RPM for Everyday Driving
 

I have a new 987 that is about two weeks old. I'm currently in the engine 'break-in' period so I was told to stay under 4200 RPM. I'm staying within those limits for now. My Porsche dealer said that once I'm outside the break-in period, the car can be driven regularly (in lower gears) pushing it to 6500 RPM to get the max power.

This is the first true sports car I have owned, so in the past when I have had manual transmissions I shifted when the engine started to whine. Seems like my engine starts whining around 4000 RPM today. So my question is, is it really OK to regularly push the Porsche to 6000+ RPM before shifting when doing normal driving. Does this create increased wear and tear?

Let me know your thoughts.

drburton, in short, the answers to your 2 questions are; yes and yes!!

It is OK to push the car into the 6,000 RPM range, and yes this does increase wear & tear. Hard to get one without the other. I don't think this will be detrimental or harmful. Just don't bounce of the rev-limiter day-in & day-out. And do the proper maintenance.

Your peak power curve is in the 4,500-5,500 RPM range.

I am also in the break in period and I can't wait to get the rev's up!

Hi,

A Car needs a Transmission as a consequence of the characteristics of the Internal Combustion Engine. Engines typically operate over a range of 600 to about 6000 ± revolutions per minute, while the car's wheels rotate between 0 rpm and a maximum of around 2500 rpm.

The engine provides its highest torque output approximately in the middle of its range. But, often the greatest torque is required when the vehicle is moving from Rest or traveling slowly (because it has no stored energy – inertia/momentum).

So, a system is needed that transforms the engine's output so that it can supply high torque at low speeds, but also operate at Highway speeds with the motor still operating within its limits. The Transmission performs this transformation. Without it, it would be difficult to operate the vehicle at differing speeds or to start from Rest.


Each gear has a specific ratio to the rotating crankshaft of the engine to allows the engine to operate in its ideal torque range for the speed desired. If you notice, there is a point in each gear where there is no longer any acceleration from the engine, you can literally feel this. This is because the engine has surpassed its peak torque and faster rotation no longer induces greater acceleration. This is the ideal point to shift to the next higher gear.


The peak torque on the Boxster engine occurs at about 4700 RPM (for the later 2.7 ltr. models), so shifting anywhere in the 4500 – 4700 range will allow the car to move smoothly and overcome the Air and Rolling resistance.


Horsepower is somewhat different than torque; and also somewhat esoteric (there is really only torque). The HP peak in a Car usually occurs much higher in the engine’s operating range, and this is why you want to drive in the higher rpms to achieve higher speeds, but that’s a totally different discussion.

The whining you hear is due to the resonances of engine internals and the exhaust at these specific engine speeds and also the shift in valve timing from the Vario-Cam which allows the engine to better combust it's fuel and derive slightly more power from it.

So long as you properly maintain the Car, running the Car up to it's RedLine will not usually have any negative short-term effects. But, like anything mechanical, operating it consistently at it's limit will cause it to wear out more quickly - moderation is the key here. Hope this helps…

Happy Motoring!... Jim’99

Just got a new toy - Gtech. Did a few test runs with 0-60 and found that I get the lowest time when I shift at or near redline. My first few runs I was shifting at about 5000rpm and got 8 seconds on my time. Then when I shifted at 6800 - 7000rpm my time when down to 5.7. Best time was 5.4.

The Gtech is pretty neat device. Still not sure how it could measure so many things(times, gforce, hp, torque, graphs etc.) by just plugging into the lighter.

Here's a non-technical answer since Jim did an excellent job of that...

In my 2.5 liter, I shift around 4000 rpm when the engine is cold and no more than that. When I am at operating temp, I shift a higher into the mid 5000 range, but only when I'm trying to accelerate for fun. I rarely push the car over 6000 rpm because I find I can't stop when I'm revving over 6000 and I'm into the red before I know it!

My mechanic routinely looks at my rev limit counts and scolds me for the sins of previous owners on the first engine. BTW, the ECU records every redline you make over the course of the lifetime of the car and it cannot be erased with the PST tool... now hackers might be able to do it on a PC link, but it's fairly permanent.

When I'm just driving to the store, or out to my office on weekends or whatever, I usually shift to a higher gear around 4000~4800 rpm

I actually try to keep the rpm's down in normal driving conditions just to save money on fuel to tell you the truth. $35 for a fill up is rediculous to me and I know lots of other people on this list pay far, far more for a tank of premium!

Thanks for the input on this, it's really helpful. This forum is great!

[QUOTE=RandallNeighbour]Here's a non-technical answer since Jim did an excellent job of that...

Hey Randall, I like you drive a '97 2.5. I am curious as to what temp you read when the car is warm? I tend to shift at very similar tach points as you. Since the car has such low miles I'm almost following the break-in recommendations. Just curious abut what your temp guage says. Mine seems to settle a bit above the 180 line. BTW just touched 13,000 miles and so far all is well. I've put about 3500 on it since purchase.

[QUOTE=rdancd816] Anywhere along the 180 line is normal,it can go slighty above that during summer. Anything higher requires a radiotor cleaning and coolant check. If that doesnt help then a trip to the dealer is required.

[QUOTE=rdancd816] Mine does exactly the same thing. While dead center on 180 is what the manual states, mine has always been slighting above that regardless of warm weather or hard driving. Just figure that's normal for your car and gauge. Now, if it deviates drastically from that - then you've got a problem.

