Highway MPH/RPM's

(I have a Gen 2, so actual numbers will vary, but the idea applies to all Prius except the PiP, which can still be all electric at 55 MPH)

When I get still air at 61 MPH I am at 1800 RPM
With a stiff headwind 2300 is possible, a Great tailwind will get me down to 1300.
Either the Prius computer, or my scangauge has accuracy to 6 RPM
Even slight up and down hills greatly effect RPM, I have a 156 miles stretch of road with a 60 foot elevation change, but most folks have more elevation change than that. (Florida may be as flat)

So do not expect that there is any one RPM that you would see more often than others, but they do bunch between 1700 to 1900 a lot.

 

Jimbo::::
that's a pretty low rpm for a 4 cyl vehicle at that speed
fantastic!
..scanguageII ?
are the readings from that device in real time or delayed in any way?

 

I thought about this thread when I finally hit a flat section of rural highway and it appeared to fluctuate between 1248-1300rpm at 55mph. I have not monitored RPM much at constant speeds but cruising RPM at 60mph is usually below 2000 RPM on flat roads. This is with LRR 15" tires.

I'll make an effort to monitor this more often.

 

When I hear the engine shutdown and look up, I often see one reading of 96 RPM, then 0 RPM. (less than a second)

 

xlnt
tks Jimbo

 

When I first got my SGII I used to monitor the ICE RPM, MG1 RPM, MG2 RPM and MPH. From what I rember, much like the others, that at 60 mph on a relatively flat surface the ICE RPM was around the 1500 RPM mark. Apparrently that is the ICE sweet spot that the computers try to control. MG2 is fixed to the wheel speed so the ICE and thus MG1 are trimmed as you go up and down inclines.

On my commute to work at 60 mph for a 2o mile stretch it was always interesting to watch the RPM's vary and then switch to torque and watch the power flow back and forth. Quite amazing to me.

 

It's both informative & entertaining watching the system take advantage of efficiency opportunity. Running the engine at low RPM is a key to the great MPG on the highway. That was especially exciting for me to witness, upgrading from an Iconic model to a 2010. I filmed a number of drives to share with y'all too, on a thread just like this! Here's my channel on YouTube... priusguru's channel - YouTube There are several videos featuring the ScanGauge showing RPM.

 

By the way, the PHV model pushes the RPM reduction even further. When driving with EV-boost, specifically at 65 MPH, it drops down to 992. With the engine running that slow, efficiency hovers around 150 MPG.

 

john1701a - you're the best!
thanks for the info.

 

Just made another trip on the same stretch of road and 60mph = 1440RPM give or take. If I even thought about moving my foot on or off the throttle it would drop to 1350 or jump to 1550.

 

F8L : I'd be curious about the r's pm at 55-60-65-70 on a relatively flat stretch in cruise control.
Was the info you posted above in cruise?
Were you in ECO or ?
Maybe you should change your handle to 'lab rat'.

 

It's hard for me to find such roads on my usual commute since it is mostly up and down hill. If traffic is light I will try to get the numbers for you tomorrow. I am always in Eco Mode. I am sitting at 63.3mpg for this tank and now that the wind has died down I,d like to get it up to 65mmpg if I can. Hmmm lab rat.....

The info above was without CC. I find it easier to maintain steady RPM or MPG without it. On the flat section of highway I will test on tomorrow I will use CC.

 

It's the transmission gear ratio that determines engine speed at a given wheel speed. The Prius has a CVT (actually an IVT) so the "gear ratio" can be almost anything.

 

As Jimbo clearly stated, his numbers are for GenII. For GenIII's larger engine, I'm finding F8L's lower numbers looking very familiar.

Remember that in the normal power band, the Prius engine runs at very roughly constant torque, varying RPM to produce whatever power is needed for the current speed (and AC and battery charging loads, if active). The needed power varies quite noticeably with even minor changes in slope, wind, tire rolling resistance, and even pavement roughness, so RPM changes accordingly.

It is nothing like a traditional manual or lockup automatic transmission, where the RPM is locked to the speed and power is adjusted by changing throttle position to adjust engine torque.

 

^^ What he said. ^^

The numbers you'll get here are very dependent on battery SoC, wind direction and speed, incline, road surface, tire pressure, altitude, phase of the moon, etc. Basically, at 55 mph, the RPMs will be something between 960 and 5200.

 

The RPM rate is so sensitive you can map the road "levelallity" by it (spell checker doesn't like that word).
You can even see wind gusts affect it.
Get in behind a semi and watch it drop (they don't like that)! Don't stay there. It's dangerous.

Fun with the HSD.

 

I'm finding that if I just use cruise control (other than up and down big hills) that the computer is pretty good at finding the most efficient path.

 

All great information. Thanks!
Once I thought about them then applied to the basic fundamentals of how these cars operate, it all makes sense.
Think I'm gonna get a SGII as I am way too curious about this kind of info.
Will post another thread on SGII location and figure out how to make HER not think this is some
kind of Popular Science research vehicle driven by Tom McCahill.

F8L - my 'lab rat' remark is because you always seem to be in the thick of trying something, or proving something, or researching and posting something.
I'm able to look beyond the pink eyes and freakish tail and appreciate your efforts.

 

No vestigial tail here but I'll accept the compliment.