Reving the throttle right before shutting of the car??

Not sure if there is some benefit mechanically. I have seen Lambo drivers do this regularly at events. Same thing immediately on startup which cannot be good for the engine. I always thought is was just a way to prove their manhood

 

LOL......that sounds about right

 

I'm not a mechanic or even just mechanically minded but i do have a theory regarding this: in the days of carburettor equipped cars by revving the engine just before shutting down this would boost the amount of fuel in the carb to help restarting the car again later on. that's just my theory and i could be soooooooo wrong.

 

Yup, they just want to hear their baby rev up one more time before they shut her off.
Technically, there is no mechanical advantage.

 

I believe on a dry sump car the thinking is to put a good film of oil on parts before shut down.

Wet sump since it sits in oil it's not needed?

 

on carb cars is a bad idea as it will dump excess fuel into the cylinders ( from the accel pumps) , which will wash the oil off the piston rings and make cold start up wear even worse. i think its some stupid "look at me" thing.

my .00002

 

i did say i could be wrong and i wasnt a mechanic but i kinda like the oil idea. by revving the engine i guess it would coat the upper part of the engine with more oil thus reducing the negative effects of wear on start up later on?

 

More info here on this with similar conclusions:

http://forums.nasioc.com/forums/archive/index.php/t-120553.html

 

I'm not sure how more statements fron uniformed people like ourselves, makes the point now truth!

I would want some input from some automotive technicians and engine builders.

 

somebody else thought my carburettor theory was right. so maybe there is some truth to it. maybe i am more mechanically minded than i thought. i should open a ferrari specialist shop me thinks

 

They had uniforms on???

 

+ .000002

It can also be very bad on the gearbox, if everything is not fully warmed-up. Even in neutral, everything in the gearbox turns. So if it's not completely warmed up, (and that includes the gears) then it's like metal on metal. And it can be very expensive to repair somewhere down the road.

 

I doubt it really makes much difference one way or the other.

I find myself doing it frequently, it is an automatic motion.

Likely I'm compensating for an undersized penis. LOL

 

More likely the reason is to clear the plugs before shutting down. On carb cars set up for racing, I have seen cars that would load up the plugs with carbon deposits at idle, fouling them and causing misfiring. Some have been so bad that letting the car idle at all would foul the plugs. Not a good thing, and while a proper carb set-up would be ideal, blipping the throttle is a quick and dirty fix

 

Not only does it wash down the cylinder walls of oil but the excess fuel makes it's way into the oil pan diluting the oil and altering it's makeup. Not good.

 

In the distant past I have read in the technical sections of several automobile magazines that it is best not to rev the engine just before shut-down. They said that this is especially important in the case of turbocharged engines. The reason that you should allow the engine to idle for a short time before shutting it down was that this allows the very hot turbine to drop its high rpms so that the turbine bearing is lubricated and cooled somewhat at shut-down and thus increase turbocharger life. I imagine that this also would be of benefit to non-turbo engines as the engine is getting good lubricant flows at low rpms just before shut-down. Those making comments about extra raw fuel in the cylinder chambers at the time of shut-down, and thus causing dilution of the lubricant oil also makes sense.

Bill

 

Well, I once seen a brand new Jeep bought by a Twins ball player come back for a another new engine at just over 40K miles. Barely a year old, only serviced at the dealer. And that was the 1000 mile service. It had no oil. This proves that a totally neglected engine that never gets an oil change can still go 40K miles before puking. Ive seen people kill engines by easing the clutch out, makes the whole car shake. Ive seen people rev high and turn off the key and let it die, and my Dad fondly remembers Grampa shutting off all his cars by pulling out the choke. Nothing will ruin the engine overnight, but certain practices can drasticly shorten its life.

Its like everything else, if it looks wrong, or feels wrong, its probably wrong. You stop an airplane engine by closing the main jet in the carb while its idling and it starves for fuel. We cant do that. So just use the key to shut it off at idle speed, its pretty benign. Dont shut it down if its real hot, dont rev it before shutting down, dont rev cold engines. But none of it matters on those race engines, they are coming apart before next weekend anyway.

 

"You stop an airplane engine by closing the main jet in the carb while its idling and it starves for fuel. We cant do that."

A little off topic but we actually run up our jet (ex military) right before closing the HP cock, then close the LP cock when RPM is below 20%......kinda like revving a car but makes a lot more noise !! The checklist says to do it so cant blame it on the size of my manhood !!

As for my Fezza I always give it a couple of mins to cool down before I switch it off.....I'm nice like that...!

 

The only thing that should be sitting in oil in a wet sump engine is the oil pick up (and the end of the dipstick). The crank is not touching the oil, but is lubed via the oil pump. If the oil is high enough to hit the crank it will rob HP and froth the oil which could lead to poor pick up by the pump.

 

We cannot generalize as we cover a wide range of engine designs.

As carreaper has noted on our old carbed girls, street cars, all you would do by revving at shut down is wash oil OUT of the cylinders and thin the oil in the pan...on mine it would also charge the exhaust with unburned HCs and most likely backfire loudly scaring the crap out of the old ladies and squirrels!

*KABOOOM!*

On start up, I agree on Neutral at gearbox, pump throttle three times no choke and get that baby fired up! Our 1976 1977 Owners Manuals CALL for a pretty high RPM, 3000RPM from memory, and while I sometimes blip it to that to clear the plugs my engines warm just fine, if slower at 1200 - 2000RPM.

If you have a problem with fouled plugs, get out your ^%&*&%&( Indian forged tool kit and CHANGE them, I wouldn't destroy a vintage engine over a set of NGKs............

The race engines have twelve mechanics and prewarm the oil before they ever crank it, so if you have all that, rev the crap out of it! LOL! Be sure to take the tire blankets off, before you start out.....

 

Plain and simple, It makes the left nut tingle.

 

How about... Blowing water vapor (by-product of combustion, as we all know) out the tailpipe before shutting off to reduce corrosion of the exhaust system?

 

That it does.............LOL!

The loud BOOM in a fueling station also causes quite a stir!!!!!!

 

Exactly what I heard from an F-car mechanic.