| A novice question: what are the performance benefits of adding a Lightened Flywheel? (3/00) |
| 1. Engine accelerates faster so feels more lively due to reduce
rotating mass - throttle response is sharper, you get places faster!
2. Engine decelerates faster .. better for gear changes 3. More power on most Dynos but (these buts are not a problem for anyone I have heard from) 1. Lumpier idle speeds due to less damping 2. Easier to stall the car when setting off due to less stored energy 3. Less damping on the engine so slightly harder on gearbox/diff (3/00) |
| Well, you accelerate a little faster due to less rotational mass, but when you approach a hill at a constant speed, the hill should theoretically slow you down faster (not that I have noticed that). Downsides are that it is easier to stall the car and that the gearbox becomes a tad noisier, probably again due to less mass = less damping. (3/00) |
| .. transmission gets more beat up because the peak torque is higher as the damping action of the mass is lost .. and the other one was the extra rattle at idle that someone pointed out .. again less damping. .. no need to raise the idle . which is not easy on a correctly set up car as the ECU should be in control of idle speed. (3/00) |
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Just from thinking about it, I'd say you'd have to up the idle speed to prevent continuous stalls. Can this be achieved with the stock ECU? So the main downside would be a reduction in fuel economy! Setting off would require higher revs/ better technique so it could become annoying after a while, esp if much time is spent in traffic jams. In a 4 pot engine, if you plot torque as a function of crankshaft angle, the graph goes OVER 200% and BELOW 0% every 1/2 turn. 6 and 8 cylinder engines are are down below +/- 20% torque variation. So 4 pots need a meaty flywheel. The stock flywheel on my V8 engine (just had to get that in) is MUCH lighter than the last flywheel I handled off an alfa twin cam - an engine less than half the displacement. I would only question the last point above, with a lighter flywheel there would be less stress on the rest of the transmission; some racers only use the clutch for starting & simply crash the box the rest of the time. I reckon highest transmission stress comes from dropping the clutch with the engine revs wrong - engine torque is puny compared to this. (3/00) |
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Just from thinking about it, I'd say you'd have to up the idle speed to prevent continuous stalls. No need to do that. (3/00) |