I have a lightweight flywheel. 8 lbs to be exact, I hear that a common argument is that when you shift , you "loose rpms" ... how is that so , when your not slowing the car down between shifts any different then with a stock flywheel (which is 20 lbs for me) ?

I can see the engine rpms falling quicker when you depress the clutch, but when you upshift your matching right up with the revolutions of the wheels , so there really is no difference in speed of the car , because your still engaging the gears at the same rpm no matter how heavy your flywheel is.

anybody following me here ? or am i just stupid and missing something ...

 

I'm no expert here, but I know its possible to get a flywheel "too light" although I dont know what the range is. You still want rotating mass to keep it going, however too little, I think that happens

 

if it drops quick , it picks up just as quick .. theoritcally , so there is no physical difference on rpm engagement when shifting because you are going to engage the gear at an rpm dependant on how fast the wheels are turning

 

its easier to bog on a launch and such. i know what your saying in a race situation, where the rpms will drop, but a decent driver should be in gear and going before they go under the shift rpm point.

for every action there is an equal and opposite reaction...less rotational mass means quicker acceleration...as well as deceleration.