this is light

[Jim Ratto]

 

[Rennsurfer]

Good Lord... there will be NO hill climbing with THAT thing. Another reason I hate ultra lightened flywheels.

[Bruce]

Good Lord... there will be NO hill climbing with THAT thing. Another reason I hate ultra lightened flywheels.

Yet another myth.  It takes hp to climb a hill.  Flywheels don't magically lift you up hills.

[Prowagen]

Surely a flywheel that light will cause problems eventually with the crank? It must make the whole rotating mass very uneven end to end?

Cheers,
Rob.

[Fastbrit]

Surely a flywheel that light will cause problems eventually with the crank? It must make the whole rotating mass very uneven end to end?

Cheers,
Rob.

Just the opposite, i would have thought. You no longer have a hefty piece of steel hanging off one end of the crank. It may make the car a little less smooth at gear changes and at idle with a big cam, but apart from that, it can be fun! Arguably not so great launching a heavy car off the line, though. I drove a car back in the 1970s with a Crown aluminium flywheel. Boy did that thing rev up nicely! More akin to a motorcycle...

[Prowagen]

So it a purely benificial to spin up the engine quicker? I always thought that the Berg Equalizer was made to combat vibrations and dampen the crank movements when you use a lightened flywheel, so surely if your flywheel is mega light you would need one hefty equalizer pulley? If not wobble wobble and eventaully boom?

[bang]

is it from a porsche rs or?

[Jim Ratto]

Porsche 906 901/20

[Rocket Ron]

thats a piece of Swiss cheese

[kev d]

Is there an ideal weight for a flywheel in a race car?
When does one become too light?
More questions..

[j-f]

I've talk with Johannes during EBI 2. He said me that a light engine is very reliable because you have less constraint. But you have to build all the engine in this way. Don't use a light flywheel with heavy pistons.
And take a look on the flywheels he use on his mouse motor 

[Rune]

Yeah, I was just about to mention the flywheel Johannes used on the mouse motor. Only 7 pounds. Still made pretty good torque: 192.4Nm/6100rpm(138,7lbs). So as Bruce said It takes hp to climb a hill not a heavy flywheel..

[Jim Ratto]

in the 90's, I built a few motors with Crown alu 6lb flywheels. No issues on the street, or with hills. Idle speeds had to be screwed up a hundred rpm or so, especially on Sheep's 1914.
I think it was the light flywheel, along with K8 and Pauter heads that were the muscle behind that motor.

[Harry/FDK]

I've seen worse, and you have to lower the car in the rear to keep the stance..

[Bruce]

When does one become too light?

When you dump the clutch at the max rpm your engine can handle and it boggs.

[Rennsurfer]

Yet another myth.  It takes hp to climb a hill.  Flywheels don't magically lift you up hills.

Not a myth at all. But you're right about the horsepower aspect. Point being... I've driven cars with big engines and lightened flywheels and wasn't real thrilled with their lack of hill climbing. Whereas a car with a big engine and a not so lightened one performed better. But that's not what most Cal Look owners are looking for. I like driving my cars in different terrain... most people build their cars to go fast in a straight line like at a drag strip.

To each their own.

I'm sure that with the right combination of lighter engine components, a super lightened flywheel would work great. I was previously referring to the average built hi-perf. VW engine. Sorry for not clarifying.
 

[stealth67vw]

Here's the flywheel I'm using on my 1915 FK-89 52mm IDA bus engine. I may lighten it a little more, I just bought a belt sander and a cordless drill   

[j-f]

It looks like an UFO in the old 50's - 60's movies 

[nicolas]

i think the one JF has in his car now maybe isn't the lightest flywheel in the world, but it was lightened quite a bit as well.

[j-f]

i think the one JF has in his car now maybe isn't the lightest flywheel in the world, but it was lightened quite a bit as well.

I don't use yours Nico.  (Next time we meet, I will give it you back)
Finally, I have to buy a new one to put in my motor 

But, yes, it is a light one 

[Jim Ratto]

Is there an ideal weight for a flywheel in a race car?
When does one become too light?
More questions..

