600 miles from a tank???
- Thread starter Phil Rusted
- Start date
timmus
A2OC Donor
Too right! I've managed figures like the many times before, but only when doing long road-trips across the country. To get over 70 during an average working week, with commuter traffic and plenty of cold starts, requires concentration and calm determination.
I'm finding it easier to get consistently high scores these days irrespective of journey type/conditions as I've got 6 gears. Given that I had the same longer 5th setup as you before the change, it's not so much the 6th gear that's helping my average economy but the standard 5th in between. However, I have noticed that my peak motorway cruising economy has gone up too, as you'd hope and expect.
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dan_b
A2OC Donor
Half-term helped with this tank I'm sure - less traffic on my commute, but also I didn't have to do so many morning and evening drop-offs with the wee ones, plus I had a couple of extra motorway trips - all adds up I think.
What's the rev-drop you've seen with the 6th gear over the longer 5th at, say, 60mph or 70mph?
What's the rev-drop you've seen with the 6th gear over the longer 5th at, say, 60mph or 70mph?
timmus
A2OC Donor
With standard tyres...
60mph: Standard 5th = 2211, 0.659 5th = 1945, 0.588 6th = 1739
70mph: Standard 5th = 2579, 0.659 5th = 2270, 0.588 6th = 2029
So, if you cruise at a true 60mph, you lose 206rpm relative to the longer 5th.
I've shaved a few rpm off those figures by using tyres with a larger circumference. I cruise at a true 60mph a whisker below 1700rpm.
Tom
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timmus
A2OC Donor
Relative to the 0.588 6th gear, the longer 5th is really a 5.56th gear, meaning it sits almost halfway between standard 5th and a full 6th.
Have a look at the graphs in this post: http://www.a2oc.net/forum/showthrea...on-and-6-Speed-Conversion&p=165096#post165096
Note that the first graph shows standard 5th, full-length 6th and a 0.65 gear in between. Longer 5th is 0.66, to 2 decimal places.
Tom
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MikeMarsUK
A2OC Donor
Just had my service at Stealth on Friday, so finally the damage done reversing over that sign on the skid pan social last year is fixed. Replaced the heatshield near the rear/left wheel, so my aerodynamics is back to what it should be, and he also found that I had damaged the handbrake cable on the left so it was not disengaging properly (i.e., probably dragging for the first bit of the journey, until it worked itself loose).
So hopefully I might start seeing 600 miles tanks again soon! It's been 500-550 miles all winter.
So hopefully I might start seeing 600 miles tanks again soon! It's been 500-550 miles all winter.
MikeMarsUK
A2OC Donor
In some ways, the advantage of the 6th gear is not so much the greater length of the top gear, but the fact you get a comfortable 5th back for medium speed driving (when you are in the 35-45 mph area).
timmus
A2OC Donor
MikeMarsUK
A2OC Donor
Finally my first 600 mile tank of 2013 (a long time coming!). 609.7 miles, 33.51 litres.
John L
A2OC Donor
I have found even with the 1.2tdi there is a huge difference on account of weather and distance driven.
Town miles in Tromsø are very bad in -10c with short trips. However, with consideration of routing and such it can be improved markedly.
For example driving a little longer but using the (flat, warm and higher speed limit) saves fuel even though it adds several KM's to each trip.
I noticed a real improvement this week going back to summer tyres.
In town it is usually 45-50mpg in the winter and up to 60 in the summer. However on longer drives I have managed over 100mpg several times.
The steep hills, 30km/h limits and the stop start nature of urban driving really hurt.
Also in winter running the engine whilst windows are cleared and such adds a fair bit of fuel burn for no distance and should be considered.
John
Town miles in Tromsø are very bad in -10c with short trips. However, with consideration of routing and such it can be improved markedly.
For example driving a little longer but using the (flat, warm and higher speed limit) saves fuel even though it adds several KM's to each trip.
I noticed a real improvement this week going back to summer tyres.
