<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/blowoff.jpg"></center><p><p>180FWD/Wetterauer/Remus/Pipercross Filter/PIAA/17" BBS RXII/Audi Rack/GReddy turbo gauge/TAS blowoff valve

 

Today is my first day testing my car after the bov installed. the test was not that good coz i was only driving to and from work, and the traffic was really really bad. I still managed to have a couple try on pusing the car and try to test the diff after installation of bov.

at the light, i squeezed my way up to the first space anticipating a green 0-60 attempt. i didnt make the tire smoke, but after the tires have good grip, i floored the car in first gear and watched my turbo gauge shot up to 1.3 bar, then up lifted my gas, i heard a "cheeee" noise from the bov and it was pretty cool. the lag was noticibly lessened. i remembered b4 bov, i used to wait a little to wait for the turbo to kick in to feel the car really accelarate. i still have stock springs and shocks, therefore the front of the car really lift up a lot when the turbo kicks in. i am waiting for my h&r to arrive. then about 6000rpm i shifted to 3rd, it "cheee" again, the lag seems to shorten in higher speed and in mid to high end. I have yet to test out the differences throughly.

the bov only let off during really hard pushing (almost full throttle), otherwise it doesnt do anything (i assume coz no "cheee" sound). i have heard that the HKS super sequencial valve sounds louder but my mechanic told me that japanese bovs might not fit as well, so i took his word for it. i have also read postings about bovs in A4s. some people have problems after installation such as losses in low end torque and turbo boost malfunctions, since this is my first day, my car functions very normal. Will post more reviews after more testings.<p>180FWD/Wetterauer/Remus/Pipercross Filter/PIAA/17" BBS RXII/Audi Rack/GReddy turbo gauge/TAS blowoff valve

 

<p>-Jenner
'00 180QX TT Garrett Stage II, Borla, H&R Sport Springs, Stable Energies Shoulder Harness Bar, Deist 6 point Race Harnesses, LLTEK rear light covers, LLTEK floor mats, Valentine 1, Custom stereo, 3M tint, etc.</a>

 

Cheee!

 

Gesundheit!

 

Heat. A wastegate must withstand brutal heat. A highly modified engine can generate over 900C/1652F--on the street! At that extreme, standard metals can melt.
GReddy Performance Products wastegates are made of high quality stainless steel and ductile cast iron that can withstand temperatures exceeding 950C/1742F.

Boost control. As good as stock wastegates are, our engineers have found that some aren't precise enough or properly sized. A wastegate that permits boost to
fluctuate between 12 and 16 psi when the target is exactly 14 psi simply isn't delivering maximum power and engine protection all the time. We've seen some of these
"leakers" dump too soon and the pressure drops drastically. The turbo has to play "catch up."<p>180FWD/Wetterauer/Remus/Pipercross Filter/PIAA/17" BBS RXII/Audi Rack/GReddy turbo gauge/TAS blowoff valve

 

The wastegate is commonly a spring-loaded valve fitted just before the turbine. The valve opens and bleeds off excess exhaust pressure when the compressor
reaches a predetermined boost. The wastegate performs three jobs:

Controls boost to keep the engine intact
Controls the speed of the turbo to keep it from self-destructing
Helps tailor the turbocharger's performance to the requirements of the engine

But consider the "working environment," and you'll understand why wastegate technology and quality are an investment.<p>180FWD/Wetterauer/Remus/Pipercross Filter/PIAA/17" BBS RXII/Audi Rack/GReddy turbo gauge/TAS blowoff valve

 

<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/OriginalWG.jpg"></center><p><p>180FWD/Wetterauer/Remus/Pipercross Filter/PIAA/17" BBS RXII/Audi Rack/GReddy turbo gauge/TAS blowoff valve

 

This is the dump or blow off valve. Don't confuse the two. The wastegate is on the exhaust side of the turbo and as you correctly said it bleeds off exhaust pressure. This is the main way that boost pressure is controlled and it can be a mechanically or electronically operated unit. The blow off valve is there to dump pressure from the compressor side of the turbo and can also limit boost pressure. The other important task it performs is to prevent the turbo from slowing down too much (or even stalling) when the throttle is closed. This is why you get the "cheee" as you put it when you change up or lift off enough. The valve is opening to vent the excess pressure in the inlet so the turbo can keep spinning. This is how a different valve can affect throttle lag by openng at a different pressure or by responding more quickly to abrubt changes in inlet manifold pressure. It may also perform some other clever function in the TT but I doubt it, as it is still mechanical.

Please don't take this as patronising, I'm trying to help )

Kind regards,
Paul

 

I could catch a glimpse of it from underneath the car (225) the other day — it had the usual metal rod coming from a mechanical pressure sensor on the compressor side.

I suppose the blow-off valve is controlled by an internal spring? No need for electronics there either?