CVT sweet spot at 68mph?

[joecvt]

I know that it is nothing like what you can achieve in the MT Insight but not too shabby for a CVT model. When I first got the car back in 2004, I took off the OEM tires because I thought the rear was a bit unstable on certain areas of the highway (right hand lanes where trucks usually travel). I saved those oringal tires with only 5K miles on them just just put them back on the car this spring and immediately saw an improvement in mileage. The best I could do on non-OEM tires (that were still considered Low Rolling Resistance tires) was 74-75MPG on the same trip.

Now that the OEM tires are back on, I don't feel as unsafe as I initially felt. Must be all the years of driving the car.

I need to find a nice long flat road in New Hampshire with a 45MPH speed limit and no stop lights to see what the max mpg I could do. I would really like to see a 100MPG run one of these days I would also need hot weather and no wind.

JoeCVT = Just your average CVT owner

[jonnyvtec]

Originally Posted by RobertSmalls

Kevin, that BSFC plot is off a CVT, and may be tainted by IMA. And if you draw horsepower isolines, you find that cruising at 4000RPM puts you in the >280g/kWh range.

I really wish we had a useable BSFC plot, because it would answer these questions authoratively.

Someone with a scangauge should be able to offer some ball parks figures for rpm againt MAP at various speeds to populate the graph with some isobars.

Could be useful in confirming observations on the road or highlighting sweet spots that are worth trying out.

[RobertSmalls]

Originally Posted by Kevin Dougherty

Johnny, the left axis is labeled "indicated mean effective pressure", which is linear with torque. Since power equals torque times rotational velocity, the isolines have the same shape for any BSFC plot:


All that says is, if you need, say, 15HP to get the job done, choose the lowest RPM and widest throttle opening that provides that. I.e. put it in the highest gear you can. Good advice, but what about lean burn, and when should you use assist even if you know you'll have to pay it back with gasoline? The plot doesn't answer these questions.