Lightweight Crank Pulley?

[uktotty]

Is that the same as a lightweight flywheel?

[SimonC_Here]

No?

One is a pulley and one is a flywheel?



Simon

[aaronjb]

Flywheel goes on one end. Pulley goes on the other.

One drives the clutch & gearbox, the other drives the accessories belt (water pump, alternator, aircon).

[markiii]

and on some cars the cams are nelt driven too, though in our case thats chain driven

there are 2 schools of thought regarding these as some say that you can kill your engine due to taking the crank out of balance

I've just added one to teh VXR and just saving 1Kg the difference was huge, was it wise? only time will tell

[uktotty]

Cheers Aaron and Mark, I still have so much to learn but reading about all this lightening thats been going on, it looked interesting.
I guess at 16stone there are a few more things I could lighten!

[markiii]

bear in mind it's rotational mass your saving on flywheels and pulleys which has a more profound effect than just losing weight persee

[aaronjb]

I've just added one to the VXR and just saving 1Kg the difference was huge, was it wise? only time will tell

Is that all?  s;) s;)

On the 300ZX the stock pulley weighed 11lb, the replacement weighed 2lb..

[cclarke99]

Very roughly, in 1st gear, a pound off the flywheel reasonably near the edge is worth about 10-15lb off the weight of the car. In higher gears the effect is less (ony 3-5lb in 4th). Lightening either end should move any resonant frequencies higher, which should be a good thing. But messing around with two part pulleys or flywheels might affect the damping effect they provide, with potentially disasterous effects. I'm surprised that taking 1lb off a small item like the pulley had any noticable effect

[markiii]

so was I

[Jaik]

I think I have a spreadsheet somewhere that will, given a flywheel/pulley diameter, gear ratios and weight difference, give you a rough estimate of the equivalent static weight loss. I'll see if I can dig it out at some point.

I fitted a lightweight flywheel to my last car that was around 3kg rather than the standard 9kg; the difference in first and second gear was totally mindblowing.

[aaronjb]

But messing around with two part pulleys or flywheels might affect the damping effect they provide, with potentially disasterous effects.

Now there's a debate that's been going for longer than I've been alive, I reckon  s;) s;)

[tom_deas]

I fitted a lightweight flywheel to my last car that was around 3kg rather than the standard 9kg; the difference in first and second gear was totally mindblowing.

even though obv massively improved acceleration didnt loosing that huge an amount of inertial potential energy in the flywheel kill everyday driveability? going from 9kg to 6kg is one thing, but 9kg to a third that weight... or were there no real problems? what car was it, out of interest?

[Jaik]

I fitted a lightweight flywheel to my last car that was around 3kg rather than the standard 9kg; the difference in first and second gear was totally mindblowing.

even though obv massively improved acceleration didnt loosing that huge an amount of inertial potential energy in the flywheel kill everyday driveability? going from 9kg to 6kg is one thing, but 9kg to a third that weight... or were there no real problems? what car was it, out of interest?

It was a Suzuki Cappuccino (~725kg, ~70hp from a 660cc 3-pot turbo, RWD) so fairly hard to compare to a lot of cars due to the unusual engine etc. It did lose a little driveability, but it was far from being a pain. I stalled it a bit right after the flywheel was fitted whilst I got used to it, but I do that with any car when I'm new to it. After that I stalled it once in a blue moon when I was being a bit lazy in traffic. There were no other downsides for me.

As I mentioned, acceleration in first and second (and less so in the higher gears) was hugely, hugely improved. I can't stress enough how much difference it made in the low gears. Also, with the Capp's short gear shift (about the same as a TRD short-shiftered MR2, if not less), downshifts could be rev-matched smoothly in a fraction of the time you could do them before.

It was by far the best mod I did to the car.

[tom_deas]

fair enough  s:) s:)

for some reason i sense a GB on lightened flywheels coming on  s;) s;)

[DannyN]

and a pulley?

