ok im racing this car, and im going 80 in 3rd and i shift into what i think is fourth, but it was 2nd!!!!!!!!! i hit over 8000 rpm! it was for about a second, so i put the clutch in, and cruz into a shopping center. theres no burnt smell or anything, so i drove it to work and its running fine. what should i check??? what should i replace? has this happned to anyone?

 

Only stuff i would be worried about, would be engine bearings, and some other small internal engine parts that might not have been able to withstand the high rpm. Shouldn't have done anything that bad though. If you dont notice anything in a week or so, its nothing, or it will turn out to be a long term unnoticeable problem that will hit you hard one day, haha, but that is worst case scenario.

 

I would think you would have a electronic rev limiter to prevent excessive rpm just in case of what happened to you

 

ya, it does have a limiter, ive hit it on mistake before, but i dont know what happned, and when i hit the 8000 it made the worst noise, it made me want to cry! but im not getting the info i need here, what should should i do? what should i check and do i need to replace anything?

 

A normal limiter can't help in this situation, it can only cut off fuel to the engine, etc, thereby not letting it rev about a certain point if, for insance, you were to put it in neutral and floor it. No car that I know of includes something to keep you from causing damage from mis-shifts. That would require a system that had final control of the clutch, and could monitor the car's speed, and what gear you have selected, and could keep the clutch from engaging at an excessive speed, even if you let off the clutch pedal (sort of like how ABS can over-ride your foot). This is certainly doable, but it would be expensive, and somewhat complicated, and I don't think you're likely to see a system like this on normal cars anytime soon. Maybe for like Driver's Ed cars or something

 

The only way a rev-limeter can limit engine rpm is to cut the spark or fuel... neither of which will keep help in this situation.

The car's momentum is what spun this engine to 8000rpm.

Chances are, the bottom end is fine, it's the valvetrain that will need examined. At extremely high rpm, the valve spring is not strong enough to make the valve follow the cam lobe. The valve gets lifted by the cam lobe, and when it is supposed to close, its inertia causes it to "float". If it is floating when the piston comes to the top of the bore, the piston strikes the valve... possibly bending it. If the valve becomes bent, it no longer seals the cylinder effectively.

You will want to do a leakdown or compression test to help evaluate the extent of the damage (if any).

Being a 4 valve DOHC engine helps you out big time. There are two intake and two exhaust valves... which are much lighter than a one large intake and exhaust valve. The lightweight valves are much less likely to float.

If this was a two valve per cylinder engine (like my mustang), I guarantee you'd have problems.

Good Luck!

 

Do you have a short throw shifter or something? I'm surprised that it even went into the gear. Plus, it's pretty hard to do anyway. Good job!

 

I wouldn't worry about the engine. DOHC engines can withstand much higher RPM (sometimes over 2K higher) than what they are redlined at. My friend has an '89 Taurus SHO which has a 3.0L DOHC V-6 made by Yamaha, and he has a chip that raises his redline from around the high 6Ks to 8K and he hasn't had any problems becuase he has a whole underdrive pully kit. Remember this is the same design that is used in racing engines. I would however be worried about your accessories; Water pump, alternator, A/C compressor, Etc. those parts aren't designed to take that kind of RPM....and that's probably the sound you heard, DEFINITELY get it checked out by a mechanic, you can never be too careful.

 

I think this was true in *that* particular motor. In otherwords, this is not something I would make as a general statement on all DOHC engines.

-Shing

 

If the water pump was hurt, it would be leaking. If the alternator was hurt, it would still be making noise, and possibly not charging. The AC compressor works off a clutch. If it was not turned on, the pully was just free-wheeling, and the compressor was not turning at all. However, the AC compressor does turn when the defroster is turned on... But if the AC still blows cold, and there are no funny noises when it is running, I wouldn't be worried about it.

Good Luck!

 

Been their done that, no problems to date. The VQ is one tough SOB.

 

Last time when that happened to me, i had a new engine put in, and that is also why i have this name "BrokenMotor"!

 

If your engine idles smoothly and runs without any new and strange sounds you have avoided catastrophic damage. That doesn't mean you avoided all damage. There may be scoring on the camshaft lobes. There may be thinning of the connecting rod bearings. One way to look at it is that you put 20K miles of normal wear on your engine in just one second.

At this point the damage is done. There is really nothing to check and nothing to replace.

I could lecture you on the dangers of racing... danger to your car, your safety, your drivers license... but I doubt you would listen. Some lessons have to be learned the hard way.

 

Just another reason to be using synthetic oils. Not only for superior lubrication but for superior film strength to help protect your engine in situations like these. No it won't help protect if a stretched rod that contacts the valves during a overrev, but it might be the difference between a spun a crankshaft/cam bearing when they want to actually touch each other and having no damage at all.

 

Actually if your engine doesn't have any problems right after then you got lucky. You'd know if you bent your valves too. Don't sweat it you got lucky.

