Air drag calculator site?

[Far Raider]

Hi Everyone,
I have a built out 1994 F350 type 1 ambulance with a 7.3 IDI and my best mpg is just north of 13. I keep looking at that big flat surface of the body above the cab and wonder how much fuel I can save by changing the aerodynamics. I spent a bit of time digging around on the internet and here but thought I would ask if anyone here knows of a good site to calculate the drag I am experiencing at a given mph (or m/s) and convert to joules/m2 of horizontal surface area. I assume the benefit gained would be that energy multiplied by the sine of the angle I create for the fairing. Any help? Thanks
FR

 

[PhulesAU]

Look at the newer U-Hual vans for faring ideas and be happy you don't drive a Jeep...... Aerodynamics are over rated.

 

[DaveInDenver]

Couldn't tell you if there's anything like you want on the Interwebs, but look into OpenFOAM and simFlow for free CFD programs. Assuming you have a way to generate a model for the mesh you'll simulate.

 

[CanucksRedRocket]

https://www.nosecone.com/service-body-models.html

 

[loudboy]

ecomodder.com has some great tools

 

[comptiger5000]

For easy things, add a fairing to smooth the air transition from the windshield up over the body. A deflector on the front of the hood might help with this depending on the shape of everything.

Smooth out anything you easily can on the undercarriage and make sure the rear bumper doesn't act as an air scoop (close it off to stuff in front of it if needed).

Look at adding something like the tail pieces some newer tractor trailers use at the rear to reduce air turbulence from the large, flat rear end.

Doing stuff like that should be able to cut enough drag to gain you at least 1 - 2 mpg fairly easily.

 

[javajoe79]

You can do your own tests using a coast down method. I haven't done it but it's basically running up to a certain speed on flat ground in the same conditions to see measure how long it takes to coast to a stop. Make your mods and try again. There is some math involved as well and you can figure out things like Cd and Cda