2-Stroke, Unleaded to Superunleaded

[TRBomb05]

Hi everyone,

I reciently got a new toy. It has a 2-stroke engine similar to one found in a brush cutter and a the moment i run it on a 25:1 mix of unleaded and 2-stroke oil. I have been wondering what would happen if i ran it on the same 25: mix but used super unleaded rather than normal unleaded. Would it make it run faster as basic logic would suggest or would i blow the thing up like Mr. Paranoia keeps telling me?

Hope you don't mind be posting this here it is sort of gardenin related because i use it to...........errr.......chew up the garden, figured that there has to be at least one gardener out there who ha tried this on a mower/strimmer etc.

Hope to get some info soon Cheers Ti

-- TRBomb05

[zxcvbob]

If you use higher octane gasoline, the fuel will last longer in storage. That's about it. A lot of 2-cycle engines specify 89 octane, and most regular unleaded gas here is 87 octane.

I buy a can of premium in the spring to use for the first tank in the lawnmower and tiller because they start easier after storage that way (I don't know why.) Then I switch back to regular.

Bob

[Treedweller]

I don't think you'd notice a difference in the performance, but at least one chainsaw repair guy I've talked to says you should use premium to get more life out of the motor. I do it all the time with no blowing up.

k

[Wolf Kirchmeir]

Actually, higher octane gasoline reduces the chances of blowing up the engine, as it reduces knock (pre-ignition). Knock is especially noticeabl when the car accelerates. It also reduces carbon build-up. If you use it for your 4-cycle (automobile) engine, it will extend the life of the engine. It also provides a small performance/efficiency boost, so that you will get about 5-10% better mileage (other things being equal.)

BTW, 2-cycle engines are horrendous polluters compared to 4-cycle engines. Your 2-cycle lawnmower will produce at least as much pollution as your car in the same amount of running time.

[cat daddy]

That "basic logic" is incorrect.

The Low-Down on High Octane Gasoline

"In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner."

What does octane mean?

"The compression ratio of your engine determines the octane rating of the gas you must use in the car."

[cat daddy]

Only if it's not tuned up and the ignition timing is wrong.

The Low-Down on High Octane Gasoline

"In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner."

At least what you say here is true.

[Robert Chambers]

[Wolf Kirchmeir]

True. And when the car is tuned for high octane, there is a noticeable performance and some mileage boost. Leastways, there is with my Taurus. But many, many cars are poorly tuned, and high octane gas will reduce knock in those situations.

Whether it's worth buying high octane for these performance and mileage gains is another issue. Some years ago, a colleague (who happened to be an autmotives teacher) did two 6-month trials with his Buick, one with low octane and one with high octane gas, and figured that so long as the price differential was 10% or less, high octane was worth buying. In those days the price differential _was_ 10% or less. Not any more. :-(

That "in _most_ cases" is the hidden hook... :-)

One reason I use a real type push mower. T'other reasons are: easier to use (the push mower is much lighter), and the reel blades cut the grass rather than smash it off. Also, you have to cut more often, as the reel mower doesn't handle high grass very well. More exercise for me. :-)

[Philip Lewis]

heh... I keep the power mower in reserve for just such an occasion. (cut the high parts just yesterday in fact.)

I hope to find enough time to reel mow the rest of the year... I hate the noisy beast.

I suppose I could get a scythe for the long stuff. ;)

[Wolf Kirchmeir]

I have a scythe, Austrian made, must be 60 years old at least. Haven't used it in years, it was always hard to keep sharp, and if it's not sharp enogh to slice a feather drifting onto it, it's a real pain to cut grass with. Besides, there's a real trick to doing it right, if you don't, you'll have one mother of a backache.

Hah!

[bamboo]

Well you have to pound the edge thin to work harden it between a cross pein hammer and a small anvil and then use a scythe stone to dress the edge. If the edge is just continually stoned it just gets thicker or worn away but when you beat it out it lasts and you get good cutting.

[Wolf Kirchmeir]

Yeah, I watched my Opa and my cousins do that, many years ago, when I was much, much younger. I don't have the requisite anvil, though I suppose I could use the chunk of rail I have. They had an anvil mounted at one end of a nicely made, which they straddled while beating out the scythe's edge, so it was a relatively comfortable job for them. I remember the lovely ringing of the steel. Beating out the edge also work-hardens it, so it keeps its sharpness longer.

I think I'll just indulge in some nostalgic memories instead of actually using the scythe, if you don't mind. :-)