Misdownshifted from 3rd to 2nd and over the redline
 

So I just now was going to upshift to 4th, but I misdownshifted to the 2nd at 93-98km/h. The revved just passed the redline like about 7700, 7800rpm...:(
That that gonna cause a huge damage for the engine and the clutch?

If I rev mine out to the limiter in 2nd I am at 98km/hr indicated. If you truly were doing 93 - 98 when you inadvertently went into second, I don't see how you over revved?

Michael.

It's totaled. Time to buy another car. I suggest a new Honda Civic in auto.
If you keep driving it, the clutch is going to brake and go through floor board and cut off your manly bits.

Lucky for you I'll gladly take that death trap of a car. I'll even give you $300 for your troubles.

I was just so scared... I cant really remember exactly how fast was that, but I just remember the rev was over the redline like couple hundreds... I'm just currently so worried about the engine and clutch if they are damaged...

nah no damage. If you misshift from 5th to 2nd, now that might be a problem

Couple of hundred is not a big deal. Just don't keep doing it. Odds are if you damaged anything you would already know it. Damage caused by a serious over rev is usually (not always but most of the time) immediate and extreme. I wouldn't be worried at all.

No need to worry. Keep enjoying your car.

That's called a money shift. Usually after you do that, you end up spending a lot of money to fix it. If it's driving fine, no problems and nothing happened after- you got lucky. Don't do it again :slap:

Did you try to press the clutch as soon as you heard it start to over rev?

It's still fine for now... luckily... thanks btw!

I did not... cause it just hit like slightly above the redline and then it dropped under the redline right away. I'm just so worried about it.

How do you manage to drop it into 2nd gear, were you aggressively driving? 4th gear from 3rd should be a short downward movement, especially on this car.

Without actually checking the ratios, I'd say this speed is reasonable for a slight over-rev with the shorter final drive of the 2017.

Different members mentioned an occasional mis-shift. I haven't heard anyone to have problems afterwards. In fact the chances after a mis-shift are to have an accident (you lose traction), than to have issues with the engine.

I could be way off, but your chances of damaging the engine from over-reving for a second is analogous to smoking a single cigarette and worrying about lung cancer. Over-reving isn't really the end of the world. If you maintained your revs in the red under heavy load then that would be bad, especially in situations when there is a poor tune, excessive heat, extra stress/hp or other factors that could occur outside of a stock motor.

Even a brief over rev can be disastrous. But that is if you drop a couple of gears and shoot it up a 1,000 or more RPM. This is when you bend and break things that are just not designed for that sudden or intense of an impact. It is the abruptness of the increase that causes issues not the duration.
In this case dropping one gear and going up a couple of hundred (which as pointed out is about all you could do at that speed) is not going to harm anything. The cut off isn't a drop dead line where one RPM over is going to blow an engine. There is a safety margin built in to deal with exactly this sort of situation.

I was kinda aggressive at that time. Usually I have no problem shifting to 4th from 3rd. I just don't know why either I would misdownshifted to 2nd tbh.

Ah, you're fine. Even Shiv's Open Flash canned tunes replace factory rev limit at 7400 with a soft cut at around 7800-ish. I don't remember exact numbers but it's a significant increase.

Here are some points that cover my thoughts:

https://www.google.com/amp/s/amp.red..._of_an_engine/

Essentially the limits to revving seem to be with handling the heat/friction from the increased speed, handling the forces on parts like the pistons from the increased speed and finally handling the air flow required to not bottleneck the process.

My thoughts are that the forces are too temporary and the heat isn't able to build enough to matter.

The example that comes to mind that is relatable is how the foot experiences two to three times a person's bodyweight when it strikes the ground during running. So a 150lb person experiences 300-450lbs on one foot. Most people would buckle their ankle under that constant load if it wasn't for a half second like it is with a foot strike. Moral of the story is that peak forces may not matter as much as sustained forces. And there just isn't enough time in my opinion for enough heat to build to effect spring recoil or to cause bearing surface breakdown/thinning.


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That doesnt really cover over-revving. A motor will pop after less than a second if it is over-revved in excess of 1k rpm; 100rpms is much more forgiving. The excess of the rpms is more determinative than the duration.

