How to shift insight?

[theaveng]

I used to run at wideopen throttle to redline (6000rpm) before shifting to the next gear, but after reading about how redline starves piston rings/cylinders of oil, I decided to try something different:

1st to 4000rpm, then 2nd at ~2000 to 4000, then 3rd at ~2400 to highway speed (then 5th)

or: 1st to 3000rpm, then 2nd at ~1500 to 3000, then 3rd at ~2000 to highway speed (then 5th). This method drains the battery fast, so I tend to avoid it. This method is also bad for the turbo in my Beetle..... another reason to avoid this habit.

In the CVT (if I recall correctly) the engine is revved to ~2600 and just held there. It drops to ~1600 for steadystate cruising.

[Cobb]

Thats a good question, it depends on what you are trying to accomplish. You after fuel economy, max acceleration, max engine or tranny life?

I am guessing max acceleration so Id take it til the rpm where the torque drops off. In the i2 that would be 4700 rpms. I use to drive my super charged tacoma the same way.

In my sidekick I often skip gears. I shift either 135 for highway speeds and 124 for city. For 35 mph zones I use 3rd to avoid speeding.

[Eli]

"Redline" doesn't starve rings/cylinders of oil. That's nonsense.

Maybe in some certain poorly designed engine out there on the road, but certainly not every one.

Redline is arbitary anyway, I bet the Insight could spin 8,000RPM if you got rid of the IMA motor.

[theaveng]

Originally Posted by Cobb

You after fuel economy, max acceleration, max engine or tranny life? ......... Id take it til the rpm where the torque drops off. In the i2 that would be 4700 rpms.

yes, no, yes, no

I2? This is an I1. So is max torque to the wheels at 4700rpm in 1st gear, or 2300rpm in 2nd? I would suspect the former, so you'd want to stay in 1st gear a little longer.

[Willie Williford]

Max. torque of engine is at 4700 rpm, no matter what gear you are in! (Engine wise)

Willie

[Cobb]

If the engine is anything like the one in the geo metro that is made by suzuki and in good health it could do 14-16 grand. Now spinning the engine faster than its useful power production range wastes energy unless you absolutely need those extra rpms like if you had a low final drive or only a few gears.

If 4700 rpms is the max torque for the i1, then that should be the shift point. Retard the cam 5-10 degrees and the sky is the limit. Thats of course you dont see 3 pistons flying through it.


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[theaveng]

Originally Posted by Willie Williford

Max. torque of engine is at 4700 rpm, no matter what gear you are in! (Engine wise)

I said "at the wheels". For ease of calculation let's just pick 1:3 for 1st gear ratio and 1:1.5 for second. Engine torque at 4700 rpm is about 9.3kg-m, and the gears multiply that differently:

9.3 times 3 (1st gear) == 27.9
9.3 times 1.5 (2nd gear)= 13.9

You're better off to stay in first, rather than shift to second and only have half the torque/acceleration. Even as you approach 6000rpm when engine torque drops off to 8, you are still getting more acceleration in 1st gear (24kg-m) than in 2nd gear@3000 (13kg-m). It's also why 5th gear feels so gutless... the torque has been multiplied to almost nothing (~5kg-m).

[Eli]

Ahem.. Don't forget the FDR. No, not the president.

Insight Ratios:

1st: 3.461
2nd: 1.750
3rd: 1.096
4th: 0.857
5th: 0.710
Reverse: 3.230

FDR is 3.208.

Of course the ratio of the numbers is still roughly the same, just a bigger number.

But torque doesn't move you down the road, power does. And power is Torque * RPM / 5252.

Peak power in the Insight is at about 5800RPM. Protip: If you redline 1st, you'll be in VTEC range when you shift into 2nd.

[biododge1]

one thing that gets overlooked is HP..Torque is worthless without HP. the optimum power and efficency is when you match both. personaly, IMO the best way to shift is with all the gears-keeping the shift points close as possible to the "sweet spot" on the motor. wide ranges of rpm is just a waste of fuel

"But torque doesn't move you down the road, power does. And power is Torque * RPM / 5252"
agreed eli.

[Cobb]

Lets keep in mind the mo gear reduction you have the more friction you have and power losses.

With the cvt, you can pick your rpm and hold it, with the gears you do need to pick shift point.

Ive always done it by seat of the pants and its my experience for me its when the torque tops out. When I drive a rental car I will floor and hold it to feel the car out. After a few times of doing this I find where it tops out, where it wants to shift and make the car shift by blipping the throttle.

Sounds like the i1 is like my old geo metro, pulls to redline. The i2 feels like it hyperventilates over 4800-5 grand. My sidekick is like this currently.

The geo I advanced the cam and ignition 10 degrees and lowered the power band so around 5 grand it tops out. Before it didnt start to really accelerate til you got to 5 grand. I could shift earlier, use higher gears and made the car over all more drivable.


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