bounced off rev-limter (question)

[moldowan]

Ok sorry if this is a dumb question but to all you with more knowledge than me, I was racing this stupid firebird and i bounced off the limter in 1st. I heard a backfire but got off the throttle right a way and into 2nd.
The question is this; how dangerous is this to my engine? is the limter there so i Don't break anything or as a last ditch effort to prevent breakage?
Sometime i have missed a shift and come close to bouncing it or either hit it as well.
Thanks for your input,
Marc

 

[Viper Specialty]

As long as the car is not FORCED beyond the limiter by such an event as a shift into a lower gear by accident when you are already at redline in the higher gear (such as a shift into second instead of forth at the top of third around 120 MPH) you will not cause damage to the engine. The limiter is there to prevent over-revving, it just cuts spark/fuel to shut the engine down when it gets to a pre-determined RPM. The engine can handle a few more R's than the limiter provides, but it is there to keep you from getting that high where damage CAN occur. However, it is an ELECTRONIC limiter, meaning it is stuck to the confines of an electronic system controlling them engine, when a mechanical force tries to spin the engine faster (such as a shift into the wrong gear) it can not prevent over-revving. Even though it shuts the engine down, the drivetrain itself is what pulls it to the point of damage.

 

[SweetRed04]

The rev limiter protects the engine. Hitting it is not dangerous to your engine. It is not something to do continually but bumping it on occation shouldn't hurt anything.

 

[Mamba King]

Would you blow the engine on the spot, by going into second instead of fourth at 120 mph

 

[moldowan]

thanks for the info guys! I feel better now.
BTW: the firebird was roasted and served up hot!!-LOL
Hope i never miss a upshift into a lower gear!!!!!!
Marc

 

[Viper Specialty]

Would you blow the engine on the spot, by going into second instead of fourth at 120 mph

If you let the engine come anywhere close to the full RPM that speed and overall gear could provide, most definitely. Consider that 6250 redline in second is approximately 80 MPH: 6250/80= 78.125 RPM per MPH. 120 MPH= 9375 RPM!

 

[Nobody]

As long as the car is not FORCED beyond the limiter by such an event as a shift into a lower gear by accident when you are already at redline in the higher gear (such as a shift into second instead of forth at the top of third around 120 MPH) you will not cause damage to the engine. The limiter is there to prevent over-revving, it just cuts spark/fuel to shut the engine down when it gets to a pre-determined RPM. The engine can handle a few more R's than the limiter provides, but it is there to keep you from getting that high where damage CAN occur. However, it is an ELECTRONIC limiter, meaning it is stuck to the confines of an electronic system controlling them engine, when a mechanical force tries to spin the engine faster (such as a shift into the wrong gear) it can not prevent over-revving. Even though it shuts the engine down, the drivetrain itself is what pulls it to the point of damage.

The fact that the viper has a very large displacement engine and it is a light vehicle
in the real word you would have to be a very VERY no so smart person going downhill, or be intentional to accomplish this, most likely you would suffer other severe drivetrain damage if you did

 

[kwiksilver]

There have been a lot of reported shifts with the factory that went down instead of up. You may find it easier than you think some day.

 

[Nobody]

That was not the point ...ahh......... I give up

 

[Viper Specialty]

Nobody- he answered your point directly, and he is right. it is a LOT easier than you would think. If you slam second instead of 4th, the drivetrain is already accellerating the car, and you are already close to redline before the shift. It does not take much.

Now, idle the car back down, shift to second, and drop the clutch at 120, yeah- you'll get a smoke show and probably crash the car if you dont destroy the drivetrain first. But, that means you have to swing that rotating assembly from 1000 RPM to 9375 RPM- thats a wide range. 6000 to 9375 is not so far, and you would likely see damage already at 7000 RPM from Valve Float.

 

[Nobody]

So I guess you are assuming EVERYONE is too STUPID to press the clutch back in after the mis shift ??

 

[kwiksilver]

It's not a matter of stupidity, it's a matter of quickness. This all happens in a fraction of a second.

 

[Nobody]

You must be registered for see images

 

[wbexxon]

I have hit the rev limiter in first gear a few times already. The supercharger makes it rev so much quicker that you really have to be paying attention.

 

[Russ Oasis]

Nobody,
Under racing conditions a shift from fifth to second instead of fourth or first instead of third (from fourth) happens all the time and it generally results in a blown engine, maybe not that momemt, but a few operating hours down the road. By the way, the guys who are racing and make this mistake are generally faster getting to the clutch than the average person and it still results in a sereiously compromised engine. The over rev of just 7000 RPM is enough to do it. Do be careful on the fast shifts.

 

[Flyviper]

Shift light will help a lot. Had same issue as WBEXXON with supercharger.

 

[opnwide]

I've shifted to the wrong gear a couple of times before while accelerating on the track. The tires seemed to lock up instantly, and I was back on the clutch before they could grab the pavement and overrev the engine. Gotta be quick, though.

 

[Smog Dog]

There have been a lot of reported shifts with the factory that went down instead of up. You may find it easier than you think some day.

I have often wondered why our friends at SRT don't specify stronger springs to return the shifter to the 3-4 position. Seems like a no cost, no brainer to me!

 

[Jim Z]

So I guess you are assuming EVERYONE is too STUPID to press the clutch back in after the mis shift ??

The average driver (who is inexperienced with such things) is likely to get stuck in an "OH S**T!!!" moment, where the next few seconds are wasted trying to figure out what to do next.

And quite frankly, your "BS" post was completely uncalled for. Go read up on what valve float is and does. It only takes a split second for an unclosed valve to get smacked by a piston, thus breaking the valve head off and dropping it into the cylinder. Once that's done, kiss your engine goodbye.

 

[Kelly06]

So I guess you are assuming EVERYONE is too STUPID to press the clutch back in after the mis shift ??

The average driver (who is inexperienced with such things) is likely to get stuck in an "OH S**T!!!" moment, where the next few seconds are wasted trying to figure out what to do next.

And quite frankly, your "BS" post was completely uncalled for. Go read up on what valve float is and does. It only takes a split second for an unclosed valve to get smacked by a piston, thus breaking the valve head off and dropping it into the cylinder. Once that's done, kiss your engine goodbye.

Jim
You are absolutely correct about the OH ***t moment---and the other things you have posted Seems like people for 06 have not recovered from 05 yet