new '04 suburban. coroplast? hood scoop? air dam ?

[abefroman57]

just got a 2004 suburban with 197,000 miles on it. i drive 120 miles per day. I'm getting 18 - 19 on the highway.

I want to try a belly pan - does anyone sell one? where can I buy coroplast ???

I might also want to try a front air dam, filling in the foglight holes, side skirts (i.e ground effects ?)

would a lightened hood and hood scoop help with weight and engine cooling (getting the hot air out ?)

Also, I'm very interested in trying to get rid of the vacuum created off of the back of the suburban. I'm an engineer and I remember in a fluids class I took, I calculated that the drag created by the vacuum off of the back of a square vehicle is a large portion (30% or more) of the total drag on the vehicle. I'm looking for some type of spoiler that will direct the air coming off of the top, sides, or underneath of the back of the suburban into the space where the vacuum occurs. If you direct air into this area, you break up the vacuum and reduce drag.

anyone done this ? I'm going to remove the cross braces off of the roof rack and maybe see if I can modify one of them to direct air downward. I'd like to install it on the rear of the rack.

any suggestions about all of this ???

cheers

[Ecky]

You should hit up the aerodynamics section. I recently made a partial pan for my Honda. It's a relatively common modification and you shouldn't have any problem finding some information on the topic.

I probably won't be the first to say that you might be better served by getting a more efficient vehicle, if it can suit your needs. 120 miles per day comes out to $8000 in gas per year, which means the break-even point of something like a Civic or Corolla would be well under a year, even if you kept the SUV for hauling stuff.

EDIT: As for the hood scoop, that's likely to be counter-productive. Increasing intake air temperature can give benefits to mileage, while cooling it off may rob mileage but give a small amount of extra power. Taking weight out of your vehicle will help more in the city than on the highway, but your break-even point will be pretty far in the future because the gains are not large, especially if you're doing mostly highway driving.

EDIT2: Check out the stickies in the top of this section too, specifically http://ecomodder.com/forum/showthrea...-mpg-5170.html

[abefroman57]

well, I also have a 2001 mazda miata, but it only gets 24 mpg. I'll probably drive both.

[Ecky]

That's pretty surprising that the Miata is rated so low, but your first and best modification is to get some instrumentation to see what you're *actually* getting, instantaneously. You might be surprised to find the Miata is capaible of much more, with instrumentation. Since both of your cars are new enough to be OBD-2, a Scangauge or Ultragauge is your easiest option. There are also some $7 bluetooth Elm327 adapters on Ebay that you can pair with a phone or tablet, but they tie up another expensive device.

Food for thought, a '98 Civic HX is rated for 39 highway but members on here regularly exceed 50mpg (sometimes more than 60mpg) in these cars. The slightly older VX trim is capable of even better economy, while also being a roomy hatchback. Records have been set in the even older CRX's and first-gen Insights in excess of 110mpg. I can understand attachment to vehicles though - I'd be pretty well served getting rid of my Del Sol for something larger and more efficient, but it has a lot of character.

It helps to like what you drive.

[oil pan 4]

No you can not buy an air dam or belly pan you have to make it.
The fog light hole block offs might be available off another GM truck front end, but you might have to make that too.

For somethingas big as a suburban dont do a belly pan, too much time, material and heat to reject coming off the engine and exhaust. A big air dam is the way to go, I put a 9 inch air dam on my old suburban and picked up around 1 full mpg.
The thing that disapates the rear low pressure sone is called a diffuser.

As stated, remove weight from the vehicle. Do you need that 3rd row seat? If no then take it out, thats up to 200 pounds right there. On a vehicle that size each 100lb removed will net a 0.1 to 0.2 mpg improvement.

Also do a search, just search "suburban", ignore "35mpg suburban" look for the poasts titled "my beast" and "86 suburban" I would link them but cant copy and paste with this tablet I use.

[mcrews]

Look at upsizing on the tires to lower the rpm at cruise.
This is tricky on trucks because at this point the past owner may have already upsized for looks.
Here is what to do:
get a scangauge (see link in my sig)
find a straight flat 10-15 mile stretch of freeway to aba test.
drive 50,55,60,65,70,75mph
record rpms and mpg
now yo should know the sweet spot in rpm for your best mpg.
upsizing your tires will lower the rpm at a given mph.

[elhigh]

I know you just got the thing, but consider its intended mission profile. Do you need that much truck? You're taking a huge amount of steel for a cross-country tour every day just to get back and forth to work; unless you're dropping five kids off at school every day I would strongly consider ditching that big thing in favor of something smaller and much more economical.

And even if you are taking five kids to school every day, you can get into the middle 20s for fuel mileage just by getting a minivan. And then ecomod that.

[mcrews]

additional thoughts on upsizing:
need to increase diameter at least 5% to have any real mpg gain.
Don't increase rim size, only tire diameter.
a taller tire 'may' only weight 1-3lbs more so rotational weight increase is really insignificant
Need to do atleast 50% freeway driving for the upsize to work
The upsize really doesn't harm intown driving because we're driving slow anyway

[freebeard]

I am also surprised at the mileage a Miata returns. I trust the Suburban is right-sized for your needs.

Scanguage ==> Knowledge is power.

Also, I'm very interested in trying to get rid of the vacuum created off of the back of the suburban.

How much pain are you willing to take on? 4 feet more overall length? 2 feet? 8 inches?

A bug deflector isn't going to move the air needed. You could look to the trick they use on big rig box vans:



Everybody likes coroplast, except me. Look for Polymetal/Alumipanel/MaxMetal type aluminum skinned thermoplastic sheet. I've only worked with samples, but I haunt the local recyclers waiting for a piece big enough to do at least a diverter/front partial pan.

It's 3 or 6mm thick with .007" skins, is about as stiff as 5/8 plywood at 1/10th the weight. It's sold for signage and used for the big billboard sized wings they put on dirt-track circle racers.

[Xist]

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