Weight reduction
 

I've heard that reducing the weight by 10% will increase the fe by 4-5%, does anyone have any data on this? Also, how much luck has anyone had with actually lowering the weight enough to make a difference. My car is around 3500 pounds so I don't know if I can drop 350 pounds out of it, I might try anyway though.

It's highly duty cycle dependent.
Sort of the inverse of aero.
Weight reduction is most helpful for stop and go.
Aero for cruising speeds.

Rotating weight is even more important for stop and go, but not easily reduced in most cases.

This is a drastic step IMO. I would start off with the small stuff first: Inflate your tires properly, tune it up, modify yourself, read up on techniques...


But here is some really really good information on how weight reduction works. It should help you out on what weight to actually reduce for the best benefit.

EDIT: forgot link...http://www.nissanclub.com/forums/200...e-modders.html

I removed the beackseat in my 94 ford aspire.

The junk weighed 40 lbs
The back seat weighed 42.9 lbs total including the rear rug, ashtray, seat belt bottoms, and rear hatch cover. (9.7 lbs)
I totaled the amount and it came to 82.9 lbs .
Hopefully That will help my MPG

Weight matters a lot in hilly country where the grade term of the road load equation is not zero.

wt/mpg
 

Society of Automotive Engineer research has demonstrated that a 10% wt. reduction would net you an average 3.8% mpg improvement.

In terms of rotating weight (wheels/tires), all else being equal (driving style) how much improvement would there be in FE? I'm looking at at wheel/tire combo that would save 4#/wheel (the more you spend, the lighter the rims, which would take years in FE savings to make up). I know most will talk about the aerodynamic efficiency of the wheels, but I think just having lighter tire/wheels will make the engine strain less both with stop/go and highway driving. The added benefit of improved acceleration/braking and looks is also attractive.

An interesting tool can be found there :

Tool for visualizing aero vs rolling resistance - GasSavers.org - Helping You Save at the Pump

or more precisely here : http://www.geocities.com/frontsidesk8er/delsolaero.xls

You can change weight, CRR, CD & FA and see how the consumption (at constant speed) varies. For me a 10% weight reduction would achieve a 3.3% reduction at the speed I drive the most often.

Have fun,

Denis.

remove everything you deem not necessary from inside the car. seats, carpet, trim, etc thats the free stuff.
if you are a guy who believes in the ends justify the means, you can get lighter tires; lighter rims, lightest ive seen is 12 pounds, replace some or all glass with polycarbonate(lexan); replace ll possible body parts with polyurethane or fiberglass or kevlar; remove the spare, and have AAA handy; switch to lighter racing seats; etc etc, you get my idea. in order to gain 4-5%, you end up spending alot of money, or time for fabrication. you decide.

Totally agree. Although you can get the semi-lightweight stuff for relatively cheap if you search hard enough. I'm down 300lbs in my second car from extreme stripping. still rockin' the stock driver seat, still have 25lbs of sound deadener to remove, haven't changed out to a smaller fuel cell, still using glass instead of poly, haven't finished removing dead weight off the front end. I'm sure I have 100lbs more I can remove. I haven't even brought the grinder out to remove random metal.

Note: ^ Not for the average user ^

Fuel is one of the most easily removed weights.
Although adding the amount every day for that day's projected use has some drawbacks. One of which I believe is evaporative emissions from the refueling process, assuming you're using a home supply via fuel cans.

1) My mileage varies from 59 mpg with a full tank to 62 mpg with an empty tank. 800 daily commute data points are consistent. 10 gallons, 6 lb / gal gas = 60 lb.
-60 lb (2.6%) = +5% mpg

2) On a certain route, with my family on board, I got 56 mpg with ideal conditions yesterday. Compare that to my 63 mpg average on that route, driving solo.
+200 lb (9%) = -11% mpg

It should also be mentioned that the more interior you start pulling out the louder road noise will be. It's obvious but the impact can be quite astonishing. I don't notice my Saturn being any louder than any other car, but my father can barely stand riding in the car. Considering that it still has all the carpet and sound deadening material, it goes to say your mileage may vary.

As almighty said, it's not exactly for the average user.

Not to mention the value of your time, or the fuel burned in making repeated trips to the gas station.

Would it be a valid weight reduction strategy to pull all the sound deadening material (all of it tends to be heavy stuff) and simply wear noise cancelling headsets?

You should probably avoid noise canceling headphones while driving.

Depends on specifics. Assuming optimal engine efficiency over your route, your car is roughly 4088 square inches which is about 2.64 square meters and supposedly has a drag coefficient of .36. At 3700lbs (200lb driver/stuff) curb it's about 16460 newtons, and assuming a typical rolling resistance of .012 needs ~198N to roll. To move through the air at 55mph or 24.6m/s, ya need, about ~352N. So... since you're at ~550N right now, shaving off 300lbs in a 3700lb car would decrease the force needed by ~3400/3700(198N)+352N=~533N, so your mileage would go up by ~550/533=1.03, aka 3%. Now, the problem is this is assuming the engine is operating at otpimal efficiency, and if it's not, which it tends not to be for most cars, then you'll see less than a 3% gain. Naturally as your average speed drops from 55mph, the gain is greater, and as it rise, it's less. On the other side of the spectrum, if you have 14" wheels available (j-yard?), you could run LRR 14" tires (rolling resistance of ~.008), and gain around 13-14% assuming ideal engine efficiency or less w/o it.

Cops around here frown on headphone use while motoring.

Just don't go too far: How to get your econobox into the 14's-A must read.

:) I love that read. Read it first many years ago, had me rolling. Certainly impressive they dropped so much weight, and gained so little time. 1674lbs from 2762lbs. That is beyond impressive, that's just insane. And gained 2 seconds and 10mph to 14.3 @ 93.2mph. I think I'll stop when the sawzall comes out. Road Rally racing needs some structure beyond the full cage.....

That car was not legal to go down the dragstrip at all! All your windows are to be up and once you start removing doors or window you must run a roll cage, even if you are running 14s and slower. If that was a NHRA or IHRA track they could or should get their sanctioning removed and their insurance cancelled.

They probably didn't run it at any kind of public event. This was a manufacturing sample with a temporary title that Nissan loaned them for testing. Typically the manufacturer crushes them once they're returned, since they can't be made street legal or insurable for a reasonable cost. SCC probably got Nissan's permission to cut this one up just for the article, since it was due to be returned and scrapped anyway.