I was recently given a 4" PacBrake (from a freightliner application) to throw on my dodge. I have an ARB compressor from a locker to run it, and have no problem with plumbing it in and making flanges for it to work but....

What kind of pressure should it be regulated too? It's only got 2 3/8" holes in the butterfly so I can't imagine closing it off completely or is it solenoid activated to flap open/shut or hold at a certain position?

 

I'd close it completely. The whole purpose is to almost completely cut off airflow much how a throttle plate cuts off airflow when closed on a gasser. There will inevitably be exhaust passing the valve through the two holes and the sides, but I highly doubt it is a duty cycled solenoid or anything like that.

 

The holes in the butterfly are set to the engines maximum backpressure, you will need to know which engine it came out of to know what the backpressure for the brake is set at. Given that your engine is a 12V your going to need 60PSI exhaust valve springs. If you go to there web site you can look up what the hole size for the dodge fixed orfice butterfly was, and then just weld up your two holes and redrill it to the correct size.

Hector

 

I gave them a shout earlier and they said the brake needed to be 'engine matched' but said it could be mod'd to fit as you mentioned. I'll have to look up the P/N on it and see where to go from there. Thanks!