Bypass question

[69bird]

I'm redoing my intercooler piping and wondering where the proper place is to mount my bypass valve? Before or after the intercooler. I have see it done both ways. Which is the right way or does it matter?

[awr68]

Between the TB and IC (after the IC). You want to use it before there's any back charge threw the system.

[Kris Horton]

On my Mustang, my bypass is mounted just before the intercooler, after the blower. That's how the kit came from ProCharger...not sure if that's gospel, just an observation.

[awr68]

Interesting Kris! Jody will have the answer!!

I do know that you need it before the SC...but why you wouldn't want it before the IC I don't know?

[69bird]

anybody else we have a 1-1 tie.

[camcojb]

I have heard to be as close to the throttle body as possible, but have seen many professional companies do it completely different ways. Malitude had one just before the intercooler, and that system was designed by Mark Stielow, Wheel to Wheel, and Nelson Racing Engines. My GTO twin turbo had it after the intercooler, before the throttle body, but 2 feet or more from the tb. I honestly am not sure that it's a big difference where it is as long as it's there somewhere.

The boost pressure in the system from the turbos to the throttle body will be basically equal (short of intercooler restrictions and pressure drop) so as long as it's vented somewhere in there and as long as it's properly sized for the turbos/airflow it'll work fine in my opinion.


Jody

[69bird]

This is on a procharged car. I've seen pics on their website done both ways. I'm thinking it doesnt really matter.

[Blown353]

If it's a centrifugal supercharger application you want mount your bypass BEFORE the intercooler. That way you aren't moving a large volume of heated bypass air through the intercooler under non-boost conditions, which will heat up the intercooler. At low speeds (low airflow) this can quickly heatsoak an air/air intercooler.

This isn't a real concern with turbos as the airflow is in proportion to engine load and not RPM, so at low load you aren't moving a ton of "unused" hot air through the intercooler and the heatload issue won't be as pronounced.

The ideal spot for the bypass valve is just prior to the point of restriction (i.e. the throttle blade) that way there is no flow-reversal in the piping when the throttle plates close-- but it isn't as big of a deal as everyone makes it out to be. Put it where you like it... but in the case of centrifugal supercharging it's beneficial to take the cruising heatload off the intercooler by putting the bypass before the intercooler.

Moving the bypass valve from after to before the intercooler on a centrifugally supercharged car with a water/air intercooler that I helped configure & tune was worth about a 15 degree drop in intercooler water temps at a steady 60mph cruise. With the bypass moved to before the intercooler the hot air from the supercharger was no longer constantly moving through the intercooler at cruise.

[69bird]

That makes a lot of sense. Thanks.

[camcojb]

Originally Posted by 69bird

That makes a lot of sense. Thanks.

Listen to Troy on this. For some reason I assumed a turbo setup was what you had. Although I doubt it's be a big problem either way, it makes sense to get it between the throttle body/carb and the intercooler.

Jody