"I dunno if i got some people wrong in here... but i had a 944 turbo wich uses a wastegate. And it is actually there because a turbo will always produce a lot more boost than an engine can handle if you don't blow of the pressure that is too much.

Some wastegates are controlled by a spring in the wastegate itself, some are controlled via electronics. The 944 turbo controls the wastegate via its KLR (control unit for "turbo related functions"). There's a certain ammount of pressure and if the turbo produces more pressure, the wastegate just opens and blows off the pressure that goes lets say above 14psi for example. It's basically to protect the engine.

This is prooved with the 944 turbo. There's a screw that acts as a "valve" in the airintake system. If you replace this screw with a normal one (you block the information about how much boost is running like this, so the KLR wont know (its a common test to see if your turbocharger is still working if the car produces not enough boost)). Now if you do this and your turbo is still fine, you will easily run pressures WAY above normal ones. And easily destroy your engine.

The wastegate is to blow off pressure that is too much, produced by the turbo (a turbo doesnt increase pressure "proportional", if you don't blow off pressure at some point it gets a lot more than the engine can handle).

I think this is way offtopic, but some people in here explained the wastegate completely wrong in my opinion.

Anyway, sorry for the offtopic... "

But the wastegate opens a way to the escape, this causes less rpm for the turbine and less air presure to the engine.

Here's some more information about it all:

http://en.wikipedia.org/wiki/Wastegate

A wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine system. Diversion of exhaust gases causes the turbine to lose speed, which in turn reduces the rotating speed of the compressor. The primary function of the wastegate is to stabilize boost pressure in turbocharger systems, to protect the engine and the turbocharger. The wastegate is controlled by a wastegate actuator.


That's just I want to say, but my poor english.....

And you can imagine that is "imposible" to ear this. Because the gases dont go out, they go inside the exhaust system mixed with the noise of the engine (poor english sorry again)

Look! Here!

I didn't say that is wrong, did i?

Quote from TRM.13 :

And you can imagine that is "imposible" to ear this. Because the gases dont go out, they go inside the exhaust system mixed with the noise of the engine (poor english sorry again)

A "divorced" wastegate dumps the gases directly into the atmosphere, instead of returning it with the rest of an engine's exhaust. This is done to prevent turbulence to the exhaust flow and reduce total back pressure in the exhaust system. Divorced wastegate dumper pipes are commonly referred to as "screamer pipes" due to the unmuffled waste exhaust gasses and the associated loud noises they produce.

hehehe, i should shut up often

I was talking about standard turbos for standard cars

I should shut up more often too... lol illepall

All the experience i have from turbo cars is from my 944. And i thought it's a "standard" turbo car... and it actually uses an external wastegate...

Just talking from my own experience, not saying there isn't any other stuff... and maybe the other stuff is even more "standard".

Well, you can definitely hear a distinct change in sound on my car and a whoosh of air when throttle the throttle is lifted. I've just got a 63 trim Garrett T3, nothing special, with no BOV. My car actually sounds a hell of a lot faster than it is, 1987 Merkur XR4Ti with a little work done.

The pressurized air has to go somewhere - BOV or not, so you can still hear it when you lift off during a boost condition.

In your first post I think your confusing a wastegate with a boost controller at the start, the wastegate isn't to protect the engine, it's to protect the turbo from air spinning it backward as pressure builds up at the throttle body when it closes. There is much debate as to wether this has any effect on it at all but for piece of mind most people drive with them.

What you were describing at the start was what the boost controller does, vents excess pressure while accelerating.

One other thing, if you do not have a bov installed, what you'll here is air cavicating over the turbine wheel when you let off throttle. Known in certain circles as 'Pigeon flutter'

Quote from NebT.O. :

In your first post I think your confusing a wastegate with a boost controller at the start, the wastegate isn't to protect the engine, it's to protect the turbo from air spinning it backward as pressure builds up at the throttle body when it closes. There is much debate as to wether this has any effect on it at all but for piece of mind most people drive with them.

What you were describing at the start was what the boost controller does, vents excess pressure while accelerating.

One other thing, if you do not have a bov installed, what you'll here is air cavicating over the turbine wheel when you let off throttle. Known in certain circles as 'Pigeon flutter'

I believe you have mixed few things now

Turbo stuff is nice topic, there will be lot of arquing, that is law of Interenet I think

Quote from NebT.O. :

In your first post I think your confusing a wastegate with a boost controller at the start, the wastegate isn't to protect the engine, it's to protect the turbo from air spinning it backward as pressure builds up at the throttle body when it closes. There is much debate as to wether this has any effect on it at all but for piece of mind most people drive with them.

What you were describing at the start was what the boost controller does, vents excess pressure while accelerating.

One other thing, if you do not have a bov installed, what you'll here is air cavicating over the turbine wheel when you let off throttle. Known in certain circles as 'Pigeon flutter'

Thats the wrong way surely? as afaik the wastegate is exhaust side and the BOV is intake side. Where to wastegate lets exhaust gas bypass the turbine of the turbo to stop it spinning too fast, whereas the BOV is a valve which dumps to atmosphere or into the airbox to decrease the pressure in the intake system (after the turbo) when the driver lifts off.

Quote from Greboth :

Thats the wrong way surely? as afaik the wastegate is exhaust side and the BOV is intake side. Where to wastegate lets exhaust gas bypass the turbine of the turbo to stop it spinning too fast, whereas the BOV is a valve which dumps to atmosphere or into the airbox to decrease the pressure in the intake system (after the turbo) when the driver lifts off.

That is correct.

You only really NEED a BOV when you run very high pressures (probably over 17-19 lbs, maybe even more) because if you slam the throttle completly shut, you will get a nasty shockwave that can damage the thrust bearings on the turbocharger.