Function f(x) = 9.61307 * 1.0959 ^ MPG
There is simpler chart that I have devised with rounded numbers to make it easier to remember. I explained it well in the link below which is essentially a guide and not something written in stone.
There are two keys to this guide. The first is the chart that respects the chance in oil demand at different rpm and load. The second is the simple method to calculate a percentage less or more oil using the mpq (Miles Per Quart of oil). So if you prefer 20% less oil, then it is a simple % calculation based on mpq which respects the need for oil at different rpm and load. I firmly believe this is a leap forward.
The hidden advantage is if a tech or the owner makes a change to the oil consumption either purposely or inadvertently, then this change becomes easy to calculate. The same holds if an engine is rebuilt or a change in track or clutching, or anything that affects the fuel consumption. As long as you know the Fuel vs Oil consumption before the change, then you have the ability to compare the before and after.
I keep thinking that I need to submit this to BRP. I know they have their own chart which is essentially what I was able to extract. But the ease in calculating the % increase or decrease may be something new.
Oil vs Fuel consumption (see pages 17 and 18)
Calculating change in oil consumption
Example A:
Sled @ 11 mpg consumes too much oil @ 70 mpq for an average ratio of 25:1
Target decrease @ 85 mpq for a ratio of 31:1
Convert mpq to quarts per 100 miles
100 / 70 mpq = 1.429 quarts
100 / 85 mpq = 1.176 quarts
Calculate percentage
( (1.176 / 1.429) - 1) x -100 = 17.7% decrease in oil consumption
An increase from 70 mpq to 85 mpq = 21% increase in distance
( (85 mpq / 70 mpq) - 1) x 100 = 21.4%
Example B:
Sled @ 16 mpg consumes too little oil @ 225 mpq for a ratio of 56:1
Target increase @ 170 mpq for a ratio of 42:1
Convert mpq to quarts per 100 miles
100 / 225 mpq = 0.444 quarts
100 / 170 mpq = 0.588 quarts
Calculate percentage
( (0.444 / 0.588) - 1) x -100 = 24.5% increase in oil consumption
A decrease from 225 mpq to 170 mpq = 32% decrease in distance
( (225 mpq / 170 mpq) - 1) x 100 = 32.4%
Simpler chart
4 mpg @ 14:1 @ 14 mpq
5 mpg @ 15:1 @ 19 mpq
6 mpg @ 17:1 @ 25 mpq
7 mpg @ 18:1 @ 32 mpq
8 mpg @ 20:1 @ 40 mpq
9 mpg @ 22:1 @ 49 mpq
10 mpg @ 24:1 @ 60 mpq
11 mpg @ 26:1 @ 70 mpq
12 mpg @ 29:1 @ 85 mpq
13 mpg @ 32:1 @ 105 mpq
14 mpg @ 35:1 @ 120 mpq
15 mpg @ 38:1 @ 140 mpq
16 mpg @ 42:1 @ 170 mpq
17 mpg @ 46:1 @ 195 mpq
18 mpg @ 50:1 @ 225 mpq
19 mpg @ 55:1 @ 260 mpq
20 mpg @ 60:1 @ 300 mpq
Edited by Daag44, 09 February 2021 - 10:22 PM.
