You got that right...
If a car can accelerate at all even uphill (mine does, any gear) it will accelerate FASTER with a lighter flywheel.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

dont be a smartarse.
i believe vizard talks about the effects on idle are affected by the type of camshaft used,
most peoples minis are different..

Vizard's actual words... why a heavy flywheel was put in-
"Basically the reason is for a smooth idle but if you put cams in with a bit more duration on them, then you find you can get just as smooth an idle with a lot lighter flywheel".

ref: HTMYM, p128, paragraph 4.

so, who would put a standard flywheel on a modified motor with a cam in then. Not moi.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Forget Vizard... I have a very light flywheel... idle is great, hills are no problem, it hammers up hills actually

Pete

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Click here for the Turbo Conversion Thread!

No, same wheel, same weight. Apparently a different alloy of iron, but i can't qualify that statement, so to me it's just rumour. I do however have two wheels here from two S motors (My old and my new at the moment) and they are a brighter iron than the usual poo-brown flywheels. It might be luck or it might be a different steel, but I would need a spectrum analyzer to find out...


Can someone clear this up?

I loved my lightened flywheel, the downsides will only upset grannies stuck in traffic jams anyway as per my earlier post.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Flywheel on an S is exact same as a Mini Deluxe or Mini-K.
However the S backplate (22G270) is SG iron, whereas previous ones were grey cast iron.
22G270 SG iron backplate was in the Morris 1100S too, not sure about the other 1275s.

Later on Minis got the 1 piece flywheel, it's a different casting.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

So what's SG iron exactly? Something they can actually pin a recipe on?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

SG is spheroidal graphite. They melt it like grey iron then add magnesium to the ladle. this causes the graphite to spheroidise. good word that..
SG iron doesn't have flakes of graphite, it's got balls.


Often used for crankshafts, conrods, etc. It's not as strong as forged steel but unlike grey iron it's ductile. And it gets a nice hard skin on the wear surfaces so wears well.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'm actually going to go out on a limb here and say the 'reduced torque at lower revs' (or on hills) comment is bad science. Yes the engine will slow faster when you're off the gas, but when on I can't accept that power output can be lower. It's higher, it has to be.
Unless of course somebody can explain otherwise

i'd argue that because a heavier flywheel is harder to slow down it is less affected by the hill.

given that you dont gain any horsepower by fitting a lightened flywheel,

you're trying to push the same car up the same hill with the same power but with less inertia.

It is all about momentum - try going 4WD-ing with a lightened fly and see/feel the difference. The flywheel is a rotating mass of iron that rotates very very quickly. When I lightened the fly in the soob, I have to be careful now of my approach angles and what I actually attempt as the lighter flywheel doesnt have the heavier rotating mass therefore tends to lug more now than what it did with the std fly.

Its not rocket science as when you are in LO-4, I use the momentum of the fly to "crank" the car over a hill whereas now I really have to watch revs and more importantly the clutch as the revs drop off quicker. I know the mini is a different kettle of fish but you get the point.

Hooroo

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Rob Forsyth
Miniot!!

You should pick one up Spaceboy, they're pretty cheap to have made or purchase from a stock flywheel. Easy to fit too, you won't be dissapointed (I reckon I could convert ya!).

Mick

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I understand the effects of momentum and inertia in this scenario, however what I am suggesting is they are not an issue if your foot is on the gas.
As for 'doesn't add horsepower'....it most certainly does add it at the wheels ie. the effective power you are able to deliver goes up.
The only way going up a hill will be harder with a lighter fly is if you didn't have enough power to get up there in the first place, and were relying on the inertia of the engine to get you there.

Having driven the same car with a lightened, a standard and a heavier flywheel fiited, I can state the following.

Lightened - Revs faster - the idle is lumpier. high rev vibration is increased. Increased fueling and timing issues. Increased fuel consumption in city driving.

Standard - well normal I suppose

Heavier - Smooooth idle, decreased fuel consumption in town. Took 500 rpm off topend in fourth. Premature bearing failure.

On the track the car when fitted with the lightened flywheel set the same times as the car with the standard. However - it felt more responsive.

i thought about it alotduring the engine build, and i stuck with a standard fly because of smoothness, my engine was already balanced, to help stop the clutch juddering and my engine builder had already spent far more money than i had.

i had a 2nd chance to do it when my clutch was being replaced, i wanted it done, the other benefit being that i get the flywheel machined true if there is any irregularities affecting the clutch. But the mechanic didnt ask me and put it all back together.

i will probably lighten it when i next take the clutch apart to get it fixed properly.