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Average improvement for two trips with the new front foil: 8 percent gain. That is huge in the aero-mod world. Handling effects are also noticeable with in-line front end stability making the drive less tiresome; attached airflow over hood and windshield evident in rainstorms as rain scoots over hood and windshield reducing need for wipers and aiding wiper effectiveness at speed; quieter cabin; headwind and crosswind pushing effects are even less noticeable; engine runs cooler (which may have been a bigger help than I realize in the 107 degree with strong headwind return trip, as she could only pull at 70mph without pushing toward overheating). All the mods combined have dropped gas used from 42 gallons (and up to 50 with variance of headwind for 3 to 3.5 tanks of 16 to 17 gallons), down to 30 gallons ( 2 tanks of 15 to 16 gallons). The math says we have 40% improvement at the low/average end.
The high end gain of worst to new average is 66%, and those worst are from headwind without the mods, and the mods seem to mitigate them.
We could tweak that with adding All Terrain tires that I run at 30psi that coincided with my aeromods, over un-modded with All Seasons that I ran at 32-34psi, which the industry estimates an mpg loss of 3% with matching psi- so maybe 4% mpg loss for the A/T tires. So the actual gain could be adjusted up to 44% at the low end, and here is where I question reality…(66% + 4%) 70% gain in strong headwinds.

An aerodynamic front end on a truck isn’t a concern for manufacturers because the back end of the truck is a giant brick that drags backward in destabilizing alternating vortices. The design response on new trucks is a massive square and flat front end that pushes a giant wall of air much larger than the truck itself, utilizing the width and length of the truck to overcome stability issues for the rear end. The Tesla Cybertruck is the only truck that created an aero solution to the rear of the truck, and so also has an aero front end- a front end that augments the solution of the rear. My previous mods stabilized the vehicle at high speed, and increased mileage by an average of 50%, but didn’t address airflow from the front bumper to the windshield.

New aeromod concept: 30″ x 7″ platform with seven airtabs on front Shrockworks bumper.
The airtabs create rooster-tails of entrained vortices that rise 3 to 4 times the height of the tab- so about as high as the floodlights and angling back/up to soften the bumper’s tube risers and the flow over the hood. The black tabs at R are from the prior mod, and stabilize air at the front wheel wells/ tires.
The tabs are just behind a run of pipe- the round edge rolls the air to the tab, rather than leading with a hard thin edge. The underside of the pipe rolls air under and stalls it below. This is an important pressure variant for front end stability.
The multiple wedges below the platform are for more than structure, they also structure the ramming/stalling air and stabilize the dead air pushing in front of the bumper. The platform without the tabs is a small wing, with the tabs it is little engine of airflow. The five black tabs under the truck are from the prior aeromod, and structure the “dirty air” below.
Cardboard mockup.
I had thought I’d use the D-Ring holes, but decided keep those clear for the D-Ring instead.
I’d thought a wedge would be best, then reconsidered the air stall v lift and went with a modified wing to increase the airflow stability on the airtabs.
The Greenest truck you know may be this Supercharged V-6 2003 Nissan Frontier with over 150,000 miles: with Danger-Mods.

Aeromods continue to deliver.

The manufacturer’s best highway mpg is 17mpg, which I could only rarely hit with tailwind in the past.

Return trip from Great Falls to Bozeman (271 miles / 11gal) saw 24.6mpg; this is 44.7% over the 17mpg best.

The trip out was a terrible headwind for 130 miles of 80mph; old mileage in similar headwind @ 80mph was 8.6mpg, this trip saw 13.8; a 60% increase.

The real number to consider is a comparison of the real actuals of mpg average improvement. Now 34 gallons for 685 miles @ 20.14mpg (Great Falls (plus 100 miles of xtra ranch trips) to SLC. Old was usually 45 gallons / 588 miles SLC to Great Falls @ 13 mpg.

The ratio of improvement from 13mpg to 20.14mpg is 55%. Two tanks of gas with an improvement of 55% proves out the third tank of gas no longer stopped for.

