Just reading an article on flywheels by Jake Venter in SA's Car Magazine.

He says "an old (approximate) rule of thumb says that 0.15 kg taken from the pistons will have the same effect as taking 1,5 kg from the flywheel or 150kg from the total mass of the car" when it comes to the effect on acceleration.

So for those of you with CEC's who want to compete with the BEC brigade - here's part of the answer - just please get it done professionally and bare in mind the impact on torsional vibration - see this http://www.indiacar.com/infobank/torsional_vibration.htm

I've known this for years - my V6 runs ally pullies at the front , and 7lb ally flywheel (stock cast iron one is 28lb )
All in I've taken something like 35lb's of rotating mass off my engine
Anything in the engine that rotates or goes up and down takes power to make it do so.........

[Edited on 24/5/09 by clairetoo]

[Edited on 24/5/09 by clairetoo]

On a similar note, a lightened prop, driveshafts, brakes, wheels or tyres will also make a good improvement.

Remember though, that flywheels not only take energy, they give it back.
This smooths power delivery on the road in normal driving.
We can all build out and out racing engines, but living with them is another issue.

Just got my car back on the road today after having new cams and a lightweight flywheel fitted. (4AGE 20v ST).

It certainly rev's much, much faster and intial impressions are very good.

I've noticed that while acceleration is excellent the engine braking also seems to have increased as well - i.e. it slows faster when you lift off - is this to be expected?

I have to get it setup correctly on a rolling road. It hunts like crazy on a very rough idle - due I assume to the Flywheel and Cams.

I'll post some before and after figures although the Flywheel won't add any BHP I hope the Cams, Polish and Port will help

Anyone wan't a used 212mm 4AGE 20v Flywheel or Cams?

Revs will drop off quicker as there is no stored inertia in the flywheel

This discussion is a good reminder of the need to build the car (of whatever type) to suit the condions in which it is to be used.

Track and competition is entirely different to road use

John

When I built the Libra a mate of mine took as much off the flywheel as he could and the thing drives fine, but the overall weight of the car is well down on the original.

Interestingly, my son is (very slowly) building a Velocity which he is intentionally building with a little 1100 X-Flow. I was chatting to my mate about the car and he was adamant that inspite of it's lowly power it was always worth lightening flywheels in lightweight cars...

I got my car re-built because I want to do many more trackdays.

It's road use is always limited due to the stripped out nature of the car.

It doesn't get used on the road that much hence the reason I was prepared to sacrifice some driveability for out-right performance.

Not everyones cup-of-tea but it suits me.

Also remember that this effect is gear dependent. The apparent weight loss (or power gain) is only anything like the figure quoted above in first gear. It diminishes significantly as you go up the cogs. So you might feel an extra 20-30bhp off the line in first, but not really much at all at driving/racing speeds, and 0 increase in ultimate top speed.

Well worth doing, but wont turn your pinto into a busa

Liam