YACT: redlining

[alphatarget1]

hi all,
i was driving my dad's 96 honda accord EX v6 with 90k miles on I-5 today. i stopped in a rest area to take a break and when i was merging back onto the freeway i didn't notice i shifted to D3 instead of D4. I was expecting it to shift but then it didn't and went to 6500 RPM or so and then i realised what was wrong and shifted back to D4. It was only 2 seconds or so when it was at 6500 RPM and the car *seems* to feel fine... could i have damaged the engine?

the redlines start at 6250 i think

 

[agnitrate]

I'm pretty sure your car is going to be fine.

-silver

 

[Spac3d]

It is a Honda, it is probably just fine. I wouldn't worry unless the car starts making weird noises or a check engine light comes on.

 

[Hammer]

lol its not a wall dude. it will be fine.

 

[ThaGrandCow]

you're fine.

 

[IanthePez]

hey, got a quick related question since his has already been answered

I have a '99 Taurus Wagon with a V6 3.0 Liter 24V, and it shows up to 7k rpm on the gauge, but has no redline...sooo...I assume the redline is at 7? Just curious. It's actually quite a powerful car for wagon, hehe.

 

[NutBucket]

I know on my Accord 6250 is the the redline but the rev limiter is at 6500.

 

[Eli]

Your fine. The redline is just the max RPM that they guarentee your engine to be dependable at.

It's virtually impossible to damage most modern cars with over revving, they all have rev limiters.

That doesen't mean you aren't going to shorten the life of your engine if you take it to redline everytime you shift..

Although, it is the most fun.

 

[LS20]

Originally posted by: IanthePez
hey, got a quick related question since his has already been answered

I have a '99 Taurus Wagon with a V6 3.0 Liter 24V, and it shows up to 7k rpm on the gauge, but has no redline...sooo...I assume the redline is at 7? Just curious. It's actually quite a powerful car for wagon, hehe.

nope, focii (focuses) do not have a visible redline either but their redline is around 5500 i tink? just step on the gas and when the car shift... or better yet put it in a low gear and when the car just doesnt rev anymore that should be your fuel cutoff which is roughly around the real redline

 

[Zenmervolt]

Originally posted by: IanthePez
hey, got a quick related question since his has already been answered

I have a '99 Taurus Wagon with a V6 3.0 Liter 24V, and it shows up to 7k rpm on the gauge, but has no redline...sooo...I assume the redline is at 7? Just curious. It's actually quite a powerful car for wagon, hehe.

Ford just hasn't been in the habit of putting redline on their guages for cars with automatic transmissions. The engines have rev-limiters to keep them from over-revving if the driver keeps the tranny in too low of a gear, but otherwise the transmission is programmed with when to shift so a redline isn't necessary. This can save some money too since this way Ford doesn't have to make a different guage face for the same vehicle when it has different engines available. For example, the Explorer had three different engines (hence, three different redlines) at one point in its history, but since redline wasn't shown on the guages, Ford did not need to manufacture three different sets of tachometer faces to show the different redlines.

ZV

 

[Shivatron]

Originally posted by: Eli
Your fine. The redline is just the max RPM that they guarentee your engine to be dependable at.

It's virtually impossible to damage most modern cars with over revving, they all have rev limiters.

That doesen't mean you aren't going to shorten the life of your engine if you take it to redline everytime you shift..

Although, it is the most fun.

With all due respect, I beg to differ. Although it is difficult to damage an engine by just flooring the accelerator (because, as you state, the limiter will cut the fuel supply), I have heard of many cases where an engine has been damaged by "mechanical overrev" -- that is, the engine being forced to a higher RPM by a bad downshift such as the situation described above.

Mechanical overrev used to be a problem in some E36 3er BMWs. BMW's have tight shift patterns to begin with, and there have been cases when someone trying to make a 5-4 downshift, or a 3-4 upshift, has missed and actually made a 5-2 or 3-2 downshift. If the engine is close to redline to begin with, this immediatly forces the engine well past redline. This spins the engine and such at rate that the valve springs cannot close the valves fast enough to keep up with the pistons. Since BMW engines are of "interference" design (ie. the pistons will collide with the valves when the valves are down and the piston is at top dead center), the valves can be bent or even break, the valve guides can be gouged, and the pistons can be damaged. In this situation, the engine will usually run for a while, but will ultimately fail catastrophically.

