Rolling road / dyno test info/experiences required please

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  1. Rolling road / dyno test info/experiences required please 
    #1
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    m43ell's Car Details
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    right then, in the coming future i am going to get my car chipped (e36 325 tds 1993) could anyone tell me what figures i will get out of a rolling road test? obv ill get bhp and torque but do they come with others like top speed or max speed in gear? also, ive heard people talking about dyno tuning how they 'tweak' the car on the dyno, how do they do this without re-mapping? i would just like some user experiences so im not going in blind and sort of know what to expect, i will be using a reputable company called ajec racing in gloucestershire, thanks, ell
     
     

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    #2
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    TheEnd's Car Details
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    The normal figures you will get are BHP and Torque for the different engine RPMs.
    Top speed is limited by aerodynamics so there's only one way to find that out, and speed in gears will remain the same.

    Tuning on a dyno is often held for more specialist work, or to get the absolute maximum out of a car. This can take the best part of a day, and works out to be quite expensive.
    The majority of remaps with rolling road reports are a before and after test to show the improvement, and not an actual dyno tuning session.
    Some may be, so it is worthwhile checking if you will be having actual dyno tuning or just a report.

    It isn't as important on a diesel, as they have a number of other limits rather than the maximum possible power.
    Petrol dyno tuning would involve setting a torque resistance for the rollers and having the car at full throttle. You then adjust the resistance to get the engine to a certain RPM, and it will sit there, matching the roller resistance.
    Changes are then made to the car using an emulator in place of the memory chip which means a laptop gives the ECU the data, and you can alter the data in real time.
    If the engine speeds up, you've made more torque, if it slows down, you've lost some.

    That would then be repeated at various spots so each point is at the absolute maximum.
    This type of tuning is know as a "live map" as the changes are made in real time, but it does involve removing the memory chip, soldering in a socket, and then connecting a chip emulator in its place.


    The other less advanced, but more common method is repeated power runs with measurements taken of air-fuel ratios, knock sensor data etc, and then the data collected is used to formulate new maps.
    It is them repeated to see if it has hit the targets , and to make sure that the power has increased as expected.
    It will be repeated a few times until everything is in place, but the time it takes makes it more expensive.

    With a diesel, however, they are rarely tuned to the maximum power output, and usually limited by the safe boost available from the turbo, and the smoke output kept at an acceptable level. Smoke is a part of diesel power, so some increases are to be expected for full power, but not to the point of leaving what looks like a jet trail behind you.



    Ultimate power leaves huge amounts of smoke!

    That then all has to be passed through torque limiters to avoid transmission slip, so there isn't as much of a limit on a diesel that has to be reached, but more down to judgement and common sense.
     
     

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    m43ell (11-04-2011)

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    #3
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    m43ell's Car Details
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    1994
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    Car Body Type:
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    thanks for that a very informative post! nice one.
     
     

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