Jetta grille block ABA testing
 

Hello all. I'm rather new to the ecomodding thing, but I finally got around to testing my first aero mod on this car; strapping tape over the grille and the three lower louvers that this car has. My test track was a 9-mile stretch of highway from 7:30 to 11 last night, so it was a little cold. I set the cruise after getting up to speed and reset the UG as I passed mile marker 114. Then when I passed #105, I would note the MPG and speed readings. The exit was a half-mile later, where I would turn around, hit the on-ramp and repeat. Three rounds trips for A, three trips for B, three trips for C. It was about 220 miles. In the future, I will be using a 5-mile stretch and exit one ramp sooner. Anyway...

Here's what I got:
A1
38.85
40.1
39.7 avg = 39.55

B
40.5
39.25
38.85 avg = 39.53

A2
37.95
38.95
37.2 avg = 38.03

Do I then average the A values?
Aavg = 38.79
Bavg = 39.53

It would seem that I gained 0.74 MPG, or 1.9%, but the B average is lower than the A1 average, and the A2 just plummeted. Perhaps the temperature dropped? One thing I did note was that the intake temperature was around 60F when I started, and when I checked it on the last run, it was down to 28F. Next: stabilize intake temperature and repeat.

Outside of that, is my testing method reasonable?

Don't suppose you have pictures of how you blocked the grills?

I'll get one today.

http://i44.photobucket.com/albums/f2...2/IMGP1418.jpg

http://i44.photobucket.com/albums/f2...2/IMGP1417.jpg

This is the grille and louvers in the bumper. I removed it for the testing, but you can imagine packaging tape over the slats in the grille, and covering the lower holes.

Arent you defeating the purpose and wasting gas by just driving around to do these tests?

well if he finds a real improvement, and a significant number of people adopt it, then net gas will be saved. From his perspective he just burnt 6 gallons of gas and 4 hours of his time and that will probably never be payed back by any savings. This sort of test is a service to the community for which I am appreciative.

A lot of these mods have already been proven, and are proven time and again by those who adopt them later on and see their mileage being improved by them.

The open road is NOT a controlled test environment, and environmental factors will always greatly influence your testing.
The effect of small mods will be almost impossible to measure and quantify accurately.

The variations within your A and B tests is bigger than the difference between the averages of A and B.
This can only be statistically significant with many data points.

The gains will however show up in your fuel records over time.
So by all means, add the proven mods, but don't go out specifically to test their effects on fuel efficiency.
A short functional or safety test will do, and if the modification is easily removed, these can even be done by starting off a bit earlier than usual on a planned trip.

The long term, long distance test is the fuel record of your everyday driving.

This entire site is full of people that do ABA testing with various vehicle modifications for the purpose of going further on one gallon of gasoline. Any thread with results in it only happened because someone made a change and wanted to see if it did any good. If I ever get to 40, 50, whatever mpg, then yes, it will pay for itself, and start the money/fuel ball rolling in the other direction.

Sounds great and I get the concept... but what happens when everyone on the site wants to do a test on a mod that we already know will work because of prior testing and they just want individual results so they make special trips just to see the gains? I dont think you have to explain to me what the whole site is about.

Nice try on the testing, having the second set of "A" runs drop off makes the test invalid in my option. The temps dropping may have played a factor.

What were the winds like?

Can you try it on a back country road? I have a 2 mile test track here that is .5 mile acceleration, 1 mile test, then .5 mile coast down. Turn around and repeat. This makes the test a lot shorter which helps by taking less time, giving less time for the environment to change, less gas is used testing, easier to toss out a run if a car passes or similar.

You can also try a coast down test, it will not give you a MPG gain but will give a % aerodynamic improvement.

Just some ideas :)

Once you get good data I will add it to our wiki:

Grill block partial or full - EcoModder

Sure, and it certainly had to be done in the beginning to prove the point.
But the effectiveness of these mods has been proven, so there's little point in repeating the tests.
It'll be a while to recover those 5.5 gallons or so used in the testing.

If you come up with some new brilliant mod, then by all means test it ;)


On a sidenote, I really need to make my quick & dirty black tape grille block into something more permanent.
And more decent, 'cause it looks gettho now.