boost) has to go somewhere . There are only two choices -Either back into the exhaust or not . The latter is called a screamer pipe .
One side effect of not using a screamer pipe is that with a straight though exhaust in the car it can actually be noticably quieter as soon as the turbos come in . A properly tuned exhaust will also take this into account.
Lastly there is absolutely no point in putting a silencer on a screamer pipe cos the only reason for having it is the noise it makes.

A screamer pipe also has absolutely nothing to do with blow off valves which are on the "inlet" side of the turbos .
These are used because the turbos are driven by the exhaust gas pressure to push extra fuel into the engine.
When you change gear and the revs go down (even momentarily) the vanes simply cant slow down this quickly and would continue to spin at the same speed without the BOV , This would mean overfuelling on a big scale as the boost level ( and therefore the fuel level) would be far too high for the lower revs.
The BOV (or BOVS on a twin turbo) reduce(s) the pressure and therefore stops the overfuelling.
An altenative to a BOV is to have a recirculatory valve that sends the "surplus" gases back to the "inlet" side of the turbo. This works fine and is the set up on nearly all standard cars where the boost is running at fairly low presssue.

However if you raise the boost ( to get extra power) using the recirculating valve method is not always safe because the boost level becomes far more critical and the recirc valves cant always handle the higher pressures.
It is safer to vent the extra gas pressure into the atmosphere direct.
Bovs can be adjusted to make more or less noise. On my car they are only noticeable on full boost and are absolutely silent the rest of the time.
Depends if you want "go" or "show"

Hope this helps .

20-03-2008, 08:21 AM	#29 (permalink)
SLEEPER Junior Member Wrench Pro Join Date: Mar 2008 Posts: 28	Re: Screamer pipe A screamer pipe gives absolutely no benefit other than a noise to frighten old ladies etc It is on the "exhaust" side of the turbos - The exhaust which is diverted through the wastegate to drive the tubo vanes (and thus produce the boost) has to go somewhere . There are only two choices -Either back into the exhaust or not . The latter is called a screamer pipe . One side effect of not using a screamer pipe is that with a straight though exhaust in the car it can actually be noticably quieter as soon as the turbos come in . A properly tuned exhaust will also take this into account. Lastly there is absolutely no point in putting a silencer on a screamer pipe cos the only reason for having it is the noise it makes. A screamer pipe also has absolutely nothing to do with blow off valves which are on the "inlet" side of the turbos . These are used because the turbos are driven by the exhaust gas pressure to push extra fuel into the engine. When you change gear and the revs go down (even momentarily) the vanes simply cant slow down this quickly and would continue to spin at the same speed without the BOV , This would mean overfuelling on a big scale as the boost level ( and therefore the fuel level) would be far too high for the lower revs. The BOV (or BOVS on a twin turbo) reduce(s) the pressure and therefore stops the overfuelling. An altenative to a BOV is to have a recirculatory valve that sends the "surplus" gases back to the "inlet" side of the turbo. This works fine and is the set up on nearly all standard cars where the boost is running at fairly low presssue. However if you raise the boost ( to get extra power) using the recirculating valve method is not always safe because the boost level becomes far more critical and the recirc valves cant always handle the higher pressures. It is safer to vent the extra gas pressure into the atmosphere direct. Bovs can be adjusted to make more or less noise. On my car they are only noticeable on full boost and are absolutely silent the rest of the time. Depends if you want "go" or "show" Hope this helps .