question about car rpm

[mAdD INDIAN]

btw, a lot of engines are detuned (meaning their fuel-cutoff is set at a lower point than neccessary). For example (yes I know i have a lot of Nissan VQ examples), the 3L VQ can be chipped to redline at 7200RPM and with a Variable Intake manifold, it makes power in that area while still being reliable. Also a few owners have accidently downshifted by accident causing the engine to hit 8000+ RPM and the car still ran fine.

The same is also true for most Honda 1.6L 4-pot engines.

 

[KingNothing]

Originally posted by: Trinitron

Originally posted by: KingNothing

Originally posted by: Trinitron
Because its your car and they aren't going to tell you how to drive it. Most cars do have rev limiters now days to keep you from grenading the motor... but redlining constantly is not any better and you get no power from it. The sooner you wreck your motor by driving it hard the sooner you have to buy a new one... another reason to think why they let you go that high in the rpm band.

That's barely true. In my car the power peak is at 5500 RPM and redline is at 6000.

Barely??? No its 100% true... if you could see a dyno chart of your engine you would see that at 5500 is peak power, after this the power band DECLINES, as does the torque curve. Peak means max, optimal, etc. If the car was making peak power at 6000 rpm then it would be advertised peaking at 6000, not 5500. There comes a point in an engine where its going TOO fast to be efficient.

Barely true as in "yes it's true but it really doesn't matter since it will take half a second to go from 5500 to 6000 rpm at which point the fuel cuts off anyway and that's barely enough time to execute an upshift"

 

[HannibalX]

LOL Eli I see you have FINALLY discovered HP is a calculation of torque... Anyway you go ahead and redline your motor all you want. Changing the oil every 3k is NOT going to reduce drive line wear from OVER REVVING components.

At red line you are on the DECLINING end of the power band, period. Yes that is more than at idle (thats why you don't move at idle) but when compared to peak power it is insignificant.

 

[HannibalX]

Barely true as in "yes it's true but it really doesn't matter since it will take half a second to go from 5500 to 6000 rpm at which point the fuel cuts off anyway and that's barely enough time to execute an upshift"

Shifting has nothing to do with it... at red line, after peak power is made the power band is declining, at 5501 it is declining, at 5502 - 6000 it is on the decline. Whether you shift or not...

 

[Eli]

Originally posted by: Trinitron

Originally posted by: KingNothing

Originally posted by: Trinitron
Because its your car and they aren't going to tell you how to drive it. Most cars do have rev limiters now days to keep you from grenading the motor... but redlining constantly is not any better and you get no power from it. The sooner you wreck your motor by driving it hard the sooner you have to buy a new one... another reason to think why they let you go that high in the rpm band.

That's barely true. In my car the power peak is at 5500 RPM and redline is at 6000.

Barely??? No its 100% true... if you could see a dyno chart of your engine you would see that at 5500 is peak power, after this the power band DECLINES, as does the torque curve. Peak means max, optimal, etc. If the car was making peak power at 6000 rpm then it would be advertised peaking at 6000, not 5500. There comes a point in an engine where its going TOO fast to be efficient.

I don't think anybody is disagreeing with you here. But that's not the point. Just because the engine isn't making peak power anymore doesen't mean anything.

The engine in the Honda S2000 makes 240HP @ 8300RPM and 153ftlbs @ 7500RPM. It has a redline of 9000. What's your point?

The redline is just the maximum point that the manufacturer guarentees the engine to be reliable at.

 

[KingNothing]

Originally posted by: Trinitron

Barely true as in "yes it's true but it really doesn't matter since it will take half a second to go from 5500 to 6000 rpm at which point the fuel cuts off anyway and that's barely enough time to execute an upshift"

Shifting has nothing to do with it... at red line, after peak power is made the power band is declining, at 5501 it is declining, at 5502 - 6000 it is on the decline. Whether you shift or not...

The point is that redline is higher than peak power so that you have a little headroom to shift in so that when you finish the shift the engine is closer to peak power. RPMs drop when you upshift, ya know?

 

[Eli]

Originally posted by: Trinitron
LOL Eli I see you have FINALLY discovered HP is a calculation of torque... Anyway you go ahead and redline your motor all you want. Changing the oil every 3k is NOT going to reduce drive line wear from OVER REVVING components.

