lorenzg

I’ve got a friend who insists on revving an engine and then shutting it off in the middle of blipping the throttle. I keep telling him this does nothing but wash the cylinder walls in unburned fuel. He says it doesn’t do any such thing. Who’s right?

DGaunt

Who is right depends on whether the fuel is shut off when the ignition is cut. On earlier cars and cars w/carbs, you are right. But, if the injectors are shut down w/ the ignition, then no fuel gets into the engine to wash the cylinders down. That leads me to ask, why would you do this anyway? They rev aircraft engines up a bit then lean them, finally cutting off the fuel altogether to prevent plug fouling from taxiing in from the main runway However, if your engine is running properly, this should not be an issue in a 911. Your friend might think it sounds cool though.....

Noel

I have never heard of this. If this was such a benefit then Porsche would have recommended it.

lorenzg

Thanks. I needed a little support on this. I'm not sure why he does it other than he's always done it. He told me it was to 'make sure the plugs don't foul.' To which I replied "BS." This is a long time racer that I think just likes to hear engines run at high revs. I don't let him anywhere near my accelorator pedal or throttle linkage anymore.

texasgooner

Isn't it just a way of saying "listen here, I have a 911, give me attention" when you pull up outside a pub, cafe, your birds house etc? One think I couldn't do when I had a 928 Auto, but now I can with the 911.....
I noticed guys on motor bikes do it constantly too.

Steve Weiner-Rennsport Systems

Hi:

Dave is right on the money,....

Its something left over from the leaded fuel-carburetor days and now, totally unnecessary.