Flywheel weight?

[xb-60]

What weight flywheel should I use?

My car’s total weight should easily be under 1100kg (2400lb)
Gearbox is a Toploader (WR)
Differential ratio is 2.92:1 (my choice)
Engine is a Tickford 302W with 220kW / 300bhp and 435Nm / 320 ft lb
My question…. What weight flywheel should I be using?
A friend who knows his stuff is suggesting a standard weight (28lb) flywheel.
My engine man is suggesting a light weight flywheel, reason being that with the car’s light weight, I'll benefit from a lighter flywheel.
He says that with a light flywheel, the engine will rev “like a Japanese engine”.

Bearing in mind my choice of a high diff. ratio, should I go standard weight flywheel, or light weight? 22lb and 14lb are available.

Cheers!
Glen

[Snake2998]

With your diff ratio I would stay standard weight especially for road use with lots of stop starts where the lighter the flywheel the more clutch slip you will need to get moving. Light weight flywheels are only of real benefit for serious track racing

To quote Google:
Cons of Lightweight Flywheels

Reduced Off-the-Line Performance. If you want to maximize performance from a standing start, a lightweight flywheel might not move you in the right direction. ...
Rough Engine Feel. With a lightweight flywheel, the engine will feel rougher while running. ...
Gear Rattle.

[Snake2998]

Read this for more info:
Light flywheels: pros and cons – Infinite-Garage

[1795]

Glen,

The article that Snake2998 provided is pretty much straight to the point. With my lightweight flywheel I have to make sure that I rev match when downshifting. With my street cobra when I had it with a heavier flywheel you did not have to. If you have a 22 lb option, that might be a nice in-between option. A little lighter than the standard, so the engine will rev a little quicker, but not so light weight that the car behaves like a race car.

looking forward to seeing what you decide on.

Cheers,

Jim

[t walgamuth]

My VSE weighs right at 2000#. It has an aluminum block 5.7 chevy taken out to 427 CI. I am running the 19# flywheel from a 67 Nova. Yeah, it feels a bit lumpy but isn''t that what these cars are supposed to be....race car like?

[Dwight]

a 302 will rev very quick with a standard flywheel.

I think you will need the weight of the flywheel to move you smoothly down the road.

I vote standard flywheel

[t walgamuth]

...in a tractor!

[patrickt]

Aluminum flywheel, please. If you do a search, you will find a quote from one of the Kirkham brothers saying you'd be nuts to put anything in a Cobra other than an aluminum flywheel.

[Alfa02]

Ok Glen, My $.03 Race car: yes Alum. Flywheel, as Jim said we're at high rpm's, quick shifts, etc. Not having to worry about coming off the line (Stop light) Std. flywheel: you're not gaining anything. Lightened: quicker revs, less internal mass, no slipping of the clutch coming off the line. I went from stock (28lbs) to a lightened (22bs) in the V-8 RX-7, made a HUGH difference without any drivable issues. You know I hate to disagree with patrickt, but sometimes you take your chances Cheers TommyRot.

[Gaz64]

Glen,

I would say aluminium if you went for a 5 speed and lower diff gears.

So a 22lb would be still a nice compromise for street, and occasional track.

Depends on the engine internals, and the whole car in combination.

Gary

[Dominik]

If your approach is merely to save total (curb) weight, you may find that your car comes easily under 2.200 lbs (1.000 kg). I had a, to you guys unknown make (LDS), 427 with cast iron 302. It did weigh 1.015 kg. With a single seater racing screen, T5 box and ally differential.

My RAM (from UK) with an all-ally 496 Chevy and Jag suspension & brakes was 2.015 lbs (917 kg)

If you like to reduce rotational weight, which performance-wise counts for much more than total weight, perhaps also consider lighter wheels and tires. I had Hoosiers on the RAM.

Drive a 302 with an aluminium flywheel. I haven't yet.
Get a shatter-proof bellhousing - (which does weigh extra).

I am dying to weigh my latest 427 with leightweight body but cast iron heads on a 427 FE.
Just for reference.

[xb-60]

I'm thinking that the safe option for my application (it's not a race car) is probably a standard weight (28lb) flywheel.
A possible alternative is the 22lb version.

A 14lb steel flywheel or an even lighter version in aluminium sounds like it would be too much of a compromise for my application... even if the Kirkhams would say I'm nuts.

The light weight flywheels would allow quicker 'blipping' of the engine, but I can't see how - apart from a tiny percentage of weight saving relative to the weight of the car - this would result in significantly quicker on-the-road performance.

I'm not too old to learn, so tell me if my logic is wrong

Cheers!
Glen

[t walgamuth]

Heavy flywheels are for smoothness, like in a Cadillac or truck. Light flywheels will allow quicker acceleration and deceleration. Take your pick. I'll always go for the lightest flywheel I can find in a car planned for high performance.

[patrickt]

An engine with an aluminum flywheel slows down faster as well. In a Cobra, I think that makes it safer. I can't think of any reason to put a heavier flywheel in a Cobra unless all you do is march in a parade line. Now, blipping the throttle when the car is not in gear is fun, especially with a big ol' FE (which you don't have). The engine does not go vroom-vroom, it just goes boom. You can't even tell that it's speeding up, it just sounds like it explodes. 800RPM to 3000RPM instantly, without ever going through 1000, 2000, or 2500. It's the magic of aluminum.

[MAStuart]

High compression, lots of rear gear , very light flywheel, damp road. You better learn to get smooth on letting up on the loud peddle. If you dont you will be sliding the rear tire without getting o the biners.

They are good for drag strip starts on traction limited cars.

[Dirty Harry]

If you are a driver who downshifts to slow down, it seems that you would get less slowing by downshifting in a car with a light flywheel.

[patrickt]

Originally Posted by Dirty Harry

If you are a driver who downshifts to slow down, it seems that you would get less slowing by downshifting in a car with a light flywheel.

That is true. But down shifting to slow down in a big block Cobra is asking to be towed home.

[6TNCRZY]

Heavy flywheels for higher geared cars, heaver cars, street only cars and cars with bigger cams. Lighter flywheel for quicker response and dual purpose cars. Everything being equal, engine with lower torque like a 302, heaver flywheel. big torque engine, lighter flywheel.

[eschaider]

Most of us regularly drive our cars at 6,000 to 8,000 rpm each time we take them out for a spin. When you combine that with normally shifting at or above 7,500 rpm it is immediately apparent why a light flywheel makes so much sense for our 7,500 rpm daily driving excursions.

I mean if we were just driving around town in third gear or so plodding along with city traffic below 2000 rpm — well obviously there would be no need for the heavier clutch and flywheel assembly. All that would do is make the car more attractive to drive in town and traffic which of course none of us would ever do.

I say dump all those depleted uranium flywheels and lets all move on to a better suited aluminum beryllium alternative, profusely drilled (of course) to eliminate all possible weight.


Ed

[1985 CCX]

Mine is an alloy unit on the gold car.
Revs fast!
Does limit burnouts however it still breaks the rear loose once Webers open.