Carbon fibre wheels

[MexicanBatman]

215/35/18 they fit fine, better than this that also owned for a while

[sudszy]

Originally Posted by SteveJH

And remember the claim was 3-8% gain..

Not as quoted by the article posted by the OP, which was what I was responding to:

Originally Posted by Bossxr8

They are claiming something like a 7-8 % reduction in fuel consumption with these wheels.

Originally Posted by buggo_gt

What do you think a realsitic number would be?
.

2-3% would be believable in urban cycle economy test. 1-2% highway.

The 7-8% being just a best case result for perhaps a car on a racetrack.

[Falc'man]

Originally Posted by sudszy

Not as quoted by the article posted by the OP, which was what I was responding to:




2-3% would be believable in urban cycle economy test. 1-2% highway.

The 7-8% being just a best case result for perhaps a car on a racetrack.

When a claim is made it's usually based on what the improvement is over the normal/mean run of the mill product when used in general conditions. I didn't think I needed to say that but mentioned it just in case.


Effectively, it's with regards to two aspects you've based your incorrect conclusions on.

First, you're assyouming the total mass saved is only 20kg. What do you base this on? Being as scientific as you are did you take your spare out of the boot and weigh it? Once you've established what the weight is, ask yourself if this is the average mass that the developers have based their findings on.

Second, you've assyoumed that in the real world the average speed is so high that no improvements in economy (from the reduced mass moment of inertia in the lighter rims) will be realised. That is not very realistic is it.

You remind me of the guy who tried to buy a banana without paying for (the weight of) the banana skin simply because he doesn't eat that part of the banana.

The below real-world example indicates about a 10% increase in fuel consumption from roughly 10kg at each corner. This isn't unusual.

Originally Posted by MexicanBatman

I put 18's on it, it used on average 1-1.5L/100km than with the 14" alloys I also had for it, they were approx 10kg heavier and 3% larger o.d

[sudszy]

Originally Posted by Falc'man

When a claim is made it's usually based on what the improvement is over the normal/mean run of the mill product when used in general conditions. I didn't think I needed to say that but mentioned it just in case.

Really, when its not qualified, I take it as a best case scenario in the automotive industry, ie like the claims for power and economy gains from electric fans and electric water pumps over fixed mechanical fans, typically their spiel quotes figures which can later are seen to be with engines doing max revs with rather than normal driving where the losses are only a fraction of that at max output.

Originally Posted by Falc'man

First, you're assyouming the total mass saved is only 20kg. What do you base this on? Being as scientific as you are did you take your spare out of the boot and weigh it? Once you've established what the weight is, ask yourself if this is the average mass that the developers have based their findings on.

The weights of standard alloy wheels at the moment can be seen here:http://www.miata.net/faq/wheel_weights.html.
There are in the range of 5-8kg depending on size. The best one could do is for a carbon fibre wheel to weigh nothing, so if you want to split hairs about how far my ball park of 20kg figure is out, go ahead.

Originally Posted by Falc'man

Second, you've assyoumed that in the real world the average speed is so high that no improvements in economy (from the reduced mass moment of inertia in the lighter rims) will be realised. That is not very realistic is it.

Its not about the actual speed its about how much the speed changes which is more relevant to the extra energy used in stopping and accelerating a more massive wheel.

No skin of my nose if the 7-8% is really achievable with normal driving, I just would like to see evidence of it and where indeed the energy losses are minimised, Im not seeing it from the vitriolic abuse supplied by xr6menace and the like here.

Originally Posted by Falc'man

The below real-world example indicates about a 10% increase in fuel consumption from roughly 10kg at each corner. This isn't unusual.

This is what you base you findings on?,obviously the comparison was done with different tyres as well as a 3% change in overall diameter, 10kg change at each corner? comparing apples with apples?.

Really 10%, , if it was true dont you think this would show up in the adr numbers when the figures are compared for a falcon with steel rims compared to a fairmont with alloys etc,

[cs123]

Not sure why people are attacking Sudszy on this.

His argument seems sound and I have the same questions. I can see savings in stop start driving but I cannot understand the physics behind any savings at a constant speed.

Naturally reducing unsprung weight will be a massive advantage to handling and also the lighter rotating mass will make a difference accelerating and stopping the wheel.

There will be no change to drive train losses that I can see.

[Bad Bird]

I agree with Sudzy here. The 'don't use your science here' mentality is pretty lame.

[Fev]

A set of Forged Aluminium wheels by Volk would do the same job over a standard set.

