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Discussion Starter · #1 ·
I am putting a turbo on a friends Mustang and he and I are having a debate. He says that with a stick shift the boost will drop off worse than with an auto. I would agree with this except we both powershift, leave the gas on the floor, stomp the clutch pedal and move shift to the next gear, how can the boost drop off? Of course when you shift the rpms of the engine will drop due to the gear ratio change but it will with the automatic also. He's not the first person I've heard say this but no one can answer my question, why?

He has a built powerglide (he just needs a converter) and a straight cut, dog ring engagement G Force T5 with the good G Force case and output shaft, so he can go either way.
 

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yeah i have heard you can can half a second in the quarter by powershifting vs not powershifting with a turbo
 

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that's the job of a blow off valve.. it's there so your boost doesn't drop .. auto OR manual
I thought the blowoff valve was to relieve excess boost pressure when you let off the throttle.. you know, turbo still making boost and throttle blade is closed equal bad things without somewhere to go.. hence the blowoff valve. I'm no turbo expert but I thought thats how it went.
 

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yeah ^ is right
with an auto the throttle never closes during shifting, boost is not lost and spool time stays relatively the same

on a manual it just relieves pressure when the throttle is closed, saves compressor from surge and helps with respooling
 

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+ if you miss a shift and dont have the right safety measures bad things can happen.. A built auto is far superior for a boosted cat IMO
 
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