Carbon Fiber/Fiberglass

[Xist]

Originally Posted by redpoint5

If you want to save weight on doors, get a Jeep.

Will the weight advantage exceed the aerodynamic penalty?

[bobdbilder]

If you ever tried cycling and moved from Aluminium Mountain Bikes to Aluminium Road Bikes, you would feel a very big difference in terms of distance and speed that you could generate.

Having said that, its not just how much weight you throw out, but where that weight is matters. If you are trying to reduce weight, give priority to the furthest from the center of gravity of your car. As you drive especially in stop and go traffic, your car will dip in front during braking and tend to load the rear wheels while accelerating. The engine has to develop enough torque to pull those far away masses. Repeat this for every time you pull up to traffic lights.

Race cars may want to relocate their batteries to the back for a balanced weight distribution in corners, but it does not do anything for fuel consumption. Since its a race car, they don't bother. The battery would be better close to your center of gravity. Ever notice why its located to the opposite side of where the driver sits? That's to offset the weight of the driver.

And if you wanted Ti or Alu bolts, try http://www.torontocycles.com/Selling...num_Bolts.html Those that's in UK could try ProBolt who makes these for motorbikes http://www.pro-bolt.com/ they are used to be called Tasty Nuts.

[RustyLugNut]

Originally Posted by niky

In the end, it's less the ease or difficulty than it simply not being worth it in terms of weight savings, if the end-goal of those savings is merely fuel economy.

At least if you look at it from the perspective of Return On Investment. But, just like the speed racers out there, Ecomodders look at a fractional gain in mileage more enthusiastically than others. From that perspective, carbon fiber construction is utterly worth the cost and effort.

I have a pair of large Cummins powered Dodge diesel pickups. The first thing other diesel pickup owners ask is "what have I done to it"? "How fast does it go"? "Can you roll coal"? Then they tell me about the 1000 dollar tuner, the 2000 dollar turbo upgrade and then the 3000 dollar injector set followed by the 5000 dollar transmission.

If someone on this forum has the inclination and skill to fabricate a set of body skins out of CF that helps him gain 2% more fuel mileage, I say "good for him/her"! That level of dedication and enthusiasm matches that of the "coal rolling crowd" and in many respects is more difficult to achieve.

Old Mechanics ground up build for a super mileage trike, Neil Blanchard's super slick people mover and pfgpro's 10 second, 40 mpg creation - none of these will ever meet the required return on investment some people may ask for. But for the builders and those who's enthusiasm runs just as deep, it is a win.

[niky]

Oh, I appreciate the thrill of the challenge... it's just that I don't see the weight savings in terms of doors as worth it... not until you've done all the other stuff mentioned, first.

[oldtamiyaphile]

Originally Posted by bobdbilder

If you ever tried cycling and moved from Aluminium Mountain Bikes to Aluminium Road Bikes, you would feel a very big difference in terms of distance and speed that you could generate.

Except that weight is actually a minor part of that comparison. I've got a MTB that's as light as a low end road bike and it's very near as fast. Most of the difference in road vs MTB down to riding position (aero - but also power generated), gearing (taller gears on the road bike), and the narrow high pressure tyres. My brother has an MTB on high pressure road tyres and although it's a bit on the heavy side, with aerobars it's really fast, but not as fast as my 7kg aero framed carbon bike

The time weight most makes itself felt is climbing hills, which is where ICE vehicles and human powered differ. More weight in a car means you'll be running closer to BSFC, while humans don't like 80% load very much

[bobdbilder]

This whole weight thing is very much dependent on how you do your daily drive. It has a lot to do about momentum.

The bigger mass is only good if you travel on highways most of the time such as in Australia, the US and the Autobahn. The heavier load means that you're having lots of momentum and you need to pay less attention with the throttle to keep the speed in the coasting range. You would then choose bigger tyres for higher gearing and bigger rotating mass. Plus this is where aero mods come to play as your speed exceeds 100km/h or 60mph

If you travel in stop and go traffic most of the time like in most Asian cities, then that mass becomes the enemy. You need more energy to bring the beast up to normal coasting speed and then braking. Repeat this for every stop or traffic lights. In which case a light weight car will always perform better and you'd stick with 15in wheels.

[Xist]

I read about a road bike so light that they actually needed to add weights to it for competitions. What is the point? I guess that if you add five pounds below the crank you would have negligibly better center of gravity than a bike that originally weighed that much, but so what?

[redpoint5]

Originally Posted by Xist

I read about a road bike so light that they actually needed to add weights to it for competitions. What is the point? I guess that if you add five pounds below the crank you would have negligibly better center of gravity than a bike that originally weighed that much, but so what?

That's done in most racing sports. Jockys often weigh under the minimum weight for a horse, so they will add ballast. There is an advantage to choosing where weight will go, even if it's small.

...and I was joking about running without doors on a Jeep. There is no chance that CF door fuel savings could be measured. It's such an insignificant place to look when considering how to improve fuel efficiency.

I've linked this before, but this guy went to extreme measures to reduce vehicle weight, and still didn't go with CF doors.

[Xist]

RedPoint, I had not seen that before, that is crazy! He jettisoned 793.2 pounds!

I linked this before, Colin Furze was put in a contest against someone calling himself The Modfather and I mostly watched because from the beginning they showed that Furze was going to remove the roof, pillars, glass, and body. He just wrapped it in shrink wrap, so he had a tiny frontal area, but horrible aerodynamics!

Also, I believe that the car was RWD without much weight in the back.

http://www.youtube.com/watch?v=G_Xewh0BNlY

I doubt that any of us approve of only purchasing three gallons of gas at once, although that would last many on here a week or more. Actually, I have many weeks like that, but I have not started working at that place fifteen miles away yet.

I wonder how much louder his car is now. Having studied Speech and Hearing Sciences, I regularly pull out my sound meter app and my car was noticeably louder last night when I folded down my seats.

[bobdbilder]

3.4 gallons (US) for me. That's approximately 23lbs? The pump station is just across the street from my kids' school. For daily commute of my kids to school about 20km/13mi one way. Lasts me about 2-3 days. We live on the fringe of the city where property tax is lower . Only recently made change to my route to reduce traffic light stops from 3 to only 2 and I get mpg gain from the mind 20s into the low 30s. Could have been better if my kids had a better sense of urgency

I have greater reason to be thrifty. Been out of a job for 8 months now and been living off the compensation money. Not much, just 10x my previous monthly take. So stretching money is not a hobby for me. Its a necessity.