wellcraft290

Let me ask been reading quite a few posts on here about missing a gear or hitting the redline etc. Do these cars have a fuel cutoff? I guess I shift too soon few hundred if not a 1000 before the redline.

So anyoen hit the redline here? What happens? Automatic engine blows up?

J richard

Unless you have a modified chip that eliminates the rev limiter you do have some limited protection, it is integral to the DME and effects the spark not the fuel. It works pretty well to limit over rev while in gear but all bets are off if you hit the money shift (4-1 or 5-2) Pulling to redline is not a problem, but you just have to be patient and methodical and not force or rush it, also if you have any wear in the shift coupling it's a good idea to replace the bushings to keep things where you want them. plenty have made the money shift, and it gets expensive. Like David Hobbs likes to say..weeaaannnggg kablooeeyy.....it done blowed up...

ian89C4

I touched the rev limiter in 3rd at a DE (VIR on the backstretch) but that was because I was not paying attention. The car just sat there around 6800 RPMs, I quickly shifted, and then smacked myself when I was back on the paddock. No issues came of it, certainly not the money shift.

I now shift at least 500 RPMs south of redline, not worth damage to the engine.

wellcraft290

yeah i am nervous. I do have a chip and LWF so afraid. I read a story here about a guy went from 4-2 pegged and blew the motor.

Henry964

The story is true and it happened a month ago in a Porsche Club meeting in Argentina, a guy with a C4 went to redline in 3rd and when he shifted to get 4th he got 2nd instead.The engine started making very ugly noises, he stopped it and called a service truck to return to Buenos Aires
I don´t usually go to redline in gears, but sometimes in an event it can happen, I never noticed hitting any limiter in this upshifts
someone told me the rev limiter doesn´t work in downshifts so there lies the danger of damaging something.

DaveK

I regularly shift up a gear at the redline, and it's never caused me any problems. I have also hit the rev limiter several times in the past 8 years (although not regularly) when I wasn't paying enough attention, also without issues. The most memorable was noticing that it hits the limiter at 140mph in 4th (on a track of course.....).

Hitting 2nd instead of 4th or 3rd instead of 5th is a whole different thing......

BlueHeeler

True.
The money shift is a mechanical over rev. You are using the tire to turn the engine rather than the inverse. An electronic rev limiter can only limit the engine not the wheels.

wellcraft290

I think if I did the "money shift" I would be so upset. Just thinking about all the money it will cost to repair.

Streetfighter

I have hit the rev limiter a few times, it doesn't sound good that is for sure. In most cases people are not paying attention to the tachometer. In terms of the money shift, don't know what to say, that is a question of knowing your cars gearbox.

911Jetta

I've hit the rev-limited a couple times. It's nice to know it's there!

Regarding the Money Shift...
What is the technical/mechanical reason that a rev-limiter exists only on the up shift, but not also on the downshift? In other words, why wasn't the system designed to not allow the engine to go past 6,800 regardless of the input?

DarrylH

A rev limiter cuts fuel to the engine to prevent it continuing to increase in speed.

Cutting fuel to a mechanically overdriven engine makes no difference, since the engine spins faster by being forced to by the transmission. I can't think of a way to stop an over-rev caused by spinning the engine faster than it can handle.

As a thought experiment, imagine the car is "off" - no fuel, no spark, not running. Put it in gear and push it fast enough, and you'll over-rev the engine, inevitably.

DaveK

How could it? For the gear you've just selected, the wheels are now turning the engine fast enough for pistons to meet valves - even without ignition. It would need to somehow disconnect the drive to the wheels to prevent this.

Jamie Summers

I discovered the expensive way that 4 does not go into 1 ! Noticed it before I'd even got the clutch all the way out, but not quickly enough to stop one valve hitting a piston and breaking a rocker. I now have an "S" shaped valve mounted on a wooden stand on my desk to remind me of what happens when you're too aggressive on downshifts ...........

Jamie

BlueHeeler

Pics? If you are going to pay the bill you might as well show it off.