Whats a bleed valve do on a turbo car?
Answers:
if it's adjustible it can be used to change the boost pressure :)
Also called boost valves,
I use mine to run cheaper gas, I can lower the boost for 87oct and raise it for 91 to get more hp :)
I think that it's to get rid of trapped air.
is it the same as a dump valve?
Do you mean a dump valve which is specific to turbocharged cars, if so it dumps to atmosphere the excess pressure built up by the turbo. If you meant a bleed valve then it could be one of many bleed valves on any type of car.
The valve lets of extra pressure so the car can run. The turbo builds pressure that goes to the intake with out the valve the engine would lock from the pressure built by the turbo. Like taking compressed air and filling a balloon.
if its the same as a blow off valve, it is so that when you rev the engine, then let off the gas. the turbo is still spinning really fast but the engine has already slowed..thus less air intake. the turbo creates alot of pressure so instead of over-boosting your engine, there is a blow off valve to let the extra pressure out. that is the quick burst of air sound you hear on turbos when they shift during hard acceleration. i might be WAY off if a bleed valve isnt the same as blow off valve.
Bleed valves are used to bleed off boost whilst under throttle application. A dump valve is used in the opposite situation (under no throttle application).
If you are using a Big cold side you can get spiking where you over boost due to the waste gate not being able to react fast enough during spool up. A bleed valve is set below the waste gate set point and stops spiking meaning you can use big cold sides at mid throttle application.
A Bleed valve sits on the prssure line between the turbocharger and the wastegate.
As a turbo spools up (increases speed) it builds pressure, forcing air into the chamber. However, you need some sort of pressure release behind the turbo or it will enter into a self imposed destruction. As the turbo applies more boost, more pressure is exerted through the exhaust onto the turbo impellor, in turn this makes the turbo want to go even faster, and apply even more boost, which applies further pressure, and you get a ciruclar problem.
To get around this, turbo's have a wastegate, this is a valve that allows excessive pressure to escape, which means that the turbo's rotational speed is limited once it hits a predetermined point.
A bleed valve sits between the turbo and the wastegate. It's used to fine tune the boost pressure for the turbo. As any Renault 5 owner will tell you, if you screw the bleed valve up, it effectively fools the wastegate into thinking that the turbo's predermined release point has not been reached, and so doesn't release the excess pressure, allowing you to run higher boost than standard.
Please don't run out and tighten it up though, by increasing boost and not compensating for it with increased fuelling, you'll get detonation and end up melting your piston crowns. Leave well alone unless your a skilled mechanic!
it is a release valve? it will help you put out the unnecessary air in your turbo so that you turbo fin don't bent so that you don need to change to the whole turbo set
GIB and Drawings are correct, it controls the amount of air to the cylinder head by 'bleeding' off the excess produced from the turbo via the wastegate.
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