The point you forget to address is the force required to move that object and it differs from front to rear.

You have a 100lbs wheel and you will need to push it to get it going. The diameter of that wheel actually has no effect on how much force you will need to exert.

Now lets say you have to move that 100lbs but by rotating the spindle/axle it's on, pretty easy if it's a rod right? Move that weight even further away from the center, lets say 10", not so easy anymore right? It'll get harder and harder as you move away from the center.

 

So with the Akebono BBK, you can't use your parking brake anymore? Didn't know that....

 

Interesting point. I'll think about that.

But the weight of that 100lb wheel still takes xx amount of force to get moving. Because in both cases, you are still using a force on a spindle to get that object rolling.

It's not like I was pushing the bike in one case and pedaling the bike in another.

 

Thats not really a true statement. You don't get any power gains from using lighter wheels, lighter rotors, etc... The output from the engine is still the same.

However, by reducing rotational weight you are reducing drive train losses, which is what is reflected by the changes you seen on your dyno runs. Engine HP remains the same, but Wheel HP will increase since losses are decreased. (i.e. less losses due to acceleration of rotational mass on the wheels)

 

Uh . . .no. My parking brake works perfectly fine with the Akebono BBKs.

 

The front wheels in our car are basically pushed by the force from the rear. The rears are spun by the axles.

Concerning the improved braking, you are right that having a larger rotor will help if you preserve the same pistons and move them further away, but in regards to the Akebono compared to the 350Z OE, the increased number of pistons is what makes the difference. There is a magazine test somewhere that compared the OE Brembo to the OE and it was quite different, but yeah, the OE Brembo do have a slightly larger rotor so it's not the ideal comparison to show my point.

 

Come on...I am sure everyone know that lightening the rotors will have no effect on the engine power... It's power to the ground that matters and any increase to it are gains...

 

The front wheels are pushed, yes. But the force pushing them is still the rear wheels driven by the axel. So it's still an axel force overcoming the rotational weight.

Increased number of pistons does not = more brake force. But more pistons help with braking FEEL.
Only increased total piston area increases brake force. And if you do increase the total piston area significantly, the brake pedal travel increases significantly. From what I remember, the master cylinder piston bore hasn't gone up much if at all over the years.

IMHO, the torque arm advantage of a larger rotor makes a bigger difference in increasing the total of the piston.

 

I see. I must've misinterpreted SDGenius' post about 2pc rotors on the last page. Thanks!