Front air dam
 

Hi all, brand new here. Been reading for the last couple of days. What an overload of usefull information. I drive very conservative in all my vehicles including my gas hungry Suburban. I don't currently own a gas mizer but expect to again soon. I was able to break 50 mpg in a 2000 Saturn SL 5 speed with high pressure in tires and lots of coasting (forgot what you called the speed up/coast method). I drove my passengers nuts and it was fun.

I, in my limited knowledge and light amount of reading here so far, believe that the biggest (changeable) factors in increasing economy would be weight, frontal area, drag, and rolling resistance (both mechanical and tires).

I'm not quite willing (ha ha, yet) to add a boat tail or pointed front end on my car and (at this point) do not want to add an entire underbody with plasticor. I am considering wheel skirts for the rear wheels as they can remain flush with the body.

My initial question then is two-fold..

1) Is an airdam on the front worth the additional frontal area if it moves air around the car vs going under it in the "dirty" high drag underbody?

2) Is there enough value to do sections of the underbody with plasticor if I don't do the entire area under the car? I mean are there areas that could be done a little easier, especially certain areas that are higher in drag ("dirty") than others?

1. Yes, because on most cars it is not "adding" frontal area- it's simply pushing that same air to "cleaner" portions of the car (sides, not underneath).

2. Generally we say if you have an air dam you don't need to do belly pans. The former takes much less time and effort for nearly the same result. Then again, a belly pan will be easier and more effective on a body-on-frame vehicle than on a unibody.

Buy a roll of lawn/garden edging and attach that to the bottom of your bumper. If your Suburban has the stock air dam already, add the edging underneath it, as the stock one isn't deep enough (I've studied the parents' Yukon).

Weight is hard to shave off in meaningful portions, and it can cost a lot. Get lighter wheels if possible, and remove the spare tire.

Frontal area is VERY hard to shave off. Deleting the mirrors and roof rack and installing lowering suspension are about all you can realistically do.

Aerodynamic drag is HUGE. My Ford Probe got 46% better highway MPG with JUST aero. 41mpg over 28 EPA. If you're going to put your time into something, put it into aero.

Rolling resistance is also important. Get thinner oil, different trans/diff fluid. There are threads on this. Tires can get expensive, though 10% improvement with LRR tires seems to be normal. And yes, whatever tires you have, pump them up to max sidewall!

I'm moving to Detroit in a couple weeks so if you need a hand don't be shy :)

Cheers!

PS- You'll be lucky to break 20mpg with a Suburban.

speed up coast down method has 2 familiar names Pulse and Glide and Burn and Coast.

If your in the suburban and air dam would help, but in the Saturn it probably wont do much. The biggest thing is to look level with the lowest part of the bumper and see if there is alot of parts in the way or not.

If you have a fwd car a belly pan would help the most if extended just pass the tranny without an airdam. As wear with a rwd the axle and driveshaft cause more drag than the rear setup of a fwd were a belly pan would benefit more

the only problem w an air dam is that it has to almost be to the ground...... and then you have scrapping issues.
I had a body kit on my Q45 and stock suspension and banged the fron edge ALOT!!!

Look at my thread in my sig on the belly pan. I ended up with just a front and rear.

Yes and thanks to all the above.
I kind of figured the belly pan area on a little front wheel drive would do the most of an underbody cleaning. I understand the futility of removing much weight short of the spare, lighter rims, etc. Would love to strip a car down to zero interior, lexan side windows, tiny battery, whatever to see how light I could get it. For the weight loss freaks there is quite a few pounds of sound deadener under your carpets, in trunk, on firewall, etc that can be stripped away.

I'm not really considering any mods to the suburban anyway. I don't drive it that much, rarely fill it to check mileage, speedo is off from tire size, etc. I just drive it easy when I have to and do better than most do with the big trucks because they have big feet. Best way to save gas on that baby is leave the keys on the hook!

I'm looking for maybe a 1 liter metro if I can find one without too much underbody rust in salty se michigan. I may go with another single cam saturn s series. I was mighty impressed how well it did under my uneducated hyper-mileing.

Things I would likely do would be air dam, lower ride height, remove passenger side exterior mirror, skinnier tires, higher inflation, lighten up trans oil, possibly clean up front end with some grill blocking, possible belly pan, kill off un-nessecary evil weight adding passengers, dump spare tire, etc.

A few of the tiny tips I've read here that I liked and will utilize are parking on thru spots, find gravity parking spots, trans fluid viscosity.

It gets to be quite a game and more to beat personal bests than the pennies saved per trip. Lots of light hearted fun too. Drove my kids nuts last summer.. "no! can't put the air conditioning on". Ha, pulse and glide even bugged them.

ooh, I'll be bypassing the power steering also, not needed for me in small light car. Thinking about playing the alternator game after reading a bazillion pages on that post.

Anyone consider the weight of a full tank of gas and simply run on the bottom half of the tank for a few fill ups and just keep track of gas added and fill up beginning and end for average?

try searching....
there is a thread on sound deadening material just this month.

also info alread done on the 1/2 tank therory