[Grunter]

Originally Posted by cs123

Not sure why people are attacking Sudszy on this.

You reap what you sow.

I'm no science major, however would it be similar to fuel consumption for city vs highway driving? Stop/start there would be no argument that lighter wheels would show a fuel saving, but highway driving I'd imagine there would be little difference.
However, most cars I believe need to accelerate to get to highway speeds, so there would still have to be some saving by the combination of less unsprung weight and overall mass?
I could see how there would be benefits for the majority of cars that drive in the city.

[MAD]

This thread should be about how awesome carbon fibre wheels are, not nit picking the claimed fuel economy gain.
When the wheels are attached to an SSC Ultimate Aero, fuel economy is the last thing to worry about.

I really dont think these are aimed at a Fiesta econetic owner.

[SteveJH]

Originally Posted by MAD

I really dont think these are aimed at a Fiesta econetic owner.

I'd say car manufacturers would have to start putting Forged Alloy wheels onto their cars before they considered CF wheels?

[SSFPARTSGUY]

After having a sift through their website, this looks like some fantastic technology. On the previous page some of the guys had some concerns about potholes etc, but if you check out their page they post results from their testing a 4" deep pothole at 50kph and a 2.25" kerb hit at 100kph. Both tests were very successful, especially when the second test is compared with an alloy rim.

With regards to weight, the figures quoted on their site are 5.6kg for 19X8.5 and 8.85kg for 20X12.5 wheels. For the wheels that most car makers use of this size, the weight is getting up to about 18-20kg per rim, which would be closer to an overall weight saving of closer to 45kg, which is a substantial amount of unsprung weight. This sort of saving would result in a few different things; reduced stress on suspension and drive train components thereby extending life, improved acceleration and handling and yes, particularly in stop-start traffic, a reduction in fuel consumption would be evident. When combined with other weight saving devices, low rolling resistance tyres and aerodynamic aides already seen on many 'eco' cars, you would expect that reduction to increase dramatically.

[SpoolMan]

Originally Posted by SSFPARTSGUY

With regards to weight, the figures quoted on their site are 5.6kg for 19X8.5 and 8.85kg for 20X12.5 wheels. For the wheels that most car makers use of this size, the weight is getting up to about 18-20kg per rim, which would be closer to an overall weight saving of closer to 45kg, which is a substantial amount of unsprung weight.

Good pick up, thats the key the weight being unsprung its worth at least double compared to taking the same amount of weight from sprung weight..

[mik]

anything that saves weight and and uses less throttle opening to get the car rolling has to be a good thing.

[Falc'man]

Originally Posted by sudszy

Really, when its not qualified, I take it as a best case scenario in the automotive industry, ie like the claims for power and economy gains from electric fans and electric water pumps over fixed mechanical fans, typically their spiel quotes figures which can later are seen to be with engines doing max revs with rather than normal driving where the losses are only a fraction of that at max output.

Good point. But why do you need to look at worst case scenario by suggesting there's no more than 20kg loss, and ONLY consider constant speed? When in reality it's more than 20kg, and constant cruising speed is hardly the majority of the time for most people?

Originally Posted by sudszy

The weights of standard alloy wheels at the moment can be seen here:http://www.miata.net/faq/wheel_weights.html.
There are in the range of 5-8kg depending on size. The best one could do is for a carbon fibre wheel to weigh nothing, so if you want to split hairs about how far my ball park of 20kg figure is out, go ahead.

5-8kgs? Apples for apples. "With regards to weight, the figures quoted on their site are 5.6kg for 19X8.5 and 8.85kg for 20X12.5 wheels. For the wheels that most car makers use of this size, the weight is getting up to about 18-20kg per rim" - SSFPARTSGUY

Originally Posted by sudszy

Its not about the actual speed its about how much the speed changes which is more relevant to the extra energy used in stopping and accelerating a more massive wheel.

So why you arguing? I don't know what your driving environment/routine/average speed is like, but here in the major city you have tens of thousands of motorists dawdling in peak hour every morning to work. And that's just on the freeway! That is not normal driving but that's reality isn't it and people have to put with it.

Originally Posted by sudszy

No skin of my nose if the 7-8% is really achievable with normal driving, I just would like to see evidence of it and where indeed the energy losses are minimised, Im not seeing it from the vitriolic abuse supplied by xr6menace and the like here.

That's where your problem is; your refutations were based off incorrect assumptions, and NO evidence.

