[Healeys] Flywheels

[Greg Lemon]

There is a multiplier effect in the lower gears especially, I took about 10-12
pounds off my BN1 flywheel, which is a boat anchor at the 40 some pounds it
weighs stock.  Anyway 1st gear in the BN1 is 9.28 to 1.  So when you
accelerate you are not only accelerating the mass of the vehicle, but also the
reciprocating mass of the motor, multplied by 9 plus times when in 1st gear.

Now I don't know if 10 pounds off the flywheel translates directly to 90
pounds off the car, but the gear ratio multiplier does have some effect.

When you upshift to match engine speed with car speed the motor needs to slow
down as you go up each gear, lighter flywheel means motor slows down faster
when you get off the gas and shift.

That all being said when I redid my 100 motor I didn't notice any change in
shifting speed, from my admittedly slow synchros in the original 3 speed, nor
did I notice any problem or change with driveability or smoothness.

I don't know what others charge, but my local clutch and brake shop charged me
$70 to take 10 plus pounds off, balance, polish, but my local clutch and brake
shop is known by the locals "in the know" as a treasure for its quality
service and reasonable prices.

So all said, IMHO, if you are building a racing engine or want that last
little bit of performance definitely lighten, if you are building your Healey
to be a street car with "a little more performance than stock with little or
no degradation of driveability" I would say it is a judgment call.  You will
probably not get a lot of seat of the pants or measurable performance
difference, but on the other hand it is all the tweaks put together that make
the better motor, balancing, maybe a little cam, compression boost, porting
and polishing etc.  So look at your goals and budget and decide accordingly.

Greg Lemon
Been there done that