Bumper / Grill-Guard DIM (Did it Myself)

[BSMcCauley]

Traveling a lot through Montana & Wyoming as well as I-10 between Junction & Ozona, TX at night tends to have one thinking about wildlife encounters, so I already had a bumper/grill-guard design down on paper when a left front tire failure kicked me off TDC on the project about 10 yrs ago. Picked up the material and completed the bumper while the body shop was making repairs to everything else the tire tore up. I used 3" sch 40 pipe for the bumper and 1-1/2" sch 40 for the grill guard. All the bends are std weld fittings and bumper tubes are connected and set up to use as an air pressure tank. B313 severe welding procedures throughout. Plate is all 3/16" diamond plate, and the skid plate is set to direct anything going under the bumper to continue below front axle. Open spaces between all the tubes is covered with 3/4" heavy expanded metal except for in front of the headlights. Mounting to frame is 1/2" plate using factory bolt holes and center of gravity ended up being directly over the mounting point to the frame. In total, about $200 worth of material at the time. Whole assembly ended up weighing close to 400# and set the front end down 3/8" when the hoist supporting the bumper was slacked off. But the front axle is still well under rated capacity as long as I'm careful with how the bed is loaded. No front-end problems in well over 125k miles since then. I used to worry that serious front end impact will likely buckle the frame, but I finally realized this impact was likely to bend the frame anyway. Have survived deer encounters unscathed @ 45 & 60 mph and it is nice to not have to risk an accident avoiding something that steps out in front of me. Have also collected the occasional tail light from folks backing into me in the parking lot at work. :-laf Before and after pictures:

 

[BSMcCauley]

For those curious about fuel economy, my original design hit me about 1. 5 mpg. I got to remembering back to wind tunnel testing in one of my engineering classes in college where we took a model of a Monte Carlo and tried doing stuff to it to reduce the wind drag and measure the results. We tried individual modifications like taping over the side window openings, extending the back out to a point, and adding a parabolic rounded nose to the front and recording each change in drag that we observed as well as various combinations of changes. We recorded the largest single reduction in drag by taping over the bottom of the model from the front bumper to the back bumper – and we all know how much detail is NOT included under the bottom of those plastic models! Basically what we showed was that it was the air going UNDER the vehicle that created the most drag rather than the air going around the top and sides. With this in mind, I added an air dam under my front bumper that extended down to just below front axle centerline with the idea being to deflect more air around the sides rather than scooping it underneath. The next time I headed down the highway out of town, the air drag reduction was immediately obvious in the lower whine from up front indicating the turbo wasn’t required to spool up so far as before (didn’t have the boost gage yet at that point). After two tanks of fuel it was evident that the air dam had reduced drag enough to get 2 more miles out of a gallon at highway speeds, or net gain of 0. 5 mpg highway over factory setup. Of course, when venturing very far off road where either approach angle or clearance is an issue, the air dam's got to be temporarily removed, but it definately pays for itself on the highway! Attaching some new pictures, I guess after 100,000 miles of stone chips, it's about time for a new coat of paint!



PS: The valve and the fitting are for using my 12V pre/post lube pump to empty out the crankcase during an oil change.

 

[13MWZ]

Nice job. I use to own some land out by Junction, I miss that area.

 

[Midnite]

That air dam also has the benefit of increasing air flow through your radiator, increasing its effectiveness. It helps lower the pressure inside the engine compartment which is what causes the increased air flow.

Good job!

 

[Arctic Taco]

So what kind of material did youy use for the air dam?

Sounds like there are lots of benefits to that set up.