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Thread: BHP Calculation

  1. #1
    Keif's Avatar
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    Jun 2003
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    BHP Calculation

    Guide to Bar Horse Power:

    Right, ive noticed a lot of magazines and stuff quoting BHP figrues against cars and thought i should take the time to explain what these are.

    Basically the figure they are quoting is the most important factor about the performance of a "phat/wicked ride".

    Brake horsepower and Torque are all very well, but the main figure that counts is Bar Horse Power, this is the figure that you tell your mates down the pub.

    To calculate this use the following rules:

    The manufacturers generally handpick an engine that they know is on the right end of tolerances for testing, this means that often its a higher figure than an average new engine actaully makes, ignore this fact and swear blind that your smoking nasty example of a now half ***ked engine makes the figure claimed, round up whenever possible, so 152bhp = 160bhp etc

    Obviously the correct way to get more power from your smoking engine with poor valve seal and rings that are about as tight as freedy mercury's arse, the way to get more power is to ignore those facts (see "starting point") and just bolt tat onto the outside of it.
    These mods can include filters/exhaust/dumpvalve etc, or even semi-internal mods like cams, we wont cover things like bearings or rings cause those arent very shiney so you wont want to replace them.
    The manufacturers always state the gains that you will get from a mod, often your car wont be listed specifically with a power gain, so just pick the biggest one that is, if a skyline can pick up 22bhp from an exhaust, then so can your saxo, again dont forget the golden "always round up" rule.
    The figures should all be added up, and round up again.

    You need to add a proportional value based on the "its a good'un" factor of your engine, basically, as this is YOUR engine not anyone elses, its special, so the mods will all make more difference, so multiply the number up a bit to take this into account.

    Race cars have them, so you need them too, the key thing here is to NOT buy ones that apply to anything you have fitted, go for stuff that isnt even made for your car, so Greddy/HKS/Blitz is ideal for an XR2i.
    Now the thing to remember with modifications to a vehicle is that they work in harmony, it all comes together as a package, exhaust will compliment head mods, filter will work well with a decat or whatever, now stickers are about attitude, and attitude is what counts out there on the street (or halfords car park).
    Take the % of your car covered by stickers and spoilers and add that onto your BHP figure as an attitude adjustment (dont forget to round up!!)

    Fiesta XR2
    quoted figure (use a guess if you cant find the manufacturers), 94bhp
    filter (using the figure for a porche 911) - 11bhp
    Exhaust (using figure for a skyline) - 22bhp
    decat (never had one so you get this without doin anything, PHAT!) - 12bhp
    sticker coverage = 47%
    spoiler coverage = 12%
    Its a good'un factor = 25%

    We'll do the rounding first:
    So the calcs are:
    94 round up = 100
    filter round up = 20
    exahust round up = 30
    decat round up = 20
    sticker round up = 50%
    spoiler round up = 20%
    good'un round up = 30%

    So 100 + 20 + 30 + 20 = 170
    plus stickers 50% = 255
    add spoiler factor 20% = 306
    add good'un factor = 397.8

    Final round up = 400bhp

    This however is only your basic Bar Horse Power figure, make sure when you quote it you increase it inversely to the age of the girl you have with you at the time, and in direct proportion to the number of pints you have consumed.

    Hope that helps if any of you are getting your "phat modded chariot" featured soon.

  2. #2
    nighthawk's Avatar
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    far more entertaining than the old formula

    Horsepower = Torque X 5252 / RPM.

    I better get some stickers on my CTR because the passenger airbag warning one must be holding me back.

    I'm also gonna have to have a look out for a saxo driver and nick his 16 year old G/F

    My CTR should be at about [Dr evil voice] 1 million horse power [/Dr evil voice]

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