rotor rev limiter..

[vash]

today, chasing my friends 928, i may have gotten alittle deep into the revs. what does the rev limiter feel like, when it comes on? i got a feeling that the ignition was shutting off in steps? three pops, with a loss of power. then i let off fast and all was back to normal. i was checking a blind spot and forgot to shift (right away). i forget these things rev like motorcycles, and it just crept up on me. BAD CLIFF! that was nerve racking. i didnt do damage, did i?

i went to san leandro to look at a 90 C2. leaking like a sieve.....$23K.

[Vintage911Racer]

Do you know for sure you have Rotor Rev Limiter? Is it 6800 or 7300? In that car it is most likely the 6800.

You should not worry, that is why it is there.

[Rot 911]

yep that's just what the rev limiter feels like

[concentric]

So riddle me this:

Will the rev limiter just catch all overrevs caused by foot application of the accelerator? I'm assuming that a missed shift (like from 4th into 1st or something) revs the engine in enough of a powerful way that the rev limiter doesn't work.

Does it work well enough that you can actually pull all the way to redline without fear? I've been coming close, but been afraid to go too close. 5.5 - 6K has been plenty enough for me without knowing the answer to this question.

JCM

[Rot 911]

It is an electric limiter and only will save you if you are just running the engine up to the red line. A missed shift and you are toast.

[Vintage911Racer]

The Rev limiter will oly work on UPSHIFTS not DOWNSHIFTS. If you go from 4th to 1st or 5th to 2nd. You are going to have some funy noises in your motor (depending on the rpm you are at at the time of the shift)

But as far as upshifts, Take it to redline a few times. Cars like to be drivne hard some time. I take my race car to 7500 every shift. It love sit.

[UTKarmann_Ghia]

Stoopid question: do the SC's have rev limiters? Mine has a normal, VW-looking rotor so I know there's not anything in there to handle it. Is it handled by the CIS or something else?

[concentric]

Thanks, that was helpful!

Jason

[Joe Bob]

Pull the cap, pull the rotor the rev limit rpm is etched into the rotor....

[vash]

matt, my rotor has a mechanism in it that when spun at some predetermined RPM, centrifugal force will overcome some spring tension and shut my ignition off. it is pretty obvious when you peek under my cap. it came in my standard tune up kit from pelican. i think the CD box in the SC cars are supposed to have a rev limiter in it. hence the missing hardware on the rotor itself.

cliff

[SpeedracerIndy]

Rev limiting rotor:


Normal, non-rev limiting rotor:


US spec SCs limit revs at the CD box. Euro SCs and earlier US spec (not sure of years) use the rev limiting rotor.

[vash]

damn, the power of photos! thanks.

[Bill Verburg]

The older cars(pre unleaded gas) used the distributor rev limiter. They changed the method to a fuel cutoff for smog compliance. Didn't want raw fuel poured down the exhaust stream.

[SpeedracerIndy]

No problemo! With the rev limiting rotor, the cut off is much softer. My father's Carrera has a much more abrupt cutout when I hit the limiter in it. Mine seems to peter out, but not bounce off the limiter like the Carrera. Not sure if there is a benefit to either. I suppose if you don't have a popoff valve, and you have a rev limiting rotor, you could be in danger of an airbox explosion since the ignition is shutting off, but the CIS is still dumping fuel into the cylinders.

[Early_S_Man]

CD,

The CDI unit on USA SCs doesn't have any control function regarding rev-limiting!!! The same TD signal that drives the tach is also fed to a speed relay that cuts off the fuel pump ... when preset revs are hit ...

[SpeedracerIndy]

Ok, scratch my last comment then... I guess that would explain the rev limit relay behind the fuel gague in US spec SCs.

[fintstone]

That is why you must be careful with rpms after swapping a US spec SC 3.0 into an earlier car....no rev limiter unless you use a euro rotor.

[vash]

thanks warren. you should tell pelican so they can change that info on their website. and fint good thing to keep in mind with the revs. i want to go 3liter someday....