Aero mod testing?

[hyperyaris]

Just a question, not any implication: Do those of you who aeromod test your mods in wind tunnels? If not, how could you possily know if your mods are really reducing aerodynamic friction? I would not think that you could just eyeball something as scientific and mathematical as aerodynamics. Just asking.

[SVOboy]

Coast-down testing

[wyatt]

Bi-directional A-B-A coast down tests or bi-directional A-B-A tests with a cruise control. Also you can look at what others have done that has worked, many of which have put in wind tunnel time. If you look at the book that gets quoted on here a lot by Hucho, there has been a lot of testing done, and lots of it back in the 1920's. Although the data is old, the same principals still work... Smooth flow around the vehicle is still better than turbulent flow. Do a search for user Aerohead, he has lots of good articles posted in his AeroDatabase. HERE is an example of some of his stuff compiled by another user with links.

[hyperyaris]

Ok fair enough. But, how can you know that yuo are putting everything at the exactly right angle?

[wyatt]

There seem to be a lot of theories, but like I said, the Hucho book is a good reference with lots of pictures and wind tunnel data. If you want hard data, that's the way to go. If you want a good rule of thumb, 15 degrees for the trailing end, underbody panneling, wheel skirts, and closing off your grill as much as possible seem to be agreed upon for the most part. If you look at the top of the page, you can go to the 60 + mods and you can read until things start making sence. It took me a long time to start aero-modding because I wanted to get it perfect the first time, but it's way faster to just try something and see what happens. I have added a half grill block, underbody panneling front and rear (not center since that's fairly smooth), and a windshield wiper block and I have been getting between 6 and 8 percent better gas milage compared to my previous best. I think I know enough on the subject to just go forward with making mods and not worry so much about over-researching things before. If you come here often, and read a lot you'll get there too... And finding a copy of Hucho's book wouldn't hurt either. Here's a tip, check at your local library, if they don't have it, try intra-library loan. That's all for now.