I am trying to figure out why my 5ktq doesn't have one. I am hoping to increase the boost levels here in the near future but I am concerned about what happens when I let off the throttle... where does the compressed air go then? Anyone have an idea or some insight?

-Kris

When you lift off the throttle the compressed air deflects off of the throttle plate and heads back towards the turbo, effectively slowing it down. With a BOV, the compressed air leaves the system, allowing the turbo's own inertia to keep it spinning until the throttle is opened again. I know Audi put bypass valves on the 20valve turbo cars, but don't know why they didn't put them (or a BOV) on the 10valve turbos.
Hope this helps.

I am thinking that it is because of the boost levels. So then, if people are running higher boost on their 10v motors, shouldn't they be installing a BOV. My concern is of blowing hoses off and damaging the turbo. Like you stated in your post, that was my understanding as well. So then who has and where or how did they find/make a BOV?

-Kris

I have a 10valve turbo as well, and I've asked several folks for recommendations as far as installing a BOV or BPV. There are theoretical pros and cons to the function of each, but I'm planning to install a BOV because a)there's less work involved than doing a BPV because you don't have to run a return line upstream of the turbo, and b)the cool sound. The BOV I'm planning to get (at this point) is the TurboXS Type H (see turboxs.com). It's made for 10-25psi applications. The only other BOV I've seen/heard on a 10valve turbo is the HKS SuperSequential, which is one of the best available.

I am thinking of doing the BPV to be more specific. Though I would agree that the BOV would be easier. I have a friend who is retrograding his twin turbo mitsubishi with a BPV because fo the side effects that the BOV have.

I did get a nice response when I posted to the VW Vortex. I think this is what I want to do too. Problem is that I don't have plastic end tanks like this fellow. Which means welding =( Here is the link:

frontpage.home.net/pjberr/bosch_by.htm

Enjoy, and thanks for the reply. =)

-Kris

I have this set up on my 1986 5KTQ. Works Great! Pulls 1.9 Bar sometimes 2.0. I have a spare set up that I put up for sale on eBay.<ul><li><a href="http://cgi.ebay.com/ebaymotors/aw-cgi/ebayISAPI.dll?ViewItem&item=595434778&r=0&t=0">High Boost Intercooler for Audi and Others</a></li></ul>

Kimberlight,

What is the strap around the I/C??

One thing though, is the red fitting sealed tight? If so, then will it fit in the space allowed? Please clarify.
If all is good, consider me a buyer.
Thanks,
-Kris

Kris,

The strap is just extra protection from a pressure spike that could blow off the endcaps of the IC if the bypass valve were to fail.

The fittings are metal fittings that are brazed (much stronger than plastic).

The red fitting is attached to the IC with threaded fasteners and sealed with a high temp (550F continuous, 600F intermittent) oil resistant gasketing material.

Ahh, that is what I was thinking it was for. Very cool set up. Thanks for the info. You have an email.

-Kris