Opinions on RPM's

[Brucelee]

A point of clarification on my posts. In the past, we have had folks state that driving your Porsche up near the red line was "good for the car."

I have stated that while it may be good for you, for your soul, so to speak, it was not a formula for longevity. Simple physics, as the small posts that I made indicate.

That in no way suggests that you should not drive your car safely at whatever RPM you want. You can ride around all day at 5000 RPM or more and that is perfectly fine with me (maybe not with your local PD).

The point was that as any engineer will tell you, on balance, slow moving engines last longer than high RPM motors. That is one of the reasons why diesels run for so many miles.


Now, to be fair, it is NOT good for your engine to be "lugged" either, so there is usually a happy medium. I have found that for normal street driving, 2000- to 4000 is a nice range for good gas mileage and being easy on a Box. Larer engines can normally be driven at lower RPM than smaller. Another reasons why large V8s can be run for so many miles.

That is not to say I don't go higher, just not all the time.

Hope that helps.

[Topless]

As Brucelee points out, there are two things that cause excessive wear on the engine. Excessive loads on the connecting rods and crankshaft and inadequate lubrication. At sustained high revs the rings tend to dry out causing excessive wear. At extremely low revs (below 2000) the loads on the rods and crank can exceed available lubrication also causing excessive wear.

Excessive heat will also cause rapid wear.

These motors were designed to use the entire rev range with momentary revs above 5000. As long as you are running through the gears your lubrication has time to catch up and replenish the rings without excessive wear. Sustained revs above 5000 or below 2000 with high loads on the motor will tend to cause excessive wear.

So what should you do to keep your motor in good health? Under normal street driving keep your car in the midrange between 2-4 k for best lubrication, cooling and lowest engine loads. Use low revs below 2k only when there is little or no load on the motor (flat ground or downhill). Use the upper range 4-6k for spirited runs and track use, shifting up when needed to avoid sustained revs above 5k. Change your oil and air filter more often.