Originally Posted by sudszy

This is what you base you findings on?,obviously the comparison was done with different tyres as well as a 3% change in overall diameter, 10kg change at each corner? comparing apples with apples?.

Much better bet than blind assumptions and the most favourable conditions. It's also better than providing a link that shows weights for much smaller diameter rims than the diameter of the CR-9s.

Originally Posted by sudszy

Really 10%, , if it was true dont you think this would show up in the adr numbers when the figures are compared for a falcon with steel rims compared to a fairmont with alloys etc,

Which series are you talking about? There are many variations in equipment and therefore weight, as well as gearing, and rim diameters. In most cases the Falcon with smaller diameter rims and less weight due to less equipment, was a little more economical than the say a G6 and G6E, when the gearing was the same.
The example given by MexicanBatman isn't bad. The only effective change was the mass of the rims. This contributed to about 10% increase in economy.

As for the rolling diameter of his new rims, on take off there's a disadvantage, but with CONSTANT highway speeds it would be better wouldn't it? Or doesn't that count now?

[sudszy]

I was quite happy to let this thread die, but take me on with this type of stuff and I get a bit cross:

Originally Posted by Falc'man

When in reality it's more than 20kg, and constant cruising speed is hardly the majority of the time for most people?

5-8kgs? Apples for apples. "With regards to weight, the figures quoted on their site are 5.6kg for 19X8.5 and 8.85kg for 20X12.5 wheels. For the wheels that most car makers use of this size, the weight is getting up to about 18-20kg per rim" - SSFPARTSGUY

Best you actually do research rather than quote people who have just come to this site with numbers. Average weight of a current alloy rim 18-20kg? since when are 20x12.5 in rims the average? Here is a whole page of rims that some enthusiasts may fit, just how many are 18-20kgs(weights are in pounds):http://www.benzboost.com/showthread....8-20-inch-rims.

However, I also pointed out earlier here:http://www.miata.net/faq/wheel_weigh...l_weights.html, the weight of the average wheel that we are talking about manufacturers improving on is in the 5-8kg range.

Originally Posted by Falc'man

Originally Posted by Falc'man

So why you arguing? I don't know what your driving environment/routine/average speed is like, but here in the major city you have tens of thousands of motorists dawdling in peak hour every morning to work. And that's just on the freeway! That is not normal driving but that's reality isn't it and people have to put with it.

That's where your problem is; your refutations were based off incorrect assumptions, and NO evidence.

Sorry, I asked for evidence/ reasoning to the claims, no I havent gone out and refuted them, just pointed out why I think the are probably not feasible based on sound logic and the calcs I did, yes Ive looked at the raw calcs of how much energy is needed to change the speed of rotating massing the size of wheels and Im not seeing that 7-8% figure is possible for anything other than extreme and frequent speed changes, as would occur on a tight race track.

Originally Posted by Falc'man

Which series are you talking about? There are many variations in equipment and therefore weight, as well as gearing, and rim diameters. In most cases the Falcon with smaller diameter rims and less weight due to less equipment, was a little more economical than the say a G6 and G6E, when the gearing was the same.

I take it from your meanderings here, that yes, Im right, there isnt a 10% difference in fuel economy visible with the same engine and drivetrain on any of the models.

If ford could get a 10% fuel economy improvement by simply putting alloys on its falcon, dont you think they'd do it, the extra cost to them is 3/10 of ba when they are supplied with these rims on mass, regardless of how much they charge for them as options. By comparison,a 10% gain in engine efficiency, development cost, in the millions.

Originally Posted by Falc'man

The example given by MexicanBatman isn't bad. The only effective change was the mass of the rims. This contributed to about 10% increase in economy.

As for the rolling diameter of his new rims, on take off there's a disadvantage, but with CONSTANT highway speeds it would be better wouldn't it? Or doesn't that count now?

He changed the rim size, would be impossible to run the same tyre, so any conclusions are not valid. Varying od, could change results dramatically , higher gearing could result in higher or lower consumption, depends on how the car is initially setup.

Even if the change in od doesnt affect actual real fuel consumption, the odometer reading will automatically change by 3%(the change for the getz) regardless and any fuel consumption figures would also change by 3%, which Im guessing the person you choose to hang your knowledge on here didnt factor in either.

It does seem amazing that you are ready to support claims just based on this.

Originally Posted by Falc'man

That's where your problem is

just because I dont think the same as you, doesnt necessarily mean I have a problem.

