It wouldn't affect HP at the crank but at the wheel, I think the dyno would detect less wheel weight as more HP and torque. The dyno is measuring how quickly a fixed weight is being accelerated and calculating HP and torque. If the wheel is lighter, the same amount of engery should make the drive wheels accelerate more quickly resulting in a higher HP and torque numbers.
They measure torque, which is easier to measure than HP. At least this dyno that was this article was written on, torque was the main measurement. With a known radius at the dyno wheel, torque can easily be measured. <br> <br> From the torque numbers, HP can be calculated, which is torque divided by a factor. <br> <br> That's why typically, when you look at a dynosheet, the torque and hp numbers converge at 5250rpm, which is when torque = hp.<br> <br> I tend to agree with Brian more that wheel weight only affects torque and not horsepower. However, since there is no other way of measuring horsepower accurately (w/ taking into account wheel weights), the dyno HPs (which is a function of torque via equations) will be affected by wheel weights.<br> <br> <br> Did any of that make sense?
Yes, now that you mention it, I remember being told the same thing...
when I had my car dyno'd. People do tend to focus on HP and not torque. So does that mean that if you just increased torque but say change the gearing that a dyno would perceive a HP increase as well? I suppose so although there is no HP increase.
I know the HP loss is due to the unsprung weight of the wheel...
basically, as mentioned above is the fact that more HP goes into getting the wheel moving. You must also remember (from physics) that it's not only the weight of the wheel, it's also where the weight is located. The further from the axis of rotation, the more torque it takes to get it moving.
Hp=Torquexrpmx(Conversion factors) (due to differences in systems of measurement used).<br> If something is affecting torque, at the same rpm it should affect hp and vice verca. At a fixed rpm/speed wheel weight should not change anything, upon acceleration or decelaration, wheel weight/mass adds to the mass that should be acc.or decelerated, so torque measured by dyno (hence the calculated hp) is less on acceleration. Any result different than this could be due to other factors associated with the wheel/tyre, like effective diameter, slip etc.
Linear Mode
