safe to drive at 1500 RPM?

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10-03-2005, 03:55 PM

#41

mavtais

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Quote:

Originally Posted by Jason@Performance

if you have a aftermarket flywheel it will chatter and vibrate through the whole cabin if below 2500 RPM

What about the nismo one? Thinking about getting it eventually.

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10-03-2005, 07:24 PM

#42

spacemn_spiff

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Quote:

Originally Posted by Kolia

I know that cylinder pressure will be pretty high if I try to accelerate from 1500rpm in sixth gear and it will last for a long while in engine time. Oil pressure might be high enough so as not to be chassed out of the bearings. I don’t know for sure.

I’ll try to contact one of the engine guys here to have their opinion.

Oil pressure that you read on the guage is oil pump pressure, that is not the actual oil pressure between the rings and cylinder or between the journal and bearings. The phenomenon is called Hydrodynamic lubrication. If you do a search you will know find out. This pressure distribution is dependant on the relative velocity of bearing and other factors. When you design the bearing for a particular speed the minimum thickness of the film is considered under maximum loading so that metal to metal contact is avoided. I dont know want to get into too much details, but you get the drift of it.

I am no engine designer, but these is the principal behind the design that I know.

Also if you hear from the engine guys that you know, I would like to know.

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10-22-2005, 03:45 PM

#43

Kolia

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I haven’t grabbed a hold of an engine designer yet.
I did discussed the subject with some of the engineers in my group
The main concern they’d have is the increased risk of detonation at low rpm and high load. Should these detonation occur at or before TDC, the main bearings will take the full force of it. Not much chance for the oil film to resist that, even at full oil pressure.

So cruising at 1500 rpm is not bad in itself. Trying to speed up for that yellow light in sixth gear might not be nice to your engine.