CR says 60 MPH = 3495 RPM

[toronado455]

I've Googled for a thread dealing specifically with this and found none so I'm posting.

Consumer Reports shows in their test data for the Prius:
RPM @ 60 MPH = 3495

That is just way off the charts high, right?

Does anyone here who monitors tach data ever see RPMs that high on the freeway while cruising at a steady speed on a level road?

[patsparks]

MG2 is turning at 3575RPM however the ICE can be turning anywhere from 685RPM under no load to about 4370RPM under high load. On flat level ground the ICE will be quite slow. Have a look here http://eahart.com/prius/psd/

[bwilson4web]

Originally Posted by toronado455

I've Googled for a thread dealing specifically with this and found none so I'm posting.

Consumer Reports shows in their test data for the Prius:
RPM @ 60 MPH = 3495

That is just way off the charts high, right?

Does anyone here who monitors tach data ever see RPMs that high on the freeway while cruising at a steady speed on a level road?

Which issue?

Bob Wilson

[jdenenberg]

Originally Posted by toronado455

I've Googled for a thread dealing specifically with this and found none so I'm posting.

Consumer Reports shows in their test data for the Prius:
RPM @ 60 MPH = 3495

That is just way off the charts high, right?

Does anyone here who monitors tach data ever see RPMs that high on the freeway while cruising at a steady speed on a level road?

This just shows a lack of CR's understanding of the Prius power train. The ICE RPM constantly changes. It is low when there is no need for HP (coasting or going downhill) and high (yes, it can get even higher than the number quoted by CR) when accelerating or going up hill. There is no fixed relationship to speed.

JeffD

[donee]

Hi tornado...,

Yes, CR is only giving you half the truth on this issue. Here is a video which demonstrates the CVT in action.


http://video.google.com/videoplay?do...arch&plindex=1

[JimboK]

The only time I see ICE RPM that high at any speed is during very brisk acceleration or maintaining speed on a steep uphill. As others suggest, cruising at 60 MPH won't do it. Cruising on level terrain generally puts it in the range of 1500-2000.

Originally Posted by patsparks

MG2 is turning at 3575RPM however the ICE can be turning anywhere from 685RPM under no load ....

The lowest I ever see it is about 980 RPM, a figure validated by many others.

[MattFL]

Fascinating demo, thanks for the link!

http://eahart.com/prius/psd/

[brick]

It's a CVT, so the common RPM vs. MPH maps don't exist for a Prius. If you need more power the engine runs faster. A level cruise at 60mph with no wind, and I see barely north of 1500RPM. Climbing an insanely steep hill, maybe it would get over 3,000. The only circumstances under which I ever see 3500RPM+ is when I get on the throttle for whatever reason.

[DaveinOlyWA]

when going downhill and the ICE is essentially just coasting, the RPMS will be around 975 AT ANY SPEED... so CR is right... at least in one circumstance...it is possible with the right conditions for the RPM to be that high at that speed but it is much more likely to be higher at much lower speeds... brisk acceleration from a standstill will easily get RPM's that high

[toronado455]

Thanks for all the replies. Just to clarify, CR lists this "RPM at 60 MPH" spec under the category of "transmission performance" and they define it as "The engine speed when cruising in high gear at 60 MPH." I interpret "cruising" as driving on a flat surface at a steady speed. So this spec wouldn't be for going up hill.

It seems likely then, that in the case of the Prius, CR must be using the RPM of MG2 rather than the RPM of the ICE. Just wish they would have made a note to that effect somewhere!