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2005 Prius on my chassis Dyno!!

Discussion in 'Gen 2 Prius Main Forum' started by BT Tech, Oct 20, 2006.

  1. BT Tech

    BT Tech New Member

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    About a year ago I had the idea to use the facilities at my work where I usually tune high horsepower cars to see how much power the Prius would put out. I posted the results but when the PC server crashed a while back all of that data was lost.

    Well I just found it and I know that there were a lot of people that were interested in looking at the data.

    I have attached the actual dyno sheet that will show the HP, Torque and Air Fuel ratio. I remember that I had one hell of a time to be able to dyno this car!! I had to physically disconnect the VSS connectors on the rear wheels so that I would be able to let the front wheels turn the dyno rollers.

    Remember this is the power that the car is making to the ground. Generally speaking an automatic transmission will show a 20 percent reduction in power however I have no idea what efficiency what a CVT would be. We normally would multiply the amount of power/torque by 20 percent for auto and 15 percent for manual transmissions for crank hp/torque figures.

    At any rate here is the graph!! :)
     

    Attached Files:

  2. Pinto Girl

    Pinto Girl New Member

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    Wow, that's pretty cool, Brian. Thanks for posting the dyno sheet!
     
  3. BT Tech

    BT Tech New Member

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    No problem Pinto... Imagine if we could get into the PCM and richen up the A/F ratio!! Take a look and see how lean the car runs accross its entire RPM range.

    I just finished tuning a 07 Z-06 tonight and the A/F ratio was 10.5-11.0:1 STOCK!!! :eek:





    <div class='quotetop'>QUOTE(Pinto Girl @ Oct 20 2006, 08:38 PM) [snapback]335932[/snapback]</div>
     
  4. NuShrike

    NuShrike Active Member

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  5. auricchio

    auricchio Member

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    What's with the hiccup at 4375rpm? There's a very minor bump in the air-fuel ratio, but a fairly big one in HP and torque.
     
  6. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    <div class='quotetop'>QUOTE(BT Tech @ Oct 20 2006, 05:48 PM) [snapback]335938[/snapback]</div>
    Toyota does that for emissions reasons. Richen it up, you'd get more power, but you'd lose that lovely SULEV rating (not to mention the 60mpg EPA city rating).
     
  7. hobbit

    hobbit Senior Member

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    I've got the two old pix from your original posting saved, one of
    which is the same as Tideland's imageshack one. If you've misplaced
    them and want 'em back or want me to throw 'em up on techno-fandom
    or something, yell.
    .
    The tests don't seem to show anything under 3000 RPM. I, in fact,
    rarely get anywhere near 3000 RPM and I would have been really
    interested in some lower-speed testing. The torque curve is
    reassuringly flat and I think some of that comes from how the ECM
    does its throttle management. The A/F is also interestingly flat;
    I thought there was a little bit of enrichment scenario when you
    really punch it and RPM gets up near 4K. Then if you back down very
    slowly from there, the ECM stays in an oddly different mode right
    down into lower-RPM regions -- not sure if it's actual enrichment
    but the injector time wanders all over the place and a lot more
    fuel is burnt in general.
    .
    _H*
     
  8. BT Tech

    BT Tech New Member

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    Hello Hobbit... When I had the Prius on the dyno it was very interesting in that the car would INSTANTLY rev to 3k and this is the reason why there was no data on anything below this RPM.

    The A/F ratio was meaaured on a calibrated Bosch wideband 02 and was VERY consitent 15:1 with a small spike around 4700 RPM. What was also interesting is that even though the HV battery level would drop the amout in affected the HP/Torque was not a huge amount. I did not however run the car with the very last 2 bars remaining so it would have been interesting to see what she would do on motor alone.

    At any rate it was pretty fun to put the Prius up there!! Especially when I had 4 other C5's to work on and they were all in a row waiting for the Prius to get off their dyno!! :)




    <div class='quotetop'>QUOTE(hobbit @ Oct 21 2006, 11:02 AM) [snapback]336078[/snapback]</div>
     
  9. Tideland Prius

    Tideland Prius Moderator of the North
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    Interesting. Your new copy shows 102hp which is more than the old copy that I saved (100.07). However, the torque is slightly down the maximum recorded on your old copy which was 115.01
     
  10. BT Tech

    BT Tech New Member

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    I did about 10 different runs and all of them varied by a small percentage. This was probably due to the state of charge of the HV battery, temperature of the engine, varying inlet air temperature and minor variations in the dyno itself.




    <div class='quotetop'>QUOTE(Tideland Prius @ Oct 21 2006, 03:57 PM) [snapback]336154[/snapback]</div>
     
  11. Tideland Prius

    Tideland Prius Moderator of the North
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    Yeah, in the old copy, I can see the battery SOC going down and so are the numbers lol.
     
  12. Sufferin' Prius Envy

    Sufferin' Prius Envy Platinum Member

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    Where are the conspiracy theorists when you need them????

    If you ask me, this looks like the missing proof that Prius technology came from other-than-earthly sources. <_<
    I think BT Tech stumbled upon the procedure of how to force the Prius to print-out the aliens' stellar cartography charts . . . complete with their flight plans.

