Lower fuel usage to oil ratios...?

[DelawhereJoe]

If the new saws are using 20% less fuel and run longer with each tank of fuel, does that mean they are running on a lower oil mix per stroke, sense less fuel oil mix is injected each stroke ? So would you have to increased the oil mix by 20% to equal the old 50:1 mix  per stroke mix, so you wouldn't under oil the internal workings ?

[Texas-Jim]

It means they arent wasting the fuel. Two strokes have not always been very efficient. The straftified engine helps solve part of wasted fuel.

[DelawhereJoe]

Isn't a carberated engine still a carberated engine, unless its fuel injected....has a mass air flow sensor and blah blah blah.

[DelawhereJoe]

If cylinder blow by is still cylinder blow by, then your saw is running on less oil per stroke, is what I'm getting at. If your saw uses 20% less fuel per stroke then theres 20% less oil mix making it to your saws internal parts that need oil.......right or wrong......

[ZeroJunk]

I don't understand the physics behind the stratifying port and piston design, but the stratified charged design traps more fuel so the fuel/air mix discharged unburned has less fuel in it than a traditional ported design.

[Bluejay27]

Before the air/fuel mix enters the saw, just air is used to push the exhaust gasses out, so it isn't dumping fuel out along with it. You do get less oil travelling through the engine. However, the air-only charge is routed along the sides of the piston to get to the transfer ports and precharge them, not into the lower part of the crankcase. So you aren't diluting the oil mixture where it is needed or losing as much out the exhaust, which should just about balance out.

[Al_Smith]

For all intents if you think about it  it's not starving oil from the bearings or cylinder  .

Discounting oil mix ratios related to the never ending war of oils they are still getting lubricated .--how much they are getting oil is the subject of that debate but being such a nice guy I won't fan the flames--this time. ;)

I for one don't see it as a savings of fuel no more gasoline than a chainsaw uses .I mean it's not like dumping gasoline out of a 5 gallon bucket to fuel a Sherman tank .It's an environmental thing which in my pea sized mind still doesn't make much  sense .

[CTYank]

Short-circuiting unburnt fuel out the exhaust might seem to be an inconsequential thing, UNTIL you notice that it's being dumped into your surrounding air, which you breathe. If you're working in an area of "dead" air, where that schmutz lingers around you, you really appreciate a lower concentration of HC. Presuming that you don't have a Scott-Pack on.
Reduced fuel consumption also helps where you have to pack your supplies on foot some distance to your work area. A strato saw can make it real easy to pack enough fuel for many hours' runtime.

[Al_Smith]

Point taken on the fumes .Honestly though I've never noticed it with one exception .Stumping right next to the ground it will get to you .I'd bet though a"strato" saw would gas you also .

[ZeroJunk]

I have to say that after running 1/2 pint to the gallon back in the early 70's with a Homelite 7-19C I don't much notice it.

[Texas-Jim]

Ok Bluejay is defiantly better at explaining than me. ;D

[Al_Smith]

 :D .What amuses me in these conversation regarding gasoline and  oil are those who go out of their way to say run high octane aviation or racing gasoline in chainsaws .Talk about better performance but in the next sentence talk about smelly exhaust fumes from older saws .Av gas smells like a fetted skunk.It will gas you in any saw .--So much for "strato " saws .--well only fanning the flames a little bit ---- 8)

[Texas-Jim]

Uhm not sure av gas is going to be enough HP boost to be worth the trip to the airport. Even in average car its just a few HP maybe 5 or 6. Its a lot higher in price as well. Racing gas should be used cautiously because additives can do damage. The only advantage to high octane fuel is its ability to not knock at a lower pressure. It doesn't burn better or with more power. Now if you could lower the area of compression there could be a lot of difference in power. The smaller compression chamber would require av gas but the dependability of the saw would drop quickly.

I fly an Ercoupe all the time and it runs every bit as good on mogas or avgas. It will knock a tad if your climbing fast but i cant see any difference in its performance. I run avgas because it doesn't knock and theres no ethanol in it.