Aluminum or steel flywheel

[DanEC]

I'm having a 460 CI FE built for my ERA with 428 block and steel heads. It will be a torquer and not a radical motor. The builder is suggesting an aluminum flywheel - but mostly because that is what everyone wants. This car is a street roadster recreation and will be strictly street driven by me. I'm questioning if I really need and aluminum flywheel for this and wouldn't be better off with a steel flywheel. What are most people using with a mild to medium build big block motor?

Thanks

Dan

[blykins]

I have some lighter steel flywheels that would work just fine. I don't see the reason for an aluminum flywheel in a car that's purely made for the street. You have to pay quite a bit extra basically just for bragging rights on a street car.

You will notice that the engine may be a little zippier and you'll notice that you may have to feather the clutch a little more on take off from a dead stop.

[bobcowan]

Originally Posted by blykins

I don't see the reason for an aluminum flywheel in a car that's purely made for the street. You have to pay quite a bit extra basically just for bragging rights on a street car.

I would have to agree with that. There are some performance differances between the two parts. But unless you're racing, I think the differances would more theory than actual.

I'd use which ever one is cheaper.

[Ralphy]

I see a large price difference in aluminum flywheels. Fidanza seems the lowest, what are some quality issues?

Ralphy

[RICK LAKE]

DanEC Dan the only thing I have found is that the Aluminum flywheel motor rev's up a little quicker than Steel It's about Mass weight and all that science stuff. Here's the thing I found out, I ran a 452 motor for 8 years before going to the 482 stroker kit. The motor was all torque with a 501-533" camshaft. Off idle I could blow the tires away without much rpm. I also had a 6,000 chip in the MSD box. By switching to a lighter flywheel from 40# to 22# the car didn't blow up the tires as easy. Less stored energy in the lighter flywheel. I am still running the same flywheel and clutch assembly for the 482 motor and having the same problem again with traction off idle. Way too much torque. I can fix this by advancing camshaft timing to remove some bottom end torque.
Dan the other question is what gears ratio in the rearend are you looking at and what trans are you looking to run?? How big is the camshaft, this is real important to street manners of the car? This will also effect the way the car runs and drivability. The other thing is with all my motors I have gotten the WHOLE rotating assembly balanced. I know 99% of the flywheels come with a 0 balance. I like the whole thing done with flywheel,dampener,pulleys, crank trigger ring, spacer, and complete rotating assembly at 1 time. Some people don't believe in this being not needed, I think it helps in the long run, IMO.
Bottom line the old story is light car light clutch assembly and flywheel, heavy car heavy parts. I use ONLY SFI parts in my cobra if possible, this includes the bellhousing, Lakewood. The flywheel, the pressure plate and clutch assembly itself. I am not saying that these parts don't break any quicker than OEM stuff, just believe they are built a little better. Rick L.

[blykins]

Ralphy,

The Fidanza wheel is the one I would use if a customer requested an aluminum wheel. I've used them personally and have sold them to customers. They're good quality pieces. The good thing about them for an FE is that they come with multiple pressure plate patterns, 11" Long, 11.5"/12" Long/Diaphragm, etc. They are also the lightest by about 3-4" lbs if I remember correctly, compared to McLeod, RAM, and Centerforce.

[vryfst2]

I recommend the steel flywheel as I have used both in my race cars and street machines. Since the Cobra is so light, once you get that steel flywheel rotating and let the clutch go, you can melt the tires. Sure the aluminum will get you the rpm's a little quicker, but not that much. In my Cobra I have the 30# flywheel and it works great. Highly recommend and it will be a lot less maintenance and trouble.

[greg schroeder]

In my opinion and theory the aluminum is nice for 1st and 2nd gear as it carries less inertia on hard acceleration. In that it will adjust slightly better to road inconsistencies keeping better traction. Also I suspect the idea that the aluminum is a bit easier on the transmission because it has less inertia on shifts. Also there might be some value to forgive bad shifts a little quicker rather than having the mass of a really heavy flywheel carry the crunch and grind longer. The clutch will last longer with a lighter flywheel particularly if you’re in marginal HP values to the clutch ability.

