Thought I'd run this by you in case you have any comments...

A poster on another forum has recently asked the question 'is it normal to hit the rev limiter at 130mph in 3rd gear'? I asked which model he was driving and his response was "C2 , with rs chip and larger throttle body with cone air filter".

I told him that if he has a standard gearbox then the engine would have to be revving at 9000plus in order to achieve that sort of speed as I have read the max speed is normally around 98mph or so.

He stated that the speedo definitely read 130mph and the revs approx 8000rpm or so....

I have since asked whether he is running standard sized wheels and tyres but it doesn't sound all that safe to me....any comments anyone?

 

Hmmmmm... 130 km/hr is very close to 80 mph. Do you think this chap may have imperialised his metrics??!!

 

Doh, what was I thinking?? 130 mph @ 8000 rpm is only 16.25 mph/1000 rev, which is probably about right. At the office at the mo, but a check of the owners manual will help - there is a graph of mph vs revs for each gear I think, in the back somewhere.

 

I am pretty sure max speed in 3rd (assuming standard gearbox) is 98mph @ 6900rpm. If he really was doing 130mph he would have to be at around 9150rpm to achieve the speed.

He states he was at 8000rpm and without any mods, this engine speed probably isn't all that safe...that's my point. It may be the new chip has changed the rev limit which also is not good...the owner should be made aware.

Let me put it this way, how many of us see an indicated 8000rpm?

 

8000RPM. Cannot be a genuine RS chip then. They are limited to 6800RPM. Standard limit is 6700RPM. I have heard of some chips allowing 7200RPM but 8000 is a tad too high. I would be interested to know the manufacturer of the chip is,
Ciao,
Adrian
911C4

 

I occasionaly accidentally hit the limiter in lower gears (1st, 2nd, 3rd). Can this cause damage?

Thanks in advance!
Piers
1990 C4 Coupe
(Horsepower unknown after mods!)

 

Adrian

It would seem to me that 130mph is on the high side unless there have been gearbox mods...

I have asked him abotu the manufacturer's details and told him I have posed the question here on Rennlist. Perhaps he will confirm direct or if not I will forward his reply. It just seems a little scary that a chip manufacturer will allow an engine to rev to 8000...or is it perfectly acceptable in which case I am creating a situation over nothing <img src="graemlins/c.gif" border="0" alt="[ouch]" />

 

Piers

Shouldn't you change the 'Horsepower unknown after mods' to 'I am going to call AMD to get a rolling road done so I can let all my contacts at Rennlist who are keenly awaiting the results, know what the deal is'....I know it's abit long but it's the truth...

Being extremely technical, the only thing I know for sure is that the rev limiter stops maniacs like you from hitting 10000rpms or more... now that would cause damage. In general though, I wouldn't think you should be hitting the limiter regularly unless either a) you are an ex automatic tranny driver or b) deaf...in any case you don't gain anything from doing it...

 

Christer

Perhaps the poster owns a Tip, that has a longer 3th.

 

Dear Christer,
I am sure Porsche put the limit at 6700RPM for a reason. Reliability performance I know would be at the top of the list. 8000RPM in third is a tad over the limit. I know Porsche are conservative but if they could have given more you would think the RS would have been the prefect platform. They gave it 100RPM more and these were street legal track racers. I would personally doubt the longevity of a standard 3.6 M64/01 or 02 running at 8000RPM would be very long,
Ciao,
Adrian
911C4

 

Hi All

i bought my car from a guy in germany, he was very much into his go faster mods.
The car was serviced and maintained by an RS specialist, with his own garage and an interest in racing.

Now here is where it gets a bit foggy for me, the car has the following,

17" wheels,
h+r lowering and adjust susp
either cup bypass pipe or a cup exhaust maybe someone can help me on this one.
upgrade chip

i dont know the maker of the chip and i will ask the previous owner as i have his email, but he did state that the RS mechanic who fitted the chip for him said it performed just as well if not better than an RS chip.

i was scheptical, but with 4 adults in a 91 c2 cab, i watched the speedo go to 285kph. Noisy with the top up.

i have never been anywhere near that speed but it is possible. But reving to 8,000 i am sure thats not healthy.

Rob 91 C2 Cab
Jersey Speed limit 40MPH <img src="graemlins/crying.gif" border="0" alt="[crying]" />

 

In general though, I wouldn't think you should be hitting the limiter regularly unless either a) you are an ex automatic tranny driver or b) deaf...in any case you don't gain anything from doing it...[/QB][/QUOTE]

Tends to happen when I get into 964 on Friday night to drive up to Norfolk having driven 2CV during the week. It all seems to happen so fast in the 964!!

Perhaps I'll get AMD to do the dyno when I need next oil change? What do they charge for Dyno?
Best regds
Piers

 

Piers

I really have no idea what they charge, and although I am a helpful chap I refuse to call them on your behalf unless you move to the U.S.! I think we need to see some commitment from you on this!
The number though is 01869 323205. Am I good to you or what?

 

Dear Adrian

The owners chip was purchased at 930 Motorsport here in the UK apparently - it is their own chip. These guys have a pretty good reputation over here actually. Apparently the chip has '3.6 RS' written in pencil on it!

The details of the car and mods are:

"1993 Coupe C2,
RS Chip
Larger throttle body
17 Cups with contisport tyres
Cone powerflow filter ie no air box
G-Pipe"

Apparently he hits the rev limiter at an indicated 150mph in 4th...

 

Dear Christer,
Thanks for the info. This data is not really much help in the topic though. This chip obviously does not have a suitable rev limit installed. This would be a racing chip rather than a road chip. 8000 RPM for a road engine like this one appears to be, only brings into my mind the words of a fellow Rennlister from a few years ago, "Grenade" pin pulled, just waiting for the lever to be released. Good luck to him if he drives like this. I just hope he can afford the repairs if they are needed. It is my personal opinion that for road use a rev limiter is probably a good idea at or around the levels of original. At least in the 964 it does not record over revving, unlike the new 911s, or so I am told anyway,
Ciao,
Adrian
911C4