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Discussion Starter #1
Hi,

I want to know the relationships between between gear ratio, engine
speed, vehicle speed, and power requirement for vehicle like the Insight with the CVT.

Can someone tell me if there are any situations where:

1. The engine rpm is rising, but the gear ratio is falling (from a
high gear to low gear) I guess this might happen if there is a great
power demand in place?

2. The engine rpm is constant, but gear ratio is falling.

3. The engine rpm is falling, and gear ratio is falling too. Any
ideas?

4. The engine rpm is rising, and gear ratio is rising too.
5. The engine rpm is constant, but gear ratio is rising.
6. The engine rpm is falling, but gear ratio is rising.

Any ideas?

I've never driven a vehicle with CVT. When it start up acceleration,
does the rpm of the engine stay constant and the gear ratio simply go
up?

Thanks
 

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Unclehan,
If you post your location maybe someone in your area with a CVT will let you drive their insight. :idea:
 

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I have a CVT. The only thing I notice is you don't have a sense of gear changes like with other auto's. You never feel the ratio changes.

You are making it to complicated. All I know is when I accelerate it goes and there is always plenty of pep. If a situation demands more pep I use the sport mod button to get higher rpms.
 

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1. RPM rising, ratio falling: pushing the gas pedal. the computer knows that peak power is made at high RPM, and instead of keeping the gears constant and waiting for the RPMs to rise with speed, the CVT will kick down.

2. RPM constant, ratio falling: imagine getting onto the freeway fairly quickly. your RPMs are at 4 or 5k, and as you approach 80mph, you let off the gas pedal slowly. usually, letting off the gas will lower RPMs, but as your speed increases, the cruising RPMs increase. I've tried to keep my RPMs pretty constant when accelerating, but you can see the engine go up or down a few dashes trying to find equilibrium.

3. RPM and ratio falling: deceleration

4. RPM and ratio rising: floor it. once your gear ratio gets as low as it can, and your RPMs get around 4-5k, both will increase until...

5. RPM constant, ratio rising: ...you reach top RPM (5200?) as your speed increases, your ratio must also increase (otherwise your RPMs would keep going up!)

6. RPM falling, ratio rising: easing up on the gas pedal.

you can feel the CVT adjusting most predominately on:
1 (that delay you get before the power really kicks in)
and 6 (especially after you just floored it. easing up afterwards gives some nice lunges back and forth as the car tries to find its new sweet spot)

I think this is what you were looking for. if you wanted actual numbers... i think you'd need the map the computer uses :p
 

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Discussion Starter #5
Allnighte said:
6. RPM falling, ratio rising: easing up on the gas pedal.
I think this is what happens after the acceleration stage if I'm not mistaken.

When you first press the gas pedal hard to accelerate. the engine rpm will immediately jump to a point where it maximizes the performance and the gear ratio will "catch up" and accelerate the car. All the time the engine rpm is "held" there.

Then after you've decided you want to cruise at a certain speed you ease up on the gas pedal. Now less power is needed so the engine rpm must drop to ensure gas mileage. But the car speed can't change so the only way to do this is to further increase to higher gear ratios.

1. But do you (or anyone else) know how fast the engine rpm drops after you ease up on the gas pedal? Is it a gradual drop or is a sudden drop? The faster the rpm drops, the faster the CVT has to shift.

2. I drive a regular automatic and anytime I ease up on the gas the engine rpm will drop very fast, something on the order of 3000 rpm/second. I don't understand how that works since the gear ratio is still the same and the car speed is still the same. Maybe the clutch or the torque converter is disengaged.

Any ideas?
 
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