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Originally Posted by drburton
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.
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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