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Lightweight Zetec flywheels
zetec7 - 30/7/06 at 05:02 AM

Anyone tried one out yet? I'm pretty sure I'm going to use one (my engine's from an automatic, so I don't have a flywheel at all yet). I'm wondering if anyone here has used one, which one they got, how they liked it, what the performance effect was like, etc...

Anyone??

zetec - 30/7/06 at 06:17 AM

I got one from Dummels. Loads of weight saved but not sure of the difference it makes as I didnt have the engine fitted with a standard item.

rocket - 6/8/06 at 07:50 AM

I'm using a cvh flywheel and clutch which is much lighter than the zetec.

I may be wrong but I once read somewhere that for even 1 lb you take off the flywheel the engine thinks you have taken 10kg off the car.

It might have been in the rv8 tuning book I have somewhere!

Flywheels are used for helping your car up hills and cruising in top gear.

As we are all building much lighter cars this shouldn't affect things on that part.

Oh yes it may make your idle a bit "lumpier" too

It will let your engine rev up quicker and also ( I believe) alter the handling to some extent also but thats one of my own theories.

Rgds

Roger

[Edited on 6/8/06 by rocket]

v8james - 10/8/06 at 08:07 PM

As far as I am aware, a lightened flywheel makes no difference to the speed as which the car accelerates as the mass of the car far outweighs a few lbs shaved off the flywheel. The advantage of having a lightened flywheel is farter gear changes and the engine the engine slows down or speeds up quicker and therefore you are able to engage the next gear quicker.

DIY Si - 10/8/06 at 09:24 PM

It doesn't affect total weight much as aid, but it does ecrese the mass the engine has to accelerate by a fair bit, as the flywheel isn't geared. Not sure if this makes sense, but I know what I'm trying to say. Ie 1lb off the car and due to the total gearing the engine may only 'see' a 1/10lb difference. Where as 1lb off the flywheel is 1lb to the engine. The difference changes as you go up the gears, with the advantage getter smaller as you appoach as top.

MikeRJ - 10/8/06 at 09:43 PM

quote:
Originally posted by v8james
As far as I am aware, a lightened flywheel makes no difference to the speed as which the car accelerates as the mass of the car far outweighs a few lbs shaved off the flywheel.


It makes a big difference in lower gears, in higher gears the advantage lessens. It's pretty obvious that the car will accelerate better, a heavy flywheel stores a significant amount of energy which the engine has to put in to accelerate it. With a lighter flywheel you actualy get more power at the wheels under acceleration, this is even measureable if you put the car on an inertia type dyno (but not a brake dyno which takes steady state power readings).

Think of it this way: The whole car is an energy storage device in exactly the same way as a flywheel, energy = 0.5*m*v^2. Due to the v squared term, the amount of energy that can be put into the car is much lower in lower gears, whereas the amount of energy that has to be put into the flywheel to take it to a given RPM is constant. Hence in lower gears, a lighter flywheel makes a bigger difference. In higher gears the overall mass of the car swamps the amount of energy taken by the flywheel so it has less effect.

02GF74 - 11/8/06 at 09:39 AM

this is schoolboy mechanics

what has not been mentioned is whre you take the weight off; this depends on how hard it is to spin up to speed.

think of a bicycle wheel. it iwll be harder to get up to speed if you put a 1 lb mass on the rim that if the same wieght was put on the spindle.

... bt getting back to the question, lighter flywheel will mean engine can spin up faster so acceleration times will go down; top speed remains the same.

TangoMan - 11/8/06 at 06:43 PM

quote:
Originally posted by MikeRJ
quote:
Lots of good advice!!


Mike is spot on with his explanation. The only thing worth adding is if lightening a cast flywheel do it sensibly and don't go too thin. The best gains are to be had by removing weight from the outer edges of the flywheel due to the leverage effect.
I see steel flywheels on eBay for £130.00. I will probably use one of these when I swap to a Zetec.

[Edited on 11/8/06 by TangoMan]