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Re: Dyno Tuning Methods

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  • Derek Capito
    Dan, What are riding conditions? Regards, Derek ... -- www.moto-lab.com
    Message 1 of 43 , May 1, 2010
      Dan,

      What are riding conditions?

      Regards,

      Derek

      On Fri, Apr 30, 2010 at 11:29 PM, Danny Whitfield <eco.usa@...> wrote:
      My version of reality is:

      In the case of a dyno, it should read actual horsepower produced under
      riding conditions. No computer correction, just real power.

      In the case of the Suzuki Hyabusa, a dyno run in still air will
      produce much lower horsepower readings than advertised.

      An actual high speed run with full ram air effect makes a very
      noticeable difference in power at higher speeds.

      So if you have a lot of money riding on a racing result, it would make
      sense to take dyno readings with a grain of salt.

      Dan

      Dan






      > Dan,
      >
      > What is reality?
      >
      > Regards,
      >
      > Derek
      >
      > On Fri, Apr 30, 2010 at 10:41 PM, Danny Whitfield <eco.usa@...> wrote:
      >>
      >>
      >>
      >> I see your point Derek, as far as the too lean adjustment is
      >> concerned. But still without the amount of air that would be rammed in
      >> at speed, how can the dyno run produce readings that would be close to
      >> reality?
      >>
      >> Dan Whitfield
      >>
      >> > Dan,
      >> >
      >> > This is only an issue on a carburetor equipped engine if the float bowls are not pressurized as well. Bikes that are originally equipped with ram air have this addressed with the float bowl vents being ported to the ram air inlets. Of course, if you were developing your own ram air, you would have to sort this out.
      >> >
      >> > This is only an issue on an injected engine if the manifold air pressure correction table is programmed incorrectly or if the sensor fails. Of course in either case, you'll have some fundamental problems, ram air or no.
      >> >
      >> > Regards,
      >> >
      >> > Derek
      >> >
      >> >
      >> >
      >> > On Fri, Apr 30, 2010 at 10:26 AM, Danny Whitfield <eco.usa@...> wrote:
      >> >>
      >> >>
      >> >> What about the absence of oncoming air (at the speed the bike is
      >> >> running) to pressurise the induction system in ram air equipped bikes?
      >> >>
      >> >> That could put you very lean on your fuel/air mix.
      >> >>
      >> >> Dan Whitfield
      >
      >
      >
      > --
      > www.moto-lab.com
      >


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    • Ken Augustine
      At Wendover, Utah — Elevation: 4,291 FT (1,308 M) http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html This means around 110.6mm of mercury
      Message 43 of 43 , May 4, 2010
        At Wendover, Utah — Elevation: 4,291 FT (1,308 M)

        http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html

        This means around 110.6mm of mercury less atmospheric pressure at Bonneville compared to sea level at standard barometric pressure.   With the specific gravity of mercury being 13.546, that would be a column of water in your hose of 1498mm or around 59" of water where

        Standard Atmospheric Pressure = 1 atm = 101.325 kN/m2 = 101.325 kPa = 14.7 psia = 0 psig = 29.92 in Hg = 760 torr = 33.95 Ft.H2O


            That is likely more delta P than you saw on your test but you have the correct idea.

        Ken A



        From: Matt Patterson <matt@...>
        To: mc-engine@yahoogroups.com
        Sent: Mon, May 3, 2010 8:27:22 PM
        Subject: Re: Dyno Tuning Methods

         

        Back in '94, the team I raced and spannered for got a Dynojet inertia dyno.
        We built a room and things went ok. One thing I was worried about (rightly
        or wrongly) was pressure in the room, was it exhausting faster than the air
        intake? or?, so all I did was made a very simple loop with PVC tube to
        compare pressure inside and outside. Interesting to see at first that an all
        gear run on a measly 250cc two stroke would actually lower the pressure in
        the room compared to outside. Not by much, but noticeable on the cheapskate
        pressure gauge :-)

        If you could be bothered to calibrate the gauge, then it would be quite easy
        to note (and see) a pressure differential. You could control fans by speed
        or orifice size to get the pressure you wanted.....maybe. ..or perhaps it's
        still early and I need another coffee.

        Regards,

        Matt.
        www.tyga-performanc e.com

        ----- Original Message -----
        From: Ken Augustine
        To: mc-engine@yahoogrou ps.com
        Sent: Saturday, May 01, 2010 3:57 PM
        Subject: Re: Dyno Tuning Methods

        It wouldn't be terribly easy or inexpensive but I have long wanted to
        approximate altitude and barometric simulation with variable inlet and
        exhaust fans in the dyno room. It would take a bunch of fan power and a
        stable independent variable control but I am sure it can be done. I have
        long thought this necessary for developing engines for racing at Bonneville
        where the altitude density is far from where I have always lived and done my
        dyno development. Under such conditions, engines with compression ratio
        and cylinder compression optimized to run at the density altitude and
        temperature on the salt will detonate in a sea level dyno room and engines
        optimized in dyno rooms at sea level will not have enough compression ratio
        and cylinder pressure.

        With pressure readings and throttle settings inside the airbox at speed, a
        map can be produced and if the dyno ventilation system can follow that map,
        the job is done. There would be a slight difference in the ambient
        pressure the exhaust system outlet would experience compared to when on the
        track but at full power, the exhaust pulse would have a large signal to
        ambient ratio and I'd bet it can be ignored.

        Ken A

        From: Danny Whitfield <eco.usa@gmail. com>
        To: mc-engine@yahoogrou ps.com
        Sent: Fri, April 30, 2010 10:41:13 PM
        Subject: Re: Dyno Tuning Methods

        I see your point Derek, as far as the too lean adjustment is
        concerned. But still without the amount of air that would be rammed in
        at speed, how can the dyno run produce readings that would be close to
        reality?

        Dan Whitfield

        > Dan,
        >
        > This is only an issue on a carburetor equipped engine if the float bowls
        > are not pressurized as well. Bikes that are originally equipped with ram
        > air have this addressed with the float bowl vents being ported to the ram
        > air inlets. Of course, if you were developing your own ram air, you would
        > have to sort this out.
        >
        > This is only an issue on an injected engine if the manifold air pressure
        > correction table is programmed incorrectly or if the sensor fails. Of
        > course in either case, you'll have some fundamental problems, ram air or
        > no.
        >
        > Regards,
        >
        > Derek
        >
        >
        >
        > On Fri, Apr 30, 2010 at 10:26 AM, Danny Whitfield <eco.usa@gmail. com>
        > wrote:
        >>
        >>
        >> What about the absence of oncoming air (at the speed the bike is
        >> running) to pressurise the induction system in ram air equipped bikes?
        >>
        >> That could put you very lean on your fuel/air mix.
        >>
        >> Dan Whitfield

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