# MAX Update No. 66: Go With the Flo

Jan Steinman wrote this comment to MAX Update No. 65: Measuring Fuel by the Tablespoon:

“If you’re REALLY into precision measurement, look to the marine industry. Veggie Van Gogh uses a FloScan 9000. This device employs tiny turbines in the fuel line to accurately measure fuel use. It even has a NEMA interface to a GPS, so you can see your instantaneous fuel economy! That has changed the way I drive!”

Now I think Veggie Van Gogh is very cool. It’s a snack van converted to a long distance camper/warehouse/workshop, it’s powered by a four cylinder turbocharged Cummins diesel engine which has been converted to run waste vegetable oil. Jan and his accomplice Carol criss-cross the country, selling their wares at craft fairs, and they couldn’t afford their gypsy lifestyle if they were buying and burning petrodiesel. Necessity is a mother, as the saying goes, and so Veggie Van Gogh was born.

However, even though I’m REALLY into precision measurement, I rolled my eyes at the suggestion that a FloScan fuel flow meter would be worth a hoot to MAX. Sure a gallons-per-hour meter that reads in tenths is useful for a van cruising 60 mph at 15 mpg; that’s 4.0 gph (gallons per hour), and if the meter pops up to 4.1 gph or down to 3.9 gph, that’s some useful information–it means their mileage has lost or gained about a third of a mile per gallon. Of course, there’s some averaging going on, but accuracy within a third of a mile per gallon will teach you a lot about your driving style.

If we put the same fuel flow meter in MAX, which cruises at 55 mph at 85 mpg, it’s going to read 0.6 gph most of the time. If it drops to 0.5, then woohoo! MAX is getting between 92 and 110 mpg. If the meter scootches up to 0.7, then bummer! MAX is getting between 69 and 79 mpg. All a 0.6 reading is going to tell me is, I’m not getting worse than 79 mpg or better than 92 mpg.

Accuracy within 13 miles per gallon isn’t worth the trouble of installing the gauge, and that’s not even considering the sticker shock (which I’ll get to). I had greater precision with my Honey Bear fuel tank and an oven timer. So imagine my surprise when I learned that Craig Henderson has a FloScan in his 100+ mpg Avion, and he swears by it!

FloScan was developed for nautical use, but some models have a feature that makes them spectacular research tools for extreme high mileage cars like Avion and MAX: they have a GPS interface that lets them calculate mpg on the fly, and apparently (and contrary to how the gph display works) it gets more precise as economy improves. If it’s showing 80.0 mpg and bumps up to 80.1 mpg, that’s an awfully fine line…in fact it’s a bit finer than its repeatability (which is within 1/2%) but a half percent is good enough for me, and if it will tell me the difference between 80.0 and 80.5 mpg I’ll be more than pleased.

Ooh I want one I want one. The only problem is, the latest FloScan with GPS interface sells for (gulp) fifteen hundred bucks. It’s a bargain as a research tool, or for a relatively high dollar fuel sipper like the Avion (Craig is planning to offer the Avion as a kit), but it’s a bit rich for MAX’s budget. So if I do get a FloScan (and I am sooo tempted) it’ll be part of my R&D toolkit, rather than a permanent feature of MAX’s dashboard.

• Published on Jan 31, 2011
Tagged with: 100 mpg, FloScan, fuel economy, Jack McCornack, MAX, Reader Contributions