Lifetime Fuel Economy: 39.49 mpg

Sunday, February 21, 2010

Finished Photos + Results

This is a continuation of the air dam + crash bumper post from a couple of weeks ago.
After completing it, I took the fam on a 1,000 mile road trip to see my grandma near Wichita, KS.
We were reminded that folks in other cities hadn't become used to the car as we got lots of gawking and laughing at stops and on the freeway.

Things unexpected: Car started overheating in the first half hour of freeway driving. I was hoping these issues would wait for summertime, or at least when I didn't have the car's heater on full blast and warming up fresh and very cold outside air (it was the whole trip)
I pulled over and moved the license plate (it was blocking 3/4 of the radiator inlet tubes). We drove a bit more, and this seemed to help, but not much.
Stopped at a home depot and I used some expanding foam to seal off gaps around the radiator (I had it pretty well sealed inside with coroplast before). Was impressed later to see that this stuff held - within 5 minutes, we were back on the highway at 70 mph.
Car still ran hot the rest of the evening (250 miles).
The next morning, it occurred to me that there was a tiny gap between the hood and the top of the air dam which would experience really low pressures and an escape point for intake air without going through the radiator. Fixed with a strip of duct tape. Drove another 250 miles, and car stayed pretty hot, but not overheated.
In KS, I added some oil and found that my amber oil (when we started out) had turned very black - a bummer to have cooked the oil with the high temps. One last effort - placed the license plate just above the air inlet tubes and used pliers to bend the bottom 1cm of it sticking out to the front, parallel to the ground. This seemed to work better, finally. I had to add some water to the car about 3/4 of the way home, but no worries with overheating, at least in cold outside temps.

I think I'm going to ditch the four individual dryer vent tubes and make one rectangular coroplast duct. (I had one measuring about 10cm x 30cm on my old grille block and it worked great, even with the A/C on. I'm also going to add a lip at the top to create a stagnation point there. Also need to find a way to create a door that can be opened from within the car. On my commute, in cold weather, I would probably keep the radiator inlet fully closed.
Will get more photos when I take them and after I really finish these plans.

Wednesday, February 10, 2010

New Air Dam + Crash Bumper

Started thinking about this midway through construction of my first air dam, and thought about it as I removed it.... and continued occasionally modifying my plans over about a year or so now. Finally got a day to dump into it, and got it started. Did take some changes to my original plan; bummer but still should work great.
Goals for this mod:
•Improve by +3 mpg highway (less than 10%) vs. car in its current state (all other aero and no front dam / belly pan) by lowering stagnation point and pushing majority of encountered air smoothly over top/sides of car to take full advantage of kammback, etc.
•Improve safety in a frontal collision by adding crush space and materials which provide significant support and resistance to crushing, but will fold up easily with substantial impact.
•Improve warm-up times in the winter by completely sealing off/controlling the radiator inlets.
•Improve ground clearance vs. original air dam

(notice my opinions about the shape of the air dam / nose of the car have changed.... more reading ;)
Pictures of progress thus far:
Framework and crumple zone complete:

Original plan was to have some of my spare lexan polycarbonate follow the curve of the following photo. Turns out this angle is way too far past the critical angle for air/polycarbonate. Translation: The majority of light from the headlight was reflected down to the ground rather than passing through.
You can also see my air inlets in this photo:
Had to solve the problem of the lexan angle; sacrificed some aero for it but still a big improvement over stock, I think. It's hard to see the lexan in this photo, but it comes down at about a 65 degree angle below the horizontal and meets a nearly horizontal piece of coroplast.
And here she sits... have to finish the other side and slap on some under-panels just going back as far as the engine/transmission to smooth things out and encourage the possibility of airflow through the radiator when it is needed. License plate will cover 2 of the 4 air inlets during the wintertime, and be moved in the summer. Planning an adjustable door for the other two.