 

i really appreciate all of your opinions, the car is driving like normal, so i dont think there was any damage, and the reason that i shifted into second was because i broke my shift ****! i think that contributed to the mis shift, damn im really glad theres a forum like this where i can get my questions answered.
thanks

 

i've heard of celicas gts (new one's) drivers driving at like 90mph in six gear trying to switch to forth to race someone and instead of putting it in forth they put it in 2nd and the needle those goes straight around and a couple days later engine seased up and when carried to dealer they said the engine went to 14000 rpms. know that is crazy.

 

Whew! Sounds like you dodged a bullet. Thank your lucky stars you weren't using nitrous oxide when you did that. You would have had a [boom, zing!] one-way ticket to the moon.

 

I've driven a new GT-S, wow, they aren't kidding, very tight gate spacing. And I really hate the shifter in terms of going into reverse. It's to the left of 1st and forward, but unlike BMW's, there isn't a really large "hump" you have to push the shifter over, it's not hard to go over to reverse accidentally. I was test-driving one and put it into reverse as I was aiming for 1st while rolling to a stop. That little beep-beep doesn't help worth a damn.

 

i did the exact thing once only the oil pump shut down and the whole engine got scrapped...now i have a 96 max with 86k miles on the car and 60k miles on the engine....get it checked just in case....course my check engine light came on.

 

This brings up an interesting discussion...to my knowledge, the JWT ECU is supposed to bump your rev limiter up to 7K from the stock 6600 or so. Does anybody think it's highly dangerous to tread into this territory? For example...my brother has a 200SX SE-R with the same motor as the old sentra SE-R...the old sentra's redline was 7400, but his was 7100, for no apparent reason...same engine precisely. However, he got the ECU, which took his limiter up to 7700, and he occasionally goes that high. I would think that JWT has researched this a lot and wouldn't do something that could lead to blown engines...though I could understand if it might shorten engine life slightly. Comments?

 

my bro's SE-R with JWT ECU i think brings it to 7800. I got a custom programmed JWT ECU and they bring the rev up to 7500rpm. i think Nabil regularly brings his VQ above 6500 territory and has no probs.

 

Slightly? What is your idea of slightly?

Running your engine at the red line puts maximum strain on the connecting rods and their bearings. Piston rings are scraping the cylinder walls at maximum speed. Engine valves are slamming shut rather than being lowered onto their seats. Mechanical parts are being pushed to their design limits. Installing an ECU which allows you to exceed Nissan's red line is just plain asking for trouble. You are defeating a built-in safety device. Ultimately there is a price to be paid...

 

i've done the exact same thing 3 times... hit 2nd when trying to get into 4th real hard (only while trying to go fast).. in my case i think its because i am used to my short throw shifter i had in my civic... the maxima shifter is like a skyscraper compared to that.... anyhow, i've noticed no i'll effects from it, just have to be careful to not do it any more. by the way, no rev limiter or electronic crap will stop a 3000 lb cars acceleration enough in an instant to prevent this... just work on not doing it...

Neal

 

It lets you put it in 2nd at speeds that high? How hard are you jamming the shifteR?

 

just be happy you didn't have a BMW. .that would have been a blown motor.. especially an M3

 

I let our intern drive my Max and he went to do a 5-3 downshift and hit a 5-1 instead. If I wouldn't have had my seatbelt on it would have threw me into the dash. I don't know what the r's were at because it all happened too fast but I'm sure they were astronomical. No problems yet though! Knock on wood.

 

This is an old thread.

 

Any reason for the backfill A year and 6 months is a long time ago.
-hype

 

I was doing a search for Mike on tranny hard to shift into gear.. and this was one of the threads i came up with.. then i remembered two people who had E36 M3's and they blew their engines with a misshift.. i also remembered all the Celica GT-S that blew from the famous mishift.. figure i would post..

 

Ahh sharing the wealth
Carry on.
-hype

 

I did that like 40K ago. And haven't had any problem with my engine you should have anything to worry about. Just don't make shifting from 3rd to 2nd a habit.

-John

 

Hi Daniel B. Martin:

Like everyone on this board, I trust your advice & take it seriously.
I am of the impression that the lower you keep your rpms, the longer your engine will last. True or False? Comparing all rpms below the Nissan specified 6500 redline.

90% of the time, I keep the rpms below 4500 and must've redlined (6500 rpms) maybe three or four times. Am I really playing safe or wear & tear just doesn't matter, as long as I keep below redline.

Thanks in advance.

 

he doesn't post here anymore

 

this thread reminded me of when brittany spears misshifted her rented ferarri and did $25,000 of damage to her car.

edit: typo on numbers in original post

 

What? I know its OT but please enlighten me.

 

here's the article... i just lookd it up on google:

http://entertainment.iafrica.com/news/732041.htm

 

He added a zero, it was only 25K, not 250k.

 

who does this remind you of?

 

8k? is that even possible?

the highest i EVER hit was 7400 (dont ask) and that was verified by my SAFC with Peak RPM hold..

as you might suspect i was kicking myself in the butt all week long.. did a compression test immediately the next day to check if i f***ed the valve springs or pistons in anyway.


but really. i didnt think 8k was possible unless you were Turtle95Max.. i think his redline is around 8.5->9k.