Is it true that the rev limiter will not kick in if you skip a gear? Say, from first to third? Not that I'm in the habit of doing that. It seems I read that in the 993 E. Companion.

 

I would be amazed if this were true and can see no practical reason for the factory to program this for the limiter.

 

I agree with Mark.

There are 2 times the rev limiter will NOT protect you:

1) Missed down shift
2) Spin- gotta get the clutch in

 

From Adrian Streathers 993 Book, page 190 :

"RPM Limiter

The DME(ECU) software has a built-in limiter to protect the engine against over-revving. This protection only works when shifting gears up or down in a known pattern. The rpm limiting system does not protect over-revving when a gear is missed.

Example: shifting from 4th gear to 1st gear and forgetting to go via 3rd and 2nd gears."

Perhaps he is mistaken? I agree that it does not make any sense.

 

Adrian is not mistaken but its phrased somewhat clumsily.

The rev limiter doesn't function when the car's speed and weight force the revs too high when there is no load. This can occur when too low a gear for the current speed is selected during a downshift and the engine's revs are forced too high after the clutch is released.

Skipping gears under load such as when upshifting preserves the rev limiter function and it works just fine.

 

The rev-limiter does not protect the car on a down shift, regardless of what gear or pattern. Only on a up shift.

 

You guys beat me to it. The rev limiter can't protect against a "skipped gear" money shift from, say, fifth to second.

 

During acceleration it is pretty common (with a straight cut/sequential transmission) to apply firm pressure on the shifter and when the engine loses power as it hits the limiter, the pressure on the gears is reduced and the transmission will shift. This works well on a bike.

 

Not the only nugget!

Fair enough, but completely inappropriate in a 993 (or any other street car for that matter).

Best,

Matt

 

I've never heard of this "technique" but I've been told that it's generally not a good idea to bang into the rev limiter and use it as an indication of redline, so I have to wonder how mechanically sympathetic adding another pressure component on the gearbox would be. I'm going to guess...not very.

 

It's not really "technique" but more along the lines of mechanics.

You cannot easily pull the transmission out of gear w/o using the clutch if the gears are under load (i.e. accelerating or decelerating) but you can easily pull it out of gear w/o the clutch during that transition moment between accel and decel (or vice-versa).

You don't really have to be driving the car hard to try this theory out either.

Next time you're in your car (or any manual car if you prefer not to try it in your Porsche), just start driving, get up to maybe 2nd gear in the 15-20mph range. As you're accelerating in 2nd, start applying light pressure on the shifter as if you're going to go from 2nd to 3rd. As you apply pressure to the shifter, lift off the throttle, the shifter should pull out of 2nd easily, and as the revs drop and you continue to hold pressure on the shifter to get it into the 3rd gate, the shifter should fall into the 3rd gear gate when the revs fall in line w/ the relative speed at which 3rd gear would be at the speed the car is traveling.

Obviously, you don't want to make it a habit of going around shifting sans clutch, but it is possible.

I assume most of you have not raced at autocross w/ hyper competitive drivers? Those guys will shamelessly ride the hell out of their limiters every single weekend if it happen to be the fastest way through a section of the course.