Light weight flywheel

[kent olsen]

Always looking for the little bit extra.

My classic Mini Cooper is just about 10 hp over stock (83/72. I have changed the final drive from 3.4:1 to 3.1:1 as at 62 mph it's turning 3900 rpm, not freeway compatible. I also added a light weight flywheel (8 lbs) in a effort to compensate for the difference. Wow you can feel the difference.

Now my Porsche (72T @ 2200 lbs and 245hp, 3.0L twin plug/webers) I know has the stock flywheel. Just wondering? It's pretty easy to drop the engine, I've done it about 4 times, I wonder? Our host has an 8lb flywheel available?? Maybe a winter project?

[icarp]

Carroll Smith wrote , for every pound you save in the line of the crank you can savor the result, times 15 lbs .The flywheel combined with the alloy clutch could net you 6 lbs , that x 15 , is like reducing the weight of the car by 90 lbs . Sounds like a good project to me .
Ian

[911 SLANT]

I run a Fidanza Aluminium flywheel and Sachs Aluminium pressure plate. I saved like 15lbs. Motor revs up fast.

[Jeff Higgins]

If you know anyone who runs one, you should see if you can drive it before you decide. I know a couple of guys who ran them for awhile and soon got rid of them. A couple of our club guys up here run them, and I've driven their cars. I would never run one on the street after having done so. You wind up having to rev the motor and slip the clutch a good deal more than you would with a standard flywheel in many situations you find yourself encountering on the street, just to keep from stalling it. Stop and go traffic on any kind of an uphill, for example, can get very frustrating with such a setup.

[911 SLANT]

I have no problems with stalling or having to rev. It to keep it going. Might be that I also run a 7:31 R&P.

[chrismorse]

I had a pumped 2.4 type 4 engine in my 72, with a lightened wheel and an aluminum S clutch. When I let up a little too quick, I could stall it occasionally, but that engine revd up quick, very responsive. Loved the car. Turn the car off and the engine came to an immediate stop.
Had a stripped auto x speedster, SC 140 hp, 6/31 with a stock clutch and a lightened wheel lots of ttods with it, again, very responsive.
2 Toyota and one Datsun work trucks with stock clutches and aluminum wheels, very little stalling or difficulty on hills, but noticeable improved throttle response.
308 Ferrari, 16 pound wheel cut down to 8, stock iron pp small improvement, but noticeable.
74 911 .2.7, still on the lift, but getting a 6.25 pound RSR wheel and a Kep 6.5 pound all aluminum PP, high hopes for this one.

For the most responsive, lively engine, you need to do both the wheel and the clutch, the iron foot of the pp and the steel housing carry a lot of inertia.
If your first gear is fairly high and/or the vehicle has a low power to weight ratio, you could experience occasionall stalling.

I really like a responsive car.

Side note: some poo poo the light wheels, pointing out that on a dyno, you see no numerical difference, but that is at a steady state, not a dynamic run. By reducing the rotational inertia that the engine must accelerate, every time it revs, you have that much more power to accelerate the car.

If all you do is dd city driving, it might not be worth it, but if you flog it through the twisties, you’ll love it.
Chris

[Mahler9th]

The old school stage one on this is to have the stock flywheel lightened a bit by someone that knows what they are doing. Lot's of folks around that have experience with machining air-cooled flywheels.

I have a flywheel like this sitting on a shelf and I might sell it-- got to check to see if it still has enough life left to be worthwhile for someone. I think it weighs 8-9 pounds.

I run a Fidanza with my 3.6, but my application is racing. I have run a Kennedy clutch cover and a Sacks all alu motorsports cover at various times. The latter units are hen's teeth these days.

The best lightweight clutch kit I have seen in recent years is made and sold by Jerry Woods Engineering. There are some pics in a different thread in these forums.

For a street-only car, I would not bother with any of this... again my application has been racing.

[kent olsen]

Thanks guys. I think it will be noticeable in the Mini as it is pretty short geared. Even with the new 3.1:1 final drive the top speed will be maybe 90.

I have always had the aluminum pressure plate in the Porsche so if I went with the light flywheel it might not be to noticeable.

Just wondering. Few more days and the rain supposed to quit and we'll get a few days on sunshine so I'll be able to take the Mini out for a test.

[911 SLANT]

Hey Kent where's the Black Beauty? Don't see it in photo.

[MichaelSJackson]

Flywheel is a momentum (= m*v) battery. Its intended use is just to help you get started from a dead stop. If you decrease the mass you need to increase the velocity to produce the same momentum. As pointed out, it can be hard on your clutch, if you live where there is hilly, city traffic (i.e. San Francisco or Seattle?). Also, bad for your 0 to 60 times.