The new Carrera GT (well it's not really new anymore) has this tiny, very, very lightweight clutch, and practically "NO" flywheel. Of course it is a big 5.7L V10, but it is a "street car"

Porsche has always been sort of maniacal about weight savings, not only in reciprocating engine weight, but through the entire car. The 1960's were especially active times int he Renn Werke...  Piech had guys weighing headlight switches, fuses, ignition keys and modifying them to make them even lighter. Anyway... if you take a good look at the Porsche race powerplants from the late 1950's-on, especially the smaller cc, very high specific output (excess of 85hp/per liter) you'll see the attention paid to light engine parts. And can anybody argue with Porsche's success record? 

[Bruce]

Yet another myth.  It takes hp to climb a hill.  Flywheels don't magically lift you up hills.

Not a myth at all.

There was some other differences in those cars that caused the driveability difference you noticed.  It wasn't the flywheel.
Physics 101:
A flywheel is an energy storage device.  You put energy into it by accelerating it.  You get that energy out by allowing it to slow down.  When you are climing a grade, the last thing most people want to do is let their engine rpms drop to get that energy out.  When I'm climbing a grade at a constant 70mph, zero energy is entering the FW, and zero energy is leaving it.  Therefore, the size of the FW has absolutely no effect.
My flywheel is 8 lbs, according to that myth, hill climbing would be an issue, it definitely isn't.

[Zach Gomulka]

I thought I remembered Gene Berg saying that the safest you can lighten a flywheel to is 12.5lbs, otherwise the flywheel may flex?? Does anyone remember this? Is there any truth to it?

My flywheel is 8 lbs, according to that myth, hill climbing would be an issue, it definitely isn't.

So why did you go that light? Is vehicle acceleration improved over a 12.5lb flywheel? Will that light of a flywheel work in any VW engine/car configuration, or is your engine/car set up specially to work with it?

[Rune]

The new Carrera GT (well it's not really new anymore) has this tiny, very, very lightweight clutch, and practically "NO" flywheel. Of course it is a big 5.7L V10, but it is a "street car"

Like the Carrera GT the WRC rally cars run basically the same set up with no flywheel. Would say they still can climb hills just fine.

[Bruce]

So why did you go that light? Is vehicle acceleration improved over a 12.5lb flywheel? Will that light of a flywheel work in any VW engine/car configuration, or is your engine/car set up specially to work with it?

It was on an engine I bought.  I only weighed it after driving it a few years.  Of all the people who've driven my car, nobody has noticed any ill effects.  It was poorly lightened.  Lots of material removed from backside of the disc area.  Where a stock FW is 10mm thick, mine's 4mm.  I've got another FW chopped and waiting.  It's been lightened all at the perimeter.  Ring gear narrowed, and undercut.  At 9 lbs, there's more to come off.

The light flywheel really does help acceleration.  And then when you take your foot off the gas, the car really slows down fast.  A lot faster than a car with a big FW.
The downside is when trying to do burnouts.  More difficult because you can't store much energy in the flywheel before you dump the clutch.  Even if I slam 2nd, the tires don't bark at all.  Not enough stored energy in the FW.  On the plus side, it sure saves gearbox parts.

[turtle racer]

The lightness is it really a good thing ??

[Prowagen]

The lightness is it really a good thing ??

My thoughts too?
Are there any proven hard facts, that a lightened flywheel makes a beneficial difference?

Say you have 2 bugs, identical weights, both with 150hp Identical setups but one has an 8lb flywheel and one has a stock weight one, will the lightened one win a drag?

Rob.

[turtle racer]

I read that preferred Gene BERG a steering wheel close to the origin!!!
That is why I ask the question.

[LGK]

I read that preferred Gene BERG a steering wheel close to the origin!!!
That is why I ask the question.

Damiennnnnn...on parle des VOLANTS MOTEURS...PAS DES STEERING WHEELS 

[turtle racer]

Yes steve on est bien d'accord !!!
Je parle bien du volant moteur... c'est mon traducteur qui n'asure pas !!!!