The dangers of hitting redline

[andrewg]

Originally Posted By: rpn453
Originally Posted By: andrewg
Tolerable for very short periods of time. Not for frequent nor daily frequency unless the vehicle is stressed for such performance. Most are not.


How short? Your Focus engine is tested to be capable of running continuously at full throttle between 4250 rpm and 6000 rpm for at least twelve straight days. I doubt the extra 500 rpm or so needed to reach the rev limiter would change that duration much.

While twelve days at 6k rpm is indeed impressive, I would prefer my vehicle to last twelve years or more at much more reasonable rpm's. Besides....since I am the one paying for it, I'll be the one that desides what's best for my circumstance. If I wanted to redline my little focus all the time, I would likely need to have my head examined.

 

[Colt45ws]

I agree. I thought something looked funny with that picture set, but I didnt really study it.

 

[rpn453]

Originally Posted By: andrewg
While twelve days at 6k rpm is indeed impressive, I would prefer my vehicle to last twelve years or more at much more reasonable rpm's. Besides....since I am the one paying for it, I'll be the one that desides what's best for my circumstance. If I wanted to redline my little focus all the time, I would likely need to have my head examined.


You could just run her full throttle, four minutes a day for twelve years to reach their 300 hour test duration.

It's definitely easier on the engine to avoid full throttle, high rpm usage. I just think that occasional hard runs are unlikely to be the determining factor in the life of an engine or the vehicle.

I redline my Mazda3 fairly regularly in the summer. I think it's a coincidence that I also need my head examined, but maybe not. There may be a correlation.

 

[pavelow]

Originally Posted By: rationull
How bad is it really to occasionally hit redline in a controlled manner? Is it practically detrimental at all? I'm not talking about revving in neutral, or cruising at redline -- just hitting it (at WOT) during acceleration and/or during passing maneuvers after everything is warmed up. To me, logic would dictate that the redline is set to an engine speed that's safe to hit occasionally (or else it would've been set lower), and that this is true whether you're talking about an engine in a sporty car or in a car with less of a sporty focus (be it a 6000 RPM V8, an 8000 RPM I4, or even a 4500 RPM diesel I4). In fact while sporty cars are probably more likely to be redlined recreationally, economy cars may be in general more likely to be in situations where the full engine speed range is actually needed and used given they have less power on tap and will need to take advantage of all of it from time to time. I don't see why higher revs would be safe in one but not in the other.

However, despite this logic, plenty of people seem afraid to hit redline or seem to think it's bad for the car. Generally the truth is somewhere in the middle -- where is the truth here? Has anyone actually experienced or heard of engine problems that could be attributed to too much revving? Ever redlined a car all the time and still had no issues after many miles?
The factory rev limiter comes into play by either cutting fuel or spark or both to keep the engine from over-revving. I wouldn't worry about it unless you are redlining a cold engine.

 

[morris]

back in the dark ages i worked for Davis mfg, later to be J.I. Case. i worked in the experimental shop, building prototype trenchers. on the small engines we would set the rpm 300-400 above the max torque. that way when you hit a load the rpm would drop into more torque, and pull through.

 

[wander2039]

If it hasn't been mentioned you'll find out if you have any bad gaskets or loose bolts if you hit the redline a few times to many. Found that out on my dad's car. I thought the valve cover gasket was bad just turned out to be loose bolts. Been on there 80k.. you would thought it would of started leaking before that.

 

[rslifkin]

Maybe the bolts had vibrated loose over time from being under-torqued, and they finally got loose enough to start leaking?