Let’s review the aeromods the truck gained over the winter:

Remember this shnizzle winter project? My aero-upgrades: enclosing the wheel wells and center plate.
Adding vortex generators making entangled-air-current providing “clean air” under the truck, and filling all air gaps with black tight-cell foam held in place with rare-earth magnets.
Vortex generators to stabilize airflow at the front wheels.
Magnetic/removeable vortex generators that I created at the line of the windshield (I also placed them forward of the rear-view mirrors), and Air-Tab vortex generators along the rear line of the shell, and a stubby radio antenna.

The drive to Montana has “varying terrain and conditions”. 5 mountain passes of varying thousands of feet elevation gain and drop, portions of 80mph interstate, and 65 & 70mph blue highway. Conditions include wind/gale lasting hundreds of miles from singular or varied direction- so a tailwind has given the unmodified supercharged truck it’s maximum expected mileage of 17mpg on the 65-70mph sections, while it usually runs at around 15mpg in still air. A supercharged engine gives maximum performance at all times, running at a matching RPM to Speed; the only variance is how much gas it takes to maintain that speed. At 80mph mileage plummets; with a tailwind getting around 13mpg, and with a headwind 11 mpg. I was expecting an at-best improvement of around 5%, which is what adding a super-sloped aero-shell can do; essentially the shape of the Tesla Truck.

The best mileage by manufacturer is 17mpg, boosted to a best now of 20mpg: 17% gain. This means 1/3 less stops for gas, or down to two 15 gallon stops for a 19 gallon tank instead of 3 stops (vs an improbable best mileage two- fill-up trip with 16/18 gallon fill-ups with the fuel light on, sometimes for tooooo long). One less stop for gas shaves about 1/2 hour off the trip, our best time ever in the past for this route was 9 hours. This past trip, with a bit of holiday weekend traffic 100 miles in and out of Yellowstone’s west gate, was 9.5 hours, and would have been 10 hours. Along with shorter time and less fuel, is the amazing stability at speed. There is no sense of sidewind/headwind push, no semi-trailer blow-by, with exceptional in-line tracking and much lower cab noise. This is due in part to stabilizing the nose of the truck by reducing lift from the high/open Shrockworks bumber, but also due to Fluid Entrainment provided by the vortex generator AirTabs along the rear line of the shell. The amount of horsepower available is greatly increased: sailing easily over all the mountain passes, and the ability to jump to passing speed is a bit giddying. A big debate is out there on supercharged engines vs turbocharged engines, and I now I know the advantage of no turbo-lag when punching it at speed: which is also a safety issue, just at the higher end of performance. (special thanks to Julian Edgar for aerodynamic modification discussions on you-tube)

Salt Lake City to Idaho Falls with 20mph+ headwind: 210 miles at 80 mph / 15 gallons : 14mpg. Old/11 to now/14 = 27% improvement. . 400# load in bed, plus two adults, one dog, three cats. (capacity is 900#)

Idaho Falls to White Sulphur Springs: 278 miles at 65-70mph / 15.3 gallons : 18mpg. Usual Old/15 to now/18 = 20% Lighter headwind and 400# load

Return trip with 250# load, same passengers, and still air through the first half of trip, with tailwind later. Lets see: Monarch to Bozeman: 140 miles at 65-70mph / can’t give straight number as filled up in Great Falls and drove around the ranch, but it looked like 20 mpg?. nutz. can’t be right.

Bozeman, MT to McCammon, ID: 270 miles / 15gal = 18mpg. (65mph/144miles, 70mph/53miles, 80mph/74miles). Usual Old/ 15mpg to Now/18mpg = 20%. Best Old/17 to Now/18 = 5% At the end of the 65mph zone we guestimated 20mpg, and best to best mileage of 17 v 20 is 17% gain, normal to now is 15 v 20 @ 33% gain. McCammon is the farthest ever travelled on a tank of gas from Bozeman. Usually we stop in Idaho Falls <74 miles prior>, and ONCE with a strong tailwind the entire way we made it to Pocatello <51 miles past ID Falls>.

McCammon, ID to SLC, UT: 140 miles @ 80mph (mostly)/ 9 gallons : 15.5mpg with tailwind. Best Old/13mpg to Now/15.5mpg = 19% (half tank remaining, we usually get home with the fuel light just coming on, a 1/4 tank at best, or having had to fill up outside Ogden).

