This was an old wives tale going back to the 30's,,even then it was a senseless idea, it was said that if you do this it filled the carburetors with fuel,making the car easier to start the next time. All cars had either a mechanical or electric fuel pump and the carburetor was always full anyway.
Back then it wasted quite a lot of fuel as carburetors have an accelerator pump, this excess petrol could also wash all of the oil off the bores, and not a good idea.
My next door neighbour always revved the whatsits off his morris minor when coming home late at night off shift (local bobby). His Father told him it left the carb full for the next time he started the engine. Even after i pointed out that his car had a electric fuel pump and that his carb would be full before starting , he still carried on revving. What a right pain he coud be to all his neighbours.
So, do you blip the throttle when turning off the motor. Good idea or bad? Discuss.
Seriously bad, because many cars use turbo charging, these turbo’s rely on the main oil pump for lubrication. Because turbo’s are driven by exhaust gases they run very hot and also at great speed. If the throttle is blipped the turbo winds up to speed, and if the engine is switched off, the flow of lubricating oil to the turbo stops causing the bearings to overheat, leading to premature failure.
Allowing the engine to tick over for a little while before switching off, allows the turbo to slow down to a sensible speed.
It was once a common practise, though. I do remember hearing it quite often in the past but nowadays it seems to be very rare. Having said that, I did hear someone blip the throttle just before turning the engine off quite recently.
Do you find that these people were also the ones to floor the throttle just after starting the engine too? Lots of noise and clouds of oil! Not good for a cold engine!