[JonT]

I have a lightweight flywheel in my SC with 3.6. It is a little fussy to drive from a stop on hills I probably would not do it again on my street car. It's mildly difficult to drive from a stop but I'm getting better at it.

[famoroso]

Between Carillo rods, Aasco LW flywheel, spring centered clutch disc and an aluminum pressure plate, we took ~20 pounds out of the reciprocating / rotating assembly in my 1987 911. It feels pretty darn good. I haven't noticed any issues in the first 1,000+ miles.

[icarp]

Originally Posted by JonT

I have a lightweight flywheel in my SC with 3.6. It is a little fussy to drive from a stop on hills I probably would not do it again on my street car. It's mildly difficult to drive from a stop but I'm getting better at it.

This is probably due to the tuning of the fuel injection. a lean condition can cause this .
I do not see a down side to lighter components . Just learn how work the clutch with the new parts .

[Shamus911]

I second the recommendation to drive one - a buddy of mine was scared off of doing an RS flywheel setup in his 993 by the comments around LWFW and when he drove my 964 with the RS setup later, he was PISSED!

I recommend them for folks who like a visceral and immediate/direct sense of what the drivetrain is doing. The sound of an aluminum flywheel is killer too but not something that everyone wants... I liken it to the sound of a race gearbox on decel...

On a 964 in particular you have to ensure that the ignition system is in top shape to 'catch' the revs since they fall very quickly when you put the clutch in... a chip from Steve Wong is useful also.

[1979-930]

I always laugh at the "not good for the street" statement when this subject comes up.
I have installed aluminum flywheels with light weight clutches, dampeners and drivelines on every performance engine and car I have ever built. There are not drivability issues.
I have a light weight clutch system on the 930 and it's easier to get going from a stop than the 07-RS. That car I have stalled... twice.

[Mahler9th]

Isn't "street driveability" subjective?

Everyone has their own definitions, right?

And if there are a number of prospective parts in question wouldn't there be multiple variables to consider?

What is the goal of a lightweight flywheel in this thread? That appears to be unstated.

The Mini had the final drive changed. In 1972 Porsche language, that might mean a change in diff or gearing or both. The flywheel has nothing to do with that.

My 911 is a '75, and it has a 3.6 in a config that makes about 330bhp. Car weighs about 1900 pounds. I use a lightweight Fidanza flywheel (requires a slight mod to the case for clearance). I now have an all alu racing Sachs motorports clutch (sometimes called an RSR clutch). These are all alu, very light and nearly unobtanium. The Kennedy stage 2 is similar but a bit heavier. These have a very high clamping force. I use a 6 puck racing clutch from Clutchnet.

This is an "on/off" clutch set up compared to all stock Porsche set-ups. I also used it when my engine was a 3.8 and made about 370 bhp.

I can drive my 911 on the street-- it is a 75 so smog exempt in CA. My clutch set-up is very challenging when I drive on the street.

So the answer is as always... "it depends."

Everything else being equal, would a lightweight flywheel do anything for the OP? Whether aftermarket like the Fidanza, or a lightened stock unit?

The answer is YES. If the alternative flywheel is 2 pounds lighter than the one in there now, the car will weight 2 pounds less. Whether that matters to the owner driver is completely subjective.

These questions have all been asked and answered in these Forums for decades. And for decades before that in publications like Pano.

[kent olsen]

911slant

Not sure if you have the right Olsen. You may be thinking of the one in Calif.

I've had the porsche for over 20 years and picked up the Mini and Vette when I retired 5 years ago.

[911 SLANT]

Sorry, for the mix up. I love your Burgandy color on the 911. My first 240Z was that color. That was the reason I bought it. I also have a 2006 JCW mini that I love. Nice collection you have.

[NY65912]

I had a Fidanza light flywheel in my 3.8 beast project. It was like a bucking bronco. Perhaps that was exacerbated by the big stroke and bore, ITBs and cam.

The engine made 375 at the wheels.

Albeit, the engine rev'ed like a cat on fire.

I say drive a car with one before you commit.

[3rd_gear_Ted]

My dream list of lightweight components:
Wossner Pistons
Pauter Rods & Wrist Pins
Findanza Flywheel
KEP Clutch & Plate
Titanium CV joints & Axles
No E-Brake
Drilled Swing Arms
Jongblood Wheels & Michelin Slicks
Stop Tech Calipers & Beryllium/Steel Rotors