Oops, when I said torque I meant inertia.

I meant extra torque not being used at idle from the supercharger.
Therefore the spinning heavy Fly should act as stored energy for take off?

Inertia/momentum + boost.

Makes sense to me, but isn't there a difference with bolt patterns (spacing)?

Must be for sure, I think Im stuck with the early a12 one.
Should be enough but was really looking to use the A15 vanette one
thats one heavy bugger.

I wasn't aware there is a difference in the mounting holes between the varying flywheels. I currently have a lightened, factory cavity back A14 flywheel mounted on the early A12 [dizzy at the front]crank. The only difference I have noticed is that the early cranks take 3/8 unf bolts instead of the later ones which use metric.

Thanks Benny thats where the paranoia could be.
Just the bolts are the issue not the flywheel bolt pattern.
Looks like Ill be using the a15 one then

big flywheel will cost u torque
if it was a motor that sat at one rev
u would have the torque of the motor and
the inertia in the fly wheel to do the job
if u try to rev the motor u will use up
the torque to speed up the flywheel
wats left will push the car
lighter fly wheel will let it rev faster and be more responsive
heavy fly wheel will idle lower,smoother,and will be more tractable(less wheel spin)easyer off the line,harder to stall
if running a blower there is a lot of fly wheel weight in the blower(cost hp torque)to spin
the less rotating mass the more torque to push the car and rev out quicker
henc lightening crank,rods,pistons,ect any thing that is driven
polished and knife edge crank,dry sump ect reduces the drag on the rotating mass, more torque

little out of topic, whats the weight of a stock a10, and a14 flywheel?

if im not mistaken, a12 flywheel is 9.4kg, and a15 flywheel is 9.8kg.

At least then if I can fit a bigger clutch to either an a10 or 12
I should be happy.

Stick with 180mm A-series clutch, its all about the friction co-efficent. I dont see the need to go with a heavier, larger clutch ~200mm. I would sooner go for a multi-plate small diameter clutch if slipping is an issue. Feral Errol has some good contacts for high performance clutch supply in Vic.