Opinions on RPM's

[gmboxster]

Thanks Bruce Lee for the info, but it doesn't do anything to answer my original question.

[jmatta]

I don't know why you wouldn't use the upper rpm range (once properly warmed). The car is so much more responsive in the upper rpms. I honestly can't speak for the 2.5s, but the 2.7s and my 3.2 love the upper band; it also makes the sweetest sounds up there.

[Paul]

I'll say it until I wear out or blow up a Porsche, the car was made to run at high rpms on the Autobahn. Running a Porsche all day long at 140 miles per hour above 5000 rpms will not hurt it. In fact most old time Porsche mechanics will tell you it will keep the motor clean.

I've been flooring and shifting warmed up Porsches near redline for decades and have not yet blown a motor.

Bruce says this is not evidence that such activities do not make the motor wear faster, I agree, but I say who cares? I've had so much fun since the 70s that I feel sorry for 90% of the owners of these fine cars.

If you bought the car to enjoy it, then enjoy it.

If you bought it as a status symbol, then wax it and put it in your front yard.

If you can't afford it and are worried about it breaking, sell it.

But whatever you do, drive it regularly and maintain it to Porsche's specs.

[gmboxster]

I usually shift at 2000 rpm just because i'm in town .. But shifting at 4000 feels much better. I can feel the engine really kickin in.. I appreciate all the opinions and i think i'll start driving harder to enjoy this car...

Originally Posted by gmboxster

I usually shift at 2000 rpm just because i'm in town .. But shifting at 4000 feels much better. I can feel the engine really kickin in.. I appreciate all the opinions and i think i'll start driving harder to enjoy this car...

only 2000 rpm ,

[FTD]

Originally Posted by Brucelee

Piston Speed
At high rpm, the piston can reach speeds over 100 mph as it nears the center of the cylinder and then slow down to a near stop at the top or bottom of its stroke. It's not hard to see the abuse both the rods and pistons undergo from this extreme acceleration/deceleration process.

The strains imposed by these excessive speeds can snap connecting rods and crack piston skirts. Another not so serious side effect is that power can be lost due to the piston outrunning the flame front. Piston speed is related to crankshaft stroke, so being able to calculate it can potentially help you steer clear of a dangerous situation before swapping in that stroker crank on your next buildup. (fig. 4

Now I'm not going to relax and enjoy my track days. bummer.

[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.