Using 100ll AV fuel in a 4-mix engine?

[skid row]

Just picked up a new stihl br600 magnum and absolutely love this machine. I have read many post's on the do's and dont's using 100ll av gas in chainsaws. What about stihls 4-mix engines? The carb on this blower looks non adjustable. I have a small supply of av gas for my 60's vintage wisconsin engines collection that all winter until the summer engine shows. Any input?

 

[blsnelling]

It's specifically designed for engines that turn less than 3,000 RPMs and has a very slow burn rate. Not for me. Made all of my modern saws idle poorly and have bad throttle response.

 

[CentaurG2]

Why bother with AV gas?? Just run premium with good quality synthetic oil like stihl Ultra or Saber Pro and you will be fine. That’s what my 4-mixers and all my 2 stokes get and I have never had a problem

 

[Wildman1024]

It's specifically designed for engines that turn less than 3,000 RPMs and has a very slow burn rate. Not for me. Made all of my modern saws idle poorly and have bad throttle response.

I've been searching all over the net and i cannot find anything saying that 100LL is "RPM limited". Do you have any of the sources so i could see?

The higher the octane the slower the burn rate. Most of your fuels are designed that way to prevent detonation and ping.

To answer the original question I dont think i would run it in the modern "Small Engine" 4strokes. I'll run the stuff in 2 strokes, race engines and older 4 strokes all day long but with the new emissions crap I wouldn't chance it. Especially if you cannot really do any tuning

 

[blsnelling]

Perhaps I've been helping perpetuate some old wives tales myself. This thread has more info on 100LL than I've ever seen. It does explain why idle and throttle response suffer. LINK

 

[spacemule]

You all are messing around with kid stuff. You really need to get yourselves some ROCKET fuel! That 'el really make 'er run like a limp toothed molested monkey from Alabama. :hmm3grin2orange:

 

[PA Plumber]

Along with a post regarding low rpm engines, I did see this in the provided link...

"Av Gas is NOT designed for low RPM motors. AV Gas is designed to not detonate/preignite causing detination. This would be the same design as race fuel. If you compare the "distillation curve" of AV Gas to Race Gas, you will find they are almost identical. The "distillation curve" controls the speed of burn across the combustion chamber."


On another note:
I have noticed that my 441 tends to idle better than my 028 AV, when using 100LL AV fuel.

 

[Trigger-Time]

I have had zero problem with 100LL AV fuel, in all my saws
and 4-mix. No idle problems at all, most dirt stock car guys use it
here as it is easy to get. just don't use it in any thing with CAT.
They say the lead will stop it up in short order. LL is low lead,
but it's low lead for AV fuel not like the old pump gas.




TT

 

[blsnelling]

You will get opinions all over the board when it comes to this topic. All I can do is report my experience with it, and the science as to why it does it.

 

[Outlaw5.0]

If you want non ethonal fuel, just find some VP SEF94 small engine fuel. The VP C10 unleaded 100 octane racing fuel is also really good.

 

[smilin possum]

I have had zero problem with 100LL AV fuel, in all my saws
and 4-mix. No idle problems at all, most dirt stock car guys use it
here as it is easy to get. just don't use it in any thing with CAT.
They say the lead will stop it up in short order. LL is low lead,
but it's low lead for AV fuel not like the old pump gas.




TT

We been running AV fuel for years and have not had the first problem with it. If you have to tear one down you won't find a cleaner engine any where. Our oldest ones look just like new ones.

 

[tomdcoker]

I have been running it in my saws and weed whacker for a couple years and have not had any problems. Tom

 

[Mad Professor]

If you want non ethonal fuel, just find some VP SEF94 small engine fuel. The VP C10 unleaded 100 octane racing fuel is also really good.

100LL AV is LESS than 1/2 price of VP. And most people in USA have an airport, no matter how small, nearby.

Like TT, never really had a problem with almost anything I ran it in. A few saws were a little rich but others didn't care a bit.

I use AV fuel, because of corn feds bad effects on rubber/organic based plastics/aluminum/magnesium parts, and the fact it stores like raw fish.

I've more saws/2-strokes than I get to run all the time, so the storage life is a no-brainer.

Even the "oxygenated/MTBE" crap they pushed on the public, before agri-business got E10, did not store well.

 

[formula_pilot]

Even though 100LL stands for 100 Octane "low lead" it actually contains a large amount of tetraethyl lead. The lead compound does not really burn and leaves large amounts of leads salts in combustion by-products. We have to clean the spark plugs every 25 hours in some airplane engines, because they are fowled so badly, they stop firing. Deposits also build up on the valves, although it is a bigger problem with lower compression engines, as they tend to run cooler. The high compression engines tend to run much cleaner. Some of the awsome saws we have today may burn it just fine, but I would monitor your equipment closely if you start using 100LL.

Storage life is spectacular, not even in the same zip code as 10% corn mogas

 

[Slamm]

We been running AV fuel for years and have not had the first problem with it. If you have to tear one down you won't find a cleaner engine any where. Our oldest ones look just like new ones.

Same here. Love the stuff.

Sam

 

[PA Plumber]

On the 026, there is a white coloring around where the exhaust leaves the muffler.

Lead? Or just suckback? Both?

 

[mtfallsmikey]

I use 93 octane/HP Ultra in my BR-550, runs just fine, easy to start.

 

[Nitroman]

I use the AVgas in everything: boat, saws, snowmachines. Run great, no probs.

 

[adam32]

Even though 100LL stands for 100 Octane "low lead" it actually contains a large amount of tetraethyl lead. The lead compound does not really burn and leaves large amounts of leads salts in combustion by-products. We have to clean the spark plugs every 25 hours in some airplane engines, because they are fowled so badly, they stop firing. Deposits also build up on the valves, although it is a bigger problem with lower compression engines, as they tend to run cooler. The high compression engines tend to run much cleaner. Some of the awsome saws we have today may burn it just fine, but I would monitor your equipment closely if you start using 100LL.

Storage life is spectacular, not even in the same zip code as 10% corn mogas

Are you running Iridium plugs or the cheap ones? "Cheap" in aviation terms that is...

 

[fearofpavement]

In aircraft the fine wire plugs are less prone to lead fouling but the 100 low lead is still a troublesome fuel for engines that were designed to run on 73 octane fuel. The 80 octane avgas that went away years ago has about 1/4th the lead that 100LL does. 100LL (100/115 blue gas) has less lead than the 100/130 green gas hence the low lead designation. It has a LOT of lead in it for a motor fuel and works great in higher horsepower, higher compression aircraft engines. I think its long storage life is one of the largest benefits of using it in non aircraft uses. If I found a ten year old sealed drum of 100LL I would have no second thoughts of putting it in an aircraft and flying off with it. I have ready access to it but don't burn it in anything but aircraft that require it. For the smaller mogas capable planes I will go out of the way to find alcohol free auto fuel to burn in those even if it were the same price.