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Jarle · Post by **Jarle** » Thu Oct 27, 2005 7:59 am

Hi,

I have just got my new alu flywheel(front). The std flywheel is 11.2kg with starter gear. The new alu wheel is 3.6kg with startergear. The crank and front pulley is also lightend a couple of kilos. I use Autronic SMc engine management.
The cranck and everything will be sent to a full engine balancing next week.
Anyone with experience around this? I can not seen any problems doing this as the heavy driveshaft is a part of the engine.

MD · Post by MD » Thu Oct 27, 2005 12:53 pm

Is this for street application?

Jarle · Post by **Jarle** » Thu Oct 27, 2005 2:02 pm

We will be testing it on street engines with stock Ecu soon. This one will be used on a race engine.

Hope to get some feedbacks from people who has tried this before.
If the results are good we may concider making some more alu flywheels.

Mats · Post by **Mats** » Thu Oct 27, 2005 11:17 pm

Problems with weight? nah, I think you will be fine bacause of the other flywheel as you said.
But Aluminum? Why not steel (not cast iron)?

I personally don't trust alu, must be a bad childhood memory or something.

MD · Post by MD » Fri Oct 28, 2005 1:28 am

Just building on Mats point.

This might be overkill but perhaps some steel reinforcement around the flywheel mounting bolts might be in order such as steel inserts for the bolt holes and perhaps a steel circular plate to distribute the stress. Is there likely to be any crush problems of the aluminium for the tensions required? If so, these are the sorts of things I would suggest you need to think through. Balance?

Great to see some innovation here. Well done.

Jarle · Post by **Jarle** » Fri Oct 28, 2005 1:55 am

I have thought of the "problem" using alu. To solve this problem I have made the flywheel much stronger in the center. Dont remember the presise numbers but mine in alu is 7mm thikker than the standard unit where it is mounted to the crank. The big advantage with alu is the weight, thats why it is not steel made

If you look at the back of the flywheel there is a 20mm long line in the middle to place counter weights. Make steel rings that fits this line so Its possible to balance it the right way.

Mats · Post by **Mats** » Fri Oct 28, 2005 3:05 am

Good point MD. Relaxation in the material is a fast way to flywheel explosion.

Personally I would use a material with a wöhler-knee, i.e. have a threshold value for fatigue.
I honestly believe you can make a steel flywheel lighter then one in Alu. I have a simulation at home that is around 1.2Kg (for Nord) with all the weight around the screws for crank and drive shaft, almost none in the outer parts. Low inertia heaven.

Maurizio · Post by **Maurizio** » Fri Oct 28, 2005 4:33 am

Aluminium is light but it's just how you look at it:

If you want dynamical performance you look at E modulus / density.
Alu 6061-T6 ==> 25.5 <--> Steel A36 ==> 26.9

When placing the material at the right position steel wins....
And taken into account that there are no real alu fatigue numbers availabe go for steel!

Jarle · Post by **Jarle** » Fri Oct 28, 2005 7:20 am

This is a test flywheel.
Most of the companies I know do not use any kind of steel to strenghten the center of their alu flywheels..... Has anyone tried alu on their V6?
I can see the theori in this but I am sertanly not convinsed. Are there any spesial reasons a Alfa V6 flywheel should need steel when almost all other kind of engines can do good with aluminium?

Barry · Post by **Barry** » Fri Oct 28, 2005 10:44 am

J,I like your flywheel very much...I have been using an ally flywheel on a 3.6l 24v for a while now and its a very reliable bit of equiptment...Have had no blow ups,disintegrating or exploding of the ally flywheelIt tok a bit of getting used to on a daily driver but this I got accustomed to pretty quick...The big thing to deside is wether or not it suites you on a daily basis...I sometimes think a steel normal weight f/wheel would be better...On the race tack its a different kettle of fish........The prop is std as is the twin plate clutch unit...The revs climb and fall dramatically quicker ,and in traffic I sometimes come across as a learner driver,jerks and jumps sometimes....
The only hing is the pegged ring gear.....The crank assy. is balanced internally using heave or "Mallory" in the webbs...

I wil not use a lightened flywheel on my street car again,but definately on a race car.....(perhaps my age is showing here......)

Barry · Post by **Barry** » Fri Oct 28, 2005 10:50 am

:roll: Ok,Wont load from my mem stick,lets see......................................................................................................................................................ah,ok...

Barry · Post by **Barry** » Fri Oct 28, 2005 10:52 am

An another.......

Barry · Post by **Barry** » Fri Oct 28, 2005 10:55 am

See the steel weights attached via the countersunk caps?? 8000rpm ,no probs.......untill it comes off of course......so far ,no probs...(over 2 years in operation ...........)

Barry · Post by **Barry** » Fri Oct 28, 2005 11:00 am

Gees,sorry guys,the spelling in my post is not that good ,is it....(been chatting to Jim K too much I thinkk-yup,there I go again........)

Jarle · Post by **Jarle** » Fri Oct 28, 2005 1:31 pm

Thanks Barry. The engine is built for racing with lots of modifications so the daily driving concerns are really no problem....
We are now about to make the rear flywheel in a lighter material also.

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