Loosing 37lbs from flywheel swap. Gains?

[elhigh]

I don't remember all the rationale and I don't have enough engineering smarts to understand why, but when Hot VWs magazine was building their "mileage motor" project, among the other changes they added to the engine was to build up its rotating mass. They added a heavier front pulley and a heavier flywheel.

In terms of drivability it's nothing but gravy: more rotating mass gives the engine more inertia, so when you hook the clutch up you're less likely to stall it out. And since your Caddy is a manual, you might miss that extra mass when you're trying to get the rest of the boat moving at red lights. It'll change the engine from feeling flexible and torquey to touchy and rev-happy.

Rev-happy is fun, but not for hypermiling. Granted, hypermiling isn't a CTS-V's mission, but there it is.

[Smokeduv]

I don't think it would be paying for itself. I don't know if it would be better if he's doing P&G, as it will be lighter and could gain speed faster, but I also don't know if a heavier car will P&G better, as it has more inertia as opposed to lightweight cars.

Anyway, I would like to try a lightweight flywheel just to do some quick gear changes

[fbov]

No great experience speaking here, but it seems to me that it doesn't matter where you store the energy, in a battery or in a flywheel, energy storage capability should reduce fuel use. Kinematically, it's the same idea as P&G.

However, were that the case, folks would be looking for the heaviest wheel/tire combos, as the roadwheels are part of the same rotational system as the flywheel, albeit with a variable RPM relationship. I see the opposite happening, judging by this thread. (the onein Success Stories about "prius-15s-better-than-aftermarket-17s-wrong-wheels-23509")

So is wyatt seeing wheel-tire differences, or is leanburn's logic (post 5, claiming low mass is better) at work here? If so, why is the result different from what kinematics leads one to expect?

HAve fun,
Frank, who on post #1, will remain linkless