bchapman

I've been using an old hand crank fuel pump and regular glow silicone tubing with my Saito FG-21 gas engine and so far no trouble. I was wondering whether I should be using the Tygon tubing instead? It was my understanding that aviation fuel (100LL) is not gasoline, but rather toluene and xylene.

jetmech05

You can get away with silicon tubing for awhile but you need to use tygon

jester_s1

AvGas is gasoline. And yes, gasoline will break down silicone tubing. For some manufacturers, the pump is fuel specific too, so you might want to check on that.

LesUyeda

"(100LL) is not gasoline, but rather toluene and xylene."

Jet fuel, perhaps????

Les

bchapman

I'm not really sure on the 100LL, but jet fuel (Jet A) is kerosene not gasoline. The 100LL doesn't smell like gasoline at all. It really doesn't have much of a smell at all. I guess it smells more like a solvent than gasoline. I was just wondering because glow fuel is mostly methanol and silicone tubing isn't harmed by that, so i thought that the 100LL was more similar to glow fuel than gasoline. I'm hoping there is someone more knowledgeable on the subject than I that could fill us in.

I'm using an old Dave Brown glow fuel hand pump. I didn't want to buy anything new until I made sure the fuel would work ok first.

jetmech05

100LL (low lead) is not jet fuel. It's av gas. It's terrible av gas at that I couldn't even use ADI fluid with.

jester_s1

According to wikipedia, 100LL is just gasoline with lead added to increase the octane rating. It doesn't smell much because it also has a higher vapor pressure therefore doesn't produce fumes as much.

So that settled, what got you interested in using avgas in your Saito? Most model engines are designed to run right on regular pump gas.

bchapman

One of the main reasons is that I don't like the smell of the gas 2-strokes. Aviation fuel just smells like airplanes and it's been cool using it.

In addition, the Saito 4-Strokes have been know to be a little tempermental, and I thought that by using a much more refined fuel might help. 100LL doesn't go stale on you either, nor does it gum up or leave varnish in the carburetor. I don't entirely agree with the information you got on the web that Avgas is just gasoline with lead added for increased octane. Try leaving some gasoline out to evaporate next to some 100LL and what you'll find is that the 100LL leaves nothing behind. It's a very refined, clean product. It really is very different than pump gas.

The Saito's also don't use a ringed piston either, so I thought that the lead in the fuel may "cushion" it somewhat as well as helping to control valve wear. I know from flying full scale that you don't want to idle the engine much so as to not foul the plugs from the lead. So far this hasn't been an issue yet with the Saito, but I think that may be because it operates sometimes at full throttle, whereas the Lycoming only does during take-off. The model has more time to burn off the lead is my reasoning for that theory.

Another thing I wanted to test was that I thought I could increase the ignition timing so get more power out of the Saito as well. You can't do that with the pump gas because it would start to detonate, but you can do it with the avgas with no ill effects. I increased the ignition timing manually and so far no trouble or detonation and the engine seems to have more power. It's definitely not a scientific test, but that's just my opinion.

You might try it and see what you think if you have a 4-stroke gas engine. Not sure how it would work in the 2-stroke chain saw engines though. I don't own any.

invertmast

My Feedback: (23)

100LL is a highly refined and strictly controlled gasoline with many additives (such as tetraethyl lead for antiknock capabilities) to provide maximum quality and performance.

The following link will provide plenty of information in the process and normalitiea of 100LL.

http://www.aviation-fuel.com/pdfs/av...md910_2011.pdf

bchapman

That's some really good information, thanks!

I think it's safe to say that's all a person needs to know about it. My 1 year of general chemistry in college wasn't really cutting it though. Pretty technical descriptions!

Brian

JohnBuckner

My Feedback: (1)

[QUOTE=bchapman;11859771

I'm using an old Dave Brown glow fuel hand pump. I didn't want to buy anything new until I made sure the fuel would work ok first.[/QUOTE]

Well regardless of what you call the gas its not glow fuel and its gonna attack the silicon piinch tube of your old Dave Brown eventually as does Jet A, auto gas, Kerosene or diesel. I don,t know if Dave Brown has an alternative pinch tube for those or not but you will need it in time.

If you prefer a manual pump then may I reccomend the Dubro geared manual which works with no problem for all the above fuels and a geared manual is so much nicer to uise. I have one on my auto fuel container and another for my diiesel fuel and for the glow fuels I us a number of various brands of geared manuals Just using the diiesel this morning out on the dry lake and the dubro pumps this fuel quite well, when used with gas it takes more cranks but still far easier than a Six Shooter.

John