[Road Games]

So anyway like he said Youssef please stop your meanderings (what the heck does that mean anyway) what would you know anyway about 2 similar falcons i mean cars comparing rolling acceleration and fuel economy.. you know one with 16"s alloys and one with 20"s aftermarket on similar power levels and drivetrains, clearly the blue falcon i mean car would achieve the same economy as the purple falcon i mean car in an acceleration comparison test as well as on the hwy at a constant speed...even though the purple falcon i mean other cars wheels weighed twice as much .. many lol's...

The real world seems pretty wacked up maybe i should get into scientology?

[Nikked]

All im going to say is...

That is they build planes out of CF, then it must be of some sort of benfit for other forms of transport.

[EDManual]

My wifes auntie in France was working at a factory making carbon fibre bicycle wheels. Pretty sure they were expensive, like in the thousands of euros per wheel. These wheels would surely be in the thousands of dollars per wheel too!

[Falc'man]

Originally Posted by XR6menace

So anyway like he said Youssef please stop your meanderings (what the heck does that mean anyway) what would you know anyway about 2 similar falcons i mean cars comparing rolling acceleration and fuel economy.. you know one with 16"s alloys and one with 20"s aftermarket on similar power levels and drivetrains, clearly the blue falcon i mean car would achieve the same economy as the purple falcon i mean car in an acceleration comparison test as well as on the hwy at a constant speed...even though the purple falcon i mean other cars wheels weighed twice as much .. many lol's...

The real world seems pretty wacked up maybe i should get into scientology?

Lol. I guess without real world experience there's only so much some can grasp. It's all good.

[Cam]

Originally Posted by MAD

This thread should be about how awesome carbon fibre wheels are, not nit picking the claimed fuel economy gain.
When the wheels are attached to an SSC Ultimate Aero, fuel economy is the last thing to worry about.

I really dont think these are aimed at a Fiesta econetic owner.

^^^^^^THIS ^^^^^^

I would not buy them for fuel savings, I would buy them for their weight savings...Besides, I am happy with my 22L/100 :P But I would LOVE to see the affect on 1/4 mile and handling characteristics...

[BigBlue]

"Optional carbon fibre wheels (4.2kg versus 9.4kg for the steel wheel) were a mass production first as well."

Fitted to the Citroen SM , March 1970.

Citroen did not offer them on any other models although they did use them on the rally cars with success until the takeover by Peugeot put an end to all rally and other motorsport ventures at the time.

Peter.

[Bossxr8]

Economy tests like our ADR tests, are conducted at varying speeds. They can only base their testing using this method.

They are not testing economy gains using constant speeds as its irrelevant to the official tests the manufacturers use.

[Falc'man]

Originally Posted by Bossxr8

Economy tests like our ADR tests, are conducted at varying speeds. They can only base their testing using this method.

They are not testing economy gains using constant speeds as its irrelevant to the official tests the manufacturers use.

The topic of economy really ends with the knowledge that it's the Deakin University that have made these claims.

It's only in the rare case where quick "calculations" from someone on the internet can disprove claims of one of the worlds highest ranked centres of excellence.

[sudszy]

Originally Posted by Falc'man

The topic of economy really ends with the knowledge that it's the Deakin University that have made these claims.

It's only in the rare case where quick "calculations" from someone on the internet can disprove claims of one of the worlds highest ranked centres of excellence.

Unfortunately you have missed the point of my query into their claims. I was asking for some qualification of the claims, ie what type of motoring produces 8% fuel economy gains using carbon fibre wheels.

On the surface their appears to be little science/physics/logic that these claims could be met for "consumer" motoring.

Indeed I was asking if anyone could shed some logic on it, so far apart from the abuse, we have received zilch.

No, we dont have any info at all from Deakin university or the manufacturer, the results are not qualified with anything, ie a 3% gain could be expected by replacing the alloy wheels on a ford fairmont when running the vehicle on the ADR fuel consumption cycle.

I did actually forget about a situation where I replaced the steel rims on a car I drove 15+ years ago with much lighter weight alloys(as much reduction as we could expect going from alloy to carbon).....purely for cosmetic reasons. I could immediately notice that braking effort was reduced considerably.

An important factor for comparison purposes the rims were exactly the same size and changed the tyres over to the new rims as well.

Fuel consumption, (which being a numbers person I measure constantly) did not measurably change, on the highway or in my urban use.

Perhaps rather than abuse me for whatever reason, future posters to this thread could actually find out for the benefit of all the background of the 8% claim.

