Carbon fibre wheels

[xtremerus]

Originally Posted by Bossxr8

A passenger doesn't add to the rotational mass that the engine has to drive directly.

I think there is some sort of rule that 1kg of rotational mass is really equal to more than that in reality, ie. the wheel may weigh 10 kg but the extra work the engine needs to do means its more like it weighs double. I can't give you the exact science of it and I couldn't be bothered researching it so you'll need to do that yourself if you want to.

And a 100kg passenger would increase fuel consumption, every article you read on how to improve economy says reduce the weight of your vehicle by removing unnessesary items from the car.

That damn freeloading passenger is costing me MORE money.
Just don't tell her.

[scj429]

You can buy Carbon Fibre rims for a motorbike and they are priced from around $3300 USD per rim and weigh 2.1 kgs. Make your scooter change direction by just thinking about it and I presume there would be similar benefits when fitting them to a car.

[EDManual]

would be strange on a motobike to have really light rims when cornering and hitting slippery spots. With normal bikes when jumping or losing a bit of control the rotation (gyroscopic) force keeps you upright. With out that i think it would be a lot easier to fall off!

[sudszy]

Originally Posted by Bossxr8

I think there is some sort of rule that 1kg of rotational mass is really equal to more than that in reality, ie. the wheel may weigh 10 kg but the extra work the engine needs to do means its more like it weighs double. I can't give you the exact science of it and I couldn't be bothered researching it so you'll need to do that yourself if you want to.

And a 100kg passenger would increase fuel consumption, every article you read on how to improve economy says reduce the weight of your vehicle by removing unnessesary items from the car.

The only rule is that it takes half as much energy again to have a wheel spin at the rate required to match its linear speed(speed along the road way) compared to the energy required to just change the linear speed of the same mass, ie total energy = 3/4 mv^2

[burnz]

Originally Posted by sudszy

The only rule is that it takes half as much energy again to have a wheel spin at the rate required to match its linear speed(speed along the road way) compared to the energy required to just change the linear speed of the same mass, ie total energy = 3/4 mv^2

un fortunatly we don't live in space, gravity kills inertia..
no road is flat!

a young fella banged he's head on an apple and yelled what the F=MA

[IDT]

Carbon Fibre Wheels PLEEEEEEAAAAASSSSSEEE!!!!
They wont sell because they complicate what is otherwise a simple item.
It's a WHEEL! Round thing that rolls back and forth!!!!!! BIG DEAL!!!!

This is seriously one of those lets use technology "because we can!" jobs.

Reminds me of those tiny mobile phones! Do the rims come with tracking devices? Do they come in 3D? Perhaps modems so you can skype your granny anywhere in the world on your iphone23. Maybe every mile you drive on them reduces global warming by 0.000000000000006gms per cubic meter of air.

Rant over ;-) Time for a lie down

[Supercharged]

Everyone is going on about the fuel savings of carbon fibre wheels what about the handling improvements as a result of reduced unstrung weight.

[Falc'man]

Originally Posted by Supercharged

Everyone is going on about the fuel savings of carbon fibre wheels what about the handling improvements as a result of reduced unstrung weight.

Very true, it shouldn't have gotten sidetracked like it did.

The performance gains are well worthy of consideration to whoever is half serious about extra performance.

Weight saving over the standard 19" FPVs is at least 34kg all round. That, in terms of raw weight taken from the car a very big number as it's not that easy to remove weight from a vehicle without compromise.

Then, as you mention, the unsprung weight allows the suspension components to work a lot better, but I wonder if there needs to be adjustments made to spring and shock rates to utilise the full advantage of the lost weight.

And last but not least, there's the inertia, like the lightened flywheel effect if you like. So much less mass to turn amounts in a fair bit more power at the wheels.

So with at least 3 different aspects there's nothing but win for this modification.

They don't look bad either and that can't be said about many of the aftermarket atrocities out there.

[Road Games]

Originally Posted by Falc'man

And last but not least, there's the inertia, like the lightened flywheel effect OR Underdrives if you like. So much less mass to turn amounts in a fair bit more power at the wheels.

Sorry mate ,couldn't resist

[Falc'man]

Originally Posted by XR6menace

Sorry mate ,couldn't resist

I can get more gain than those by using lighter wheels studs

/where's Gregory... he'll hit the rev limiter if he reads that

[sudszy]

Originally Posted by Falc'man

Very true, it shouldn't have gotten sidetracked like it did.

Hardly sidetracked when that was the key thing mentioned by the OP.

I dont have any problems with claims for better handling.

Originally Posted by Bossxr8

http://carbonrev.com/index.html

This is something that I have taken in interest in, Carbon Fibre wheels developed here in Australia, with Carbon Revolution working in conjuction with Deakin University here in Geelong.

This will be the next big thing in fuel economy. They are claiming something like a 7-8 % reduction in fuel consumption with these wheels. They will soon be building a factory here with production expected to reach 50,000 sets in its first year. They have had significant interest from a number of European manufacturers and look like being a success story.

Good to see an Aussie company doing good.

Originally Posted by Falc'man

Then, as you mention, the unsprung weight allows the suspension components to work a lot better, but I wonder if there needs to be adjustments made to spring and shock rates to utilise the full advantage of the lost weight.

Yes, springs and shockers are tuned to the mass of the wheel, especially important for corrugations, though less mass will probably be an improvement in most systems without adjustment.

Originally Posted by Falc'man

And last but not least, there's the inertia, like the lightened flywheel effect if you like. So much less mass to turn amounts in a fair bit more power at the wheels.

Since the change in mass is unsprung,the improvements in handling/suspension performance occurs for exactly the same reason the car can accelerate faster, less inertia both linear and rotational. The power at the wheels would remain near identical, as could be measured on a dyno.

[tex]

Originally Posted by Falc'man

I can get more gain than those by using lighter wheels studs

Funny you say that, several people have suggested I change to titanium wheel nuts over the last couple of years to reduce unsprung mass. hahahaha, bang for buck, NOT!

I personally find the concept of Carbon wheels for everyday use laughable, a proper race car, I see the application, but on a road car. Please.

Gutter rash, impact damage, dirt / gravel roads, stones. Yeh right.

My wife would destroy some carbon wheels the first time she reverse parked.

[naddis01]

I just got some tyres pulled off some 19" wheels today so I thought I would weigh them when I got home. They weighed 11.9kg each for a stock 19x7.5 Mazda CX7 wheel. Admittedly they are only 7.5" wide but how much weight would another inch of width add? 1-2kg at the most?

So from the figures quoted above, the carbon fibre 19x8.5 wheels (5.6kg each) would see a weight reduction of 25.6kg from the stock 19x7.5 wheels.