J-160 fuel burn /economy

[kgwilson]

if the tank is half full there will be mostly vaporised light components in the other half so there will be little exchange from the outside to bring in water vapour and you only need to add a litre or 2 to refresh those components. Full is OK but temperature expansion and contraction of the fuel will waste some out the overflow and contraction will suck in (moisture laden) air. I think the half full comment is more to do with the ability to refresh what is in there. You can't if it is full.

 

A very empty tank will end up with a lot of exchange of air from the atmosphere. I have fixed a number of generators when they would not start after being left for months and after adding fresh fuel, by removing the outlet hose & carburettor float bowl to let the water out. At my SES unit we have a dozen or so generators and run them once a month for 5-10 minutes under load & keep the tanks with some fuel in them. I add 100ml to 500 ml of fresh fuel each time they are started. This way I know when we have a major power outage and need them, they will always start and run properly.

 

The comments regarding high revving engines and old fuel is very true. A fairly new Stihl 192T chainsaw was used on a SES job after some months of no use. It went OK but the comment I got back from the user was it seemed to lack grunt. After that job it would not start. The Stihl shop took 5 minutes to find the piston had a hole in it, the big end bearing was stuffed, the bore scored badly and rings were most likely broken. The simple reason was overheating due to old fuel. The saw was written off & I replaced it with a battery powered one.

 

 

Edited August 13, 2022 by kgwilson

[lyle janke]

On 12/08/2022 at 7:57 AM, lyle janke said:

hi 

"The wooden prop is a fair way down on efficiency compared the the composite prop- it bends.  the composite prop is a great upgrade."

the prop on the J-160  i understand was replaced in recent past so i`m wondering what prop i have fitted  ( are no`s easy to read without removing the prop ) 

i had composite prop on my previous J-120 aircraft  (definitely agree on up-grade )

 will get a set of no`s  next flight  (cost of fuel is not making it easy to fly for pleasure at the moment  in the bush - $3.60 P/L)

hi all 

 found ID on prop when i checked this morning 

DWG 000242

D=60    P=42

jab 2200

something to ponder 

[spenaroo]

On 13/08/2022 at 9:21 AM, sfGnome said:

Thanks KG. That was really interesting. With regard to the bit I’ve quoted, are they saying “don’t leave it empty”, or “don’t leave it full” (or both)? What’s the reasoning?

interestingly with motorcycle's it was always completely drain the tank and leave it empty and dry so that the fuel didn't turn to varnish/jelly and destroy the fuel pump and lines.
or leave it completely full with some stabilizer, so the moisture couldn't get in and rust the fuel tank.

 

when it was left half is when everything would be completely destroyed. would only take a few months of sitting to leave it completely cactus. and 98 fuel was the absolute worst for it.

[spacesailor]

Now , we top up with 98 fuel to keep the tank good !.

The Ethanol separates when left unused, for long . Or even a few months.

I often go two months between refueling.

BUT

Our second car can be 6 months plus,

I do keep a fuel log on both cars. One petrol , the other diesel. 

spacesailor

[RFguy]

but there isn't Ethanol in 95/98. or shouldnt be. Most brands go out of their way to spell out that their PULP does not contain Ethanol.

 

[spenaroo]

My understanding is that 95 is regulated. But the manufacturers can put whatever they like in 98.

Which is why all the manufacturers advertise their 98 as a special blend. Notice that these days it's advertised for its detergents "cleaner engine' not any performance benefits