(By the way, this is why you owners of interference design engines NEED to keep your timing belt/chain maintained. If it breaks, you can kiss you head and some of your pistons goodbye!)

Fortunatly for you, kenlung, you were only 250rpm above redline, which isn't enough to do any damage...

 

[geno]

Atticu5, there's a difference between overevving the motor while accelerating, and overevving due to a missed shift (in a stick car) mainly because if you floor it (for example) in first gear, you'll just bounce off of the rev limiter...shouldn't hurt/kil the car. However, if you mis-downshift into 2nd when you go for 4th, it wouldn't matter what your rev limiter is at until you either put the car in neutral or engage the clutch....a situation like that is like you described, and will most likely cause damage if you shift into a much lower gear at a higher speed than you intended to

 

[Eli]

Originally posted by: Atticu5

Originally posted by: Eli
Your fine. The redline is just the max RPM that they guarentee your engine to be dependable at.

It's virtually impossible to damage most modern cars with over revving, they all have rev limiters.

That doesen't mean you aren't going to shorten the life of your engine if you take it to redline everytime you shift..

Although, it is the most fun.

With all due respect, I beg to differ. Although it is difficult to damage an engine by just flooring the accelerator (because, as you state, the limiter will cut the fuel supply), I have heard of many cases where an engine has been damaged by "mechanical overrev" -- that is, the engine being forced to a higher RPM by a bad downshift such as the situation described above.

Mechanical overrev used to be a problem in some E36 3er BMWs. BMW's have tight shift patterns to begin with, and there have been cases when someone trying to make a 5-4 downshift, or a 3-4 upshift, has missed and actually made a 5-2 or 3-2 downshift. If the engine is close to redline to begin with, this immediatly forces the engine well past redline. This spins the engine and such at rate that the valve springs cannot close the valves fast enough to keep up with the pistons. Since BMW engines are of "interference" design (ie. the pistons will collide with the valves when the valves are down and the piston is at top dead center), the valves can be bent or even break, the valve guides can be gouged, and the pistons can be damaged. In this situation, the engine will usually run for a while, but will ultimately fail catastrophically.

(By the way, this is why you owners of interference design engines NEED to keep your timing belt/chain maintained. If it breaks, you can kiss you head and some of your pistons goodbye!)

Fortunatly for you, kenlung, you were only 250rpm above redline, which isn't enough to do any damage...

Huh?

You just said the same thing I did. Where are you differing from me? Either the engine is going over redline, or it isn't. "Mechanical overrev" is the same thing as "overrev".

I said that going to redline isn't going to hurt anything. If you take the engine passed redline - doesen't matter how you do it, then yes.. you have the potential to eat a valve, throw a rod, etc.

 

[Zenmervolt]

Originally posted by: Atticu5

Originally posted by: Eli
Your fine. The redline is just the max RPM that they guarentee your engine to be dependable at.

It's virtually impossible to damage most modern cars with over revving, they all have rev limiters.

That doesen't mean you aren't going to shorten the life of your engine if you take it to redline everytime you shift..

Although, it is the most fun.

With all due respect, I beg to differ. Although it is difficult to damage an engine by just flooring the accelerator (because, as you state, the limiter will cut the fuel supply), I have heard of many cases where an engine has been damaged by "mechanical overrev" -- that is, the engine being forced to a higher RPM by a bad downshift such as the situation described above.

Mechanical overrev used to be a problem in some E36 3er BMWs. BMW's have tight shift patterns to begin with, and there have been cases when someone trying to make a 5-4 downshift, or a 3-4 upshift, has missed and actually made a 5-2 or 3-2 downshift. If the engine is close to redline to begin with, this immediatly forces the engine well past redline. This spins the engine and such at rate that the valve springs cannot close the valves fast enough to keep up with the pistons. Since BMW engines are of "interference" design (ie. the pistons will collide with the valves when the valves are down and the piston is at top dead center), the valves can be bent or even break, the valve guides can be gouged, and the pistons can be damaged. In this situation, the engine will usually run for a while, but will ultimately fail catastrophically.

