The dangers of hitting redline

[ekpolk]

Originally Posted By: andrewg
Originally Posted By: bigmike
Originally Posted By: ryansride2017
No thanks. First off, if I would take my vehicle to the red line, the last thing I would worry about is the engine. I do a fair amount of maintenance on my own vehicles including bearings, axles, differentials, etc. Why unnecessarily beat on a car when it very well could cost you more in repair costs (and I'm not talking about the engine here)? To each their own I suppose. I'll just continue driving my vehicles in a normal fashion and keep repair/maintenace costs as low as possible.


+1

I'm glad I'm not purchasing some of the vehicles being mentioned in this thread.

Agreed....there is a reason it's called a REDline. Anything mechanical (or physical as well) that you stress frequently to the point of excess, would have a higher likelyhood of wear and/or failure.

===========================================

Originally Posted By: Colt45ws
Yes, thats why the redline is not plucked out of thin air. Its calculated to keep stresses on the parts within tolerable levels.



Colt is right. What you see as the "published redline" will be well within the range of safe for longevity purposes. The car maker would be insane to set the redline at (or anywhere near) the point where actual damage would be immediate. And they don't. This is, of course applicable to production street cars. I am equally sure that racing engines have redlines that mean what they say...

 

[ekpolk]

Originally Posted By: SteveSRT8
In a modern car the rev limiter is set to protect the motor.

You can't hurt it if you tried.

And I agree with addyguy, probably good for most engines.


Well, there is at least one scenario in which you can blow up your engine through rpm abuse, though I'd imagine it happens more often by accident than with someone trying.

Take a manual trans stick shift car to 100 mph. Declutch. Select second gear (usually done in a mistaken effort to find fourth). Engage clutch. Watch in awe as the engine dramatically disintegrates, literally flinging shrapnel in all directions.

Over the last eight or so years, I've seen several sets of photos of cars whose drivers killed them in this way. The first (and best) was of a little red Integra. It's block and head were literally shredded, and it had bullet-hole-style punctures in the hood where engine pieces had been flung through the metal at nightmarish velocities.

Yes, there is a way, if you have a manual, and you're either dumb enough, or sufficiently inept at selecting the right gear.

 

[Nick R]

money shift!

 

[ekpolk]

Yet another set. That's a major ouch...

 

[OVERKILL]

Originally Posted By: ekpolk
Originally Posted By: SteveSRT8
In a modern car the rev limiter is set to protect the motor.

You can't hurt it if you tried.

And I agree with addyguy, probably good for most engines.


Well, there is at least one scenario in which you can blow up your engine through rpm abuse, though I'd imagine it happens more often by accident than with someone trying.

Take a manual trans stick shift car to 100 mph. Declutch. Select second gear (usually done in a mistaken effort to find fourth). Engage clutch. Watch in awe as the engine dramatically disintegrates, literally flinging shrapnel in all directions.

Over the last eight or so years, I've seen several sets of photos of cars whose drivers killed them in this way. The first (and best) was of a little red Integra. It's block and head were literally shredded, and it had bullet-hole-style punctures in the hood where engine pieces had been flung through the metal at nightmarish velocities.

Yes, there is a way, if you have a manual, and you're either dumb enough, or sufficiently inept at selecting the right gear.

Did that in my Mustang. Watched the tach fly past the end (7K) before I could get the clutch back in. Didn't hurt it, LOL!

 

[morris]

+-









in 1965 in November my dad ordered a dodge charger with a 383 ,4 barrel. a tachometer was stock in the dash. we got it in late jan 1966. the first thing my dad did was order a factory service manual, the first thing he did was check the rpm that the max horsepower came in, 4800 rpm. in about 30 days it would drop cylinders before that rpm. took it to the dealer. the service writer said well we didnt drive it like that. dad said "the book says it should go to 4800 rpm and it darn well better do it." they had a realy good mech and he knew to put a spark plug in that was a heat range colder. it run great after that. after that i allwas colder plugs that called for, as long as it dont foul out iam ok.

 

[Colt45ws]

Originally Posted By: OVERK1LL
Originally Posted By: ekpolk
Originally Posted By: SteveSRT8
In a modern car the rev limiter is set to protect the motor.

You can't hurt it if you tried.

And I agree with addyguy, probably good for most engines.


Well, there is at least one scenario in which you can blow up your engine through rpm abuse, though I'd imagine it happens more often by accident than with someone trying.

Take a manual trans stick shift car to 100 mph. Declutch. Select second gear (usually done in a mistaken effort to find fourth). Engage clutch. Watch in awe as the engine dramatically disintegrates, literally flinging shrapnel in all directions.

Over the last eight or so years, I've seen several sets of photos of cars whose drivers killed them in this way. The first (and best) was of a little red Integra. It's block and head were literally shredded, and it had bullet-hole-style punctures in the hood where engine pieces had been flung through the metal at nightmarish velocities.

Yes, there is a way, if you have a manual, and you're either dumb enough, or sufficiently inept at selecting the right gear.

