Opinions on RPM's
 

My RPM gauge redlines at 6200 (roughly). I do NOT do the following but would like your opinions. Is it harmful to the engine to routinuely rev up to 5000 RPM's before shifting up to the next gear. A salesman told me during a test drive to only shift up after passing the 4000 RPM mark. That was with a 2005 Boxster, I have a 1998, if that makes any difference. I look forward to your opinions. Thanks..

My car redlines at 7,200 RPM. I do a lot of shifting north of 5,000. Except from 1st to 2nd. I don't want to get whiplash!

Its safe. Reving it over 4000rpm once a day is actually healthy for the engine. Keeping it over 4000rpm all the time like road racing wears out the engine faster depends how good the motor oil you use.

I drive a '97 2.5. I wil not rev the car above 4000 RPM's until fully warmed up. After hitting the 180 degree mark I rarely shift below 4000 RPM's. That's the power curve sweet spot on the engine. Power mangement is what makes the 2.5 a lot of fun. It's not a rocket, but it does deliver good performance if managed properly. Experiment a bit but respect the machine. IMHO!!

My car is perfectly happy shifting at low rpms and it loves high rpms too. That is one of the things I like about these engines, they are so linear.

I was cruising in town the other day at 35 mph and pushed down on the gas, car accelerated fine, then I looked down and noticed I was in 6th! Unbelievable how smooth and how much power is available even at those low rpms.

I think the dealer that told you above 4k rpm just wanted to help sell the car. I would say you don't want to "lug" it by always being in too high a gear on a regular basis. But beyond that, these cars are made to both drive subdued and sportier high revving driving, so both should be fine. People often say that is one of the things about boxsters and 911s is that you can use them every day compared to some of the more high strung cars.

like rdancd816 said, make sure your engine is up to temp before high revs. i personally shift at 3K RPMs until the engine is warmed up. then, it's whatever the situation demands. i hardly ever shift past 6300 RPMs because you can grab a higher gear and still stay around 4K RPMs where the torque peaks. although, i have to admit that i've hit the rev limiter in 1st gear several times just from having too much fun.

after im warmed up, i always shift above 4000 rpm :D

The variocam kicks in at 4200 rpm on our 2.5's; the car is designed to be driven in the 4-5k rpm range.

I run mine up to 6k routinely when I take it out to drive the car for the sake of driving the car.

I don't keep it at 6k though while cruising at any speed. No sense wearing out the engine.

Conversely, wearing out my engine would give me a great excuse to put a 3.4 in it!

When the car is warming up I shift below 4K and cruise at about 3k. Once the car is warmed up I shift between 4K-5k, unless I am out to just drive, then I'll shift between 5k-6k. I normally cruise between 3k and 4k.

I didn't know that. It sounds like it would strain the engine to cruise at that high an RPM. But if you have a valid source, please post it. Maybe I should change my driving style.
:cheers:

The car is meant to be driven hard, but not abusively. Like other said, wait until the water temp is 180 deg. F before going over 4K. E46 and later M3's have this restriction built-in, wouldn't be a bad idea for Porsche. Once fully warmed up, you shouldn't be afraid to be north of 4K, for a car out of break-in.

Sabre, there is no way you were going 35 in 6th, and certainly no way it accelerated well. If I did that I would be ready to stall!!

How wrong you are. I came off the highway and leasurely cruised into town and flowed with traffic dyadreaming and never shifted down... and it did accelerate just fine and was not about to stall at all.

I wonder if a person could start in 6th and go to 162mph in one gear? Now that would be something. It probably can't be done but maybe in 5th? Not willing to burn my clutch to try but it would be interesting. These engines are amazing.

If you look in your manual there should be recommended shifting RPMs. At least there was for my 99'. I believe it was 3k-3.2k depending on the gear,for everyday driving.

Psh,4 & 5k rpm,that's nothing I'm starting to get closer and closer to 6k every on-ramp and the car loves it.

As long as the vehicle is within the correct operating temperature ranges (typically between 160 and 240 degrees) feel free to use all parts of the tachometer range, up to redline. On my 2000, it had a 7200rpm redline and pulled great from about 4K rpm till redline. I could shift at 3k rpm or 7k rpm.

I would like to see quantified just how much you would "wear out the engine" by using the designed for operating range. Seems a bit hogwash. Like when the first V-8s were invented, folks wondered how you wouldn't "wear out" the bottom side of the pistons. It just doesn't happen.

mines tiptronic so i put my foot down on the pedal, the needles goes all the way to the redline then it changes. im sure if this was a bad thing then all the boffs at porsche would have changed the gear change.

people that never go over 4000 revs on an engine that will go to 9000 dont deserve there car and i imagine drive like ****************e

Well since you admited to driving slow.. the torque you felt at 35mph in 6th gear felt fast enough to you while it wouldnt to some of us that routinely hit the 4k rpm range to feel that torque against our backs and asses.

Thats probably why it seems good enough for yah.

Don't know what you are talking about "driving slow". I rev over 4k often if for no other reason to hear that sweet sound above 5k or so and I shift at the redline when driving fast. :confused: I was talking about how the engine has amazing torque even at ridiculously low rpms.

TOP GEAR BBC did a demo starting in 5th but ran out of road before redline. speaking of revs @ track days i'm having a hard time shifting to 2nd from 4th whats a safe # in 3rd. or if your in 3rd and slowing it's always safe to pull 2nd. 2002 S stock.

Taken from an engine patent application
 

Well-designed conventional reciprocating engines operating at conservative powers and speeds, irrespective of size or type, generally last about 5×108 revolutions before wear-out of the piston rings and the cylinder bore. Note that the engine life expectancy is a function of the number of revolutions rather than the total piston travel distance. Such a fact implies that wear-out is primarily due to the ring reversal event, i.e., the reversal in direction of ring travel that occurs twice each revolution. It is well known that maximum bore and ring wear occurs at ring reversal due to the "squeeze-out" of the oil film between the ring and bore when the ring is not moving.

Also, higher piston speed increases wear rates because of the increasing difficulty in maintaining an adequate oil film. It is generally accepted that average piston speed should not exceed about 2000 feet per minute, and low speed engines enjoy a life advantage over high speed engines.


As can be seen from FIG. 3, as engine speed increases, the frictional horsepower losses become quite significant in the conventional engine

From an engine builder
 

Piston Speed


Vehicle speed and engine speed are both obvious quantifications we consider every time we turn the ignition over and step on the gas. But piston speed is something just as important, and is more often than not forgotten about.

It's usually measured in feet per minute and is the rate at which the piston travels up and down the bore. But the rate changes, as you might expect, alongside rpm changes.

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

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

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.

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.

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 :eek: ,

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

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.

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. :)