At red line you are on the DECLINING end of the power band, period. Yes that is more than at idle (thats why you don't move at idle) but when compared to peak power it is insignificant.

I finally discovered HP is calculated from torque? What is up with your

Most street cars have a power band of about 1000-3000 rpm where they make their torque and 2000-6000 where they make their horsepower.

comment, then?

As I've said, there is nothing wrong with "redlining" your engine. It's not going to throw a rod, or any of that other crap you stated, unless there is already something wrong.

I'm not denying that RPM kills, indeed, it does. The lower you keep your average RPMs, the longer your engine will last, all other things being equal.

But you make it sound like redlining your car every once in a while is going to cause it to self destruct in short order, which simply isn't true.

 

[Ylen13]

so basically if i come to redline from start and then when i get up to speed it drops down its not that bad for engine. Btw i done over 110 and never came close to redlining the car that way

 

[HannibalX]

The point is that redline is higher than peak power so that you have a little headroom to shift in so that when you finish the shift the engine is closer to peak power. RPMs drop when you upshift, ya know?

No its not, it DOES NOT work that way. There is no headroom. After the peak power the POWER BAND DECLINES. If you were making 500 HP peak at 5000 rpm then at 5500 you are making maybe 450, at 6000 you are making maybe 4000. In the case of the S2000 that engine was designed to flow air at that RPM, 99% of street vehicles were not so the S2000 is not a good example. You know that Eli.

 

[Evadman]

Trinitron has no clue. you can basicly ignore most of what he says. He once argued with roger saying that you calculate torque by multiplying rpm, horsepower, volumetric efficency and displacement. He is a doof.

The question: Is redlining your engine bad?

Te answer: It depends. . Taking your engine TO redline is fine. you will get accelerated wear, but your engine will not exlplode, nor will your halfshafts come out of the transmission. Going past redline is much worse. past redline, the valve train is going faster than it was designed, and a valve can hang open as the spring can not snap it shut in time. the valve and piston colide, and you get some nice schrapnel. You can also snap a con rod or many other things. Basicly, going TO redline is alright, but past is bad.

 

[WinkOsmosis]

Originally posted by: Trinitron

The point is that redline is higher than peak power so that you have a little headroom to shift in so that when you finish the shift the engine is closer to peak power. RPMs drop when you upshift, ya know?

No its not, it DOES NOT work that way. There is no headroom. After the peak power the POWER BAND DECLINES. If you were making 500 HP peak at 5000 rpm then at 5500 you are making maybe 450, at 6000 you are making maybe 4000. In the case of the S2000 that engine was designed to flow air at that RPM, 99% of street vehicles were not so the S2000 is not a good example. You know that Eli.

Are you stupid? Seriously. When you shift, the rpm goes down. It goes to below peak.... because a transmission has different gears... that's why you shift. I'd like to know where you got the idea that shifting at peak power will somehow allow you to stay at that peak. LOWER RPM below peak = lower power. FOR CHRIST'S SAKE!!!

 

[Eli]

Originally posted by: Trinitron

The point is that redline is higher than peak power so that you have a little headroom to shift in so that when you finish the shift the engine is closer to peak power. RPMs drop when you upshift, ya know?

No its not, it DOES NOT work that way. There is no headroom. After the peak power the POWER BAND DECLINES. If you were making 500 HP peak at 5000 rpm then at 5500 you are making maybe 450, at 6000 you are making maybe 4000. In the case of the S2000 that engine was designed to flow air at that RPM, 99% of street vehicles were not so the S2000 is not a good example. You know that Eli.

What does flowing air have to do with it? The engine was designed to run at 9000RPM, that's it's redline.

It's no different than an engine that redlines at 6000RPM, makes peak HP at 5500rpm and peak torque at 4500RPM.

 

[HannibalX]

As I've said, there is nothing wrong with "redlining" your engine. It's not going to throw a rod, or any of that other crap you stated, unless there is already something wrong.

Feel free to think that. Tomorrow call some repair shops and ask, they will educate you.

