Red Lining a 993 (or any 911) engine
11-04-2010, 10:58 AM
#16
Race Director
11-04-2010, 01:24 PM
#17
Rennlist Member
true, there is some compliance in bearing shells , piston - piston pin interface and the rods may stretch a tad, but i think measuring this somewhat minuscule "growth" would be challenging and difficulty to quantify.
be safe
Craig
be safe
Craig
11-04-2010, 01:39 PM
#18
Race Director
very much so. I'd guess its simply not having the piston stop at the exact same spot each revolution. Further, this ring is generally carbon, which most people agree can be blown out with a good italian tune up.
I don't think about how I drive the car. Sometimes I drive at 1500rpm with little throttle, other times I'm hitting the rev limiter often. I don't pay attention to how many times i hit redline or how early I shift.
I don't think about how I drive the car. Sometimes I drive at 1500rpm with little throttle, other times I'm hitting the rev limiter often. I don't pay attention to how many times i hit redline or how early I shift.
11-04-2010, 02:41 PM
#19
This may sound stupid, but I am a mechanical engineer. It is fact that wear is produced by friction (which is motion). So if you wind up your engine in the higher rev ranges, you must, by defintion, be wearing them faster then if you don't. Look at F1 engines, or even NASCAR engines. They are designed to perform at very high engine speeds - and they do not last very long. I think this year's F1 series allows the manufacturers only 8 engines for the season - and that's it. I know they measure all types of variables so that they even out the wear expecting the engines to require rebuilding. I'm talking normal wear and tear and not catastrophic failure (such as a connecting rod breaking at very high rpm).
I read on these boards often that many rennlisters routinely red line their cars in everyday driving. While the 993 (and any air cooled 911) engine has that special sound - especially in the higher rev ranges (for the most part above 4000 rpm), I can't believe it does them any real long term good. If you take piston travel per mile driven, it defies any engineering data to suggest it will last longer at more piston/feet/mile travelled than less.
Same with tires, brakes - any item in or on a car that "wears" from use. Even windowglass gets pitted and eventually needs replacement - and that's just friction of little particles in the air hitting off the glass as you drive.
While I'm not advocating putting your car in the garage and not driving it, I do see lots of "harry high school" types driving their muscle cars at full throttle all the time and these cars when they get only a few years old look like the walking wounded.
I read on these boards often that many rennlisters routinely red line their cars in everyday driving. While the 993 (and any air cooled 911) engine has that special sound - especially in the higher rev ranges (for the most part above 4000 rpm), I can't believe it does them any real long term good. If you take piston travel per mile driven, it defies any engineering data to suggest it will last longer at more piston/feet/mile travelled than less.
Same with tires, brakes - any item in or on a car that "wears" from use. Even windowglass gets pitted and eventually needs replacement - and that's just friction of little particles in the air hitting off the glass as you drive.
While I'm not advocating putting your car in the garage and not driving it, I do see lots of "harry high school" types driving their muscle cars at full throttle all the time and these cars when they get only a few years old look like the walking wounded.
Usually it's valve train that is the limiting factor in a motor.
F1 uses peumatic valves.
