truck aero mod ideas

[Sparkchaser]

Hey all,
just been reading lots about the vortex generators etc on trucks. My vehicle is a 1999 Dodge Cummins Turbo Diesel 4x4 pickup with a canopy. Current average is abot 17.5 to 18 hand calculated over the past year or so. So, I was wondering if I could improve the aerodynamics of this brick of a truck up front with mods to the front bumper and a hood with a raised scoop area like the old Trans-Ams used to come with- the opening toward the windshield. I'm thinking perhaps this could improve air flow over the windshield, making the windshield have less drag. And the front bumper being larger and very similar to those big 4x4 winch/grill guard bumpers, but maybe angles chosen for better aerodynamics. And of course belly pans disguised as running boards, and spats to smooth airflow over the tires. Any thoughts on this?
Sparkchaser

[COcyclist]

Sparkchaser, Welcome to Ecomodder. If you do some reading on this site you will find the biggest aerodynamic gains come at the back of the vehicle. It's kinda counter-intuitive. Many pick-up drivers here have used an aero bedcover with good result. The Dodge Ram has huge fender openings so it may help to close those up a bit. I have seem improved mileage with a belly pan on my vehicle but a 4x4 may be more challenging. Do you ever go off road? Do big axles and suspension disrupt under-body airflow. I would start with an aerocap and grillblock first.

[Sparkchaser]

Hi CoCyclist,
Thanks for the reply! Yeah, I know this beast is a brick for aero, but gotta work with what I have! BTW I'd love to have a TDi VW for my commuter... Anyways, I was looking at that aero canopy that other guy made, nice, but gotta have ready access and room to haul lots of stuff (like bales of hay and feed tonight). I was looking at an article on semi truck aero mods using strakes or aerotabs at the rear of the canopy and bed. Pretty simple. I think I'll start with that. And perhaps a simple partial belly pan. I rarely go off road, but I do need 4x4 to get to work in the winter. Though next time tires are due, I'll be going to a little narrower tires. Current ones are 33-12.50/16.5 BFG AT's. Nice tires and long lasting but probably not the best rolling resistance! The grill block is a for sure thing. I have some foil covered foam insulation board ready to cut out, but I need to clean the crud off the radiator before I block too much airflow. I tried that this summer with cardboard and got about 3 mpg's but ran a little hot. But now its Fall! I'll post my results when I start the mods!

[COcyclist]

I hear you about needing your truck bed. There is some research showing that a 2/3rds tonneau (open directly behind the cab) really helps aero on pick-ups. Could you fab up a folding one that you could stow when not hauling hay? I would skip the aerotabs unless you have some reliable way to test A-B-A to make sure they are not hurting more than helping.

[miket]

Aerohead has gotten 30+mpg highway with his gas Toyota T100.

The roof of some aerocaps pop up for extra space underneath. Theres another thread where someone is going to use a roll up toneau cover to make the roof of the aerocap and have the sides solid.

I cant use a sloping aerocap because i need the storage space of a flat top cap most of the time. I do however plan on adding a sloped inflating boatail to the back end which will inflate and extend at highways speeds but roll up at low speeds so the vehicle isnt too long to park. It a mythical creature much talked about but rarely made here lol.

Some people use solid hubcap covers on the wheels. The rear wheel opening can be covered since those wheels dont turn to the sides. The gap around the front wheels can be partially filled if their bigger than neccesary as they often are on trucks. A few people here use front wheel skirts that articulate out when turning.