flywheel lighting

[gte-87]

hi when you get your fly wheel lightened is it done on a cnc machine? and also what is the lightest you should ge it to weigh??thanks dan

[mowgli]

it is simply done on a lathe by a competent machinist.... you skim as much as you dare off it. i don't see how it will be any better if you are using the car as a daily... but for track use, it might help.

[gte-87]

yeah that what is for a track car and also it has some marks i want to get machined out i have some cnc machines at work i might speak to them asnd see if they can do it thanks for your help

[mowgli]

remember this. don't skim too much off the front face, as it will affect the travel on your clutch. i believe people skim more off the 'engine' side & also slot them out near the ring gear.

[mk1nova_rich]

Usually done on a centre lathe as its far quicker and easier than messing about on a CNC machine. The only time you would use a CNC is to machine a flywheel from steel billet

[bazil]

am i right in saying lightening the flywheel can improve BHP figures and rev quicker but reduce torque figures?

[AlexW]

It wont up the bhp, Just increase the speed of the rev, You might lose a bit of torque, But I don't think its much to worry about.

You need to get the flywheel balanced after lightening, And as to how thin etc to do it, Its down to experience and knowing what will keep the strengh.

[bazil]

cheers again Alex, im looking towards torque tuning my engine rather than a high bhp figure

[mowgli]

now, in my way of thinking, a light flywheel will make for a lumpier idle, & help it rev up in neutral, but when you connect a gearbox, some driveshafts & wheels & car into the mix, and any flywheel lightening is pretty much insignificant.
apart from actually lowering the weight of the car, i don't see where the gains are.

[AlexW]

I disagree tbh, Having driven a car with a pot type and then a flat flywheel, Even on the road the one with the lighter flywheel revved quicker.

[Dayle_]

Am i right in thinking you loose some of the engine braking with a lighter flywheel and a loss of power on steep climbs?

[Balley]

I disagree tbh, Having driven a car with a pot type and then a flat flywheel, Even on the road the one with the lighter flywheel revved quicker.

same with a 1.5 fly wheel and 1.7. 1.5 revs much easier

[Royston]

Lightened flywheel does not increase hp, it inproves the engine rpm spin up acceleration due to reduced inertial resistence due to the mass of the flywheel.

The gains are acceleration in the lower gears, iirc for every kilo off the flywheel can be the equivelent performance increase of @200kg off the kerbweight!! obviously dependant on kerbweight, engine etc, you lose the percentage advantage as the gear ratio increases.

Down side is you loose cruising ability due to the reduced mass of the flywheel i.e. the engine has to work harder to maintain speed due to loss of mass in th flywheel (the energy stored in the flywheel is less)

If that makes sense;)

[Royston]

Am i right in thinking you loose some of the engine braking with a lighter flywheel and a loss of power on steep climbs?

It's not loss of power but reduced momentum in the flywheel

[Dayle_]

Sorry didn't mean power loss meant the amount of energy that is stored in a heavier flywheel moment of inertia and all that.

[Royston]

Sorry didn't mean power loss meant the amount of energy that is stored in a heavier flywheel moment of inertia and all that.

:thumb:

[gte-87]

so they is a plus and negative to lighten flywheels the reason i am doin this is because the thrust bearing fell a part and the bears marked the fly wheel so if you machine it the ,arks will come out thanks for the help dan

[Mk1'SR'Dan]

i was thinking about having my 1300 fly lightened, but on the basis of this thread, im not going to bother... the idle is WELL lumpy enough already... even more when i get my 287 cam...

[Royston]

My SR is fine on forties and lightened flywheel with a 270 cam, as is my Sport with a Piper 285;)