Quote:
Originally Posted by Speedy Squirrel
If I have a properly functioning decel valve and you don't, under hard braking I will not be in the ridiculous position of standing on the brake AND giving it a little gas at the same time while I downshift.
When you are upshifting, the throttle slams closed and all that momentum for the airflow converts to pressure. You have a big boost spike, and little airflow. Now, go look at a compressor map at a low airflow and 2.0 pressure ratio. What do you see? Nothing. It is to the left of the surge line. The compressor can't run there so it stalls until it gets to a pressure it can run at, and you've just lost your turbo speed. Not the fast way out of the corner. Don't think your blowoff valve is going to save the situation either. It's way too slow. The decel valve is the "first responder" and keeps you out of trouble from the boost spike 'till the blowoff valve can bypass the compressor.
Also, without the decel valve you can get 35-40 inches Hg vacuum under decels, which sucks oil down the intake valve guides and mucks up your plugs.
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WOW, "Speedy" - interesting points - definitely something to think about . . .
Ron