Aluminum or steel flywheel

[greg schroeder]

Here is some Gs data for acceleration runs, black with heavy steel flywheel, red with light weight McLeod aluminum and SPEC Stage 3 clutch. Either of them shift like butter around town, but I think that has more to do with taking 500 miles of easy driving when the Tremec TKO 600 is new.

Note the black steel spikes at shifts because the inertia of the heavier flywheel, but it then drops way back to provide the opposite reaction. The red recovers to a more useful curve and doesn't have as much of an inertia spike to as easily break tires loose in subsequent gears at shift. At start also note these are about from idle. The steel starts spinning all smooth while you can see the aluminum jitters a bit as it's recovering in the road inconsistencies upon rolling on the throttle. Also note the red produces a notably better start.

The aluminum is better in a Cobra in my opinion given the car is light. There shouldn't be a bogging issue with 500 ft lbs of torque if your carb is set up right. Keith Craft will probably bolt on a Pro-Systems carb, so you probably have that covered. I guess if the plan was to build a car to spin tires and make the car heavier the steel might be nice.

[DanEC]

Well, that's a graphic presentation you don't see every day. So, an aluminum flywheel and clutch change was roughly worth a half second and 5 mph in the quarter? That's something else.

[greg schroeder]

Originally Posted by DanEC

Well, that's a graphic presentation you don't see every day. So, an aluminum flywheel and clutch change was roughly worth a half second and 5 mph in the quarter? That's something else.

Sorry, I should have given more information. The red line is also about 45 more HP at the wheels. This generally would make things a bit more exagerated, but even with another 45 HP at the wheels it is more in control than a steel flywheel with less power to use.

[DAVID GAGNARD]

Isn't a steel flywheel about $250 and an aluminum flywheel about $500? Assuming that's about right, isn't worth getting an aluminum flywheel for additional $250? Makes sense to me in a Cobra.

Nothing about stuffing a 600+hp engine in a 90" wheelbase car weighing sometimes as little as 2400 lbs. with no top or side impact bars, no airbags and very little driver protection to start with makes much sense to me........

but that's part of the thrill of having a having a car like that!!!!!!!!

In the grand scheme of things when spending big bucks for a car like a Cobra, a couple of hundred extra dollars is nothing......

it all boils down to whats best for the engine combo and the way the car will be used...

David

[RodKnock]

Originally Posted by DAVID GAGNARD

Nothing about stuffing a 600+hp engine in a 90" wheelbase car weighing sometimes as little as 2400 lbs. with no top or side impact bars, no airbags and very little driver protection to start with makes much sense to me........

but that's part of the thrill of having a having a car like that!!!!!!!!

In the grand scheme of things when spending big bucks for a car like a Cobra, a couple of hundred extra dollars is nothing......

it all boils down to whats best for the engine combo and the way the car will be used...

David

The Kirkhams have been putting their car on a diet for a long while. With the aluminum rear end, Quicktime bellhousing, aluminum flywheel, and an all-aluminum FE, their cars are under 2,150 lbs.

I talked with several FE engine builders before I picked one, but not one of recommended a steel flywheel.

[DanEC]

There doesn't seem to be a clear consensus here. The light car - light flywheel rationale makes simple sense. I guess I will go with the aluminum flywheel as recommended by the builder.

Thanks for the responses.

[DougD]

Originally Posted by DanEC

There doesn't seem to be a clear consensus here. The light car - light flywheel rationale makes simple sense. I guess I will go with the aluminum flywheel as recommended by the builder.

Thanks for the responses.

I've always used the formula one pound of flywheel for every 100 pounds of car. So a 2400lb Cobra would dictate a 24lb flywheel. Once again, it's the weight, not the material it's made from.