[Falc'man]

Originally Posted by sudszy

Unfortunately you have missed the point of my query into their claims. I was asking for some qualification of the claims, ie what type of motoring produces 8% fuel economy gains using carbon fibre wheels.

On the surface their appears to be little science/physics/logic that these claims could be met for "consumer" motoring.

Indeed I was asking if anyone could shed some logic on it, so far apart from the abuse, we have received zilch.

No, we dont have any info at all from Deakin university or the manufacturer, the results are not qualified with anything, ie a 3% gain could be expected by replacing the alloy wheels on a ford fairmont when running the vehicle on the ADR fuel consumption cycle.

I did actually forget about a situation where I replaced the steel rims on a car I drove 15+ years ago with much lighter weight alloys(as much reduction as we could expect going from alloy to carbon).....purely for cosmetic reasons. I could immediately notice that braking effort was reduced considerably.

An important factor for comparison purposes the rims were exactly the same size and changed the tyres over to the new rims as well.

Fuel consumption, (which being a numbers person I measure constantly) did not measurably change, on the highway or in my urban use.

Perhaps rather than abuse me for whatever reason, future posters to this thread could actually find out for the benefit of all the background of the 8% claim.

Your query from the beginning was pointless as it was based off assumptions which were proven to be incorrect.

You first come up with a figure of 20kg. What were you basing that off?
You provided the first link which showed us rim sizes considerably smaller than that of the CR product. Why did you need to do that??
This alone throws your argument out as it indicates you're weren't comparing apples for apples.

You're blowing your own trumpet about being all mathematical and analytical, but you ignore the fact that you're not comparing the same rim.

When pushed you then give us another link of aftermarket rims of the similar size as the CR product. But the purpose of buying the CR rim, in most cases, is to replace your OEM product so how do you expect anyone to take you seriously after that second link you posted? Honestly, have some respect for all the people from around the world who log in specifically to read your posts.

The most NORMAL case is when you compare it an OEM rim of the same size, and the mass of a 19" factory rim is at least 14kg. I'll let you do the maths. Importantly, this throws out your argument by a fair bit now doesn't it, so don't ask us to focus on what the background of the 8% claim is if you yourself cannot get the simple numbers right in the first place.


Reading your example of changing from steel to alloy rims was entertaining, thanks for the laugh.

[sudszy]

Originally Posted by Falc'man

Reading your example of changing from steel to alloy rims was entertaining, thanks for the laugh.

No doubt I would receive a warning/banning if I persued this in the tone contributed, so I wont.

I dont see any point in further responding to anything you have to contribute here as it appears you dont have anything else in mind(or any information to contribute) other than to try and discredit myself, and rationaling looking at what I have put forward is not something you want to consider..

[Bossxr8]

Originally Posted by sudszy

No doubt I would receive a warning/banning if I persued this in the tone contributed, so I wont.

I dont see any point in further responding to anything you have to contribute here as it appears you dont have anything else in mind(or any information to contribute) other than to try and discredit myself, and rationaling looking at what I have put forward is not something you want to consider..

They have claimed 3-8%, which is more than likely based on what wheel sizes are used. Obviously a small set of rims for a small car will return lower results than a set of 20x12's fitted to a supercar. Obviously a bigger wheel made in CF will return bigger gains in weight reduction than a smaller one.

The fact that Euro manufacturers are showing significant interest in them for fuel economy reasons shows that their claims are more than guesswork.

[2011G6E]

I do seem to recall many moons ago that there were claims that alloy wheels too were lighter and would "increase fuel economy".

The weight difference should be spectacular with CF wheels...as long as they are engineered well. Also as long as people realise they are a "non-repairable" item and a throw-away if they even get a chip in them from, say, a kerbing. This creates what is called a "stress riser", giving stresses somewhere to concentrate on, a weak spot, which will eventually lead to catastrophic failure sooner or later.

The problem won't be Australian manufactured wheels...it will be wheels that are a lot cheaper and made in certain overseas countries. There have been problems with cheap large diameter alloys from Asian countries, everything from dents easily happening to busting the centers out of them.

[xtremerus]

So, will a change in driver weight from 100 kg, to one of 60 kg, see a 3-8% improvement in fuel use?
Does one passenger of 100 kg make a dramatic increase in fuel consumption?
Food for thought.

[Bossxr8]

Originally Posted by xtremerus

So, will a change in driver weight from 100 kg, to one of 60 kg, see a 3-8% improvement in fuel use?
Does one passenger of 100 kg make a dramatic increase in fuel consumption?
Food for thought.

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.