The difference in diameter is just the wheels but not the overall diameter, at least not significantly. But the weight difference are significant there. This is talking about transferring power to the ground. If there's no additional power going to the ground to move the car quicker then what does?? Power at the engine is the same but there's not as much loss used to rotate the mass of the wheels hence enabling the power more to move the car.
Ok I'm beginning to see the disconnect now. What you're saying here is you'll potentially
regain some lost power. You won't
gain power like what was said originally. This much I can agree! But I also did say the gains is minimal in the beginning.
Diameter of the whole wheel package (tyres and all) between a 20" and 18" is pretty significant. Based on the dimension given by the bloke in the 2nd video, it's roughly 5% difference. That alone would contribute to the slower acceleration on top of the wheel weight. Anyway, the 2nd and 3rd video has too many discrepancies. What we should do is make a video comparison between same diameter, same tyre and just a difference in wheel weight.
Anyway thinking too much about this is giving me a bloody headache. I'm done thinking. Hahaha! We all generally agree that lightweight means more better.
I suck at math and only loves to look at the outcome.
However, since we all agree that gb eats up some hp from the engine thus making hp at the wheel lower to hp at the flywheel...i am guessing whatever parts (including the rims) which are there to transfer the power from the engine to the road will have impact in hp figure. Its a matter of how much.
Would be interesting to see a dyno chart though. Then do the dyno again...this time removes the drive wheel disc brakes...i would love to see the outcome.
You know what we should do? We should start a ZTH video channel where members get together to properly mythbust or discuss topics like this and share on Youtube.
Cuz I sure would like to see for myself how this'll turn out on a wheel dyno and hub dyno.