Horsepower based on fuel consumption

Discussion in 'PSI Superchargers Tech Questions' started by Danny Humphreys, Jan 16, 2009.

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  1. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    hp

    didn't racepak or someone make a "onboard dyno" that could be mounted on the car and give a measure of hp. i think strasburg told me they had one on their fuel car one time. somehow measured torque vs driveshaft to rpm....

    surely i didn't dream this up...
     
    #21
    Will Hanna, Jan 19, 2009
  2. Mike Canter

    Mike Canter Top Dragster
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    Yes, you can attach a strain gauge to the driveshaft and measure horsepower. I have seen a company at PRI demo it.
     
    #22
    Mike Canter, Jan 19, 2009
  3. aj481x

    aj481x Member

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    Sorry, asking about a typical AFC, trying to relate it to the fuel numbers discussed earlier.
     
    #23
    aj481x, Jan 20, 2009
  4. Joseph Satterfield

    Joseph Satterfield Member

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    Fuel Consumption

    You can not tell the horsepower of the engine by the amount of fuel used. You would have to know the Nv " volumetric efficiency," Nc "combustion efficiency," and Nm "mechanical efficiency." These are theoretical so there is no way to know.
     
    #24
    Joseph Satterfield, Jan 20, 2009
  5. Joseph Satterfield

    Joseph Satterfield Member

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    A engine can have way more than a 100% volumetric efficiency ratings. One reason being the advancements in superchargers. The sky is the limit on how much fuel one can burn.
     
    #25
    Joseph Satterfield, Jan 20, 2009
  6. Mike Canter

    Mike Canter Top Dragster
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    Joseph it is pretty easy to estimate HP via BSFC from naturially aspirated racing motors. The will always have a BFSC of in the low .4. ProStock motors are way down there. Blown motors are a liitle harder because of the different types of supercharging. A turbo motor will have a different BSFC from a Rootes motor as it will from a screw blower motor BUT you can pretty well estimate HP from each of those types with specific BSFCs. We are only talking about estimating HP but it does turn out to be pretty accurate. I understand what you are talking about with all the different efficiencies but in well built race engine they are all pretty close to the same.
     
    #26
    Mike Canter, Jan 20, 2009
  7. aj481x

    aj481x Member

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    It probably should be added that using fuel consumption numbers is only going to be accurate if the engine is tuned close to it's potential.
     
    #27
    aj481x, Jan 20, 2009
  8. Mike Canter

    Mike Canter Top Dragster
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    I agree and that is one of the purposes of BSFC especially on a dyno run is to find out just how efficient the motor is. The lower the number then the better both the design and tuning of the motor.
     
    #28
    Mike Canter, Jan 20, 2009
  9. ta455

    ta455 Member

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    "onboard dyno" /0-5_volt_rotary_torque_transducer.htm
     
    #29
    ta455, Jan 20, 2009
  10. JustinatAce

    JustinatAce Member

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    Could you do the same with the input shaft? Talk about ultimate, by the numbers clutch tuning!
     
    #30
    JustinatAce, Jan 20, 2009
  11. Mike Canter

    Mike Canter Top Dragster
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    It would be harder because the device has a doughnut clamped on the driveshaft that is wired to the strain sensors glued onto the middle of the driveshaft. This rotating doughnut transmits the data to a close by pickup.
     
    #31
    Mike Canter, Jan 20, 2009
  12. JustinatAce

    JustinatAce Member

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    I guess what would be most helpful would be the torque "load" numbers on the input shaft/disc pack. It still couldn't account for track conditions, but man, it would be helpful. :)

    What we have for calculators now, you can input one setup vs. another and it will show you the plate load through the RPM band, both numerically and graphically.

    Another thing we do is actually kick out the equation for the particular setup and you can add it via a math channel in Racepak to see your plate load through the run.
     
    #32
    JustinatAce, Jan 20, 2009
  13. TOL

    TOL Active Member

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    Yes it can be. You need a custom/longer input shaft, and machine your own spacer between the can & trans.
     
    #33
    TOL, Jan 20, 2009
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