CVT swap? (Into 2005 Civic, replacing 4-spd auto)

[Fat Charlie]

My first reaction is to wince, because CVT. It's a great idea but mechanically, nothing beats an actual box of gears. It's the old rule that In theory, there's no difference between theory and practice. In practice, there is.

Originally Posted by EcoCivic

I'm not interested in a ridiculously tall geared transmission either as that would negatively affect acceleration.

Taller gearing only matters in lowest gear and highest gear. It's great in fifth, and in first... at least with an MT you're already in first, while the guy next to you is hoping his TCM helps him out a bit. In between low and high, it's your responsibility to juggle power output and gearing. If you want to simply floor it and have the power, buy an electric. It's the right tool for that job.

Until I get a Tesla, I'm in a manual. The limitations of gas engines and my requirement for responsiveness dictate it. If I need to downshift before stomping, so be it- I'll still get the results I want faster and better than an AT or CVT. When I finally get an electric, I can finally give up babysitting the powertrain.

[EcoCivic]

Originally Posted by Fat Charlie

My first reaction is to wince, because CVT. It's a great idea but mechanically, nothing beats an actual box of gears. It's the old rule that In theory, there's no difference between theory and practice. In practice, there is.



Taller gearing only matters in lowest gear and highest gear. It's great in fifth, and in first... at least with an MT you're already in first, while the guy next to you is hoping his TCM helps him out a bit. In between low and high, it's your responsibility to juggle power output and gearing. If you want to simply floor it and have the power, buy an electric. It's the right tool for that job.

Until I get a Tesla, I'm in a manual. The limitations of gas engines and my requirement for responsiveness dictate it. If I need to downshift before stomping, so be it- I'll still get the results I want faster and better than an AT or CVT. When I finally get an electric, I can finally give up babysitting the powertrain.

I agree that gears are better and I prefer the feel of a solid connection over a CVT or auto with an unlocked torque converter, but I don't hate the feel of a CVT and I can live with the less direct feel if it provides a tangible improvement in performance and efficiency, but a CVT is heavier and isn't nearly as mechanically efficient as a manual so in practice a manual may be the fastest and most efficient.

As for the gearing, unfortunately things aren't that simple. Transmissions that are geared taller often have wider spaced gears, so the engine will be at a lower RPM after a shift and therefore acceleration will suffer. For example, let's say I am racing someone from a stop. With an EX transmission, I could reach 36 MPH in first gear and be at 4120 RPM after I shift to second. With the taller geared HX transmission I could reach 37 MPH in first, almost the same. However, when I shift to second, I would be down to 3451 RPM. That's going to hurt acceleration.

Another scenario- Let's say I am getting onto the highway at 40 MPH. That's too fast for first gear on either transmission, so the lowest gear I could choose would be second. With the EX transmission I would be at 4578 RPM, pretty decent. However, with the HX transmission, I would only be at 3731 RPM. The difference in power between 4600 RPM and 3700 RPM is dramatic with my engine.

With a CVT I could floor it going 40 and almost instantly be at 6K plus RPM, which is a dramatic difference compared to the 4600 I could be at with a manual and also drop my cruising RPM significantly. Best of both worlds! In theory anyways. In reality the manual transmission is going to be the clear winner if the CVT takes a crap and leaves me on the side of the road. Also, considering the superior efficiency and lower weight of a manual transmission, the difference in real world performance and efficiency differences between the manual and the CVT may not be as much as I think.

[cRiPpLe_rOoStEr]

Originally Posted by EcoCivic

I'm one of the people who doesn't hate the feel of a CVT, likely because I understand the undeniable benefits that they provide.

It takes a while to understand a CVT won't operate in the same way a traditional automatic does.

[EcoCivic]

Originally Posted by cRiPpLe_rOoStEr

It takes a while to understand a CVT won't operate in the same way a traditional automatic does.

I'm not sure what exactly you mean by that? I have driven cars with CVTs before and I don't mind it the feel, it is more different than bad in my opinion. I have never owned a car with a CVT though so I may not be understanding what you are saying. Also, all 2 of the CVT cars I have driven have had a torque converter instead of a start clutch, so maybe that's a different feeling.