I'm not denying that RPM kills, indeed, it does. The lower you keep your average RPMs, the longer your engine will last, all other things being equal.

This is a correct statement.

But you make it sound like redlining your car every once in a while is going to cause it to self destruct in short order, which simply isn't true.

I said if you will read that doing it every once in a while is not going to hurt things. Read my VERY FIRST POST in this thread.

And about the HP/Trq thing. Because you are making torque does not mean you are making HP... HP is a math formula and its anything "real", you have to make torque before HP or your car would not move. (This is even impossible because without torque there is no HP).

 

[KingNothing]

Originally posted by: Trinitron

The point is that redline is higher than peak power so that you have a little headroom to shift in so that when you finish the shift the engine is closer to peak power. RPMs drop when you upshift, ya know?

No its not, it DOES NOT work that way. There is no headroom. After the peak power the POWER BAND DECLINES. If you were making 500 HP peak at 5000 rpm then at 5500 you are making maybe 450, at 6000 you are making maybe 4000. In the case of the S2000 that engine was designed to flow air at that RPM, 99% of street vehicles were not so the S2000 is not a good example. You know that Eli.

For the love of...okay, look.

Here is a dyno chart for a BMW 325i

Redline is 6500 RPM. The RPMs do drop after the power peak at 6000, but not so dramatically as you'd make it out to be. In that chart, they drop to the same point as 500 RPM before the redline. Therefore, if the gears are 1000 RPMs apart, and you shift at 6500, now you're at 5500, 500 RPM away from the power peak. If you shifted at the power peak of 6000, you'd be at 5000 RPM, which is 1000 away from the power peak. Do you get what I'm saying?

 

[Mill]

Please don't listen to Trinitron. He doesn't know what he is talking about.

 

[HannibalX]

What does flowing air have to do with it? The engine was designed to run at 9000RPM, that's it's redline.

Actually is has a lot to do with it. The reason an engine makes peak power at a certain RPM and then declines is based on two thing. 1.) The components ability to handle the RPM and 2.) The amount of air an engine can pump efficiently. The reason you don't make power at 6000 rpm when you do at 5500 is because the internals of the engine (intake runner, head runners, combustion chambers, exhaust ports) are not SMOOTH enough to flow air to make power at that RPM. Yes the engine ca physically rev that high but there is no air to create power. This is why the power band declines. Cars that have valve jobs and porting work done flow well into their red line and the power band does not decrease, like the S2000 - this DOES NOT mean the components are able to take the RPM though.

Wheww that was allot, I hope I have educated you a little at least.

 

[Mill]

Originally posted by: Trinitron

The point is that redline is higher than peak power so that you have a little headroom to shift in so that when you finish the shift the engine is closer to peak power. RPMs drop when you upshift, ya know?

No its not, it DOES NOT work that way. There is no headroom. After the peak power the POWER BAND DECLINES. If you were making 500 HP peak at 5000 rpm then at 5500 you are making maybe 450, at 6000 you are making maybe 4000. In the case of the S2000 that engine was designed to flow air at that RPM, 99% of street vehicles were not so the S2000 is not a good example. You know that Eli.

No, this is not true. After peak power the powerband can stay quite fat for more RPMs. It depends upon the engine, but I will give you an example. A 4.6 SOHC found in the GT makes peak power around 5250. Redline is at 5500, yet you can still make GOOD power up until 6200 where there is a huge drop off. It depends on how much air your heads can flow, where the manufacturer put the redline, and the other components in the engine. If they can handle the stress then things are fine. Is there wear and tear? Yes, just like if you drove normally, albeit maybe a tad more.

 

[KingNothing]

Originally posted by: Trinitron

What does flowing air have to do with it? The engine was designed to run at 9000RPM, that's it's redline.

Actually is has a lot to do with it. The reason an engine makes peak power at a certain RPM and then declines is based on two thing. 1.) The components ability to handle the RPM and 2.) The amount of air an engine can pump efficiently. The reason you don't make power at 6000 rpm when you do at 5500 is because the internals of the engine (intake runner, head runners, combustion chambers, exhaust ports) are not SMOOTH enough to flow air to make power at that RPM. Yes the engine ca physically rev that high but there is no air to create power. This is why the power band declines. Cars that have valve jobs and porting work done flow well into their red line and the power band does not decrease, like the S2000 - this DOES NOT mean the components are able to take the RPM though.

