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Is there any difference in the stress on your engine going to redline in gear vs in neutral?
 

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yes there is but I am not sure how, from what I understand when in gear you have the driveline spining with it so there is more of a balance on the engine than with it in neutral, you don't want to do it too much in neutral.
 

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um... dont do it! but if you have to i supose in gear is better for the engine and out of gear is better for the trans
 

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ive heard free reving out of gear will cuase floating valves as opposed to in gear
 

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"In Gear" will float Valves as well.
Maybe worse, due to the resistance.

 

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Very basic but,

Driving (say up a hill) you have a load on the engine (Torque). Just sitting there, you have nothing but a spinning engine.

A car engine rarely sees more than 30-40 hp when you're driving down the road.
 

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On a side note, a Zetec with stock cams doesn't make any real usable power past 6k. On the autocross course I shift at 6, unless I have to downshift a split second later, then I hold it. On occasion I need to tap the rev limiter rather than shift to third... But that is okay, because that is what rev limiters are there for!
 

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Can anyone else confirm whether either situation induces more stress or damage than the other??
 

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Interesting question. I don't know the answer, but ever try to throw a ping pong or tennis ball hard or far? Know how it makes your arm hurt cause there is no load/resistance against your effort? But throwing a relatively heavy baseball is comfortable?

I always thought reving an unloaded engine would make its reciprocating parts feel the same way.

[ 02-08-2003, 11:24 AM: Message edited by: Welding Rod ]
 

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Originally posted by Welding Rod:
Interesting question. I don't know the answer, but ever try to throw a ping pong or tennis ball hard or far? Know how it makes your arm hurt cause there is no load/resistance against your effort? But throwing a relatively heavy baseball is comfortable?

I always thought reving an unloaded engine would make its reciprocating parts feel the same way.
<font size="2" face="Verdana, Arial">There wouldn't be any torque (or horsepower) on an unloaded engine would there?
 

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Phillip, Interesting question, since torque is the measure under load. I think reciprocating mass would classify as load. Kinda a falling tree thing.
 

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Originally posted by rheacer:
Phillip, Interesting question, since torque is the measure under load. I think reciprocating mass would classify as load. Kinda a falling tree thing.
<font size="2" face="Verdana, Arial">Hey, I heard that!
 

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Without significant combustion load, wouldn't the downward force on the piston be smaller? Therefore the load on the piston pin/rod to stop the piston at the top of the bore and then pull it back down would be higher than usual without the equalizing force of the larger combustion occuring.... So the rods would be under a higher tensile load... Right?

Maybe?



I bet it has something to do with that equalizing of force... the same thing that makes it so that a turbocharged engine doesn't have much extra stress over an atmospheric engine.

I bet that's it.


[ 02-09-2003, 02:05 AM: Message edited by: OmniFocus ]
 

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I've noticed in the past with various Ford rental cars with auto transmissions that in neutral the rev limiter would limit the engine to ~4k rpm but in gear it would go to the engine's full redline. If the computer is programmed to do this, then I'm sure it's for a reason. They wouldn't go through the trouble if it was "advisable" to rev the engine to the limiter with no load.
 
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