Just wondered if any of you have used it? It is readily available where I live, about the same price as premium fuel if not cheeper, and 100 octane unleaded.
staggs65
Moderator
does your sled require 100 octane?
For what it's worth, I read an article about this and what I got out of it was not to do it. AVGAS doesn't burn fast enough for high rpm engines since a normal aviation engine maxes out around 2500 to 2700 rpm and snowmobile engines obviously max out in the 8500 rpm range.
dmax66
New member
If it is 100LL aviation fuel, it still has lots of lead in it. The LL stands for low lead. Unless you have bumped up your compression it wont benifet you. It does work not to bad if you mix half and half, and smells nice too.
I have an sxr700 piped, ported, reeds, reedspacers and two layers of head gasket removed. I blow it up last year becuase of detonation. I was thinking of mixing some in with premium to be on the safe side.
Like dmax66 says, you'll actually make less horsepower with 100 octane. Now if you jet for it and that is all you plan to use then you may be able to better your performance with the leaner mixture.
Av gas burns at a slower rate than regular gasoline as the higher octane rating makes the fuel less volatile than regular gas. hope some of this makes sense.
Av gas burns at a slower rate than regular gasoline as the higher octane rating makes the fuel less volatile than regular gas. hope some of this makes sense.
Your thoughts are correct and will work to a point.joehunt said:
For this year did you clean the carbs and are you jetted properly for your conditions? This will help you NOT repeat last year...
Also are you sure that your carbs are in sync?
grapeape
New member
adding a couple gallons per tank will help your detonation issue. 50/50 and above I would re jet.
I do understand about the slower burn rate. I used to do a little drag racing and if you put premium in a car that didn't need it (around stock compression) it would run slower, but as you add cylinder pressure (timming, compression or even boost) you need the slower burn rate so it does not detonate. Anyways
Carbs are clean, I'm going to up jet two size from 140's and work from there. And I may have to look in to seeing if the carbs are in sync. I think I just seen a post on that.
Carbs are clean, I'm going to up jet two size from 140's and work from there. And I may have to look in to seeing if the carbs are in sync. I think I just seen a post on that.
I just noticed that I posted in the wrong spot. I have a viper frontend on my sled so that counts right.
So to sync the carbs I just have to make sure the slides are all the same hight?
So to sync the carbs I just have to make sure the slides are all the same hight?
I can chime in one this one. Avgas 100LL was specifically designed for use in forced induction motors. It has an equivalant octane rating of 130...I say equivalant because the octane scale only goes to 100. 100LL is graded on a scale called "supercharge"...hence the 130 equivalant. The lead does help with detonation so it would retard your timing so to speak. I'd never run it straight as it will wash your pistons clean....definitely nothing more than 50/50 if that. Put it this way...if you spill it on the ground in the summer it will evaporate before your eyes. Just my 2c
ryan2001sx600r
New member
Don't do it. 100LL has 5 times the amount of lead as regular leaded gas that hasn't been around forever. The A&P's use to pick the lead BB's out of the spark plugs on airplanes during the 100 hour inspection. Also, not sure where you think it is about the same price as high octane gasoline, i just filled my plane friday and paid $5.65 per gallon for 100LL. Oh, and 100LL is run is thousands of normally asperated engines.
So by the sounds of it, it's not that good of a thing to try.
I don't know what you guys south of the borded are paying for premium but it is $1.40 per L up here, about $5.3 a US gal. And last time I bought avgas it was cheaper than premium at the time.
I don't know what you guys south of the borded are paying for premium but it is $1.40 per L up here, about $5.3 a US gal. And last time I bought avgas it was cheaper than premium at the time.
ryan2001sx600r
New member
not sure what it is up there but i do know it has went up quite a bit in the past 6 months. It's price jumped when gas was $4 gallon and never came back down. If you put a gallon of it along with 10 gallons of gas it probably will help with your detonation like the guys said but i wouldn't go 50/50 and if you get any on your hands, wash them as it has alot of lead, 2.12 grams per gallon compared to about 0.0001 grams in unleaded automotive gas. If you get some on your hands and let it evaporate, your hands will have a whitish residue on them, the lead. That is why they use to use lead in paint, gave it a white base.(i think i may be watching too much TV!!!)
Why wouldn't you just add octane boost? There have been many posts on this site about the Viper's detonation indicator. What it seems to boil down to is find good premium fuel and throw some octane boost in and you will well protected from detonation provided you are jetted correctly. This method seems to be proven by most of the senior / experienced members and I certainly trust what they say about it. What a great knowledge base here.
Nothing wrong at all to add a couple gallons to a fill up, it will keep the sled from detonating on the "crap" they call pumpgas these days. It will bump up your octane some and make the sled slightly richer. I agree with grapeape, add up to 2 gals no jetting needed, you wont be changing pistons from now on. 
140 mains, what pipes are you running? That could be part of the problem, I run 150's with the same set up and Bender pipes.
edunn69 said:
good catch right there, I missed that part, but adding the AV gas still is ok to do, but better check mains as suggested. By removing 2 layers of gasket your squish is fairly tight, youll need more octane.
what altitude and temp are you running the 150's at? I'm 3000 to 5000 ft and I'm running slp's. The plug come out tan color.
mod-it
Member
I run the same altitude as you and have SLP's...none of the other mods you have. I do have the flo-rites cut into the dash and don't take any underhood air, my plugs are cardboard color running the stock 156.3 jets.