Potential Horsepower Decrease?

[MKE_M3]

Originally Posted by Tony B

Over-revving when cold (and that means anything less than normal operating temperature) is the quickest way to ruin your engine, either catastrophically (something breaks, or a head gasket pops) or by rapidly increasing wear.

I think you are vastly over stating this risks. I'm not saying it isn't bad, but engines can take a lot more than most people give them credit for.

[BCA]

Originally Posted by DARK_M3

How does one "accidentally" hit redline with a cold engine?

I see what you mean. But I'll give you one example: when I had my M3 with DCT, I would sometimes think I was in D mode when accelerating from a stop when I was actually in S mode. Redline comes pretty quickly in 1st gear! I did that a couple of times with a cold engine and it bugged me but caused no obvious damage. I recall seeing at least one other post on this forum by a concerned member who did the same.

Originally Posted by Mike Benvo

Not true..

It will let you rev up to about 6K on an cold engine. Way too high. I don't go over 3000 RPM until the oil is atleast 160F. Then gradually raise RPM as temp raises.

Originally Posted by Tony B

Definitely agree - anyone who relies on the variable red line as a source of useful should think again....this reminds me of the mis-translation from German to English, in the E46 SMG manual...."the shift lights indicate the optimum up-shift revs"......erm no, they dont.

Over-revving when cold (and that means anything less than normal operating temperature) is the quickest way to ruin your engine, either catastrophically (something breaks, or a head gasket pops) or by rapidly increasing wear.

Originally Posted by jdemetry

I think you are vastly over stating this risks. I'm not saying it isn't bad, but engines can take a lot more than most people give them credit for.

I pretty much agree with all of this. I'm always careful with cold engines and try to keep RPM under 3k until pretty warmed up. At the same time, I think that my concern is likely a little overkill and the engines can take more than we give them. As long as you don't really push (or redline) your cold engine regularly, it's probably just fine.

[Small Yellow]

Originally Posted by DARK_M3

How does one "accidentally" hit redline with a cold engine?

I made a stupid mistake once. I was waiting for a friend in my car for a long time and I wanted to extend my legs so I pressed down on the gas pedal. When I saw my friend I stepped on the clutch and started the car and basically redlined the car when the car was cold. It was bad... I felt bad so I gave my car a bath the day after