[Anonymous]

Has anyone experience of what flywheel is the best value for money  s:? :? s:?

[DannyN]

I think Markiii liked the RPS one

[markiii]

RPS is very very nice

[Anonymous]

It was a Suzuki Cappuccino (~725kg, ~70hp from a 660cc 3-pot turbo, RWD) so fairly hard to compare to a lot of cars due to the unusual engine etc. It did lose a little driveability, but it was far from being a pain. I stalled it a bit right after the flywheel was fitted whilst I got used to it, but I do that with any car when I'm new to it. After that I stalled it once in a blue moon when I was being a bit lazy in traffic. There were no other downsides for me.

As I mentioned, acceleration in first and second (and less so in the higher gears) was hugely, hugely improved. I can't stress enough how much difference it made in the low gears. Also, with the Capp's short gear shift (about the same as a TRD short-shiftered MR2, if not less), downshifts could be rev-matched smoothly in a fraction of the time you could do them before.

It was by far the best mod I did to the car.

I don't think you can call a 3 cylinder engine unusual - it's got to be one of the best balanced engines around - its the 4 /6 cylinder engines which are the pain as they are un-balanced and therefore have to use large counterweights on the crank.

Again not convinced it's a good idea to mess with the rotating mass of the crank, either flywheel or pulley end - especially if it alters the driveability to the extent of causing a stall - I don't drive the car enough to get use to it  s:oops: :oops: s:oops:  

Rob

[Jaik]

I don't think you can call a 3 cylinder engine unusual - it's got to be one of the best balanced engines around - its the 4 /6 cylinder engines which are the pain as they are un-balanced and therefore have to use large counterweights on the crank.

Again not convinced it's a good idea to mess with the rotating mass of the crank, either flywheel or pulley end - especially if it alters the driveability to the extent of causing a stall - I don't drive the car enough to get use to it  s:oops: :oops: s:oops:  

Rob

By unusual I meant more in terms of power delivery. It's your stereotypical early '90s turbo engine power curve with all the power high up, which in such a small, torque-free engine means it's somewhat easier to stall anyway.

I thought 3-pots needed a counterbalance shaft and 6-pots were naturally the smoothest, most balanced engines?

[tom_deas]

3 pot wont be totally naturally balanced without some kind of aid no

5 pot is ideal ish

well, i wonder if anybodies considered making a straight 7 engine... hmm...

and a pulley?

now theres an anorack for you. GB on pulleys. "check out the efficiency with which my ancillary belt drives my alternator. i thought shaving a few hundred grammes on the pulley would drive throughput 400% quadrametrically, introducing a whole new paradigm of energy saving measures. its taken my 1ZZ from 140bhp to a speculative 400bhp"

  s:wink: :wink: s:wink:

[Anonymous]

By unusual I meant more in terms of power delivery. It's your stereotypical early '90s turbo engine power curve with all the power high up, which in such a small, torque-free engine means it's somewhat easier to stall anyway.

I thought 3-pots needed a counterbalance shaft and 6-pots were naturally the smoothest, most balanced engines?

I used to run a Charade Turbo - great fun little car, I was looking at the GTTI which was one of the best 3 cylinder engines you could get, power was pretty low down on these cars and they were used a lot for rallying.

Rob.

[tom_deas]

one of the best 3 cylinder engines you could get, power was pretty low down on these cars and they were used a lot for rallying.

dont forget the Smart cars  s;) s;)

[Anonymous]

one of the best 3 cylinder engines you could get, power was pretty low down on these cars and they were used a lot for rallying.

dont forget the Smart cars  s;) s;)

I will   s:D s:D    s:wink: :wink: s:wink:

[tom_deas]

i wonder if smart would ever make a rally car...

by rally for a smart car i of course mean a bit of wet tarmac  s;) s;)

maybe we could hook it up with some lightweight pulleys to help it break the sound barrier