Drive Accord Honda Forums banner
1 - 20 of 26 Posts

·
Registered
Joined
·
181 Posts
Discussion Starter · #1 ·
So I have a '13 sport cvt and wouldn't miss having a 6mt so much if the stupid rev limiter automatically switched gears when I'm not even red lining. I'll go from 1st to 3rd because the car switches gears and I do also with the paddle shifters. Maybe going into diagnostics or remapping the CPU? Maybe something that can be done waaayyy down the line?
 

·
Registered
Joined
·
4,223 Posts
So I have a '13 sport cvt and wouldn't miss having a 6mt so much if the stupid rev limiter automatically switched gears when I'm not even red lining. I'll go from 1st to 3rd because the car switches gears and I do also with the paddle shifters. Maybe going into diagnostics or remapping the CPU? Maybe something that can be done waaayyy down the line?
Are you driving in the Sport mode or in Drive?
 

·
Registered
Joined
·
4,223 Posts
There doesn't seem to be that much difference in getting to 60 MPH regardless of the mode used. I didn't time each one to 60.
 

·
Registered
Joined
·
181 Posts
Discussion Starter · #5 ·
yea I do drive it in sport mode when I'm trying to get higher revs and its definitely better than in drive mode, but even in that video you can see that it gets to like 6500 when using paddle shifters. It would be nicer to get it over 7000, I know it stresses the engine more but I really miss the umph from some other cars and think it isn't maxing out each gear.
 

·
Registered
Joined
·
1,429 Posts
yea I do drive it in sport mode when I'm trying to get higher revs and its definitely better than in drive mode, but even in that video you can see that it gets to like 6500 when using paddle shifters. It would be nicer to get it over 7000, I know it stresses the engine more but I really miss the umph from some other cars and think it isn't maxing out each gear.
Why do you want to go above redline?!? A couple hundred more RPM isn't really gonna get you anything. Making this happen would void your warranty and stress the engine. Seems ridiculous to even consider, to me, but hey it's your car! Also, the CVT doesn't have "gears" so there is no "shifting" going on.
 

·
Registered
Joined
·
181 Posts
Discussion Starter · #7 ·
I think getting to 7000 is perfectly safe, I know 500 more revs isn't doing much but with a manual you can max each gear, I really feel like I'm not doing that with the cvt, but maybe thats me still needing to adjust to the cvt over a traditional transmission auto or manual
 

·
Registered
Joined
·
4,223 Posts
yea I do drive it in sport mode when I'm trying to get higher revs and its definitely better than in drive mode, but even in that video you can see that it gets to like 6500 when using paddle shifters. It would be nicer to get it over 7000, I know it stresses the engine more but I really miss the umph from some other cars and think it isn't maxing out each gear.
The red radial begins at just below 7,000 RPM. I don't know if that is the ultimate limit or the normal upper limit on the stress of the engine components. If the red radial is the ultimate RPM limit than the metal parts of the engine will become deformed under the stress and either fail immediately or be reduced in strength due to stretch or creep and fail at a lower RPM in the future.

Why would you want to over stress your engine? It's the most expensive part of your car. Also, defeating the fuel cutout system will void your warranty. And, I would not be surprised if the engine computer is not compiling RPM history which can be downloaded by the dealer when you have the car towed in for an engine rebuild under the warranty. :notworthy
 

·
Registered
Joined
·
1,429 Posts
I think getting to 7000 is perfectly safe, I know 500 more revs isn't doing much but with a manual you can max each gear, I really feel like I'm not doing that with the cvt, but maybe thats me still needing to adjust to the cvt over a traditional transmission auto or manual
Yeah, you are probably still driving your CVT and not letting go of the control a manual offers. I know how it feels; I went from a '12 Civic Si to my Accord Coupe CVT. It did take a little while to get used to driving and accelerating at such low revs and not really getting close to redline without feeling like I was flogging the CVT. Just let the CVT do its thing and use Sport Mode when you want a little more control. You'd do yourself more favors with this method than trying to defeat the rev limiter and all that.
 

·
Registered
Joined
·
4,223 Posts
Yeah, you are probably still driving your CVT and not letting go of the control a manual offers. I know how it feels; I went from a '12 Civic Si to my Accord Coupe CVT. It did take a little while to get used to driving and accelerating at such low revs and not really getting close to redline without feeling like I was flogging the CVT. Just let the CVT do its thing and use Sport Mode when you want a little more control. You'd do yourself more favors with this method than trying to defeat the rev limiter and all that.
Does the manual transmission allow the engine to be revved above the 7,000 RPM redline?
 

·
Super Moderator
Joined
·
7,853 Posts
Does the manual transmission allow the engine to be revved above the 7,000 RPM redline?
Only if you miss-shift into a lower gear than you intended, such as intending to shift down from 5th to 4th, but into 2nd instead........ :)

Rev limiter will not protect against a "money shift".
 

·
Registered
Joined
·
4,223 Posts
Only if you miss-shift into a lower gear than you intended, such as intending to shift down from 5th to 4th, but into 2nd instead........ :)

Rev limiter will not protect against a "money shift".
So when accelerating the engine will not permit you to exceed the red line by cutting off the fuel. However, in a downshift to too low a gear the engine will over speed?
 

