... hit the gate wrong as in you ended up in Neutral?

 

The "overrev in neutral" theory should be pretty easy to test. Take a car, put it in neutral, floor the accelerator, see if the rev limiter kicks in, then take the engine apart and examine it for damage. Don't think I'd want to test it unless I was already going to have some engine work done, though. I do think we'd see a lot more cases of it if it could happen, though.

I think it's more likely that it was a mechanical overrev. If he was already stepping on the gas, most likely he was already releasing the clutch as well. If he had shifted into first instead of third, we'd expect an overrev. What if he was bouncing off of first - are the synchros strong enough to overrev the engine even if the transmission isn't actually in gear?

Of course, the problem may have nothing to do with an overrev.

 

RT, yes. My interpretation is that he hammered the gas in nuetral when he was already at a very high RPM.

Warren, I'm confident the ECU would be able to protect the engine from an overrev in nuetral from idle. I'm also confident that the ECU would protect a "healthy" engine from an overrev in nuetral starting from a high RPM (I've done it). What I'm concerned about is the latter scenario with a high mileage, poorly maintained engine. The current argument is about how many revs beyond the 8900 RPM limit can a stock motor reach in nuetral (starting from a high RPM) before the ECU shuts it down.

I am an engineer who was great in Engineering Physics, but I'm not a Mechanical Engineer. I'm interested to know how fatigue due to mileage effects the ability of the F20C's head to handle revs, especially if the valves aren't adjusted to "spec".

 

You have it right gernby, missed the gate on the 2-3 upshift and gassed it while not in any gear. It's possible that the damage was caused by some other failure waiting to happen but I'm not sure. I took posession of the car with less than 2500 miles on it, it now has around 26000.

It's been discussed before but I'll say it again, I never felt any fuel cut off. If the rev limiter failed, it would be the first case I've ever heard of. The head's coming off in a day or two so we'll know more soon...

 

WHAT?! I thought it had over 100K on it! If it only has 26K, then I'm done with this argument.

 

 

 

Just a few comments:

1. Honda has advertised the "snapping" response of the F20C (time it takes to rev from 1000 rpm to 9000 rpm) as about 1 second or so. This is a suitable acceleration rate to use for RT's calculations.

2. The Honda ECU is capable of discerning single cylinder misfires using its myriad of rotational sensors. Remember that there is not only a crankshaft position sensor, but also two cam position sensors as well. The ability to detect a misfire on a single cylinder with two cylinders firing per revolution should give you some idea of the resolution of the rpm measurement of the stock ECU. At worst, implementation of a rev limiter (or other function) should be no longer than 1 revolution + ECU processing time.

3. Even if the stock ECU were to allow an overshoot of 100-200 rpms over the set limit (unlikely given my experience), a single overshoot will not kill the engine. In our experience racing a completely stock engine, we were able to sustain a rev limit of 9200-9300 rpm for several races before finally succumbing to a valve retainer failure at 7800 rpm. In all likelihood, the car suffered an overrev in the past, leading to a fatigued retainer which eventually failed.

UL

 

I humbly apologize. I was getting 2 threads confused. I thought this was due to a >106K mile engine with only 1 possible valve adjustment done by a dealership.

I guess I need to reduce my intake of beer.

 

[QUOTE=Warren J. Dew,Mar 5 2005, 04:14 PM]The "overrev in neutral" theory should be pretty easy to test.