JLKunka
Active member
- Joined
- Feb 8, 2009
- Location
- Richmond, VA
- TDI
- '99.5 Jetta - parts car, '99.5 Jetta - black, '02 Jetta - silver, '13 Jetta DSG - black
My 7th grade daughter chose to compare mileage in a controlled experiment for various blends of biodiesel. The vehicle was a '99.5 Jetta TDI, 5-speed with 140,000 miles. We carefully planned a route and test scheme to minimize external variables. Ratios were chosen to minimize emptying and filling of the tank while still providing useful results. B5 was included to determine if lubricity alone would affect mileage.
There was a requirement for three trials of each ratio, which dictated route length to keep the time reasonable. We charted an out & back route of exactly 26.0 miles. We used a rural road that is little travelled and locked the cruise on exactly 55 MPH. (For those of you who don't have one, the Jetta holds an amazingly steady cruise speed.) Fuel level was initially topped off and refilled after each run with a graduated cylinder. We filled right up to the neck, using the vent slot as our mark. The results surprised us:
(This table doesn't post well. Original Excel data is linked in this post.)http://biodiesel.infopop.cc/eve/forums/a/tpc/f/419605551/m/678101253
Distance Driven per trial(mi) 26.0
No 2 Btu/gal 129050
Biodiesel Btu/gal 118170
* * * * * * * * * RATIO * * * * * * * * *
ml Consumed Trial # B-0 B-50 B-100 B-5
1 2137 2328 2180 2147
2 1963 2170 2203 1943
3 2049 2151 2084 1931
AVG 2050 2216 2156 2007
Gallons consumed 0.5415 0.5855 0.5695 0.5302
MPG 48.02 44.41 45.66 49.04
% change 0.00% -7.52% -4.92% 2.13%
Theoretical energy 129050 123610 118170 128506
% change 0.00% -4.22% -8.43% -0.42%
Note that the changes in MPG do not correlate with energy content of the blends. We'd love to hear your feedback and questions on the results. More data can be found in the Excel file.
There was a requirement for three trials of each ratio, which dictated route length to keep the time reasonable. We charted an out & back route of exactly 26.0 miles. We used a rural road that is little travelled and locked the cruise on exactly 55 MPH. (For those of you who don't have one, the Jetta holds an amazingly steady cruise speed.) Fuel level was initially topped off and refilled after each run with a graduated cylinder. We filled right up to the neck, using the vent slot as our mark. The results surprised us:
(This table doesn't post well. Original Excel data is linked in this post.)http://biodiesel.infopop.cc/eve/forums/a/tpc/f/419605551/m/678101253
Distance Driven per trial(mi) 26.0
No 2 Btu/gal 129050
Biodiesel Btu/gal 118170
* * * * * * * * * RATIO * * * * * * * * *
ml Consumed Trial # B-0 B-50 B-100 B-5
1 2137 2328 2180 2147
2 1963 2170 2203 1943
3 2049 2151 2084 1931
AVG 2050 2216 2156 2007
Gallons consumed 0.5415 0.5855 0.5695 0.5302
MPG 48.02 44.41 45.66 49.04
% change 0.00% -7.52% -4.92% 2.13%
Theoretical energy 129050 123610 118170 128506
% change 0.00% -4.22% -8.43% -0.42%
Note that the changes in MPG do not correlate with energy content of the blends. We'd love to hear your feedback and questions on the results. More data can be found in the Excel file.