AusS2000

It seems most S2000 engines die as a result of a mechanical over-rev. You're at redline in third but shove the stick into 2nd instead of 4th....

I was watching one of the F1 support races on the weekend and was reminded about a feature of the 996 Porsche 911. My memory is sketchy, but I believe if you accidentally mechanically over-rev it the clutch disintegrates or something and protects your $25K engine. But as the clutch in that thing cost about what an engine does in an S2000 it's probably not worth adapting.

What I was thinking was we could use a device like Modifry's Redline Shift Warning Beeper and set the alarm to trigger at 9300. We could use the output to trigger a solenoid that operates the clutch (very quickly) and disengages it for a couple of seconds. No more menchaincal over-rev!!!

Whatcha think?

Slows2k

Not a bad idea, I think Billman250 suggested something similar before as well. Finding an actuator/soleniod that is small enough to mount on the clutch fork, and strong enough to pull the fork will be the hard part.

Old Civic's would "furrball" the clutch on a mechanical overrev. The clutch wasn't strong enough to transfer the power.

Boston Duce

Those are SMG tranny's on F1 cars. Computer controlled sequential manuals with the clutch actuation hardware to support it.

There is no such thing for 996 (or 997) series Porsche's.

It's either full slush box, or grenade-able 6 speed- if you miss a downshift you'll turn your flat 6 into mechancally separated bratwurst.

$25,000 is the sales tax on one of those F1 engines.

Regards
BD

Spoolin

Why not just come up with a gate lock out. Your ECU reads the rpm and if it's too high for a specific gear, than a gate locks the shifter from engaging until the rpm is safe.

chris_barry

I think these clutches were in the GT2 or GT3. The Porsches had deliberatly weak straps locating the clutch pressure plate. They were designed so that if the engine was accelerated too quickly by the gearbox spigot, the straps would fold up the the clutch would release.

It worked when needed, and a lot of time accidently. Seems that even roll starting a car could fire the clutch fuse. Lots of the racers would also fold up the straps if they got lost between gears, let the revs drop, the find the gear lift the clutch suddenly, even where the engaged revs were engine safe. Most racers replace the clutch with more convential unit.

Speedracer.

AusS2000

Thanks Chris, I knew I wasn't going mad. Boston Duce - how would you like your crow cooked.

I would imagine making a bracket to mount at the same point as the slave cylinder. You could easily modify the fork by welding an extension on it and having the solenoid actuator parallel with the slave actuator and pushing on the extended fork hence providing more leverage. I think there is enough room there.

But this is the sort of mod that only people who have over-revved an engine will do. They're a bit like airbags. No one would have airbags if it wasn't legislated.

chris_barry

Problem is that the electronics would need to know you were in the wrong gear for the revs. It would need a gear position sensor. Many ECU's have gear detection, but these use speed vs rpm after the clutch has been released. Trick sequential gearboxes have position sensors on the gearbox itself.

My view is you can only protect people from themselves so far. At the end of the day you have to leave things up to the driver.

Speedracer.

AusS2000

Why do the electronics need to know what gear you are in? Surely all we need to know is revs. The only way the revs can exceed 9200 is by mechanical over-rev and the engine is pretty safe up to about 10,500. If use Modify's Redline Module to count revs and activate the solenoid at 9300 then hoepfully we catch it before damage.

CrazyPhuD

maybe the key here is how quickly you can respond. It will take some time for any component to respond. Not sure if the proposed solutions can respond quickly enough to preven overrev. Any idea how much time elapse between shift engage and rev ramp up?

mikegarrison

I doubt anything you have proposed here would work, except for the "fuse pin" idea of having a sacrificial mechanical link that would break. It just happens too fast.