Lightened Flywheels, some sums on how they work/effectiveness

[Royston]

Thought this may be of interest to some of you, regarding the effect of lightened flywheels.

Thought it may be of interest, especially the sceptics;)

http://www.v8forum.co.uk/forum/viewtopic.php?t=9828&postdays=0&postorder=asc&start=0

It is from the V8 forum, of which I am also a member

[novarally]

Thanks Royston, some interesting info there, although I've only skimmed it as it's pretty in depth.

Wish I'd paid more attention in Maths lessons now.....

[Royston]

Wish I'd paid more attention in Maths lessons now.....

Me toolol

[Stuart]

Nice, followed most of it.

So in short (as most of us knew anyway) if you are going to whip weight off the flywheel, try to have it taken off the outer edge :)

[mowgli]

stu, we agree on something.. now i just need to find out who actually weighs their clutches & crank pulleys, & factors them into the flywheel weight.

[Stuart]

but if you assume you arent changing the weight of the clutch/pulleys then dropping flywheel weight will still improve transient speeds.

[mowgli]

it should, but skimming 2kg off a 9kg flywheel sounds a lot, but skimming 2kg off a 25kg flywheel & clutch isn't quite so good.

[autoworksnovasport]

but any weight taken from the flywheel will help its only for throttle response really (sorry if this has been said havent read entire thread)

[mowgli]

its all about how far out from the crank centreline the weight is too

[Royston]

its all about how far out from the crank centreline the weight is too

The sums are there Mowgli;)

[mowgli]

i'm going to dig out my old textbooks & get my head round it, cos i can't get my head round how the assumption made that its the same as taking 1000lbs off the weight of the car in 1st...with the gearing in that car, it would be up to about 40mph in 1st & making out that sort of gain in a car that weighs just over a ton sounds too good to be true.

[scott.parker]

I'm not going to say i fully understand all his maths, but i found it very interesting about how its described and his findings with the different methods of weight removal from the fly, and has now made me think it's a very very good idea for the track car, as that alone could easily sort out my acceleration for 1/4 miles plus give better drive on track etc.

[mowgli]

the best way is to lighten the bits that stick out furthest. thus the ring gear can be a problem.

[Stuart]

Hence why you just get a light weight properly designed steel fly made :)

[simonm]

I've had lightened fly wheels on a few things now over the years and makes a big difference on acceleration it's been on here before with some agree and some don't but I still firmly believe it helps an engine speed up and slow down and any maths and formulas to help do it right is a big help

[Jon_nova1]

but any weight taken from the flywheel will help its only for throttle response really (sorry if this has been said havent read entire thread)

Surely any performance mod is for throttle response? To be honest I think I've had the best experience for and explanation, yes we all know it releases BHP, when I put my 1.7td onto an F28 I had to use the F28 flywheel which is 4KG lighter than the derv one, the power is amazing, the thing either wheelspins or torque steers till you get to 4th, the only downfall is when the derv pump makes the torque drop off you notice it instantly, there's never hitting the limiter even thought I have no rev counter and the poor thing tops out at 100 even though it takes next to no time to get there

[mowgli]

i am guessing that your speedo is way out cos my std astra i used to have did way more than 100..... and the f28 is hardly a low geared box....

i'd guess you need to get your suspension geometry looked at too

[MK999]

Surely any performance mod is for throttle response?

A big american V8, even tuned quite well, will have the throttle response of a 1.2i, but you had better believe the performance is a touch different. You could make an engine that had crap throttle response and plenty of torque, or vice versa.

[Stuart]

Surely any performance mod is for throttle response? To be honest I think I've had the best experience for and explanation, yes we all know it releases BHP, when I put my 1.7td onto an F28 I had to use the F28 flywheel which is 4KG lighter than the derv one, the power is amazing, the thing either wheelspins or torque steers till you get to 4th, the only downfall is when the derv pump makes the torque drop off you notice it instantly, there's never hitting the limiter even thought I have no rev counter and the poor thing tops out at 100 even though it takes next to no time to get there


lol, you've not unlocked magic power there!

[Jon_nova1]

i am guessing that your speedo is way out cos my std astra i used to have did way more than 100..... and the f28 is hardly a low geared box....

i'd guess you need to get your suspension geometry looked at too

I know the standard speed, but as soon as the torque starts dropping off its incredibly noticable, its like hitting a rev limitor, it wil do 30MPH in 6th and it was done using satnav as i have standard nova dials so the speedo was out anyway, it was tracked the other week as it was well out, the only thing that could be suspect is turbo stall due to the exhaust, but we'll find out over the next couple of days

and no its not magic power, it was a hell of a surprise to us when it was finished and we took it for a drive though lol

[mowgli]

all diesels drop off, our 480 scania runs all day at about 1400 revs and is designed to do it, the 1.7td will run out of steam at maybe 4500 revs. and a 6 speed box will not be ideal tbh

[andy_mk3]

i'm going to dig out my old textbooks & get my head round it, cos i can't get my head round how the assumption made that its the same as taking 1000lbs off the weight of the car in 1st...with the gearing in that car, it would be up to about 40mph in 1st & making out that sort of gain in a car that weighs just over a ton sounds too good to be true.

I thought that also, that's a massive amount of weight!

[MK999]

It's an equivalent inertia, so it's not like dropping 1000lbs off the car, it's like dropping 1000lbs off the combined inertia of the entire engine and drivetrain assembly including wheels etc, and the weight of the car.... that kinda drops the percentage increase down a tad.