Dynoed my prius

Discussion in 'Gen 4 Prius Technical Discussion' started by Yippeekyaa, Nov 26, 2021.

  1. Yippeekyaa

    Yippeekyaa Active Member

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    Recently entered a competitive event that required entrants to dyno their cars. Did three pulls on the dyno. Pull 1 was in normal mode. Hp 102.83 torque 84.98. Second and third pulls were in power mode and some interesting things happened. 2nd pull, 92.55 hp and 136.29 torque. 3rd pull 87.04hp snd 109.26 torque. No time was allowed between pulls to allow the battery to recharge. The dyno graph was the strangest one of all the cars that day. It was the only hybrid in the group. E299004B-C3F5-48D9-BAE8-B39376E21790.jpeg
     
  2. Yippeekyaa

    Yippeekyaa Active Member

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    This was on my 2017 gen4 with 98k miles. All pulls were done with the car in maintenance mode as well.
     
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    So PWR mode is not just pedal sensitivity but also torque output?
     
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  4. Yippeekyaa

    Yippeekyaa Active Member

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    Apparently that is the case. A 52 point increase in torque between normal and power mode. Also note on the graph at how linear the power band is and what happens at higher rpm’s when the electric motor kicks in.
     
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  5. jerrymildred

    jerrymildred Senior Member

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    That seems to reinforce the Prius expert I got my Prii from who once told me that those modes affect valve timing as well as throttle mapping.

    I'd like to see some more testing on this to see how repeatable it is. This is pretty interesting.
     
  6. ChapmanF

    ChapmanF Senior Member

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    Looking at the photo, there are some RPMs there that a Prius engine never hits: 9.33, 9.10, even 5.85 is clearly unrealistic.

    It looks as if the dyno software is making some assumptions about engine RPM from wheel speed without having much of a clue about the Prius CVT. Then those bogus RPMs figure into HP and torque arithmetic. There might be a way to get the kind of information being sought here, but this doesn't seem to be it yet.
     
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  7. AzusaPrius

    AzusaPrius Active Member

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  8. Yippeekyaa

    Yippeekyaa Active Member

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    I wouldnt put too much emphasis on those rpm numbers. It was a marathon session of getting over 20 cars on the dyno in a 5 hour window. They didnt have time to enter data for each and every car like tire size and what not. Two other cvt equpped cars had similar rpm numbers and their hp ratings were reasonable compared to the cars rated output. The gen4 is rated at 122hp, this dyno run shows 102 at the wheels. Dont think taking the time to calibrate the machine to the specifics of the car will drastically change the end results.
     
  9. ChapmanF

    ChapmanF Senior Member

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    Really no getting around the arithmetic though. Power is torque times RPM. If the machine's estimate of RPM is off by factor of two (which an RPM of "9.33" nearly is), then its estimate of at least one of the other two will be similarly off. That's more than a small error. (In many settings, a factor of two counts as a "back to the drawing board" matter.)
     
    #9 ChapmanF, Nov 27, 2021
    Last edited: Nov 27, 2021
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  10. TMR-JWAP

    TMR-JWAP Senior Member

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    Just 'by the numbers', at least the Blue run makes sense. 92.55 hp @5320 rpm and 136.29 ft-lb torque at 2820 rpm measured at the wheels. The other two runs need a bit of deciphering.
     
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  11. Tideland Prius

    Tideland Prius Moderator of the North
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  12. Yippeekyaa

    Yippeekyaa Active Member

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    Surprised none have asked about the competitive event that required dyno testing. Well here ya go.

    Good pics of my car and setup at 6:13 and 7:05 into the video. A few other pics and you can see it if you look close.
     
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  13. Mambo Dave

    Mambo Dave Active Member

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    You're thinking what I'm thinking. A Cannonball run in a Prius might make for an interesting time.

    I love it.

    Tell me more as to how the Prius worked for this event. So interesting that it's so low on HP, but yet (at least mine) does nice clean holeshot accelerations. I can see why they dyno'd it as being suspicious since the Prius (again, at least mine) out-performs for what so many expect it to do. Sometimes I get to wondering if the battery in my lower model puts out more energy for torque, faster, than the upper-trim-levels.
     
  14. jerrymildred

    jerrymildred Senior Member

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    Even my Prime does pretty good hole shots. Your Eco is considerably lighter, so should launch even quicker. It's that 100% torque at zero RPM that gets you off the line so quickly.
     
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  15. Tideland Prius

    Tideland Prius Moderator of the North
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    Also smaller rims will have a very slight advantage over the 17” rim versions.
     
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  16. Yippeekyaa

    Yippeekyaa Active Member

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    The car worked extremely well. My intent was to drive non stop. 64 gallons of auxiliary fuel tanks were added in the back hatch area. This took quite a bit of time and engineering to do and worked perfectly. Over the course of the last year i did multiple deliveries for a local defense contractor and used those as test drives for the cannonball. At a steady 90mph the car returned 43-44 mpg so used this as my baseline to determine how much fuel i needed. Turns out at a steady 110+ the prius does not return those numbers. The sub 30 mpg forced me to do a single fuel stop in colorado where i added 57 gallons to the auxiliary tanks. There was a 6 hour window where i drove 628 miles. I was leading the pack for a very long time and was on track to do a roughly 33 hour run. Most took the southern route, at the last minute i decided on the northern route as all my mapping devices said it was just over two hours faster. All participants used a group tracking app called joiner that showed everyones location. Ive included screenshots of that app and the blue dot is my location. Unfortunately tragedy struck in colorado near veil canyon. An accident shut down the highway and after a 38 minute stop on the highway a reroute was made on a two lane road for 48 miles to get around the accident. This caused a near 3 hour delay which also caused me to enter the Los Angeles area during rush hour which added further delays. My finish time was a disappointing 36:55. But i became the 10th person in the 50 year history of cannonball to do it solo which is quite an achievement. Got an award at the finish party which was cool. After two days of fun and rest i then undertook another adventure. I drove the coast to coast run, solo, nonstop. San Diego to Jacksonville Florida. Made that run in 30 hours. Spent the night in Jacksonville and drove home the next day. Made it just under 3000 miles from san diego to florida to my home in north Carolina and never made a fuel stop. Car had a quarter tank left too. Over the course of 7 days i drove over 6,500 miles, added photos to show that as well. Overall this event took over a year of planning, a few thousand in money and turned out to be the most fun ive had in a long time.
     

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  17. Mambo Dave

    Mambo Dave Active Member

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    I am SOOOO happy for you, and thank you a ton for trying it in a Gen4. It's been something that's been on my mind ever since I got the car.
    I knew that the extra weight would detract from the MPG, as well as the speed. Was hoping the aerodynamics would make up for it, and I'm sure aero did help.
    I'm getting about 36 to 40 MPG with my commuting speeds, so 30 MPG seems right.
     
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