Hi, I have a 2008 FEH and I have noticed (as previously posted on this forum) that you can get the eCVT transmission to "upshift" if you back off on the accelerator pressure a bit. Has anyone see a table of MPH vs RPM
when the transmission is in its highest "gear".

Thanks

 

Engine RPM and wheel speed are independent and are based on the generator speed and the planetary gearset ratios.

Motor RPM will increase with wheel speed since the motor is directly connected through gears to the diff.

 

Thank you for your quick reply, just to clarify my request--- I understand that the engine rpm will differ depending on the final ratio of the transmission. I just want to know when the transmission is in its highest "gear" by looking at the Speed and engine RPM. This would only be when I am doing over 45MPH constant speed on a level highway so all the vehicle power is coming from the ICE.

Thanks

 

I would suggest looking at the tachometer. Whatever the lowest it is during cruise corresponds to your highest effective gearing. I forget what the planetary ratios are, but they can be figured out from the traction motor/generator speeds vs. vehicle speed charts in the Powertrain/Emissions Diagnostic Manual. I think gpsman posted them somewhere, too.

If you get your SOC above 53%, though, you will get electric assist even at a 45mph steady state cruise. You can see this on the nav screen or with the SG xgauge PID display. You will be astonished at how good your FE is in this mode!

 

kpdandjad -

In my limited experience - 3,500 miles on my MMH - the CVT seems to reach max gear ratio around 45 to 50 MPH at 1,500 RPM. Achieving a speed above 50 MPH will require higher RPMs. So it appears that max fuel economy using the ICE is achieved at about 48 MPH. I read somewhere else on this site that at 48 MPH fuel economy is about 48 MPG. Easy to remember - 48 at 48!

 

I would guess at some slower speed the cvt would hit it's final drive ratio.
I would suspect at higher speeds, it would not be able to do so, as the ice wouldn't have enough torque to maintain the absolute top ratio.

The 'fake shift' is a means of getting the cvt to slip up into final drive.

I know none of this rambling answers the key question of what the gearbox's final drive ratio is. Is it 1:1 or can it overdrive?

Mark Mooney

 

From the Powertrain/Emissions diagnostic manual, the generator/ICE ratio when the traction motor is not moving is 3.394:1, which means R/S=2.394, which means if the generator is held, the ratio of ICE to ring would be 1/(1+1/2.394)=0.705:1, so a pretty typical overdrive ratio.

 

Carl:
Thanks!

MM

 

Does this help?




-John