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Hugo
06-22-2002, 12:40 AM
Hi,

I'm going to turbocharge my BMW 2002. Just two questions.
1) Should the dump-valve be close to the turbo or close to the throttlevalve? There's quite some tubing and an intercooler inbetween.
2) My Garret T3 has a bypass valve controlled by the pressure in the compressor houding. Can I block of this housing outlett and sample the pressure to control the bypass from close to the throttlevalve?

Thanks,

Hugo

KC Ron Carter
06-22-2002, 10:06 AM
The purpose is to relieve the surge in pressure due to the closing of the trottle body and you want to relieve it so it does not cause a intake tube blow out. Most I have seen have always been in the next upstream element from the throttle body.

<img src="http://members.roadfly.com/kcroncarter/tornado.GIF">

Now for a little do I really need this. Unless you plan to blip the throttle to pressure and no pressure and then pressure again with no load, maybe not required. These where added to keep very overboosted systems in control.

My guess is it may function 2 times a month and even then the rubber in the intake can provide this function with less cost and care.
Having said that I have a BMW popoff valve being shipped from SW to install on mine.

On the control of the Garrett t3 I will pass on that question.

I have included a link to the discussion of my m30 conversion to a FORD MAF.

Later,
Ron Carter
<img src="http://members.roadfly.com/kcroncarter/635.JPG">

Paul
06-24-2002, 03:18 PM
Bypass valve is closed loop ie takes metered pressurized air and sends it back to inlet of turbo compressor under vacuum conditions or at steady cruise can bypass the turbocharger(sort of)
Dump valve(blow off valve) sends the pressurized air into atmosphere and is quite abit louder hence why the ricers like it.
I would suggest placing a bypass valve close to the turbo compressor outlet as the main reason for it is to prevent pressure surge from stopping or slowing the spinning turbo between full throttle shifts. Also on high boost systems it can prevent actual damage the the turbo shaft. There is a noticable surge without the bypass valve on throttle closures after boost.
As for the wastegate you should not remove it from the system, you can block it off and get an external wastegate(I have an external wastegate which dumps to atmosphere completely separate from the rest of the exhaust)This device is needed to properly limit the boost pressure, not dump it after its been created.
I suggest you at a minimum pick up a book by Corky Bell called "Maximum Boost" answers to pretty much all you questions in there.


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