Itinerant Air-Cooled

I just tallied up the gas purchases/usage from last month's trip up North. I was surprised at the low total MPG that I came up with.
Do these numbers seem reasonable? Should I be investigating the low MPG further or just drive?
The bus was fairly loaded down with 2 passengers, a dog, and camping gear. Highway driving was done at about 55-60 mph and Interstate was about 70mph.


Mileage Gallons Price/gal. Total Cost MPG
Lake Zurich 34,569.00 6.24 $4.10 $25.57
Caledonia, WI 34,624.00 2.20 $3.99 $8.77 25.03 mixed
Mishicot, WI 34,731.00 6.30 $3.89 $24.51 16.98 Interstate
Fish Creek, WI 34,849.00 7.80 $3.99 $31.11 15.13 highway
Manitowoc, WI 34,986.00 9.16 $4.19 $38.39 14.95 mixed
Palatine, IL 35,137.00 11.52 $4.15 $47.81 13.11 Interstate



total miles 568.00
total gallons 43.22
total cost $176.17

MPG 13.14

With a healthy, stock engine, I'd expect your average to be closer to 17mpg. Might be worth looking into. Now, if you have a "performance" cam or other engine modifications, that's another story.

I'm running a stock fuel injected 2.0. Valves, dwell, and timing all adjusted before the trip.

I think I'll try pulling a plug to have a look.

vwlover77 wrote:With a healthy, stock engine, I'd expect your average to be closer to 17mpg. Might be worth looking into. Now, if you have a "performance" cam or other engine modifications, that's another story.

If everything is up to snuff he should be getting roughly 20mpg on the highway @ 60mph or so. Anything above 65mph and your mileage will start to suffer. The gearing vs hosepower/weight have a lot to do with the mpg's. Throw in some added headwinds and rough/bad roads and mpg's will suffer more.

As for a 'Performance' cam...that depends on what cam your running. Along with any other add-ons needed. If one changes the cam then you'll need to chuck the stock exhaust as well. And also upgrade the heads. With my 72' Hardtop I average 21mpg highway @ 65mph and 17mpg around town.

There, it's readable now.

As for the dropping mileage, maybe it was super lean at first and then went into being super rich?

That looks weird - was 34,569 your starting mileage? If so, that first line for gallons etc is immaterial, as I assume that was to fill the tank for a starting point.

If so, then it is 568 miles using 36.98 gallons, giving an average of 15.36mpg - better than the original calculation, but still a little low.

rallybug wrote:That looks weird - was 34,569 your starting mileage? If so, that first line for gallons etc is immaterial, as I assume that was to fill the tank for a starting point.

If so, then it is 568 miles using 36.98 gallons, giving an average of 15.36mpg - better than the original calculation, but still a little low.

Looks like a progressively clogging air filter or deteriorating TS II or fuel leak!
Colin
(is your odometer recording correctly? Chloe reads only 8 1/2 tenths per mile)

You should check your odometer with your phone gps. Like Colin, mine is off too but by .05 miles per mile so when I fill up at 220miles I actually went ~231. Also if you can find a place that sells pure gas http://pure-gas.org/ you might find a difference in your mpg for the better. If I can get the real stuff I get about 1.5 mpg better. Too bad the place closest to me that sells the stuff is about a 17 mile round trip so it is not worth getting so I am stuck with ~16mpg in city driving. Ethanol fuel is a real waste of resources I wish there was a way to optimize the aircooled for the ethanol fuel.

What grade of gas are people running in their FI 2.0? I've been running regular then read somewhere I should be running premium. If I switch are the results immediate?

RussellK wrote:What grade of gas are people running in their FI 2.0? I've been running regular then read somewhere I should be running premium. If I switch are the results immediate?

Regular is fine!
Our compression ratios are barely that of a common lawn mower!
Colin!

(only with modern engine management systems might you see an increase in fuel economy with premium, since the timing is advanced in the absence of knock sensor signals)

I finally did a trip with all highway driving, since the last round of AFM tuning to get head temps in check.

160 miles, and 13.666666 MPG.

I to travel .something miles further than my odometer reports, so ill say 14MPG is my official highway reading.

Roof rack on, and absolutely loaded to the gills with gear. Drove at 65-70 the whole way, flooring it up every hill encountered. Head temps never went above 419 at the absolute worst, and this was in 80* heat south of here.

Im SUPER pleased with how cool the bus can run now, especially with the rack/weight.

just FYI. im not going to chase my tail around messing with things just because of it. I was barely doing better than that when this thing was still running the O2 sensor/cat and an insanely lean AFM.

the way the motor was built must somehow have effected it's ability to do decent MPG, which is a bummer, but the cost of rebuilding an engine is certainly greater than paying a little more often for gas.

airkooledchris wrote:I finally did a trip with all highway driving, since the last round of AFM tuning to get head temps in check.

160 miles, and 13.666666 MPG.

I to travel .something miles further than my odometer reports, so ill say 14MPG is my official highway reading.

Roof rack on, and absolutely loaded to the gills with gear. Drove at 65-70 the whole way, flooring it up every hill encountered. Head temps never went above 419 at the absolute worst, and this was in 80* heat south of here.

Im SUPER pleased with how cool the bus can run now, especially with the rack/weight.

just FYI. im not going to chase my tail around messing with things just because of it. I was barely doing better than that when this thing was still running the O2 sensor/cat and an insanely lean AFM.

the way the motor was built must somehow have effected it's ability to do decent MPG, which is a bummer, but the cost of rebuilding an engine is certainly greater than paying a little more often for gas.

Feel free to do little tiny lean adjustments with mpg documentation separating them. I found the sweet spot with Chloe and now have 18-ish and no head temps above 380*. With a carburetor, 1/4 turn of the mixture screw makes a noticeable difference.
Colin

Add me to the 13mpg club. Fully loaded, two adults, various roof racks, and a big Yakima box. It made me happy knowing the van is happy. :)

luftvagon wrote:Add me to the 13mpg club. Fully loaded, two adults, various roof racks, and a big Yakima box. It made me happy knowing the van is happy. :)

Yesterday, I was in the 16.4 mpg club with the BobD, with 410* on the hills. Then I started screwing the AFM and am lost once more.
I do have a desirable shut-down of fuel injection at off-throttle, 22-24 on decel.
16.3 warm idle ratio.
12.5 partial throttle
11.3 full throttle at 55 mph.
416* long hill pull at 70 mph

The day before yesterday, though, I had it just about perfect, barely hitting 400* excellent power, a wince-worthy 10.4 under full throttle with what looked like a wasteful 12.3 on decel! yet the stupid fuel economy was 16.6! I can't believe this! Still practicing. I have a book to write. I must get the grip on these cause/effect/magic results!
Colin

MPG UPDATE :

I was able to hit 16.6 mpg on my Vanagon doing 65-70mph on the interestate. 55 mile trip resulted in use of 3.3 gal. What now? Should I push it further?