S rev limit?

[NeilW]

I recently fitted a new AFM and while road testing the car accidentally found the rev limiter in second gear. This isn't something that I normally do, but I was caught out by the car reving that bit quicker (me lud[8|]). Anyway, the limiter cut in at 6,500rpm whereas I though it was supposed to be 6,800rpm for an S, otherwise why bother with the differently marked rev counter?

To test that it wasn't me mis-reading the dial I had a second go, same result. This isn't something that I plan on repeating, I've probably hit the rev limiter 3 times in 3 years of ownership (including twice in the last week). Even on a blast I tend to drive with a 6K limit in mind as this seems to be a sensible compromise between fun and engine preservation.

Are there are any S hooligans out there who can comment on the rev limit?

 

[Fen]

I don't think there is any reason not to use all the revs regularly, subject to the car being properly maintained and fully warm before you do. What you don't want to do is drop gears and cause it to overrev beyond the limiter when engine braking. As an aside I keep meaning to search Rennlist for a suggested rev limit for a balanced 2.5 engine. I have set it to 7,000 for now but I know some of the ProMax chips raise it to beyond that without expecting the bottom end to be balanced, so what do people think is safe?

 

[eastendr]

Buby WUF definately ran to 6,800 with the original chip.

 

[NeilW]

Fen,
I suppose you're right about regularly hitting the rev limiter, I've just read so many stories of No.2 rod bearing that I refrain from such practice. In truth, the S doesn't have a lot of power after 6K anyway.

Rick,
Thanks. This gave me two thoughts, 1) My car has an S2 DME (don't know if that would even work), 2) The rev counter is inaccurate, the calculation is based on a short-term average presumably. Fast reving = average lagging behind. Hmm, maybe not.

 

[Guest]

Fen,
I think the limitation is in the valve system (I would think you'd get some valve bounce after 7k), so running a higher rev limit just because your bottom end is nicely B&B'd doesn't really change a lot. I think Either John at Vitesse or Chris White said something to that effect a couple of weeks back. drop 'em a mail if you can't find it. I'm sure they'd help.

 

[mik_ok]

I think it's most likely your rev counter is just "softened" slightly over the years.

I tend to use a 6,300-ish change-up point in the S2 as it's definately tailing off by that point, and upshifts still drop you nicely into the fat of the torque band.

Fen - have you got a dyno from your car with latest mods? Asking as there is no point raising the limit if torque is dropping towards your existing limit.... but I'm guessing you're aware of that. []

 

[Fen]

The car hasn't been on a rolling road yet and you're right it might not be worth going over 7k (200mph attempt aside [8D]) but I wonder if it's safe trying to go much further to see what happens when it gets on the rollers. There is plenty of boost left and there will be sufficient fuel, but that's only part of the story.

 

[944Turbo]

there was a discussion on rennlist a month or so back that said the rev counter is usually off. I know mine 'stalls' briefly on the way up, IIRC it also reads low on the limiter but If I hit the limiter I am not usually looking at the rev counter - Boost guage, AFR and out the window.
Tony

 

[Mikie_gb]

I will happily wind mine right up into the red (not a huge fan of banging rev limiters tho) very very often and to be fair, I have never been in the mood to scrutinise the rev counter close enough to spot an exact limit. As for engine damage..... Engine fine, everything strapped to it is flying to pieces.

I once had a 4 stroke bike that reved to 11800 rpm and it was deeply unpleasant to hit the rev limiter as it dropped the revs from 11k to 8k and it would bounce between the two trying to chuck you off. Or you could let the throttle go and return to 10 mph in .3 seconds while you carry on at 70mph into the scenery.