Did that in my Mustang. Watched the tach fly past the end (7K) before I could get the clutch back in. Didn't hurt it, LOL!

Did that in my moms old Saturn as well. It swung over to 8 grand before I was able to clutch it again. Did I ever mention I hate manuals?

 

[ekpolk]

The cars whose engines blew up didn't just brush up against 8k or so rpms. I'm sure that they were well into the five-figure rpm range by the time disaster struck. Minor excursions above redline are one thing. Taking a 6-7k redline engine up to 15-20k rpms is a very different matter. As in ka-boom.

 

[OVERKILL]

Originally Posted By: ekpolk
The cars whose engines blew up didn't just brush up against 8k or so rpms. I'm sure that they were well into the five-figure rpm range by the time disaster struck. Minor excursions above redline are one thing. Taking a 6-7k redline engine up to 15-20k rpms is a very different matter. As in ka-boom.


That would have to be some rather INSANE gearing.

My T5 is geared as follows:

1. 3.35
2. 1.99
3. 1.33
4. 1.00
5. 0.68

So, if I am rowing the gears doing 6K shifts and I pull out of 3rd gear at 6,000RPM to stuff it into 4th, (which would put my engine at 4,511RPM) but instead, hit 2nd gear with the clutch fully disengaged, my RPM would be 8,976RPM.

Now, I'm not sure in what the ratios on popular import trannies are, but I'd imagine they are closer ratio than a T5 is, making that jump less severe....

 

[Vikas]

It is highly likely that it was a missed downshift that caused the mess. Instead of downshifting to 4th rev match, he got 2nd and double the revs!

 

[rpn453]

It would take some serious force to ram it into gear at engine-damaging rpm. If you need more than your fingertips to move the shifter into gear, you're doing it wrong!

 

[HangerHarley]

Originally Posted By: rpn453
It would take some serious force to ram it into gear at engine-damaging rpm. If you need more than your fingertips to move the shifter into gear, you're doing it wrong!


+1

It grinds at you, doesnt usually go in. 5-2 usually is just a "Grind" followed by instantaneous "Oh shoot" then 4th. Not "MUST! GO! INTO! SECOND! -RAM-"

Pop-starting is same principle. Pop-started a car ONCE. Worked well.

Knowing the max limit of each gear and "Gear-braking" down is a different story. Works well, and keeps everything nice and hot!

 

[ekpolk]

Originally Posted By: rpn453
It would take some serious force to ram it into gear at engine-damaging rpm. If you need more than your fingertips to move the shifter into gear, you're doing it wrong!


And yet, it seems to happen with some regularity. Probably with cars that are geared to be more "rev happy" than others. That red Integra that disintegrated was probably an archetypal example. At any rate, anyone who cares to run a few searches on the internet will find all the pictures of radically exploded engines that they care to find.

 

[HangerHarley]

"MUST! GO! INTO! SECOND! -RAM-"

 

[andrewg]

Originally Posted By: Colt45ws
Yes, thats why the redline is not plucked out of thin air. Its calculated to keep stresses on the parts within tolerable levels.

Tolerable for very short periods of time. Not for frequent nor daily frequency unless the vehicle is stressed for such performance. Most are not.

 

[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.

 

[Steve S]

The load on the engine has to be taken into consideration. Too much ring flutter from unloaded max RPM "approx 80% to max RPM" potentially can cause accelerated wear.

 

[Lethal1ty17]

that depends on where the redline is set.

example. there is a 19% increase in stress between 5,500rpm and 6,000rpm.

 

[Steve S]

Originally Posted By: Colt45ws
Originally Posted By: OVERK1LL
Originally Posted By: ekpolk
Originally Posted By: SteveSRT8
In a modern car the rev limiter is set to protect the motor.

You can't hurt it if you tried.

And I agree with addyguy, probably good for most engines.


Well, there is at least one scenario in which you can blow up your engine through rpm abuse, though I'd imagine it happens more often by accident than with someone trying.

Take a manual trans stick shift car to 100 mph. Declutch. Select second gear (usually done in a mistaken effort to find fourth). Engage clutch. Watch in awe as the engine dramatically disintegrates, literally flinging shrapnel in all directions.

Over the last eight or so years, I've seen several sets of photos of cars whose drivers killed them in this way. The first (and best) was of a little red Integra. It's block and head were literally shredded, and it had bullet-hole-style punctures in the hood where engine pieces had been flung through the metal at nightmarish velocities.

Yes, there is a way, if you have a manual, and you're either dumb enough, or sufficiently inept at selecting the right gear.

Did that in my Mustang. Watched the tach fly past the end (7K) before I could get the clutch back in. Didn't hurt it, LOL!

Did that in my moms old Saturn as well. It swung over to 8 grand before I was able to clutch it again. Did I ever mention I hate manuals?
Did I ever mention I hate automatics?

 

[Steve S]

Originally Posted By: Nick R
money shift!

The pistons have 2 valve reliefs and the head has head bolts and the block studs. that is not the same block assy that matches the head.