Something heavier is an inertia push when you shift quickly to the next gear. If you have the traction to hook a 2nd, 3rd or 4th gear shift the heavy will give you a bit of go for an instant before it corrects to the next gear. The problem is you'll be hitting that gear and spin most of the time if you're on general road tires. The condition is exaggerated with a heavier flywheel, not fun. In that case the aluminum being lighter will hook the next gear faster as the RPM will correct lower to the next gear with less inertia.

I went from a heavy steel flywheel and replaced it with light weight aluminum. It’s more fun. There are no issues with street drivability.

[Chilibit]

Most of these comments have to do with the acceleration phase. I believe that less motor inertia will affect the downshift behavior and deceleration in general. I seem to have a natural rhythm on shifting which is not very aggressive. The decay time on the rpm's is important to my rhythm. I am not arguing that it is better, just that some setups suit me better. More of a satisfaction thing than a performance thing. A smooth oneness with the car is more important to me than the last ounce of performance.

[DanEC]

Great input thanks. A 30 lb steel flywheel might be a great compromise to suggest to the builder.

Keith Craft is putting together the motor and I am planning to have him get the clutch and flywheel and balance with the motor. He's use to people asking for aluminum flywheels, but then he builds some mega-HP motors for a lot of them.

Mine will have a 4.25 inch stroke, somewhere between 9 - 9.5 compression and he was thinking a 222 to 232 duration cam when we talked. I'm using a 3.31 rear and WR toploader. This is a street replica build and not a sunday race car so I'm interested in a smooth off-idle, first gear starts and reasonable driveability.

I know, I know - no overdrive 5 speed. I'm old school. I wouldn't know what to do with if the engine wasn't buzzying along on the highway somewhere around the crest of the torque curve. Believe me - this is going to be worlds better than my 427 Vette with 4.11 gears.

Dan

[Bobcat]

Generalization .... heavy car , heavy flywheel , light car , lighter flywheel . Some of my squirt racer friends had a program that told them what flywheel weight to run . But , a fairly heavy flywheel helped off the line as the engine didn`t bog and helped keep the rpm up when shifting . Again , it required experimenting at the track . On the other hand , when I ran dirt track , the lighter you got the flywheel , the better ( for me ) . The car accelerated faster out of the turn and decelerated quicker when letting off the gas ( One year , I machined the counterweights off the crank ... boy , did it rev quick and decelerate fast .... also destroyed bearings fast ! ) . Flywheel weight , IMO , is a personal choice .... I happen to like a light flywheel , but if you have a really long cam , a heavier flywheel can help the idle and starting from a stop .

Bob

[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.

[mikeforte]

Hi,
I love aluminum flywheels and recommend them all the time. Crankshaft weight is worth 15 times dead weight. Wheel weight is worth 3 times dead weight.
My car revs like a bike. Make sure you have a rev limiter on your MSD. Mine bounces off the 7600 limiter in 3rd gear often. I also like the Tilton or Quarter Master multiple disc clutches. Zoom Zoom Zoom!!!!!

[Rick Parker]

My next clutch WILL be a Quarter Master small diameter multi disc. A LOT to be gained by reducing the OD and subsiquent inertia. That's why the F1 boys use a 5" multi disc clutch.

I'm witcha Mike.

[mikeforte]

Hi Rick,
I not only recommend them, I sell them too....

[lovehamr]

Speaking of aluminum flywheels; is it normal to have to heat the FW to get it onto the crank? I had to use my specialized parts heater (oven while the spousal unit was away)to get my Fidenza on my Scat crank. That puppy is snugg!

Steve

[blykins]

Yep. Tolerance stacking. Sometimes the Scat cranks are a tad oversize, sometimes the flywheels are a tad under.

I used a Fidanza aluminum wheel on my 428....the flywheel had to be touched inside to get it to fit correctly.

[CobraEd]

I love my RAM aluminum flywheel!!! You can also get pressure plates with aluminum rings and save an additional 5 lbs. I wish I woulda done that too:

http://www.speedwaymotors.com/Ram-10...ord,33276.html


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[PANAVIA]

I like Steel Flywheels, they are durable and tractable. Aluminum can spin faster , but that is just an additional expense I just cant see on a street car.