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Revving before you shut it down... Why?
This is kind of funny. My mother asked me that the other day and I couldn't come up with an answer. I didn't even realize I did it. I know my dad does/did it with his Chevelle and I know a lot of hot rodders do it. I guess I just picked up the habit.
Is there any point to this other than enjoying the sound it makes? |
Re: Revving before you shut it down... Why? (Cookwithvette)
Becuase it sounds so cool. :cool: :cool:
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Re: Revving before you shut it down... Why? (Cali,77,L-82)
Just for jollies and kicks. :D :D :D :lol: I do that too, guess I never thought about it though, until now. I'm gonna keep on doing it anyway. :smash:
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Re: Revving before you shut it down... Why? (Cookwithvette)
LOL - I do the same damn thing. I have no clue why!
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Re: Revving before you shut it down... Why? (Cookwithvette)
I believe it's one of the worst things you can do to an engine. When you rev it up, you are sending much more fuel into the cylinders which washes the oil off the cylinder walls. When you rev up and shut off, the cylinder walls have little or no lubricant on them when you start up the next time - can't be a wonderful thing. I let it idle 10-15 seconds, then shut it off.
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Re: Revving before you shut it down... Why? (Cookwithvette)
Here's one for ya...
I fly model airplanes, which use glow fuel -- a mixture of ethanol (or is it methanol...alcohol!), nitromethane (10-15%) and lubrication oil (16-20%). At the end of the day, we'll remove the fuel line, open the throttle, connect the glow plug driver, and take the starter to it to run the engine "dry." The reason for this is because the alcohol is hygroscopic. That is, it absorbs water like crazy. This leads to rusted bearings and general corrosion inside the engine. So if you want a lame excuse for why you rev your engine, tell folks you're running the fuel out of it! :D |
Re: Revving before you shut it down... Why? (page62)
now that you mention it , i have always done it too
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Re: Revving before you shut it down... Why? (Titanium Rat)
I always thought it was meant to let the neighbourhood know that you were home, just in case they couldn't hear you coming down the street in 1st. :lol:
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Re: Revving before you shut it down... Why? (gdh)
I always thought it was meant to let the neighbourhood know that you were home, just in case they couldn't hear you coming down the street in 1st. :lol: Especially at 1:00 in the morning. :lol: :lol: |
Re: Revving before you shut it down... Why? (Cookwithvette)
Cook, there is only one reason ever to do that, if the choke if misadjusted and or the engine is still cool, but warm enough to 'run on' due to open throttle on high idle,....goosing it will cause the choke flapper to pull open momentarily, while then snapping the throttle blades closed will bypass the high idle cam really quickly....close completely..., otherwise the engine MAY 'diesel' or 'run on' due to open throttle position....
GENE |
Re: Revving before you shut it down... Why? (Cookwithvette)
I sometimes do it if i know someone is nearby. And yes, it is done to let people know that your personal version of Americas true sportcar has returned to her place of birth. I rev her, let her idle to let the mere mortal ponder the mighty V8, and then let her sleep. (Untill when next she awakens to terrorize again)
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Re: Revving before you shut it down... Why? (sharkthehunter77)
God I love you guys! If I go onto the KILL section and said something like that they'd say "Yeah your loud, old, slow, antiquated V-8 etc. etc. quite inflamitory stuff. I got flamed there, and I'd like to think I'm a bigger man for not responding (actually a c4 owner) so I don't go back.
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Re: Revving before you shut it down... Why? (Cookwithvette)
In most cases it's just because our engines sound so damn good but there are cases where it actually serves a purpose. Engines with radical cams may load up at low rpm, like while parking or in stop and go driving. Raising the rpms for a moment before shutting down can help clear the plugs. As already mentioned though, a quick stab of the pedal without letting it stay at a higher rpm long enough may result in more raw fuel left in the cylinders than just shutting it off.
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Re: Revving before you shut it down... Why? (Cali,77,L-82)
God I love you guys! If I go onto the KILL section and said something like that they'd say "Yeah your loud, old, slow, antiquated V-8 etc. etc. quite inflamitory stuff. I got flamed there, and I'd like to think I'm a bigger man for not responding (actually a c4 owner) so I don't go back. |
Re: Revving before you shut it down... Why? (MotorHead)
Thanks guys, these are great responses. :cheers:
It's really funny how we can pick up habits and not even know it. You guys brought up something I had been thinking about before hand. The way my dad would shut an engine down would be to rev it a couple of times but shut it down before it had reached idle again ~3000rpm. I always thought this was a rather nasty thing to do to a carbureted engine. It's just going to spread fuel everywhere from the cylinders to the exhaust. I had always revved it a couple times and then let her rest for a bit before shutting down. I hadn't thought about the choke or cam things. Thanks guys! |
Re: Revving before you shut it down... Why? (Cookwithvette)
i think revving right when you start it is whats bad for it. i do it to let my dogs know im home :)
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Re: Revving before you shut it down... Why? (Cookwithvette)
Years ago I had a friend with a turbo charged ricer. You know how they can be real finicky. He said he let his engine idle for 30 seconds or so before shuting the motor off. This is to allow all pressures /temperatures to equilibriate. I dont have a turbo, but the logic seems reasonable. I do this with all my vehicles.
