Lightened flywall...pros? cons?

I remember reading about an unbalanced flywheel that someone had tried to lighten by drilling it, and it ripped itself apart at high revs, smashed straight into the cabin and took off the driver's leg just below the knee.
 
OllyM said:
Isn't this a bit overkill? :confused:
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It will eventually be a track only toy. I'm even contemplating doing the group B racing next year. Hence me thinking of doing it now save pulling it all apart again in the future.

I think I'm gonna go for it :)
 
Dogbreath said:
A flywheel is an energy storage device. To accelerate it up to a given speed in a given time requires a fixed amount of power. Reduce the weight of the flywheel (or more accuracy reduce it's moment of inertia), and for the same power input you reach the same speed more quickly.

A lightened flyweel can give worthwhile performance improvements in lower gears, where the flywheel is a significant fraction of the total load on the engine. The advantage drops off in higher gears, since the load of the mass of the car swamps the effect of the flywheel.

One thing to bare in mind; a badly modified cast flywheel is basically a fragmentation grenade. The damage they can do if they explode at high RPM is frightening, the parts will slice through bellhousings and thin steel body panels like butter. A billet steel item should always be used if you want to save a significant amount of weight.
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this sounds exactly like the conclusions i came to before fitting a lightened one to my car.

on the road, expect it to change the response of the engine. it will respond more immediately to your throttle inputs. one thing i noticed was before hand the engine wasnt "urgent" until about 4krpm, with the new flywheel this point was brought down to about 2.5kprm, making fast starts easier (because you needed less revs) and when driving at low revs, the engine had more response sooner in the rev range. (i put this down to having less inertia to overcome)

the flywheel and a flowed throttlebody reduced my PB 0-60 time from 7.0 to 6.6s.

only downside is that when taking off from a standstill in traffic etc you need fractionally more throttle. trying to get out of lydden hill car park was a bit of a pain as the clutch effectively felt slightly more on/off
 
Phate said:
It will eventually be a track only toy. I'm even contemplating doing the group B racing next year. Hence me thinking of doing it now save pulling it all apart again in the future.

I think I'm gonna go for it :)
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In which case you have significantly bigger issues than the microscopic improvement a lighter flywheel would give you.

Spend money on improving suspension with decent quality equipment, better brakes, and removing seats and other interior parts.

Better than that, spend every penny you can on tuition. It will make a significant difference, moreso than any mod you can afford.

I'll also echo how dangerous trying to lighten it yourself is. Don't people here remember the guy who lightened his nova flywheel himself and it come in through the dash .....
 
I swapped to an ACT 5.4kg flywheel on my old b16a and I would say it wasn't worth it. The ACT hdss clutch on the other hand, was awesome....
 
Conanius said:
In which case you have significantly bigger issues than the microscopic improvement a lighter flywheel would give you.

Spend money on improving suspension with decent quality equipment, better brakes, and removing seats and other interior parts.
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Fully aware of that, a lightened flywheel is just all part of the package.

Only other performance mods really will be a remap so I'll be at the 200bhp mark and maybe NOS to take me to 240, 250 but I doubt that for the time being.

Next in the list of mods are coilovers, polybushing, 4pot brake system, lightweight wheels with some R888's to. :)

I'll also echo how dangerous trying to lighten it yourself is. Don't people here remember the guy who lightened his nova flywheel himself and it come in through the dash .....
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Hence why I won't lighten it myself, just not worth the risk.
 
If you've the gearbox is getting dropped and you understand the pros and cons of it, no brainer really.

The facelift EP3 CTR has a lighter flywheel as standard and most prefacelift owners fit one when changing their clutch etc.
 
Phate said:
I'm even contemplating doing the group B racing next year.
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I like to think I know a little about club level racing but I've no idea what you mean by this. The only "Group B" I know of was the 80s nutter turbo monster class which doesn't exist any more.

On top of this I'm not sure I can think of any form of circuit racing which allows NOS. Please expand further.
 
kaiowas said:
I like to think I know a little about club level racing but I've no idea what you mean by this. The only "Group B" I know of was the 80s nutter turbo monster class which doesn't exist any more.
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I'll find the exact details for you :)

On top of this I'm not sure I can think of any form of circuit racing which allows NOS. Please expand further.
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NOS is just an idea/fantasy, I have no idea if its allowed or not, if its not then obviously it won't be fitted :)
 
no effect on idle here either. doing manoeuvres like parallel parking on a steep hill were pretty tricky, but having a fairly stiff clutch probably contributed toward that the most.
 
205!!! jeez....

I paid 400usd for my clutch AND streetlite flywheel

For 205 I don't think I would bother tbh. Money is better spent elsewhere. Just have the stock one resurfaced should it need it.
 
gurusan said:
because it does not make a world of difference....
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Based on What?

My Old Rover Turbo went from a 11.5kg ish flywheel toa 8kg (modified standard one).

On a rolling road the operator asked me if it had a lighter flywheel as it seemed to rev up a lot faster than the other cars there.
 
it revs up a bit faster and engine braking is improved slightly, but if you are paying 205 quid for one it's not worth it IMO.

I had a 5.4kg one in my civic and it helped a "tad".....I did not pay anywhere near what the OP is going to be paying though, so I didn't really care too much.


**edit** although if his original flywheel is 17kg....that is quite heavy actually.

but still, 205 is a LOT to pay IMO.
 
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