·
Corvalis TTX
Joined
·
4,609 Posts
So when accelerating the engine will not permit you to exceed the red line by cutting off the fuel. However, in a downshift to too low a gear the engine will over speed?
With a manual gearbox, yes, this can happen. People have destroyed engines by doing this. There is no way around it with a manual gearbox that I'm aware of.
 

·
Super Moderator
Joined
·
7,853 Posts
So when accelerating the engine will not permit you to exceed the red line by cutting off the fuel. However, in a downshift to too low a gear the engine will over speed?
Correct, rev-limiter cannot reduce engine RPM when it is mechanically back-driven through incorrect gear selection in the transmission.

The end result is valve float when the valve springs cannot keep the valve opened and closed in sync withe the piston position, often this will cause bent valve stems which binds in the valve guides to cause further damage when piston hits jammed valves, it just gets worse from there.
 

·
Corvalis TTX
Joined
·
4,609 Posts
I think getting to 7000 is perfectly safe, I know 500 more revs isn't doing much but with a manual you can max each gear, I really feel like I'm not doing that with the cvt, but maybe thats me still needing to adjust to the cvt over a traditional transmission auto or manual
But you don't always want to get to redline to maximize acceleration. At redline many engines are producing less torque than do at lower RPMs.
 

·
Registered
Joined
·
4,223 Posts
Correct, rev-limiter cannot reduce engine RPM when it is mechanically back-driven through incorrect gear selection in the transmission.

The end result is valve float when the valve springs cannot keep the valve opened and closed in sync withe the piston position, often this will cause bent valve stems which binds in the valve guides to cause further damage when piston hits jammed valves, it just gets worse from there.
Of course, I wasn't thinking the about the engine being driven by the wheels during deceleration.
 

·
Registered
Joined
·
181 Posts
Discussion Starter · #17 ·
lol, if it wasn't for my whole family using my car from time to time I would totally have gotten the 6mt, but the cvt isn't bad, the paddle shifters help a little.
 

·
Registered
Joined
·
1,038 Posts
No reason whatsoever for you to want to rev this engine to 7000 RPM. The Accord Sport is listed as having 189 HP @6400 RPM. Torque is listed as 182 lbs-ft @ 3900 RPM.
Your car is functioning as designed.
 

·
Registered
Joined
·
3,682 Posts
When I first read this post, I wasn’t sure what you were asking. It sounds like you simply want the engine to rev higher to help it go that much faster.

I think there are few concepts worth noting here. The first is average piston speed. That will ultimately determine engine safety. Piston speed is a function of stroke and rpm. The formula is:

Piston speed = (Stroke X RPM)/6

Most car engines – the connecting rods to be specific – can generally handle about 3,800 to 4,200 feet per minute. (The higher the rpm, the more the rods stretch and potentially break.) A well built car engine can handle about 4,600 -4,700 ft./min. But those are VERY well built engines.

The 2.4 liter Accord engine has a stroke of 99.1mm or 3.90 inches. That is sort of a long stoke. At 6,800 rpm the piston speed is (3.9” X 6,800rpm)/6 = 4,420 ft./min. At 7,000 rpm the piston speed would be 4,550 ft./sec. That is what the Acura TSX pushes, but that is getting VERY high.

For a comparison, the older DOHC 2.0-liter Si or RSX-S engine could rev to 8,200 rpm. But that had a stroke of 86mm or 3.38m inches. At 8,200 rpm the 2.0 liter’s piston speed was 4,619 ft/min. A Ferrari 458 has a 9,000 rpm redline and a stroke of 3.18 inches. The 458 has a 4,770 ft./min piston speed. That is about as high as you will see on ANY road car.

But get this! An F1 engine has a stroke of about 40mm or 1.57 inches. At 18,000 rpm the piston speed is 4,724 ft./min!! That is about the same as a performance road engine. Don’t focus on rpm as much as piston speed when worried about engine damage. And know that the 2.4-liter Accord engine is already very close to the danger zone.


It might also be worth noting what makes a CVT transmission special. First, an engine will accelerate the car it’s fastest when it produces max horsepower (basic physics). In cars with gears the engine produces max hp for a brief moment (at redline), at which time the gears change (either manually or automatically) and the rpm fall, thereby producing less power again. With a normal gearbox, the gears are fixed and the rpm changes. But this implies the engine is always revving up to redline and producing less than peak power 99.9999% of the time.

A CVT is the opposite. With a CVT the engine rpm is the constant and the gear ratio constantly varies. The benefit of this set up is that the once the rpm reach redline (peak power) it stays there, providing maximum thrust. The gear ratio changes to increase speed. That is theoretically a better system.

To be candid, I laugh when someone who has a CVT wants it to artificially change gears. Why ask it to do something that makes it SLOWER? Anyone who understands what makes a CVT special would NEVER drive in sport mode. Sport mode is total marketing bull crap. It only exists to strike a familiar sound and feel in order to sell cars.

If you want max acceleration from a CVT, let it do what it is designed to do. And over revving a 2.4-liter will NOT increase power. If anyone does, they need to know the engine already operates at close to max safe piston-speed.
 

·
Registered
Joined
·
1,038 Posts
Baldeagle,

Thanks for the excellent post. Very knowledgeable. Again, Thanks for sharing.
 
1 - 20 of 26 Posts
Top