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Fuel ecconomy?

P

Penis Rotor

GT Godfather!
Joined
Oct 28, 2008
Messages
2,833
Location
Bungendore, NSW Australia
Just out of interest on the weekend I had a bit of a ride down the coast and decided to go the 'Long' way via Brown Mountain rather than the Clyde. Apart from the change being as good as a rest one advantage of this route is that between two fuel stops, one in CAnberra and one in Cooma the road distance is almost exactly 100Km, in fact its 100Km and 300metres! This allowed me to do a fairly accurate assesment of the big G's fuel ecconomy. For the record Cooma is about 500 metres higher than Canberra so it was 'Uphill' but the weather was good, temp in the mid twenties and no wind to speak of.

According to the on-board calculator I was using 5.1 litres per hundred Km, according to the bowser I was using 4.9 Litres per hundred. Average it out and that's 20Km per litre. A huge improvement over the original 6.8 per hundred it started out with!!!!

Speed averaged at about 105KPH but most of the time I was sitting at about 120, the average being bought down by slowing down for little towns like Bredbo and Nimitabell. While nowhere near as ecconomical as my Mana which will run on the sniff of an oily rag I don't reckon its too shabby.

Pete
 
Interesting Pete.

The screen readout on my Breva has generally been a bit pessimistic compared with an actual fuel-used/distance travelled calculation but it still takes a lot of careful cruising, with the occasional burst of course, to get as much as 20km/l. Usually it's more in the 18km/l range. By comparison my Buell 1200 under the same conditions gives 22 - 24km/l, and I've never seen worse than 20km/l.
 
I found that fuel consumption is temperature dependent. I may get to as low as 6.5l/100km in winter, in summer I usually see 5.1-5.6. Long rides on slow roads may get me below 5l/100km, highway speeds are worse. I found that Breva computer may underestimate economy up to 5% as compared with gas pump readings.
 
Yeah, the computer doesn't "know" how much fuel is being used. It is likely trying to calculate it based on fuel pressure and how much the injectors are open. It will be close but mine is pessimistic as well.
 
Does the computer work in US gallons rather than imperial? According to my computer (Stelvio) I get about 38 mpg, but the reality is about 45mpg (imperial) That was based on a four day 1200 odd mile journey of very mixed riding comditions from northern England to northern Scotland.
 
Fuel injectors are calibrated, and calculations based on this data should be pretty accurate. Within 5% is good enough, there are other factors that affect accuracy- meter on gas station pumps and level of gas after refuel.
Display can be switched between American MPG and civilized world's l/100km on my US-spec bike. I guess yours should display imperial gallons.
 
Fuel injectors are typically not calibrated. They are simply manufactured and should fall within a "tolerance". That is why some people actually flow injectors and balance them to improve the way their engine runs. But you not only have the variable of how much the injector actually flows but what the fuel pressure actually is. Both these are going to have a tolerance to them and will vary from bike to bike (and the pressure may vary from day to day). So the odds are that what the computer says will not be 100% accurate. But it should be pretty close. mine is about 10% low.
I would expect that the computer measures in US gallons and not imperial gallons. From what I have heard plus the logistics of who uses what I doubt they bothered with a third option of imperial gallons and simply have kilometers and liters or miles and US gallons. But that is an opinion and not a fact.
 
3ackok said:
Display can be switched between American MPG and civilized world's l/100km on my US-spec bike. I guess yours should display imperial gallons.
Click to expand...

'Fraid not......Guzzi system ain't that sophisticated! Strictly US gallons/miles or litres/Km. No imperial option!......unless someone brighter than me has found it?
 
GuzziMoto said:
Fuel injectors are typically not calibrated. They are simply manufactured and should fall within a "tolerance".
Click to expand...
I guess "calibrated" was a poor choice of word. I meant that they are made to pretty tight specs. Admittedly I don't know details about tolerances in fuel systems, but considering capabilities of the modern manufacturing , 5% variation in fuel flow rate seems reasonable.
Anyway, I have questions I wanted to ask for a long time.
How long could you run with Low Gas light? Once I ran for about 20 miles and than drained the tank to replace the fuel filter. It had about 3 liters (0.75 US Gallon) of gas left.
If I ride until bike will run out of gas, will it hurt the fuel pump?
 
No, it will not hurt the fuel pump. Keep in mind that you may run out of gas with gas still in the tank. I have seen bikes in the past that did not properly pick up all the fuel in the tank before sputtering to a stop. I have gone just over 30 miles with the light on before, and would guess that I could go about 40-45 miles with the light on with out running out. But it is not something I want to push. The light seems to come on on my bike with about a gallon in the tank, based on the published tank capacity.
 
fatal said:
Does the computer work in US gallons rather than imperial? According to my computer (Stelvio) I get about 38 mpg, but the reality is about 45mpg (imperial) That was based on a four day 1200 odd mile journey of very mixed riding comditions from northern England to northern Scotland.
Click to expand...

From another UK stelvio rider, (also big boned!), I've just done two back-to-back full tank to fuel light runs. Mixed roads (apart from motorways), mixed riding styles. Both runs - 35.6mpg. The bike's done just over 4000 miles. And the rear Pirelli is about to give up the ghost. Hm.
 
GuzziMoto said:
No, it will not hurt the fuel pump. Keep in mind that you may run out of gas with gas still in the tank. I have seen bikes in the past that did not properly pick up all the fuel in the tank before sputtering to a stop. I have gone just over 30 miles with the light on before, and would guess that I could go about 40-45 miles with the light on with out running out. But it is not something I want to push. The light seems to come on on my bike with about a gallon in the tank, based on the published tank capacity.
Click to expand...

Your estimate of 40 - 45 miles after going on reserve is exactly what I have experienced while carrying spare fuel I ran it out on purpose. Carrying the extra 2 gallons allows one to push the reserve with out fear of running out. A GPS really helps as you always know where the gas station is. With extra fuel and a GPS the Stelvios limited fuel capacity is much less of an issue. I have gone 170 miles between fill ups and took on 16 ltrs. This was mostly highway riding but the bike was carrying 40 lbs of gear and I was riding just a tad over 60 mph.
 
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