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[Go Fast or Go Home]

My thumb’s getting tired from scrolling past some of these posts!

 

This goes in the complaint thread.

 

Don~

[MotoXR]

 
Half a tank? That is cheap. I wonder if they used the XPS blend lol 
 
So without knowing what sled/engine that you were riding, the actual fuel consumption in mpg could be estimated from the oil consumption. Not bad for a simple chart.

 

It is a lot simpler than most things we get involved with in our careers and our homes. For a comparison, I would consider how you worked out a problem with the water well to be far more complicated. In hindsight I believe the reason we have trouble understanding something simple as oil consumption is because we never paid enough attention to the subject.

 

Pretty sure its mostly that no one really gives a crap about any of this... just a thought. 

[Daag44]

1.5 : 1 Fuel to Oil Ratio
 
I figured that I was doing something wrong and I realized that IcutMetl was spot on. To paraphrase, too much explanation for too little return.
 
So this morning I got up early to test a theory that two stroke oil was combustible. I knew that a four stroke push mower would run on 4:1, so I figured why not try 3:1 . After running it 30 seconds with no visible smoke and no noticeable power loss (remember that a push mower has a governor), I figured that this was too easy. So I poured another 40ml of XPS Mineral straight into the tank for a 1.5 fuel to oil ratio. After running the mower for 2 min it was working ok, but a little sputter. I stopped the mower wondering if I should try more oil? I shook my head and thought I better see if it starts again. It took 5 pulls, but I started again. This time I mowed 3 mins before it quit.
 
If it doesn't sound right, take the 20 min to do your own test. Keep in mind that my push mower always starts cold on one pull even after a 6 month storage. When hot it is usually one pull or two at the most two. I also did not dump the gas in the float bowl.

[Daag44]

600 EFI Fuel and Oil Consumption
 
 
I found this YouTube video on the 600 EFI thread with accurate fuel/oil consumption.

The oil consumption is roughly 15% less than what I have in the chart.

The 174 mpq matches 16.3 mpg in the chart, which is 1 mpg off from the consumed 15.2 mpg.

My hope was to reach within +/- 1 mpg which is close enough in my opinion.

Don't mind all the numbers for now.

I am using this as a real example to explain a principal in the next posts.


2021 Ski-Doo Expedition Sport 600 EFI


15.2 mpg @ 174 mpq

73 miles
4.8 gal of gas
0.42 quarts of oil


Decrease in oil consumption

100 / 147 mpq = 0.680 quarts
100 / 174 mpq = 0.575 quarts

* The 147 mpq was taken from the chart @ 15.2 mpg

( (0.575 / 0.680) - 1) x -100 = 15.5% decrease in oil consumption


Increase in distance per quart of oil

An increase from 147 mpq to 174 mpq = 18.4% increase in distance
( (174 mpq / 147 mpq) - 1) x 100 = 21.4%

[Daag44]

Which means more?

Percentage decrease in oil or Percentage increase in distance?


The oil consumption shown in the chart is higher than I would like out of two stroke, but I based it off of the 800/850 E-TEC which also works for the 600 and higher engine cc.

BRP had planned on a 40% increase in distance which works out to be 28.5% decrease in oil consumption.

From a marketing standpoint, one may assume the 40% is more marketable. But this is a flawed assumption, because it also means having to back further from a claim as it was done for the release of the MY2017 G4 850. So marketing had nothing to do with it.

Note the calculations in the 600 EFI post that showed a decrease in oil consumption was more involved than an increase in distance. Think about when you are riding, what does a 28.5% decrease in oil consumption mean? It is not tangible without using a calculator.

To get a 40% increase in distance, then off the top of my head I can figure 100 mpq will become 140 mpq. On one quart of oil I will travel 40 miles more than 100 miles, hence 140 miles.

Even with an odd number like 147 mpq it can be rounded to 150, drop the zero and multiply 15 by 4 to give 60, then add 150 = 210 mpq which is close enough to 205.8 mpq.

[Daag44]

It is all about doing fast and easy calculations

We all have a range for when riding hard with our buddies at say 13-14 mpg, and riding slower with the kids at 15-16 mpg. Seasoned riders will consume/guess for different snow conditions without even thinking about it. So fuel consumption is a no brainer.

All riders that I know will have the trip A or B set before each ride to count the miles ridden. Fuel consumption and miles ridden are two values that are guaranteed for each ride. This leaves only mpq. With two typical types of riding, hard and slow, only two numbers are needed for the respected oil consumption in mpq. For example, 13-14 mpg @ ~120 mpq, and 15-16 mpg @ ~170 mpq. Don't worry about accuracy because it doesn't matter. If you have a sled that gets 18-19 mpg, then add one more point for a total of 3 simple mpq numbers to remember.

In the example below, note that I am low balling the oil consumption. The reason is the chart is so rich/high in oil consumption, that I can afford to error on the wrong/low side. For example the chart shows 13 mpg @ 102.7 mpq. An increase by 18% such as with the 600 EFI example, brings it to 13 mpg @ 121 mpq. Also note that I am using rounded numbers, because it is more about the relationship between fuel and oil consumption.

Example:
13-14 mpg @ ~120 mpq Hard riding
15-16 mpg @ ~170 mpq Light riding


Let's use some simple numbers and take it step further. Assume the same hard riding @ 13-14 mpg @ 120 mpq. Go 60 miles and stop for gas. Fill up with the usual 4+ gallons and the oil tank is down a half a quart. Your riding partner on a 800 CFI Polaris with a mechanical oil pump puts in just over a gallon, but consumed only half the oil. That is completely in the opposite direction with too little oil. I don't know if you care about the Polaris, but you may end up towing it, then overheat the engine and blow a belt doing it for the savings of a few dollars in oil. Try towing a car with a car. It ain't good on anything, and no better on a sled. You know how it goes, Ski-Doo uses too much oil and the Polaris works fine until the engine quits. This goes both ways, but I am merely talking about oil consumption. It can also be a sled in your fleet that someone in the family is riding. The point is with only a couple of numbers you can square away the sleds that are running good, and point out those that are in the left field.

The 600 EFI example gives a good clue on much leaner in oil we can go while remaining on the safe side. The calculation is easy by simply adding the percentage to the mpq. For example an 18% increase in distance to 120 mpq gives 13-14 mpg @ 140 mpq. I purposely error on the safe side with the 18% compared to BRP's initial 40%, but you can play it however you like. If the sled is out of warranty then the limit is when the engine quits and your pocket book for a shortblock. With a sled in warranty, then you can work with the OEM to correct a sled that consumes remarkably too much oil. In other words I hold to the chart for a sled under warranty.

This thread has never been about having to use a calculator on the trails. It is all about the relationship between fuel and oil consumption, and how to work it easily at the fuel pumps.