GAS: Regular? Premium? Ethanol?

[scrappy isb67]

What is it? A diesel?

nope, it is a VW 2.0t gas engine. the 2.0t uses direct injection just like a diesel (but at much lower injection pressure) because if the direct injection, high compression is workable. (fuel can't ignite if it isn't in the cylinder) all on 91 minimum octane.

 

[radioman]

funny -- ever since my state added up to 15% ethanol to our gas --- I been getting in touch with my inner small engine mechanic side, learning every crook and nanny of little carbs and jets with all of my little engines. trimmers, tiller, chainsaws, hedge clippers,push mowers, etc . This is more then I care for to do but being poor can just makes you learn. :thumbsup:

 

[s219]

I really wouldn't worry too much about octane for 2-strokes -- it's a much smaller factor than ethanol. I'd take 87-octane ethanol-free over a 93-octane ethanol-blend any day. Ethanol gas is just pure evil for 2-stroke power equipment.

 

[murphy1244]

the wife's car is turbocharged and running 12:1 compression. just because it is turbocharged does not mean it is lower than NA. especially in modern engines.

No way in heck its 12 to 1 in a turbo or any usual car.

 

[ruffdog]

"The cooling effect of directly injecting fuel into the combustion chamber lets VW get away with a high-for a turbocharged engine-compression ratio of 10.3:1."
2006 Jetta 2.0 turbo

 

[ruffdog]

The 2013 beetle 2.0 turbo is running a 9.6 : 1 compression ratio

 

[ruffdog]

The problem with ethanol and 2-stroke premix is as the ethanol absorbs moisture, it will start to separate the oil out. With non ethanol fuel, the water would just sit on the bottom. With ethanol, it gets absorbed and pushes the oil molecules out. That is why, with ethanol, you should always use fresh fuel.

 

[joshuabardwell]

That's interesting that turbocharged engines don't typically run higher compression than NA engines. Did that used to be the case? Seems like the whole point of a turbocharger is to allow running a richer mixture, which would require higher compression to combust. But I guess nothing's stopping an NA engine from being designed to run in that same state.

What do you think about my argument about octane, though? Do typical 2-stroke engines run high enough compression to benefit from higher-octane gas? I've done some web searching and found at least one person who says his Stihl chainsaw says 93 octane right on the gas cap, but other than that, nothing but people asking the question and getting mixed answers, just like on here.

 

[cropdusting]

I saw this thread and thought I would throw my OPINION into the ring with everyone elses, but my opinion comes from maybe different experiences. From the below pictures you will see I have a lot of different gasoline engines all requiring different lubricants and fuel requirments. As you can see a "one size fits all" doesn't work for me.

My main race bike (I have others) because of its high performance (14.5:1 compression, 45 rwhp verified at 5,550 ft elevation) and relatively narrow operating range it is the most fuel sensitive (jetting, altitude, air temp and density) of all my bikes. So its performance will vary if consitant fuel (and jetting) is not used. Idealy I use VP 110 or C12 leaded non-oxygenated fuel and jet for that, however I can use with some success and minimal performance loss 93 pump gas with an octane boost, ethanonl does not seem to matter other than the lower performance. I do have to rejet for fuel changes though. My mix is 40:1 with full synthetic with caster oil.

The bike on the liftis a similar type of engine only I jet for using 93 pump and same oil, its engine porting characteristics lends itself to slower speeds as it is my "trail/play" bike.

Both of these bikes don't really have a preference for fuel

My trials bike(s) as I have two, these require premium pump and octane boost gas at least, they run decent on ethnol as they are low rpm 2 strokes but high compression. oil mix is 100:1

Most of these bikes can handle the cheapest low octane pump gas with little or no pefromance problems, some are oil injected so an oil that is designed for injections is nessary (for the 2 strokes of course)

I have numerous outdoor power equiptment that I use what ever fuel I have laying around (obviously not mix in a 4 stroke)

Bottom line is I treat any and all fuel I use or store reguardless of where it is used. I prefer Startron as years ago I WAS sponsored by them, but after the sponsorship was up I still continued to buy and use the stuff.

 

[CompactTractorFan]

This thread has seemed to wonder off a little, so getting back on track...

We used to use regular gas (mixed with oil) for all our 2-stroke engines. We purchased an Echo leaf blower last Fall, and the dealer recommended using high octane fuel, so we switched to that for all the 2-stroke stuff. We still use regular gas for all our 4-stroke small engines.

No fuel problems yet either way...