What would happen if you left the car in neutral and stomped on the accelerator to maximum rpm for...a while? Would the rev limiter prevent catastrophe (for a little while at least? maybe 1 minute, 2 minutes?).

Curious,
Greg

 

Curious because you did it (or was it a "friend"), curious because you were thinking of doing it, curious because you were bored on your commute and thought about this... Do tell

 

traffic does things to people...

 

My experience is, with my just-for-fun 1992 Mazda Protege, that when you rev to redline in neutral, it prevents redline by cutting off fuel supply. Eventually the car just shuts off. I've done it, and I'm sure if my 1992 model of a commuter car is capable of this, I'm sure the MINI is as well....

Only one way to find out! Don't upset the neighbours..

 

 

I'm curious. I was recently researching synthetic versus non-synthetic oil and found a video where they're "gunning" the engines and of course, the non-synthetic results in the engine parts departing a lot sooner (probably Castrol-funded "research"). No, neither I nor my "friend" have done this...yet.

 

do it

 

http://www.youtube.com/watch?v=r0viVq1Vooc

 

Dang! I'm impressed the car didn't self-destruct before the good samaritan shut it down. Too funny

 

The rev limiters shut the engine down until the computer senses it's safe again EXCEPT when you downshift to the wrong gear, then I think you can overrev the engine.

 

yep, most cars will cut off when you get too high rpm's. I've driven nearly every car I've owned at redline at least one time or another (w/ load, not revving in neutral) and there is usually a momentary cut off of gas to the engine ...takes a few seconds then your back w/ power again. I've done this not for fun, but to achieve best times, etc.

 

If you downshift to the wrong gear you force the engine to spin at whatever speed is dictated by the selected, fixed gear ratio, with or without fuel. So, a second gear downshift at 90 mph would not be a good choice! First gear, if it didn't self-destruct the gear or the clutch, would probably launch you through the windshield!

 

The guy wasn't moving. Was he dead drunk? Dead? managed to get the keys to the ex-wife's new car? Suicidal?

 

I am sure it is not good for the car.

 

BMW/MINI build in a pretty big safety factor on their cars for maximum rpm. If you leave a MINI in neutral and hold your foot to the floor, the engine will hit near redline and have its ignition retarded and fuel cut off till you back off the throttle a bit. The cutoff point is pretty low, so the only thing that would happen for sure is you'd start to overheat, since you aren't getting any cooling air blowing through. (just like on a Dyno) The CPU does record these "events" so if something went wrong, the dealer would be able to tell what the maximum engine rpm was.

 

What if that poor guy was dead!!!????? mysticturner is probably right, he was just sloppy drunk.

I was in the pits at Sebring this year when a corvette drove by (not the ALMS corvette) and blew his engine. Not sure if he over-reved it or if it was just in dire need of a rebuild. Either way it was very noisy and dramatic.

 

What would happen is that the engine would get very, very hot. If the MINI didn't cycle off the fuel, it would continue to get hotter and hotter.

If it gets hot enough, the smaller metallic parts will absorb enough energy to soften slightly, and, under pressure, warp until they're out of spec, to the point where the engine will no longer function.

If that didn't happen, and there's no guarantee it would, the larger metallic parts would absorb enough energy that their structural integrity would be in jeopardy, again, causing the engine to fail.

If that didn't happen, and there's no guarantee it would, the heat would travel throughout the entire car, melting all the plastic and setting fire to anything flammable, destroying the automobile and anything near it.

If that didn't happen, and there's no guarantee it would, the unrelenting output of extreme energy would shear the fabric of space-time, engulfing you in a local bubble of non-Euclidian geometry, permitting you to shape reality to your will, and making you a god among mortals.

I say do it.

 

Exactly. Not sure I understand the point of this thread. Sort of like hitting yourself in the hand with a hammer to see if you'll scream...

 

That ends the discussion. I'm unsubscribing. Bye.

Try it with your mom's minivan.

 

That didn't go over very well.

The computer should prevent damage but I wouldn't try it with my stuff. Mechanics at work do it a lot. Don't worry - company vehicles. I cringe everytime I walk through the shop when they do that.

 

Yea, I watched a tech at a Ford dealership do this to a Superduty diesel. One of the test they do is hold the motor up against the rev limiter for 2 minutes and then check the oil to see how much it foams up. With the oil driving the fuel injectors also, the oil can't foam up much, otherwise the fuel pressure drops off. Kinda scary to watch, but he told me that the Powerstroke was so "overbuilt" they were pretty much impossible to destroy. 225,000 miles later, I'm inclined to agree.

 

Your ECU has no clue whether you're doing any damage to your engine or not. All it knows is that your engine is exceeding the preprogrammed rev-limit, at which point it's told to cut fuel (Keeping it at the rev limited RPM).

You can sit there for a week bouncing off the rev limiter provided there's enough cooling over the radiator to keep the car from overheating. The ECU isn't going to do a thing...

 

Okay technically, you are right. The rev limit will prevent over-revving for 2 minutes. I should have stated the computer will prevent damage from over-revving. If you lose oil pressure, spin a bearing and throw a rod the computer will still attempt to let the engine merrily beat itself to death.

On that note, I tore down an engine with a broken rod and a nice hole in the block. I bought the car as a beater with the blown engine and swapped a junkyard motor in. I don't know what happened to this thing. I don't know if the guy missed a shift and did 4th to 3rd or what.

 

what is the point of this post?

 

Figured what the heck, let's try it. So, I pegged the red line in neutral to see what happens and... it's not good...just kidding... everything was AOK.

As some have suggested, the car programming just lets the car run right at redline and not exceed that at all except on short-burst revs. I was impressed b/c it sounded perfectly fine and just behaved/revved happily. There was no sputtering or recognizeable cutting of fuel, just limited revving, so the rev limiter does indeed work.