(By the way, this is why you owners of interference design engines NEED to keep your timing belt/chain maintained. If it breaks, you can kiss you head and some of your pistons goodbye!)

Fortunatly for you, kenlung, you were only 250rpm above redline, which isn't enough to do any damage...

That's nice, but we were not talking about mechanical over-rev, and you have have to get a hell of a lot of valve float before you had clearance issues even with an interferance engine. In the situation you describe, I would be more worried about over-speeding the clutch.

As for your comments regarding the timing belt breaking on an interferance engine, while it is certainly possible to cause piston and cylinder damage if the valves break, this is far from common. Most often the valves are simply bent. While that still requires a top-end rebuild, it's much less damaging to one's wallet than replacing pistons or re-boring cylinders.

ZV

 

[Lithium381]

how the heck do you guys hit redline??!??!?! i don't think i've ever put mine past 4krpm.....i shift at about 2700 sometimes as high as 3k, but dang........how are you getting up so high? that's not good!!!

 

[DaiShan]

Car will be fine, I have same one, less miles though, redline is 6250, it is a sturdy built engine.

 

[Shivatron]

Originally posted by: Eli

Originally posted by: Atticu5

Originally posted by: Eli
Your fine. The redline is just the max RPM that they guarentee your engine to be dependable at.

It's virtually impossible to damage most modern cars with over revving, they all have rev limiters.

That doesen't mean you aren't going to shorten the life of your engine if you take it to redline everytime you shift..

Although, it is the most fun.

With all due respect, I beg to differ. Although it is difficult to damage an engine by just flooring the accelerator (because, as you state, the limiter will cut the fuel supply), I have heard of many cases where an engine has been damaged by "mechanical overrev" -- that is, the engine being forced to a higher RPM by a bad downshift such as the situation described above.

Mechanical overrev used to be a problem in some E36 3er BMWs. BMW's have tight shift patterns to begin with, and there have been cases when someone trying to make a 5-4 downshift, or a 3-4 upshift, has missed and actually made a 5-2 or 3-2 downshift. If the engine is close to redline to begin with, this immediatly forces the engine well past redline. This spins the engine and such at rate that the valve springs cannot close the valves fast enough to keep up with the pistons. Since BMW engines are of "interference" design (ie. the pistons will collide with the valves when the valves are down and the piston is at top dead center), the valves can be bent or even break, the valve guides can be gouged, and the pistons can be damaged. In this situation, the engine will usually run for a while, but will ultimately fail catastrophically.

(By the way, this is why you owners of interference design engines NEED to keep your timing belt/chain maintained. If it breaks, you can kiss you head and some of your pistons goodbye!)

Fortunatly for you, kenlung, you were only 250rpm above redline, which isn't enough to do any damage...

Huh?

You just said the same thing I did. Where are you differing from me? Either the engine is going over redline, or it isn't. "Mechanical overrev" is the same thing as "overrev".

I said that going to redline isn't going to hurt anything. If you take the engine passed redline - doesen't matter how you do it, then yes.. you have the potential to eat a valve, throw a rod, etc.

Oh... yeah... my bad. I saw "going to redline" and I interpreted "going past redline". Sorry!

(Oh, and Zenmervolt, I was only replying to my mistaken interpretation of Eli's comment... )

 

[Syringer]

Hmm, how fast were you going? Redlining in 3rd gear is close to 100mph isn't it? On my Integra it'd be about 110.

 

[Eli]

Originally posted by: Atticu5

Originally posted by: Eli

Originally posted by: Atticu5

Originally posted by: Eli
Your fine. The redline is just the max RPM that they guarentee your engine to be dependable at.

It's virtually impossible to damage most modern cars with over revving, they all have rev limiters.

That doesen't mean you aren't going to shorten the life of your engine if you take it to redline everytime you shift..

Although, it is the most fun.