Wheww that was allot, I hope I have educated you a little at least.

I've learned to not listen to you in any of the car threads from now on.

 

[FrustratedUser]

Why redline in the first place? No point besides winning the dragrace at the lights.

 

[Mill]

Originally posted by: Trinitron
It is not a good idea to run the car into the red section of your tach ( or to red line it) on a regular basis. Once in while won't hurt but the engine was not designed to run in that power range. in 99% of cars on the road, NO POWER is being made at the red line anyway, and redlining the engine will not make it go faster. Most street cars have a power band of about 1000-3000 rpm where they make their torque and 2000-6000 where they make their horsepower. Anything above this USUALLY shows an immediate decline in the power band...

As I said... a GT makes power about 800+ RPMs passed it redline.

 

[HannibalX]

Hey KingNothing you proved my point thanks.

 

[mAdD INDIAN]

btw total power is usually AREA UNDER THE CURVE!

Also, when you shift gears, the engine RPM changes depending on the gear ratio. So when you upshift, the engine RPM drops. Therefore if your engine makes peak power at 6000RPM and you upshift at 6500RPM, then when you get to the next gear, your engine RPM will probably be at around 5900-6000RPM whihc wlll put you in the meat of the powerband in your next gear.

Also even though at redline the engine is not producing PEAK HP, IT IS STILL PRODUCING HP that is usefull, and if its a good breathing engine, the power drop-off won't be too great allowing the engien to stretch its legs and maybe give a bit more oomph to get that higher MPH at the end of a 1/4mi.

 

[Mill]

Originally posted by: Trinitron
You will put allot of wear on the car by redlining it frequently. You could reduce the life of your engine by half or more. You could through a rod, blow a head gasket, and in some cases with front wheel drive cars I have seen the half shafts COME OUT of the differential... that is BAD.

How in the FVCK would a halfshaft be affected by the engine RPM? Unless you were spinning down the track or had a very good hook up after dumping the clutch, I don't see how a halfshaft would even be related to engine RPM. God, you are a MORON!

 

[KingNothing]

Originally posted by: mAdD INDIAN
btw total power is usually AREA UNDER THE CURVE!

Also, when you shift gears, the engine RPM changes depending on the gear ratio. So when you upshift, the engine RPM drops. Therefore if your engine makes peak power at 6000RPM and you upshift at 6500RPM, then when you get to the next gear, your engine RPM will probably be at around 5900-6000RPM whihc wlll put you in the meat of the powerband in your next gear.

Also even though at redline the engine is not producing PEAK HP, IT IS STILL PRODUCING HP that is usefull, and if its a good breathing engine, the power drop-off won't be too great allowing the engien to stretch its legs and maybe give a bit more oomph to get that higher MPH at the end of a 1/4mi.

Yeah, I kinda said that already. Had a graph and everything.

What point is that, Trinitron?

 

[HannibalX]

Originally posted by: KingNothing

Originally posted by: Trinitron

What does flowing air have to do with it? The engine was designed to run at 9000RPM, that's it's redline.

Actually is has a lot to do with it. The reason an engine makes peak power at a certain RPM and then declines is based on two thing. 1.) The components ability to handle the RPM and 2.) The amount of air an engine can pump efficiently. The reason you don't make power at 6000 rpm when you do at 5500 is because the internals of the engine (intake runner, head runners, combustion chambers, exhaust ports) are not SMOOTH enough to flow air to make power at that RPM. Yes the engine ca physically rev that high but there is no air to create power. This is why the power band declines. Cars that have valve jobs and porting work done flow well into their red line and the power band does not decrease, like the S2000 - this DOES NOT mean the components are able to take the RPM though.

Wheww that was allot, I hope I have educated you a little at least.

I've learned to not listen to you in any of the car threads from now on.

Ignorance is bliss, if you don't believe me than whatever. No use trying to make the blind see. I am ASE cert. so you all can think what you want. Mill I am not even to start in on your posts. You can tell me I am wrong but at this point I know otherwise. So think what you like.