Ok so take your person running and slam their foot into the ground just once at 2,000 pounds force and you are describing a gross over rev more accurately.
It has nothing to do with heat build up and everything to do with valves, cylinders and other moving parts. They are designed to move at a certain maximum speed and if you exceed that by to much even briefly things start to hit each other. This is what causes damage in an extreme over rev.
Again, you are not going to cause any damage at a coupe of hundred over since redline is a design spec not an absolute.

Why?


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Got an example of someone over-revving a motor through missed gear selection for a second while not under load (accelerating) and causing valve float interference or piston/rod force related failure or friction/heat bearing/piston ring failure?


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Not sure what you are saying.
There are thousands of documented examples of miss shift causing severe over rev and causing valve float interference or rod failure .
It is a known failure mode.
There are probably 10 on here alone.
Go check the internet it is all documented for you in great detail.
You study at the Gforce school of physics?
I am sick of debating basic concepts with people that just want to believe their own version of reality.

The OP said he hit 7800 rpms and is concerned. You have thousands of examples of engines going over redline by 400rpms for a second and failing? Because I have millions then going over redline and surviving. Im sure you are aware that the true limit of the engine is significantly beyond the manufacturer redline, especially for over revving under nominal conditions like revving in neutral or missing a shift for half a second.

Sure, take the car to redline then accidentally money shift and you are probably screwed. But lets not compare apples to oranges. The OP went 400 over the suggested limit for a second.


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Did you even bloody well READ what I said before?

I want to attend this Gforce school of physics.

You could get your Uberversity Diploma.

IIRC there was a post on Temple of Vtec a long time ago where somebody's Razo shift knob cracked and the dude money shifted into 2nd gear and hit 11,000rpm. The engine survived but the gearbox blew.

I think now he will go back to school.
:lol:

That can be a result as well. A lot depends on the clearances and some engines can take it better than others.
I just used the 1,000 rpm as a sort of place holder number. You could go over 1,000 or 10,000 a hundred times with no issue or you could blow things apart at 950 the first time you did it. It isn't an exact science.
I miss shifted a drag set up Pinto once. The engine survived fine, the tranny had some minor damage and the u-joints all but blew apart.


As far as the OP here goes he is fine.

It is called money shift..sounds so Gangster....
I think you are fine if you don't do it all the time...
plus, it is very hard to mis-shift from 3rd to 4th....little more practice, yeah?

I believe, for the fa20, the weak link from an acute over-rev is between the wrist pin and piston. The holes stretch and give up the ghost. It has been covered here a few times.

Which astonishes me considering the floofiness of the valve springs. The valves must be super light.

Yea. Even a thousand bro.


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Holes stretch? From force or heat/friction? Acute overheating would cause metal expansion, right, and lubricants to heat to dangerously thin levels resulting in metal on metal contact? If that is what we are talking about then could that much heat really occur in a second or two max? I can't see it happening.


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You are stuck on heat. There is much more than heat involved in a miss shift over rev situation. The parts are simply not designed to move that fast and they hit things or shift and blow apart. Heat has nothing to do with that. We are not talking about sitting there with you foot on the gas at redline for an hour.

Tell 'ya what. Why don't you just go out and make some videos of a few miss shifts at just 1,000 rpms over redline. Just a dozen or so would satisfy me that everything I have know and experienced about over revs is totally wrong. Hell you really want to convince me then do a couple at only 2,000 over since that should be fine as well.

Early on when I started driving mine I miss-shifted from 5th to 4th. I immediately hit the clutch to save it but definitely freaked myself out. I've driven probably 30k miles since then and haven't noticed any issues. If you know for sure something doesn't feel right, then get it checked out. Just learn from your mistakes and it should be fine.:thumbsup:

I haven't figured out yet if this guy did it on purpose or by mistake. I was reading somewhere that he was trying that day to get used to the right-hand drive position:

https://j.gifs.com/LgE8x4.gif

On the other side, it is a bit bizarre to miss shift by accident and manage to make a lap record.

Peak linear accel. Casting yields.