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Power to weight comparisons

Discussion in 'General Motorcycling Discussion' started by Riderman, Oct 8, 2010.

  1. Hi guys,

    Just a quick question regarding power/weight

    I just want to gauge a 600 sports bike against a car.

    Let's take an R6, 90kw / 190kg. That would be 473kw/tonne.

    What is a car which has a 473kw/tonne result?

    And would that car be the same acceleration as the R6? My guess is from standing start, R6 would be, but from a rolling start, the car would be faster due to more torque.
  2. If you had a 1400kg car (inc driver) it would need about 662kw to have the same power/weight ratio as your bike (without a rider).

    Thats just under 900hp...so bugatti veyron territory (first model was 1000hp).

    But given that you can't exactly ride a bike without a rider, an r6 would be 333kw/tonne with an 80kg rider.

    So a car would need around 620hp for the same power/weight. Eg. lambo murcielago

    This is all conjecture-racing obviously, since torque, traction, driver ability etc. come into play and have huge implications for acceleration.
  3. It depends if your talking production car or modified car.

    Most 600s run high 10s in the quarter, your average lambos and ferraris run high 11s.

    My drag car (around 350kws, 1100kgs) will run high 10s and match the 600s but that is due to being set up for drags, the interesting part is the car will murder the bike off the line but the bikes make it up in the deep end crossing the line at higher speed. If the same 600 was set up for drags it would do better again (low 10 high 9).

    Edit: don't be fooled at the traffic lights though the biggest prob with bikes is using the theoretical performance of it, a modern Supercar with a novice behind the wheel would probably make a fool of you at the lights if your not experienced at drag racing. I almost flipped my bike on the lights a few times practicing hard launches.
  4. Yep, 'launch control' coming out on some of the higher end sportscars takes most skill out of the equation.
  5. Always need to include the rider + gear, which on average, is about 85kgs. Legally, for purposes of LAMS power to weight ratio, and various ADR regulations concerning motorcycles, it's 90kgs.

    Need to add 80kgs to the weight of any car for the driver as well, and that does make up a real difference.

    Also, are we comparing rear wheel power, or power at the crank here? Manufacturers almost always quote crankshaft power, but overall bikes have slightly lower transmission losses than cars do. Cars can beat bikes off the line because sportsbikes are largely limited to around 1.3-1.4g's of acceleration before the front wheel starts to lift. Longer and lower bikes can do better. Cars don't start to wheelie until much, much higher accelerative forces, hence their ability to get off the line quicker.

    Overall though, a bog standard R6 is really about 80kW at the rear wheel, and you're looking at about 280kgs with fuel in the tank and a rider + gear aboard. That's about 286kW/tonne.

    A Bugatti Veryon weighs in at around 1950kgs with driver + fuel last I looked. That works out to around 383kW/tonne given crankshaft power, or realistically, about 306kW/tonne for rear wheel power.

    You could also stick your 600cc bike on a weight diet, and throw on a better exhaust system, like I did with my project bike. It weighs in at 240kgs with me aboard with gear and fuel, and puts out around 85kW at the wheel, for 354kW/tonne.