Need help ASAP: Aviation fuel question! (OT)

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limpingcrab

Trad climber
the middle of CA
Topic Author's Original Post - Feb 28, 2018 - 08:07pm PT
I'm about to drive to Tahoe to buy a snowmobile that only runs on 100 octane aviation fuel, but a friend said there's new law so that now you can only buy and use it in airplanes?

Is this true?

I can't find anything about this new law online and I'm in a pinch to figure this out before I waste a few thousand bucks on something I might not be able to fuel up.

Please help if you have inside info!



PS: I'll delete this waste of space thread once I get this sorted out, thanks in advance
Mungeclimber

Trad climber
Nothing creative to say
Feb 28, 2018 - 08:36pm PT
whatever savings on the price of the sled are offset on the gas burned getting up there, plus the headache of having to refuel at a moments notice to want to ride the conditions, no?

oh, and sorry, I have no idea about new laws on aviation fuel.
Reilly

Mountain climber
The Other Monrovia- CA
Feb 28, 2018 - 09:02pm PT
Haven’t flown lowly gas guzzlers for yonks. Used to see the hot rodders buying av gas all the
time BITD. After 9-11 access to even general aviation airports changed such that that in itself
made the practice difficult. It is also unnecessary- simply go online and you can find a list
of gas stations that sell racing fuel and then there are the additives readily available. Unless
you are going into racing I can’t imagine why you would want such a high strung beast.
rottingjohnny

Sport climber
Sands Motel , Las Vegas
Feb 28, 2018 - 09:06pm PT
check out a small airport...they usually have Hi-octane...isn't there some kind of additive that will boost the octane...?
micronut

Trad climber
Fresno/Clovis, ca
Feb 28, 2018 - 09:16pm PT
Is there some reason it only runs on avgas? Call Tanner. He used to be into sledding and my brother-in-law owns a bunch of high-powered sleds and Tanner runs anything that will run on Avgas. I think he puts the stuff in his remote control car, his golf cart, his Toyota tundra and his blender.
Reilly

Mountain climber
The Other Monrovia- CA
Feb 28, 2018 - 09:18pm PT
BITD, avgas was different only in its lead content to keep valves from melting in the aviation
air-cooled engines. Dunno if it still is so. Can’t imagine a snogo engine built in last 25 years
needs any lead in its fuel.
Tom

Big Wall climber
San Luis Obispo CA
Feb 28, 2018 - 09:21pm PT
First of all, call the airport and ask them about getting AV Gas. The issue may be gaining access to the tarmac, where the fuel trucks are. After 9-11, the SLO airport would change the gate code about once a month. Every time my father flew down, I'd get the new gate code so that I could drive out to his airplane and pick him and his baggage up.



Auto parts stores sell octane-boosting additives for high-compression hot rod engines. If you don't live near a hot rod gas station, like in the San Fernando Valley, you can make your own 100 octane out of ordinary civilian gasoline and a bottle of additive.

As I recall, those additives were methanol, or ethanol. They weren't too expensive, either. AV Gas at an airport is really expensive, because it's not just high-octane, but high-purity. The gas at your local station is dirty garbage, by comparison.


Just for the record, a car that supposedly requires high-octane gas, like my old Range Rover, runs fine on regular most of the time. If I am going on a trip in hot weather, with steep grades at high altitude, I use supreme. But, the rest of the time I use regular, and the engine never knocks.

Detonation, or knock, typically occurs in an engine that is hot and under high loading, and not when it's loafing along. High octane gas inhibits the onset of detonation, so that it doesn't occur anywhere within the vehicle's expected range of operation, including its maximum output in adverse conditions.


Stay light on the throttle of your snowmobile, and you might get away with using supreme from the local gas station.




EDIT: Tetraethyl lead was originally used to boost the octane rating of gasoline and allow higher compression-ratio engines with more power. The valve lubricating qualities were secondary. During the transition away from leaded gasoline, in the 1970's, it was still available for older cars that needed the valve-lubrication qualities. I remember when rebuilding VW engines, or getting a valve job, would involve the option of replacing all the valve guides and valves with lead-free versions. A lead-free valve job on a VW would cost about twice as much as a basic valve job. I don't remember ever having the option of having the valve seats replaced.



EDIT EDIT: A brief googling of 'octane booster' shows that A) getting 100 out of 92 supreme may be difficult, and B) at least some are not recommended for 2-stroke engines, presumably because the additives (like napthelene) reduce the lubrication of the crankshaft bearings.

What kind of monster engine is in that snowmobile? A custom-made rig?


