Did I do any damage by pushing my RPMs to the rev limiter yesterday? *NM*

... for over 215,000 miles.
As long as you don't over-rev because of a bad downshift, there is no damage hitting the limiter.
These cars need to be taken to the limiter now and again.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

That makes me feel better. It was 68F and I had the top down. A loud Harley challenged me from a traffic signal and I couldnt hear the engine. In 2nd gear , the car started to feel fuel- stareved and when I glanced at the tach, it was wound way over. Because I was so focused on driving, i dont know what the revs were, but I know I hit the limiter.

Thanks Pedro.

there's no nothing to really worry about.

Sincerely,

MarcW.

Best to wait for the car to be warmed up before doing so. Need to strech their legs ever so often. Not paying attention on down shifts, however, can toast these engines as I believe the limiter doesn't kick in on down shifts.

by either (or both?) shutting off fuel delivery or ignition. This will not help a bad downshift (say, from 5th to 2nd at a high vehicle speed) that causes the wheels to drive back through the transaxle to the engine; a direct mechanical connection. I suppose you could calculate maximum downshift vehicle speeds in any gear combination once you have the proper speeds-in-gears, transmission gear ratios, final drive ratio, maximum engine speed information, etc.

I'm not saying its the thing to do for no reason, btu its within the motor's operating envelope.

Best if done with a warm motor and good oil.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Quote
grant
I'm not saying its the thing to do for no reason, btu its within the motor's operating envelope.

Best if done with a warm motor and good oil.

Grant

For optimum performance, would it not be best to time your shift just before (a split second) you hit the rev limiter? As soon as you hit the limiter, you're not getting maximum power any more.

I realize that during the heat of the race, there will be times when you just miss that split second, so the rev limiter saves damage to your engine.

.. just before another corner where you need the lower gear. exanmples, the downhill striaght at Monticello; stright before turn 7 at Lightning.... where, for me, 3rd gear (105 mph at redline, 5 sp, 986 2.7) is about all i'll get anyway.

note that shifting earlier means you shift at the power peak, but it also means you wind up lower on the torque peak than you otherwise would have....so it cuts both ways. I dont knwo the exact perfect point.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com



Edited 1 time(s). Last edit at 01/30/2012 04:22PM by grant. (view changes)

Edited 1 time(s). Last edit at 01/30/2012 04:27PM by Laz. (view changes)

... you can let it hang there and nothing will happen other than the engine getting hot because of the high rpms.
On my car I moved the rev limiter up from 6800 to 7100.
I now generally hold 6900 - 7000 when at the track, so in essence I'm constantly over revving by 100 - 200 rpm.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

I'd bet these engines are good for 9000 rpm stock, without any special crankshaft hardening, etc.

unable to close the valves fast enough and valve and piston contact occurs with almost certain disastrous results.

Even so, I have to say I find it rather amazing that even after all of the miles the valve springs in my 02 Boxster still manage to close the valves on time. I know springs that are worthy of the name do not loose their springiness (metallurgy is, putting it mildly, an interesting field one of many I wish I had more in-depth knowledge of) but I still can't help but wonder at the springs' ability to keep springing.

While I can never know for sure I believe there is considerable margin in these (in fact almost all) engines.

During a track drive of a Carrera GT a magazine writer (I read about this in a car mag published in the UK and the test driver/writer was claimed by the UK writer reporting on this to be French) missed a shift, going from 4th to 2nd. The engine blew up.

A postmortem (DME dump probably) found the engine rev'd to around 14K rpms before something let go.

I was talking to a Porsche tech the other day and he mentioned the C-GT's red line is IIRC 8K. That is wondrous enough, but I pointed out that the redline is 8K at 1 miles (well, 2K miles or after break-in) and 8K at 100,000 miles and probably if one ever gets driven enough at 200,000 miles.

Or to put it another way, there is nothing in the owners manual of my car that says the red line diminishes with miles driven. Words fail me.

All I can say is that these engines run at all is amazing. That they run like we demand of them for many owners over thousands and thousands of miles with nary a hiccup is beyond amazing.

Sincerely,

MarcW.

2002 Porsche Boxster
1987 Porsche 944S
1982 BMW 528e
1965 Chevrolet Corvair Corsa turbo convertible
[www.motortopia.com]
Edited 1 time(s). Last edit at 01/30/2012 04:49PM by Eric in Lincoln. (view changes)

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MY 2000 S, Ocean Blue, Metropol Blue, Savanah Beige.
Bought June 2000 - Sold May 2010