I think I'll get it checked. Thanks for the reply. Car runs fine but the reading seemed a bit hot for 70 degree weather. Trunk floor is dry so I don't think the coolant tank is bad. Paranoid probably, but an ounce of prevention is worth a pound of cure! Old Boxster owners die hard!

There's the theoretical and the practical side of the question and since the title of this post was "RPM for every day driving" I think the practical side makes much of this boy-racer discussion, academic.

In the 987 with the 5 speed, 6500 rpms will get you:

1st @ 33 mph
2nd @ 63 mph
3rd @ 93 mph

Unless you routinely get up to 100 mph everyday let's keep the discussion around 1st and 2nd gear. The whole point of redlining the engine as MNBoxster notes would be to achieve a higher speed as quickly as possible, but it's my experience that redline driving doesn't match real world driving conditions (although I wish it did).

In the world I live in, there's frequently someone driving a car in front of me; most folks drive in a band between 35 - 55; you're only first in line at the traffic light maybe 20% of the time (if you try to be); there's usually a nun who steps into the crosswalk without looking; it's 2:30pm once a day so you're in a school zone now; there's often a cop at the next intersection; everybody starts to slow down while you're speeding up cuz there's an accident or some hot chick is waiting to cross the street....yada yada yada.

So you can consider whether you'll be routinely shifting at 6500 rpms when you get out of your break-in period but I can tell you that you won't be and you won't want to...unless you live in a world where:

People wave to you just cuz they're happy to make human contact; traffic lights or stop signs are separated by miles; you're a nun-killer without regard for innocent children just trying to learn and make the world a better place (they're only children...why do you have to try and scare them with your 2.7 litres of horizontally-opposed fury?) your brother's on the police force; no one ever crashes their car in your municipality of homely women...yada yada yada.

More than the shift point, I think the more pertinent question for engine wear would be what RPMs do people routinely sustain at speed rather than during acceleration? If you think it's prudent to cruise @ 60 mph in 2nd gear or drive through that school zone at the redline knock yourself out, but in general I think shifting at or sustaining near-redline RPMs would be hard to characterize as anything but recreational and occasional. In general your own common sense and local vehicular code will prevent you from doing much damage to yourself or your car and the occasional opportunity you'll have to really rev that engine is well within the tolerances that Porsche has engineered.

rdancd816:

My temp needle used to remain between the 1 and the 8 in "180". In bad traffic, it rose to right of the zero, and I discovered one of my radiator fans had burned out.

You should check to see if your fans are working before you take it in. When the car is fully heated up after a spirited drive, park it in idle, turn on the AC real low, and get out of the car and put your hand under the front bumper, just in front of both wheels.

You should feel a blast of hot air from both sides. The driver's side is the primary radiator and the passenger side is the secondary, which usually starts up under an AC load.

If one or the other isn't working, this may be the reason behind your needle moving up and you'll be able to gauge the costs involved (the part cost me $175 and the labor was 2 hours. Stealership wanted $650 but I cheated the man once again). I temper this statement with the fact that my car's cooling system is working well and not leaking, and sitting in traffic does raise the needle a bit, but not much. Certainly within operating range... and Houston's outrageously hot most of the year.

Today, my needle sits squarely on the line marking 180 to the left of the numbers... probably a bit lower than it should be. That's because I swapped gauge faces and getting those needles back exactly where they belong is an artistic talent I do not possess. Search on my gauge face thread for all the gorey, frustrating details.

I find little reason to rev higher than 5000 RPM unless I'm really out for a sprint. Coming out of the northbound I-15 onramp at Mira Mesa Blvd. in San Diego, from eastbound on Mira Mesa Blvd. is an example of where one might hold revs up to redline-- it's a big, wide "clover leaf"-style right-hander, ending in a new, empty lane. :)

I think this is very sound advice. Frankly, "bouncing the car off the rev limiter" is for folks who have PLENTY of cash to spare. Moreover, for you guys under warranty, porsche keeps the data on the rev limiter and will use it to deny warranty repairs if they are in the mood.

That latter issue is a fact, I have seen it happen.

If one looks at the HP and torque CURVES of the Box, that bad boy starts to flag as it approaches 6000 I believe.

Running past there is more an exercise in ego than anything else. But, it is your car and your license.

Isn't freedom wonderful!

In the 987 with the 5 speed, 6500 rpms will get you:

1st @ 33 mph
2nd @ 63 mph
3rd @ 93 mph


SD987, I assume these stats are for the standard 987 Boxster. Does anyone know what they are for the Boxster S?

:d
 

I can definatly state that I have become more knowledgeable by MNBOxster's posts.

Thanks MNBoxster, I enjoy ALL your posts!

Could be my imagination, but...
 

I think the shifts seem smoother if done above 3500RPM. Might also indicate I'm concentrating more on the shift if I'm driving it a little harder, though...

I agree. My shifts are a bit clunky unless I shift above 4,000 in 1st and 2nd. If under 4000 I give the gas a little blip as I shift to the next gear. This matches my rpm with the car. I think the car unloads quicker than I can shift and when I do shift I'm not rev matching any longer. Thus the clunk. :cheers:

Great advice above. One other key point to keep in mind is that the biggest risk for over-revving the engine is not really on acceleration but rather deceleration. If you're an engine braker, or otherwise downshift unintentionally and don't match gears properly to your road speed, you can easily blow past redline and stay there (unlike when accelerating). On acceleration, the rev limiter is going to help protect the engine and back you off from redline - there is no rev limiter protection on deceleration, when the wheels are backdriving the engine through the tranny.