Are lightened flywheels worth it?

Car_54

Richard53 wrote: »

For road use by the average Joe, yes. A massive flywheel stores energy, smooths out the power pulses and makes the engine easier to start. With a highly-tuned racing engine, a light flywheel has less inertia and the engine will rev more quickly, but at the expense of being harsher and less able to chug through a roundabout in second without touching the clutch


Skimming and lightening the flywheel is a well-attested part of race tuning an engine, but I wouldn't have one in a road car at any price.

Are you suggesting the OP is a below-average Joe?

Richard53

[quote=[Deleted User];75929974]Are you suggesting the OP is a below-average Joe?[/QUOTE]
Heaven forfend, Sir.

AdrianC

I'm just chuckling at the thought of how spending over £400 to save ~5kg from the flywheel is going to make the car faster when it's actually in gear and the engine's pushing 270x as much weight forwards.

Richard53

AdrianC wrote: »

I'm just chuckling at the thought of how spending over £400 to save ~5kg from the flywheel is going to make the car faster when it's actually in gear and the engine's pushing 270x as much weight forwards.

In a racing environment, you absolutely would. Remember that although you're only losing 5 kg, that 5 kg is rotating weight, so it counts for much more than the static weight of the car itself.


As the old cyclists used to say: an ounce off the wheels is worth a pound off the frame.


But yes, 5 kg off the flywheel will make f-all difference to a road car, except to make it less pleasant to drive.

Car_54

Richard53 wrote: »

In a racing environment, you absolutely would. Remember that although you're only losing 5 kg, that 5 kg is rotating weight, so it counts for much more than the static weight of the car itself.


As the old cyclists used to say: an ounce off the wheels is worth a pound off the frame.


But yes, 5 kg off the flywheel will make f-all difference to a road car, except to make it less pleasant to drive.

Possibly, but the OP isn’t in a racing environment. Or, if he is, his prospects aren’t too good if he’s relying on this forum for engineering advice.

Richard53

[quote=[Deleted User];75930114]Possibly, but the OP isn’t in a racing environment. Or, if he is, his prospects aren’t too good if he’s relying on this forum for engineering advice.[/QUOTE]


As I said earlier to your point about a massive flywheel being a benefit ...

Richard53 wrote: »

For road use by the average Joe, yes.

Skimmed flywheels are for genuine racing environments. For a road car, the negatives outweigh any benefits. Speaking of rotating masses, I hear that if you take off the rear discs, A Yaris can be persuaded to do a sub-11 second quarter.

jimbo6977

Friend of mine took the radiator out of his track-day Austin Mini to save weight. However, in the queue for the pit exit it overheated.

Some things are so not worth it, they're not even worth starting a thread.

motorguy

Richard53 wrote: »

But yes, 5 kg off the flywheel will make f-all difference to a road car, except to make it less pleasant to drive.

And when your sills are rotting out, you're on ditch finders and your suspension is shot, you've already got enough problems without adding to them.

Kentish_Dave

ginashamz wrote: »

Car in question is the RX-8 PZ. The suspension from factory is designed for the track but I want something that will make the car rev faster. I am not sure if it’s the low torque but feel like it would be a lot more entertaining if it could take less time going up the gears as it revs to nearly 9.5k RPM.

Racing Beat (official Mazda rotary tuners) sell a flywheel that’s more than half the weight of the stock flywheel for around £500. Is it only worth fitting this when I change my clutch too? I think that’ll need doing within the next year

It will make the engine rev faster when not under load, so if you heel and toe and rev-match on the way down the gearbox you may notice a difference, but under load, I.e, when acceleration, it’ll be unnoticeable.
Spend the money on something that’ll make a bigger difference, lighter wheels, better bushes, better tyres, better brakes etc.

AdrianC

motorguy wrote: »

And when your sills are rotting out, you're on ditch finders and your suspension is shot, you've already got enough problems without adding to them.

Just imagine how bad it'd be if it really existed...