Mechanical over-revving

[Adam]

If the valve stems were bent I would definately know that right!?? I remember the thread you are referring to and Tool Pants showed a OBII scan of one of his friends boxster S's that had 9 range twos. He said the guy was on his 2nd engine, but I couldn't tell if he was joking or not or if it was due to the over-revving. There wasn't much techical info in that thread either. No one seems to know much about this subject. There is a video of a guy with an Acura RSX doing a 3-2 shift at redline(like I did) on the net and his was engine finished. I guess the pistons slammed into the valves? If my motor doesn't seem to have any apparent damage do you guys think I'm in the clear??

[Brucelee]

If you overrev to the point of valve float, you literally have the stems of the valves bouncing off the cam and such.

Hmmm, how could this be anything but bad for your box? I THINK that is why they have that whole red line thing?

[Adam]

Well, I know it's definately not good but I took my car out today and it runs stronger than ever. I know that it was definately an over rev(again) because I was at redline in 3rd at appox 100mph and I dropped it into 2nd! The back tires locked up and stutter skipped on the pavement and the engine went weeeeeeee. It sounded kinda like a super-bike for a sec now that I mention it. I guess these Flat 6 engines can handle quite a bit! If there was any damage I think it would be immediately apparent(bad noises and blinking lights etc etc). I think I dodged another bullet but I'm going to be more careful from now on and not try to be ultra quick shift speed racer boy. Thanks for the responses.

[Brucelee]

Damage is of course, a relative thing. Some damage is micro in nature and simply leads to issues down the road. Other damage is massive and immediate.

I am all for using the Box towards it strengths, as long as one knows that there is no cheating the laws of physics. You play, you pay!

But you seem to know that now and hey, who am I to talk???

[Adam]

Very true, anytime stress is placed on a part it could weaken it enough to lead to complete failure down the road. Sometimes it is more immediate and easily noticed. I remember reading an article in a magazine around the time the Carrera Gt was released. An automotive jounalist misshifted and over-revved the to extremely high engine speeds....to the tune of 14,000 rpm when Porsche checked the computer. The result was immediate engine failure. Hopefully if my engine ever gives out it will be within the next 5 and half years so it will be covered by my warranty.

[BuffaloBoxster]

Possibly not if you have a history of over-revving it

Be careful, and don't rush your shifts.

[ntmatter]

Here's a technique that I picked up when I was running my Viper at the track a lot - the Dodge gearbox was definitely suseptible to a 3-2 mis-shift:

Notice when shifting from 1st to 2nd to 3rd that your hand is held much like you're holding a soda can, with the top of your wrist pointing to the passenger window. When shifting from 3-4, rotate your wrist counter-clockwise about 90 degrees, so that your wrist is now positioned as it would be on a bike's handlebar. Rotating your wrist like this will make it nearly impossible to go from 3-2. Practice this in your street driving so it's second nature, so that if you're under the stress of hard driving and upshifts you don't yank the shifter towards yourself and grenade the motor.

A