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Flywheel... How 'Light'
scootz - 11/11/13 at 11:21 AM

Can't say I have much experience of playing with various flywheel weights, so looking for some input from the LCB massiv!

I'd imagine there's a great deal more 'engine-braking' with a lighter flywheel... and I guess it could be quite unpleasant when just pootling around? Does anyone have any opinions on how light is too light?

Cheers!

daveb666 - 11/11/13 at 11:29 AM

I had 3.5kg on my old Vauxhall Corsa with an XE on throttle bodies, it revved like a bike and I honestly never saw any down-side to having it.

I'd go the lightest you can go without having to resort to a non-standard clutch.

scootz - 11/11/13 at 11:49 AM

Cheers Dave!

matt_gsxr - 11/11/13 at 02:09 PM

BECs have no flywheel. What is not to like?

v8kid - 11/11/13 at 03:58 PM

I fitted the lightest available flywheel on my V8 and like others said there are no downsides only positives in a light vehicle. May be different in a 4x4 offroader if that's your thing

Cheers!

prawnabie - 11/11/13 at 04:01 PM

I would imagine most of the engine braking comes from the fact that the throttle boddy is closed and there is nowhere to suck air from.

richardm6994 - 11/11/13 at 04:31 PM

quote:
Originally posted by v8kid
I fitted the lightest available flywheel on my V8 and like others said there are no downsides only positives in a light vehicle.
Cheers!


ditto! I fitted the lightest flywheel in my v8. It sounds amazing when all 8 pots instantly light up to 6k from idle!

as taken from the tinter-web (mini spares);
For every 1 lb removed from the flywheel, the engine sees 11.22 lbs less to accelerate off of the total car.

Therefore by lightening the flywheel by 8 lb, the engine sees a total reduction of the cars accelerative weight of 89.68 lb.

Obviously this is regarding classics mini's and related to their gearbox ratio's, but I'd say it's not a bad "thumb in the air"

ashg - 11/11/13 at 04:32 PM

4kg on a zetec seems to work ok from my experience. 6kg on the saab turbo engine is the lightest i could go without swapping to an ali one with steel plate insert.

makes a fantastic difference to a nice light weight 7.

MikeRJ - 11/11/13 at 05:39 PM

quote:
Originally posted by matt_gsxr
BECs have no flywheel. What is not to like?


They do have a flywheel, just a very small one.

chrism - 11/11/13 at 06:02 PM

Engine braking doesnt have much do to with flywheel weight and more to do with cylinder sizes and compression. You learn this from riding V-Twin motorbikes. My Ducati 748 (Increased to 853) doesnt have much in the way of a flywheel and it has incredible engine braking due to the large cylinders, when I ride it around town I very rarely use any brakes at all until I need to come to a standstill or have the clutch pulled in.

The only bad side I have heard about lightened flywheels is apparently it can affect acceleration when going up a steep hill, don't ask me why I just remember hearing it somewhere.

Paul Turner - 11/11/13 at 07:06 PM

Whatever you do please do not risk fitting a lightened standard flywheel, but a properly manufactures steel one (or alloy with a steel insert).

A lightened standard one can kill.

For the sake of £200 do it properly.