    How else could any sane person explain grid charts with a weird numbering system, overlaid with star and nebula markings, and complete with route marking lines converging into a circular pattern around a single point . . . EARTH!!! :blink:
     
  13. BT Tech

    BT Tech New Member

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    When I go back to the shop on Monday I will pull up all of the runs that I did that day and graph them all together. This way we could see the varying numbers due to the HV battery fluctuations.





    <div class='quotetop'>QUOTE(Tideland Prius @ Oct 21 2006, 04:37 PM) [snapback]336163[/snapback]</div>
     
  14. David Beale

    David Beale Senior Member

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    You mentioned you had to disconnect two sensors? VSC problems? We had that when dynoing RX-8s. Had to remove the sensors from the rear wheels (it's a rear wheel drive) as turning of DSC didn't help. Otherwise the computer freaked out that only two wheels were spinning. We still only had 20-40 sec. of "test time" as the computer eventually realized two wheels were still only spinning and "shut us down" again.

    Aint modern technology fun. ;)
     
  15. BT Tech

    BT Tech New Member

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    When I first strapped the Prius down on the dyno I knew that there would be a few "issues" to overcome. Since the front wheels were turning the drums and the rears were stationary the computer saw this as a slipping condition and the red triangle came up on the dash along with a reduction in power.

    I tried everything that I knew to disable it. Since there is no manual over-ride mode I pulled all of the fuses that control the VSC but the damn thing still caused an error. I then thought that the only way the car knows that the rears are not moving is due to the speed sensors on each axle. I simply unplugged each sensor on the rears and we were IN BUSINESS!!

    The only problem this caused afterwards is that the red triangle stayed on the dash until aproximately 50 miles of driving or so. I suppose that the computer has to see X amount of miles or time where there is no VSS error for it to extinguish the light from the dash.

    At any rate it was a fun and informative day on the dyno!!


    <div class='quotetop'>QUOTE(David Beale @ Oct 21 2006, 06:12 PM) [snapback]336192[/snapback]</div>
     
  16. ekpolk

    ekpolk What could possibly...

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    Interesting info. It does make me wonder about a couple things. First, I realize that dyno equipment is not designed with a "Prius mode", and of course, who would expect that. Which leads to my next thought -- the car is rated, on the torque side, at 295 ft-lb from 0-1200 rpm (just the MGs, totally apart from the ICE). I know very well that there's usually a substantial difference between rated hp and tq, and what comes through at the wheels (dyno results), but a loss of almost 200 ft-lb???? That's some loss -- if in fact it's really lost. That, in turn, leads to my next question -- does the fact that the dyno data starts at 2750 rpm distort the result for the Prius? In other words, would we see different numbers if the data was plotted for lower rpms? Finally, how does the variability of battery SOC impact the dyno results? If someone puts a Prius in a low SOC on a dyno, is it going to show lower output than one with a full, green screen, SOC? Sorry for the scattershot of questions -- interesting stuff. Thanks for the dyno results.
     
  17. BT Tech

    BT Tech New Member

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    Let me try to answer your questions. Yes, the electric motor does produce the rated (295) ft/lbs of toque from 0-1200 RPM's. The problem is that when you go WOT (Wide Open throttle) the RPM's instantly jump to 3k RPM's so this is why you do not see any data below this engine speed. The rated torque of the electric motor is not lost but is only present at the low engine speeds not depicted in this graph.

    All vehicles with a transmission (manual, automatic and now CVT) suffer from parisitic losses in the drivetrain caused by gears, viscosity of fluid, weight of rotational masses..etc..etc.. We generally subscribe to the fact that we lose aprox 12-15 percent of a given engines power with a manual transmission and 20 percent with an automatic. I have no idea where the CVT would fair and the only real way to know would be to take the engine out of the car and connect it to an engine dyno. Then one can compare the figures to what we are getting on the chassis dyno.

    Regarding the power output when the HV battery is in different states of charge, yes it does impact the amount of power it generates. Like I mentioned before when I go back to the shop on Monday I will overlay all of the dyno runs on one sheet and upload it here. This way you can see the hp/tq over 4-5 runs and at the varying levels of the HV battery.



    <div class='quotetop'>QUOTE(ekpolk @ Oct 21 2006, 08:24 PM) [snapback]336227[/snapback]</div>
     
  18. baxsie

    baxsie Member

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    I have a friend in Australia who is kind of a car buff. He sent me these two pics by IM today. No explanation, but they were on his server, so I think he personally took the photos.

    I am pretty sure they are from this event: http://www.toyoshow.com/

    [​IMG]

    [​IMG]
     
  19. Bill Lumbergh

    Bill Lumbergh USAF Aircraft Maintainer

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    Interesting they measure power in kilowatts and torque in newton-meters.
     
  20. molgrips

    molgrips Member

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    Those are the international standard units!

    Brian - I think the electrical losses in the transmission are 15% when driving normally caused by one MG generating electricity and the other consuming it. At high speeds with your foot down this would be less though since both MGs being motors.

    I don't think you can compare the Prius to any other CVT though.

    The power figure you came up with seems about right - it feels about as fast as other 100hp petrol cars I've driven :)