Discussion
My car doesn't seem to have a rev limiter and will pull through to late sixes (when I got scared). Is this normal? I only noticed this the other day when teaching a TT quattro a good lesson and was quite shocked as I thought I wouldn't be allowed to get that high and so was a little caught out!
According to your profile you are running a 98 4.0l? AFAIK in Chims of this vintage (possibly all) the ECUs have a limiter which is either at 6000 or 6500 rpm depending on all sort of things - with possibly chance being one of them. Mine cuts in at 6000.
I would be a bit alarmed if it allowed you to pull much more than 6500 as the pistons (assuming they are standard cast items)are only safe up to this speed and then really only above 6000 for brief bursts. Unless the engine is seriously modified there is nothing to be gained from revving above 6000 rpm as the standard (TVR standard that is) engine's peak volumetric efficiency - as dictated by the design of the Rover heads - is quite low down the rev range hence the great torque and drivability.
It probably needs to be checked out, 'cos even though it takes a pretty determined effort to rev these engines beyond those sort of speeds the consequences of a piston crown detaching from the skirt at that (or any) speed doesnt bear thinking about!!!
. I wonder if someone has fiddled with the ECU at some point.
I had an incident a couple of weeks ago when my throttle stuck wide open whilst overtaking (because some cretin... me DOH!... had forgotten to fasten down the over-carpet and this had rucked up at the bottom of the footwell and snagged the throttle pedal.... OMG!!
Reminder to those of us who have oevr mats on our cars....
Realising that the surge of acceleration wasnt stopping I immediately dipped the clutch and killed the ignition and coasted to a halt in a lay-by without any drama. The point being that on dipping the clutch - in the second or so it took me to turn the ignition back one notch - the revs were bouncing of the limiter several times. Had it not been for the limiter working properly my engine could have potentially grenaded itself!!
>> Edited by tahiti450 on Tuesday 28th March 14:39
>> Edited by tahiti450 on Tuesday 28th March 14:40
I would be a bit alarmed if it allowed you to pull much more than 6500 as the pistons (assuming they are standard cast items)are only safe up to this speed and then really only above 6000 for brief bursts. Unless the engine is seriously modified there is nothing to be gained from revving above 6000 rpm as the standard (TVR standard that is) engine's peak volumetric efficiency - as dictated by the design of the Rover heads - is quite low down the rev range hence the great torque and drivability.
It probably needs to be checked out, 'cos even though it takes a pretty determined effort to rev these engines beyond those sort of speeds the consequences of a piston crown detaching from the skirt at that (or any) speed doesnt bear thinking about!!!
. I wonder if someone has fiddled with the ECU at some point. I had an incident a couple of weeks ago when my throttle stuck wide open whilst overtaking (because some cretin... me DOH!... had forgotten to fasten down the over-carpet and this had rucked up at the bottom of the footwell and snagged the throttle pedal.... OMG!!
Reminder to those of us who have oevr mats on our cars.... Realising that the surge of acceleration wasnt stopping I immediately dipped the clutch and killed the ignition and coasted to a halt in a lay-by without any drama. The point being that on dipping the clutch - in the second or so it took me to turn the ignition back one notch - the revs were bouncing of the limiter several times. Had it not been for the limiter working properly my engine could have potentially grenaded itself!!
>> Edited by tahiti450 on Tuesday 28th March 14:39
>> Edited by tahiti450 on Tuesday 28th March 14:40
Thanks Tahiti. Its fairly modified - another reason why I've only just noticed as it had a knackered cam before which would only rev to a little past 5000!
Perhaps mine limits at 6500 and I actually backed off just about then, but thought it was more? Don't really want to try it again though!
Perhaps mine limits at 6500 and I actually backed off just about then, but thought it was more? Don't really want to try it again though!
tahiti450 said:
According to your profile you are running a 98 4.0l? AFAIK in Chims of this vintage (possibly all) the ECUs have a limiter which is either at 6000 or 6500 rpm depending on all sort of things - with possibly chance being one of them. Mine cuts in at 6000.
OH
mine was a 4.0, limiter used to kick in and I mean KICK in at 6000.my 450 limit comes in hard at 6500. How do I know ? Ah well youngest son (age 8 future racing driver) jumps in while shes ticking over on the drive and presses loud pedal to the floor - lots of noise and the poor engine bouncing off the limiter repeatedly - scared him silly he was white a sheet by the time I had sprinted over and removed the keys....
He has learned by this experience and when he is eventually let back out of his room at about age 12 Im sure he wont do it again
He has learned by this experience and when he is eventually let back out of his room at about age 12 Im sure he wont do it again
bigdods said:It won't last long at those revs - so far past the power peak it is laugh able 6k should be tops for a 4 or 4.5 and 5.8ish for a 500.
my 450 limit comes in hard at 6500. How do I know ? Ah well youngest son (age 8 future racing driver) jumps in while shes ticking over on the drive and presses loud pedal to the floor - lots of noise and the poor engine bouncing off the limiter repeatedly - scared him silly he was white a sheet by the time I had sprinted over and removed the keys....
He has learned by this experience and when he is eventually let back out of his room at about age 12 Im sure he wont do it again
I have yet to get my finger out and put my engine back together after an excursion to the rev limiter (courtesy of a jammed throttle when fibreglass chunks were sucked up through a disconnected air filter hose). A few seconds bouncing off the limiter were enough to bend valves, break a piston skirt, drop a couple of liners and blow the head gasket. Or maybe the latter of these happened anyway and was the cause of some of the others? Whatever, I wouldn't count on the rev limiter actually doing much to prevent engine damage personally.
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