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Re: Revving before you shut it down... Why? (pws69)
I believe it's one of the worst things you can do to an engine. When you rev it up, you are sending much more fuel into the cylinders which washes the oil off the cylinder walls. When you rev up and shut off, the cylinder walls have little or no lubricant on them when you start up the next time - can't be a wonderful thing. I let it idle 10-15 seconds, then shut it off. |
Re: Revving before you shut it down... Why? (SIGNGUY)
I always thought it was a carryover from the "good ol' days" when cars had generators and revving it then shutting off the ignition let it charge the battery a bit without sapping any juice from it.
It didn't make much sense then either. |
Re: Revving before you shut it down... Why? (Frank75)
I never realised I did it until reading the post. I do remember Dad doing it on his 55 Chevys.
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Re: Revving before you shut it down... Why? (Cookwithvette)
The reasons are very obvious, it's to let your wife know you are home so her boyfriend has a few seconds to gather his things and run out the back door. :lol:
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Re: Revving before you shut it down... Why? (Cookwithvette)
I asked this same question of a mechanic that I know and trust very much.
He has been racing cars for more years than I have been alive and is a consistent winner. He said it is the worst thing to do for an engine as it floods the cylinders with gas and washes away lubrication. He feels letting the engine idle normally before shutting down is best for it. Also, revving slings off oil on reciprocating parts by centrifugal force (spelling?) which wouldn't happen normally when the engine is running because more oil would be pumped but since you are shutting down, you are shutting down dry if you rev just before you turn it off. I don't know if this is true but he knows a hell of a lot more than I ever will and has torn down and built more engines than I can count. He is still working on cars on a daily basis and will be 94 years old in December. This guy can listen to an engine and diagnose everything about it. Most of the local guys who race, stop by with the cars in the trailers, they fire them up and he tweaks this and adjusts that and off they go to the races. |
Re: Revving before you shut it down... Why? (Frank75)
I always thought it was a carryover from the "good ol' days" when cars had generators and revving it then shutting off the ignition let it charge the battery a bit without sapping any juice from it. It didn't make much sense then either. |
Re: Revving before you shut it down... Why? (ksbunting)
I asked this same question of a mechanic that I know and trust very much. He has been racing cars for more years than I have been alive and is a consistent winner. He said it is the worst thing to do for an engine as it floods the cylinders with gas and washes away lubrication. He feels letting the engine idle normally before shutting down is best for it. Also, revving slings off oil on reciprocating parts by centrifugal force (spelling?) which wouldn't happen normally when the engine is running because more oil would be pumped but since you are shutting down, you are shutting down dry if you rev just before you turn it off. I don't know if this is true but he knows a hell of a lot more than I ever will and has torn down and built more engines than I can count. He is still working on cars on a daily basis and will be 94 years old in December. This guy can listen to an engine and diagnose everything about it. Most of the local guys who race, stop by with the cars in the trailers, they fire them up and he tweaks this and adjusts that and off they go to the races. |
Re: Revving before you shut it down... Why? (Road Racer)
Wilmington, MA
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Re: Revving before you shut it down... Why? (ksbunting)
To go along with a previous response, I to disagree with the revving procedure before shutdown. think about it, not only does it wash the cylinders down, but picture yout oil pan, filled with oil, you then rev the engine which in turn sucks all of the oil from the pan into the upper part of the engine, to then shut it off!!! Why would you want to to that???? If you go to restart the engine, where is all of the oil???? Think about it!!! Like someone else stated, if you like to rev, let it idle about 15 seconds after before you shut it down, your engine will last longer. Remember most engine wear occurs at start-up, you want all of your fluids, especially the oil to be where it is supposed to be!!!!!!!!!!!!!!!!
Later................................... ........................................ ..Tom |
Re: Revving before you shut it down... Why? (lbell101)
LOL - I do the same damn thing. I have no clue why! |
Re: Revving before you shut it down... Why? (Cookwithvette)
I do it to make sure the alternator fills all the wires with lots of electrons and coulombs. Otherwise the wires will dry out. And starting up a car with empty electrical wiring is real bad for the car. :D
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Re: Revving before you shut it down... Why? (Stevo81)
http://www.corvetteforum.cc/zeroimg/...withstupid.gif
dry/empty wires can destroy a canooter valve on a distributer real quick :) [Modified by Titanium Rat, 1:24 PM 10/21/2002] |
Re: Revving before you shut it down... Why? (ksbunting)
Wilmington, MA :hat |
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