[cRiPpLe_rOoStEr]

Originally Posted by EcoCivic

I'm not sure what exactly you mean by that? I have driven cars with CVTs before and I don't mind it the feel, it is more different than bad in my opinion.

It might be due to our different perspectives, notice we're from different countries and only in recent years the automatics became more widespread here in Brazil. Some people who have previously driven cars with other types of automatic transmission might not expect the feeling of a CVT once they drive one for the first time. Getting used to the lack of engine-braking while driving downhill is also more critical for someone who also used to drive manuals more often than automatics.

[EcoCivic]

Originally Posted by cRiPpLe_rOoStEr

It might be due to our different perspectives, notice we're from different countries and only in recent years the automatics became more widespread here in Brazil. Some people who have previously driven cars with other types of automatic transmission might not expect the feeling of a CVT once they drive one for the first time. Getting used to the lack of engine-braking while driving downhill is also more critical for someone who also used to drive manuals more often than automatics.

Oh okay that makes sense. Honda's CVTs have 3 different modes: D, S, and L. Mode D basically chooses the highest gear possible for the best efficiency. Mode S is sort of a sport mode and keeps the RPMs a bit higher than mode D for better response and more engine braking. It also makes the trans more eager to downshift when hitting the gas for a more sporty feel.

Mode L is the mode I am confused about though. I know that L stands for Low, but it is unclear to me whether mode L will simply lock the transmission in the lowest "gear" possible and not allow it to upshift or whether it just sets a higher target RPM than D or S. In other words, what happens if you put it in Mode L and floor it from a stop? Will it just max out and bounce off the rev limiter or will the trans continue to upshift as the car accelerates? If anyone has an answer to what exactly Mode L does please let me know, I would really like to know and no one seems to have an answer. Thanks

[Tahoe_Hybrid]

the civic GX is a CNG engine

[Gasoline Fumes]

Are the 0-60 or 1/4 mile times better with a CVT Civic over the equivalent manual Civic? I don't feel like looking it up myself. But from what I remember, both the MPG and acceleration of the CVT version fell somewhere between the auto and manual versions.

[Ecky]

https://www.zeroto60times.com/vehicl...-60-mph-times/

^ According to this, the Civic Hybrid is faster to 60 with its tall manual transmission than with the CVT - 11.1 vs 12.6 seconds. I don't see any other obvious comparisons, but that manual transmission is the tallest available in that generation.

[EcoCivic]

Originally Posted by Gasoline Fumes

Are the 0-60 or 1/4 mile times better with a CVT Civic over the equivalent manual Civic? I don't feel like looking it up myself. But from what I remember, both the MPG and acceleration of the CVT version fell somewhere between the auto and manual versions.

I can't find the 0-60 time for the Civic HX CVT, but I found this video of someone doing 0-100 KPH in a Civic Ferio with the same engine I have (the EX VTEC engine) and a CVT and I timed the 0-60 MPH at around 8.8 seconds, faster than the short geared EX 5 speed. No idea what the weather conditions were like or anything, but it's the best I could do.

https://www.youtube.com/watch?v=Cqr-FxrjRn8

With the tall geared 5 speed I found that the HX does 0-60 in 10.2 seconds with a quarter mile time of 17.7 seconds. The shorter geared LX 5 speed (with 1 less HP) does 0-60 in 9.3 seconds with a quarter mile time of 17.2 seconds. The short geared EX 5 speed with 11 more HP than the LX and 10 more than the HX does 0-60 in 9 seconds with a quarter mile of 16.5 seconds.

Unfortunately the LX, HX, and EX all have different engines, but the gearing seems to be a significant factor since even the LX with 1 less HP than the HX still did 0-60 0.9 seconds faster with a 0.5 second faster quarter mile. I wish I could find a comparison

EDIT: I found that the 0-60 time for a Civic Ferio 1.7 5 speed is 9 seconds with a quarter mile time of 16.8 seconds, the auto version does 0-60 in 10.6 seconds (slow!) with a quarter mile time of 17.6 seconds, and the CVT version does 0-60 in 9.4 seconds with a quarter mile time of 17.1 seconds. All these cars have the same 1.7 VTEC engine. Here's where I found the specs: https://www.automobile-catalog.com/m...edan/2004.html