How does all this mpg play out at Blue Highway speeds? Best Old (17) to Avg Now (18) @ 5%. Avg Old (15) to Avg Now (18) @ 20%. Avg. Old (15) to Best Now (20) @ 33%

How does all this mpg play out on 80mph Interstate? Headwind Old (11) to Headwind Now (14.5) @ 31%. Tailwind Old (13) to Tailwind Now (15.5) @ 19%.

Quite a few additional aero-mods: let’s look at the nubs along the roofline.
The windshield’s transition to the roof is a major point of lift/drag. Connecting airflow back to the truck is the issue. These rip at-speed above the windshield-stalled air, activating the airflow above the truck mixing out the stalled/reversing air. Big pickups sometimes have a forward jutting roofline “visor” with slots acting like a front wing, arresting the upward flow and directing it over the roof. This is my removable innovation for a similar result. >update= we had a slushy snow of a few inches that froze overnight, then used the truck for a few errands with the ice/snow on the top…about a foot behind the nubs the snow/ice was obliterated by the connective airflow, with a bit of a “windfence” roll of snow just behind the nubs. So it works!
These are special magnets with rubberized feet for cars, used for applying vinyl car-wraps. I cut the handle down to just emerge from the area of stalled air, and shaped it to cut into the air at speed above the truck and spin it down to reactivate the stalled airmass. I hoped it would keep the air flowing far enough to jump from the cab to the shell, and it seems to have done so as the air-noise from that gap is gone.
The line at the windshield is complemented by the line of Air Tabs at the back of the shell.
These little gizmos were created with Nasa and the U.S. Department of Transportation back in the 1980’s for Semi-Trailers. Each one creates a paired vortices spinning in unison toward each other. Placed forward on a vehicle they create connective surface airflow, acting both as a lubricant against stalled air or “dirty” air (weird flows created by forward movement, tirespin, engine heat, etc). Placed at the rear edge they help create a clean break for air from the square back end, helping lessen lift, and also interrupting the pocket of drag and stabilizing the rear end. This is through the physics of Fluid Entrainment: how a Dyson fan, after accelerating air by creating a low pressure area, entangles air at the outside periphery of the hoop end allowing air to “blow” past the ring without dispersing. This is such a crazy new understanding that a bladeless/propless plane has been created that can hover for landing and take-off, through the lift created by this function.
Many people note that their rear windows stay clean with the air tabs, demonstrating that the stalled/backflow of air has been broken and pushed away from the truck This may even improve gas mileage at highway speed, as some light truck owners anecdotally confirm. As speed increases, drag becomes exponential, squaring at every 5mph increase past 65, and getting crazy from 75-80. This is where they should really perform, and 75/80mph is where my mpg usually tanks, so it should be an obvious difference on our MT trips.
I’m only putting them on the shell for now, and they need a 5″ long flat space that is at most 12-16 inches from the rear edge. I had to jump from the shell to the windows. I ordered them black, and painted some of them to match the truck. On today’s test drive we headed out into a stiff headwind toward the Great Salt Lake, passing semis with no “blowby” from the windshear (one of the air-tab benefits), and experimenting with acceleration, coasting, and alignment/tracking. All were notably improved.
Placing them on the front bumper ahead of the front tires helps the unstable air at the tire and wheel well, and may reattach air to the side of the truck as well. New trucks and cars have this built into the bumper.
The airflow under pickups is always problematic- a “dirty air” mess where the stall force at the back of the vehicle can move all the way to the front, and any back-flowing air is disrupted by all the big under-hanging parts and gaps. In my imagination, these front air tabs will help. I also did something that is actually proven to help: I set foam (black) to block out any front facing gaps- with the magic of magnets! Prior to this at 70mph a roar started, became a clear low note at 75 that I could set my pace by, and faded out after 80. Gone now. I used magnets so I can remove them in the heat of summer if the lessened airflow effects the radiator’s efficiency. If I’m not hauling anything, the current opening should be fine.
This is a gap looking down on the bumper, which weakened air-ram to the radiator.
I removed the three foot whip antenna for the radio and replaced it with this 7″ stubby.
Someday, we’ll head back to the ranch and find out the full benefit. I’m hoping our 130 miles of 80mph interstate section of UT-ID sees better gas mileage. I hardly have to touch the gas now to keep her around 80. I know from today that even driving into a stiff headwind it is more stable, smoother, faster on acceleration at speed, and much quieter. E notices all these things as a passenger as well.