With all due respect, I beg to differ. Although it is difficult to damage an engine by just flooring the accelerator (because, as you state, the limiter will cut the fuel supply), I have heard of many cases where an engine has been damaged by "mechanical overrev" -- that is, the engine being forced to a higher RPM by a bad downshift such as the situation described above.

Mechanical overrev used to be a problem in some E36 3er BMWs. BMW's have tight shift patterns to begin with, and there have been cases when someone trying to make a 5-4 downshift, or a 3-4 upshift, has missed and actually made a 5-2 or 3-2 downshift. If the engine is close to redline to begin with, this immediatly forces the engine well past redline. This spins the engine and such at rate that the valve springs cannot close the valves fast enough to keep up with the pistons. Since BMW engines are of "interference" design (ie. the pistons will collide with the valves when the valves are down and the piston is at top dead center), the valves can be bent or even break, the valve guides can be gouged, and the pistons can be damaged. In this situation, the engine will usually run for a while, but will ultimately fail catastrophically.

(By the way, this is why you owners of interference design engines NEED to keep your timing belt/chain maintained. If it breaks, you can kiss you head and some of your pistons goodbye!)

Fortunatly for you, kenlung, you were only 250rpm above redline, which isn't enough to do any damage...

Huh?

You just said the same thing I did. Where are you differing from me? Either the engine is going over redline, or it isn't. "Mechanical overrev" is the same thing as "overrev".

I said that going to redline isn't going to hurt anything. If you take the engine passed redline - doesen't matter how you do it, then yes.. you have the potential to eat a valve, throw a rod, etc.

Oh... yeah... my bad. I saw "going to redline" and I interpreted "going past redline". Sorry!

(Oh, and Zenmervolt, I was only replying to my mistaken interpretation of Eli's comment... )

No problem. Didn't mean to seem brash or anything.

Welcome to the forums.

 

[LS20]

Originally posted by: Lithium381
how the heck do you guys hit redline??!??!?! i don't think i've ever put mine past 4krpm.....i shift at about 2700 sometimes as high as 3k, but dang........how are you getting up so high? that's not good!!!

why not

 

[Zenmervolt]

Originally posted by: Atticu5
Oh... yeah... my bad. I saw "going to redline" and I interpreted "going past redline". Sorry!

(Oh, and Zenmervolt, I was only replying to my mistaken interpretation of Eli's comment... )

No worries. It's nice to have someone who's familiar with the concepts. Eli and I disagree about things every now and again too, but I like to think that we're both reasonably well-informed. As you certainly seem to be as well.

ZV

 

[Eli]

Originally posted by: Lithium381
how the heck do you guys hit redline??!??!?! i don't think i've ever put mine past 4krpm.....i shift at about 2700 sometimes as high as 3k, but dang........how are you getting up so high? that's not good!!!

You step on the gas and don't shift until redline?

 

[Zenmervolt]

Originally posted by: Eli

Originally posted by: Lithium381
how the heck do you guys hit redline??!??!?! i don't think i've ever put mine past 4krpm.....i shift at about 2700 sometimes as high as 3k, but dang........how are you getting up so high? that's not good!!!

You step on the gas and don't shift until redline?

That's fun to do. Not the smartest thing in my 924S though. Has a mechanical rev-limiter in the distributor (I think it's in the distributor) that grounds out the spark if the engine over-revs under load. Hit the rev-limiter and you send a lot of unburned crap into the catalytic converter as well as lose time. Best to shift right before I hit the limiter.

ZV

 

[Howard]

Haha, you said distributor.

 

[Ultima]

Originally posted by: geno
Atticu5, there's a difference between overevving the motor while accelerating, and overevving due to a missed shift (in a stick car) mainly because if you floor it (for example) in first gear, you'll just bounce off of the rev limiter...shouldn't hurt/kil the car. However, if you mis-downshift into 2nd when you go for 4th, it wouldn't matter what your rev limiter is at until you either put the car in neutral or engage the clutch....a situation like that is like you described, and will most likely cause damage if you shift into a much lower gear at a higher speed than you intended to

I thought the transmission would just prevent you from shifting if that gear would be over the redline? I know in my friend's car you can't put it in 1st unless the car is almost stopped.