Replacing parts with lighter parts to save weight?
 

I was thinking, if I had a '96 honda civic, in order to save weight, would it be cost effective to replace things such as the Windows (except windshield), Hood, trunk and doors with lighter materials?

Carbon fibre is quite expensive, but fibreglass should be cheaper, also Fibre glass weighs less unless we're talking lb for lb strength. So I was thinking I could replace at least the hood and trunk (Bonnet and Bootlid) with fibreglass and or carbon fibre parts. I'm not sure if they have this but I would if I could replace the fenders with fibreglass and or carbon fibre as well. For the Windows, I'd possibly replace them with something like Perspex. The only thing I'd worry about for the Perspex is how likely am I to damage it and how much would it cost. I'd try and store all the original OEM parts in the event that said replacement parts get damaged or whatnot. They also make a carbon fibre door but I don't know how much that would cost nor how it'd impact safety. Would going with an aluminum door be possible? And would it add a significant amount to weight savings?


How much does the Hood, Trunk and windows (including rear) weigh individually?

Just read about Lexan, maybe this would be a better alternative to the perspex? One reason I'd want to use the lexan is because it'd be stronger than the glass, making breaking and entering into my vehicle more difficult, not to mention safer for me. I also don't care too much about tint.

I think the cost of doing something like that would be very significant. also I have heard (and this is just what I have heard) that it takes 100 lbs of weight reduction to get .1 second better in a qtr mile. I know we aren't racing but we use a lot of racing technology for FE.

also of note: I have a friend that rides to work with me. he weighs 220ish lbs and I don't notice a difference in gas mileage when I drive alone vs when he rides.

I think there are long term advantages to weight reduction but you would have to lose a lot of weight and it would take a while to recoup the money you put into the weight reduction.

just my opinion

How often do you ride with your friend? Has he ever been with you through an entire tank of gas?

Gym membership : $35 - $80/mo, Personal trainer, $20 - $40/ session

Weight loss is expensive and a lot of effort... ;)


I have a friend that is 450 pounds. I always think what kind of mileage increase he could get by loosing weight. When he rides with me in my truck he is so large sometimes he has difficulty buckling the seat belt.

Now, to be a bit more on topic, there is a bunch of crap I never use that's just thrown in the back seat, and in the bed of the truck. I figure I could easily shed at least 200 pounds from the vehicle by taking that stuff out and putting it in the garage. Its just the problem of finding time to do it.

-Jay

I don't know the actual costs, but for CF replacements for fenders and hood, you'd be beyond $1000 invested, and only save 50-60lbs, if that. Fenders don't weigh much, being so small. And the structural supports built into a CF hood only allow for 10-20lbs of reduced weight. A CF hood for my GP is only 15lbs lighter, yet costs $650. Even tubular control arms save 3lbs each. I remember reading someone decked their GP for drag, completely stripped (bare metal inside, lexan windows all around), with lightweight parts swapped. It weighed ~3150lb with a 200lb driver, vs me and my GP at 3520lbs. Extreme example, not worth doing on a daily driver.

There are better ways to invest in your car than expensive weight reducing parts. Areo-mods are more likely to increase FE than weight reduction.

as far as my comparison with and without my friend in the car, I have a scangauge and I have one of the displays set at trip mileage and that is what I am basing it on. I drive 20 or so miles each way to work so it is a descent comparison. I haven't done complete tanks both ways but the difference is so minimal from the days that we don't ride together that I didn't worry about that experiment

one day he jokingly said something about weight reduction by taking out the rear seat (I think it is less than 30 lbs) and I said if I could just get the 200lb weight out of the passenger seat, I would be doing even better. He didn't think that was funny.

my mileage may suffer because he rides with me but we carpool and take alternate days. I went from filling up every week to just about two weeks between fill ups.

I would think you would gain more (dollar for dollar) by blocking your grill and working on aero than replacing body panels. if you look at racers, they do weight reduction last because it is the least bang for the buck in my opinion

I replaced my Civic's hood with a CB hood. cost me $700 before shipping. looking for a CB trunk lid that's a little cheaper but they are still quite pricey at $500 to $600.

it can be done and lighter cars do get better FE but at what cost. save in gas but it will take a while to realize the benefits.

there was an article about why there wasn't a 50mpg car today and ford said they could make a focus do that easily. they went through all the details about aluminum frame and aluminum body panels all the electronics to make it happen but he finished the conversation by saying the car would cost around 60k which most people wouldn't spend on a focus regardless of the mileage.

I think the idea is the same.

not sure how much you care about looks, but don't forget to factor in the cost to paint the parts.

So if weight is a minimal factor, then why do people try to justify the Civic VX getting better mileage because its curbweight is 2094lbs vs 2313lbs of the Civic HX? Also why does the HX weigh more than the DX coupe which comes in at 2262lbs?

I think that curbweight has a greater factor on city driving MPG than highway driving as I've seen quite heavy vehicles get about 30-34MPG on the highway but 20mpg in the city. At 1000lbs differences, it's really about gaining momentum (city driving) and maintaining momentum (highway driving). It'd be interesting to see a comparison of two vehicles one weighing 6000lbs and one 3000lbs being the same in every way except weight and seeing what kind of highway MPG they get.