ARB Bumper, air dam? (1 Viewer)

[PDPerry]

Getting ready for the annual summer trip from Sacramento, CA to Winter Park, CO and back.

Always think of this while tooling-along and watching the scanguage read-out the rapid drop in MPG whenever the speed gets above 70mph...

Has anyone configured an air dam for their ARB front bumper?

I figure that for highway travel, moving some of the air to the sides rather than underneath a lifted and - aerodynamically - dirty undercarriage might improve the MPG a hair. And those hairs can add-up on a 1,000+ mile each-way trip.

Wondering which material to use and/or if this is just some sort of pipe dream...

 

[Manhattan]

You're not alone - I've thought of this... going back to my FJCrusier. When, looking at the front of the truck, you could just about see the tops of both front tires... that's some pretty bad aero. There was a year/generation Jeep Grand Cherokee that had a removable chin spoiler. I always thought that was brilliant.

But, I think your final words summed it up - a pipe dream. Moving that much air at 70+ mph would require some engineering and some sturdy material. Very doable... except that I bet it'll fall into that "Those who can do it, don't care about it. Those who care about it, can't do it"

 

[geanes]

Wait......these things get above 70mph? My 98 LX seems to average 13mpg no matter how fast or slow I drive it. I would be curious if things like the Slee or BIOR underbody panels might improve the "aero" and mpg. My wife's Hyundai Sonata Hybrid (the absolute polar opposite of an LC, I know) has the entire bottom covered by panels for aero efficiency.

 

[jLB]

Wouldn't the air dam just add more frontal area, giving the aerodynamics of an even larger "brick"?

 

[geanes]

Wouldn't the air dam just add more frontal area, giving the aerodynamics of an even larger "brick"?

Depends. The "dam" would be engineered to redirect airflow efficiently and reduce turbulence as found around things like suspension components and even wiring. These components cause what's called a Karman Vortex Street which creates drag = bad. Splitters (as their known in the racecar world) redirect airflow for maximum efficiency.

 

[jLB]

Depends. The "dam" would be engineered to redirect airflow efficiently and reduce turbulence as found around things like suspension components and even wiring. These components cause what's called a Karman Vortex Street which creates drag = bad. Splitters (as their known in the racecar world) redirect airflow for maximum efficiency.

Yes, I understand this, but aren't we talking about a sleek sports/race car that sits just a few inches off the ground.

Aren't we talking about a 3 ton SUV w/ the aerodynamics of a brick? Probably lifted (exposing more wheel/tire), w/ wider tires and an ARB bumper (less aerodynamic)? My ARB sits about 24" off the ground, or roughly 10sqft of frontal area underneath an ARB bar.

 

[PDPerry]

All the big rigs now look like race cars w/ dams, skirts, boat tails, etc. They look to have about 1" of clearance.

geanes has the right idea w/ adding those underbody panels. Most of the newer cars these days look to hide their bellies with sheets of plastic.

But, yea... @ 70mph there's prolly a whole lot of air mass that needs to be moved to the sides pushing against what needs to be a pretty substantial dam to do any good.

So if I try to fab something, best bet would be for a stiff type of rubber. At least if it fell off, it'd just be like running over a tire gator...

 

[Manhattan]

Yes, I understand this, but aren't we talking about a sleek sports/race car that sits just a few inches off the ground.

Aren't we talking about a 3 ton SUV w/ the aerodynamics of a brick? Probably lifted (exposing more wheel/tire), w/ wider tires and an ARB bumper (less aerodynamic)? My ARB sits about 24" off the ground, or roughly 10sqft of frontal area underneath an ARB bar.

Size is irrelevant. The Concord was enormous, but really aerodynamic. The idea is to clean up the surfaces... suspension, axles, springs, etc... this is the worst type of frontal area. Creating any type of dam - even a flat/brick shaped damn would be a huge improvement. But, creating a slightly pointed dam to split and redirect the air would be ideal.

BUT (and it's a huge but)... any air damn would A) Likely look dumb as hell. and B) Probably take 100,000 miles to recoup the cost (design, fab, etc.)

 

[jLB]

Size is irrelevant. The Concord was enormous, but really aerodynamic. The idea is to clean up the surfaces... suspension, axles, springs, etc... this is the worst type of frontal area. Creating any type of dam - even a flat/brick shaped damn would be a huge improvement. But, creating a slightly pointed dam to split and redirect the air would be ideal.

BUT (and it's a huge but)... any air damn would A) Likely look dumb as hell. and B) Probably take 100,000 miles to recoup the cost (design, fab, etc.)

Assuming the same medium [air] and speed, aerodynamic drag is a function of frontal area, surface texture and shape. A land cruiser's "2 stacked bricks" shape is not the most efficient aerodynamic shape and the height/width adds up to a substantial frontal area (for its size) which doesn't help either.

(The concord wasn't shaped like a pair of bricks, and for its size had a relatively small frontal area)

 

[Evan Kapel]

We drive Land Cruisers for other things than
good mileage. After driving my 60 series for 30 years, I learned to take it slow and drive the backroads, enjoying the
beautiful country we are lucky to live in. I now drive a 100 series but keep the same attitude, concentrating on the journey
rather than the destination.

 

[PDPerry]

We drive Land Cruisers for other things than
good mileage. After driving my 60 series for 30 years, I learned to take it slow and drive the backroads, enjoying the
beautiful country we are lucky to live in. I now drive a 100 series but keep the same attitude, concentrating on the journey
rather than the destination.

Agreed that getting there is half the fun. And our shared familiarity the notorious w/ LC mileage for me comes from 25+ years of LC ownership (one 62 series and two 100 series).

But if I could gain 1 mpg over the course of a 2,000+ mile trip getting there and back (say an avg 15 to 16), that's a whole $25 more in my pocket!

Hmm, that's not much, is it? Darn!

Well... Like you said. It's the journey! Building something that makes Mister Bubbles a wee bit more efficient is fun. I'm just wondering if a fellow Mudder had taken this trail already before I go too far on my own.

 

[Muddy Bean]

If you want to drive and trail ride a tank, own a Land Cruiser and stop worrying about MPG.

If you want to drive and trail ride an economical albeit possibly unreliable vehicle, buy a Jeep Cherokee EcoDiesel.

But you can't have both.

 

[abuck99]

Where are you going to store your aero kit when you get to where your going?

Budget an extra $200 for fuel, pin it and have fun on your trip. Worry about other things like .... double IPA, or white IPA in the cooler, Carneros or Sonoma Pinot with your campside steak.