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[BazaJT]

Talking at work and setting the world to rights on a variety of topics-as you do-and talk turned to cars,particularly turbo'd ones with dump valves.now as I understand it[I've never owned a turbo]you accelerate turbo spools up from exhaust gases you ease off slightly to change gear,dump valve sneezes you get back onto throttle and off you go again.If this is the case-and this is the question I posed that no-one there knew the answer to-would it still sneeze on a car with an auto box?After all auto's tend to slur their way up/down the box rather than coming off/getting back on throttle.just curious really.

[biggriffin]

Haven't played with turbo's for many years, but I seem to recall, something to do with fuel pressure,

[LC0112G]

They "sneeze" in a manual because when you lift off to change gear, the throttle butterflys close and stop the engine injesting more air. However the turbo is still spinning like a whirling dervish pumping air into the inlet tract. The pressure in the inlet tract therefore spikes through the roof. A dump valve relieves this pressure by opening and venting to atmosphere.

With an auto, you don't lift off when changing gears. The throttle butterflys stay wide open and therefore the engine continues to injest air so the manifold pressure won't spike, and a dump valve won't 'sneeze'.

[BazaJT]

Thought I'd got the general idea right re the manual option just didn't know about the auto as you don't lift off of course,thanks for explanation.