In town it is usually 45-50mpg in the winter and up to 60 in the summer. However on longer drives I have managed over 100mpg several times.
The steep hills, 30km/h limits and the stop start nature of urban driving really hurt.
Also in winter running the engine whilst windows are cleared and such adds a fair bit of fuel burn for no distance and should be considered.
John
timmus
A2OC Donor
Wow! Well done Mike! That's 82.6mpg.
The other day, before refuelling, I drove my car right down to the end of the reserve tank - Given the circumstances, I had no choice, and it made for a nervous last few miles. However, when refuelling, I managed to squeeze in 32 litres, including vent & brim.
This gives me an indication of the calibration of my gauge, and suggests I needn't be scared of using the reserve, as the tank alone, without vent & brim, is 34 litres.
My last few tanks have been around the 65mpg mark, as I've been doing a lot of Lakeland driving, including numerous journeys back and forth over Hardknott Pass; the antithesis of motorway-based eco-driving: http://en.wikipedia.org/wiki/Hardknott_Pass
MikeMarsUK
A2OC Donor
MPG versus temperature...
On the left chart, this is simply mpg on the Y axis, temperature on the X. The number against the correlation line is the strength of the correlation (where 1 = perfect correlation, 0 = no correlation, and -1 = perfect negative correlation). There are effectively 3 different data sets, since each time I modified the car it will have changed the mpg anyway. So I have given each data set it's own correlation line. Also my recording of temperature was pretty weak at the start (hence the long flat 'minimum mpg' line, and the low correlation for the first data set).
On the right-hand chart, Red = high temperature as seen on the temp display in the car, blue is the low, the midpoint is in green. The bars are mpg.
On the left chart, this is simply mpg on the Y axis, temperature on the X. The number against the correlation line is the strength of the correlation (where 1 = perfect correlation, 0 = no correlation, and -1 = perfect negative correlation). There are effectively 3 different data sets, since each time I modified the car it will have changed the mpg anyway. So I have given each data set it's own correlation line. Also my recording of temperature was pretty weak at the start (hence the long flat 'minimum mpg' line, and the low correlation for the first data set).
On the right-hand chart, Red = high temperature as seen on the temp display in the car, blue is the low, the midpoint is in green. The bars are mpg.
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John L
A2OC Donor
The temperature and mpg chart is very interesting.
The killer for small engines and fuel economy is steep hills and stupidly low speed limits. Around the town here there are very steep hills everywhere coupled to low speed limits 30km/h is the norm with the highest speed (on good dual carriageway and in long flat straight tunnels) is 70km/h. According to the DIS my average speed on a month without any out of town trips is 26km/h.
As soon as I get on the longer main road I find a huge performance increase that even seems to offset the role of the temperature.
I guess humidity would also have a small effect?
John
The killer for small engines and fuel economy is steep hills and stupidly low speed limits. Around the town here there are very steep hills everywhere coupled to low speed limits 30km/h is the norm with the highest speed (on good dual carriageway and in long flat straight tunnels) is 70km/h. According to the DIS my average speed on a month without any out of town trips is 26km/h.
As soon as I get on the longer main road I find a huge performance increase that even seems to offset the role of the temperature.
I guess humidity would also have a small effect?
John
MikeMarsUK
A2OC Donor
Yes. Additionally altitude also has quite a big effect on air density & hence mpg, but that doesn't really affect me since I always drive in the same altitude range.
MikeMarsUK
A2OC Donor
A combination of that, and also air density increases when the air is colder.
I have the webasto (the diesel heater), last year I calculated that it roughly took 10 miles for it to break even - i.e., at that point the fuel burned by the webasto equalled the fuel saved by the higher efficiency of the engine due to warming up quicker. That was with an average temp of 0c, so would probably be different in Norway!
My guess is that the electrical heater would be slightly less efficient, due to the extra overhead of the charge/discharge cycle through the battery, but it's only a guess.
I seem to recall that it was something like 1 mile altitude (Denver, Mexican plateau) would give you something like 20%. But it has been a while since I look at the numbers for that.