Fuel Expert Discusses Using Aviation Gasoline In Automobiles



EDIT EDIT EDIT:

That Av Gas contains lead, and a lot of it. So, it is definitely on the EPA/DOT's list of stuff to NOT put into your car. The heavy fine is because of environmental poisoning, not because of some sort of War On Terror gibberish coming from me. My link just above discusses how the lead fouls everything from spark plugs to oxygen sensors to catalytic converters.

Look into the octane booster additives. Or find some racing fuel. The Rocket Brand link below mentions a 112 octane racing fuel they sell.

justthemaid

climber
Jim Henson's Basement
Feb 28, 2018 - 09:57pm PT
I'm about to drive to Tahoe to buy a snowmobile that only runs on 100 octane aviation fuel

How about turn around and head back home to shop for a snowmobile that doesn't need such ridiculously difficult to obtain fuel?
limpingcrab

Trad climber
the middle of CA
Topic Author's Reply - Feb 28, 2018 - 10:02pm PT
"AvGas is also illegal to use in anything except aircraft engines. Violations can carry a potential penalty of $25,000 per day of violation.'...
Wait, what!?


To the other questions/comments. My old snowmobile ran on 100 octane and it was easy to buy at the airport down the street last winter so I was wondering if there was a law change coming down? I do admit it was annoying to not be able to use normal gas but when the price is right I'll deal with it

The one I'm buying Friday is a great deal but it has a turbo that has been built for 100 octane and supposedly (I don't know) it can't be ran on premium unless the turbo is removed. I don't care about the turbo so I'm fine with that, mostly just don't want the hassle or expense of changing things.

I'm gonna call the airport tomorrow morning before I leave to see if anything changed, but what Cosmic posted above has me worried?

Thanks for the replies so far! I'd prefer stock everything, but there aren't a lot of option in CA for sleds that can take two people up a mountain in deep powder for $4,000 or less.

Edit: micronut, I just texted Tanner, thanks
limpingcrab

Trad climber
the middle of CA
Topic Author's Reply - Feb 28, 2018 - 10:04pm PT
How about turn around and head back home to shop for a snowmobile that doesn't need such ridiculously difficult to obtain fuel?
I've been searching all winter to no avail. Also, I'm impatient and it's snowing :)
fear

Ice climber
hartford, ct
Feb 28, 2018 - 10:07pm PT
Leave it in Tahoe.

Most stock modern snow machine engines make crazy power and will run fine on high octane pump gas.

Reminds me of all my friends(amateur old guys) modding their 450 mx bike engines.... why... just why?
limpingcrab

Trad climber
the middle of CA
Topic Author's Reply - Feb 28, 2018 - 10:17pm PT
Most stock modern snow machine engines make crazy power and will run fine on high octane pump gas.
Again, I totally agree, but that's not what's on the used market right now


That boostane stuff seems like an expensive alternative
Tom

Big Wall climber
San Luis Obispo CA
Feb 28, 2018 - 10:17pm PT
How long have you been in California? Environmental protection laws change all the time here. You can't even get a free plastic bag at the grocery store because they kill whales.

My link above discusses how LL110 Av Gas has a lot of lead in it. So, the EPA doesn't want it being used in cars. They tolerate it in airplanes because they, apparently, need it.



If you just remove the turbo, the engine may end up with a really low compression ratio, and really poor performance. Was that turbo just an add-on to an engine that ran fine, and they wanted extra power? Or was the engine originally designed by the factory for the turbo, with a basic engine compression ratio of 6:1, or something?


Av gas, apparently, was the cheap go-to fuel for homemade hot rods needing high octane gas. To say that snowmobile only runs on av gas is probably not correct. 100 octane racing fuel would probably work, but might be pretty expensive.



Find out if the turbo is an after-market rig that was put onto a perfectly good snowmobile engine to hot rod it. And, if taking it off just gets you back to the original stock performance that came from the factory.

limpingcrab

Trad climber
the middle of CA
Topic Author's Reply - Feb 28, 2018 - 10:20pm PT
Find out if the turbo is an after-market rig that was put onto a perfectly good snowmobile engine to hot rod it. And, if taking it off just gives you the original stock performance that came from the factory.

It's aftermarket. How big of a hassle and/or how expensive is it to go back to stock? I'd prefer stock
Tom

Big Wall climber
San Luis Obispo CA
Feb 28, 2018 - 10:40pm PT
I think the first thing to do is find out from the seller if he can reverse the turbo installation for you, or at least provide all the information and old parts so you can do it yourself.

And, look into 100 octane racing fuel for cars. The extra cost may not be that bad. The extra power from the turbo could wear the engine out faster if you always drive it really hard. And, the turbo itself may not last very long (cooling and oiling issues). But, if you can find the 100 octane racing fuel, it might make sense to just keep the turbo, and go light on the throttle to minimize wear on the engine.




I'm not any kind of aftermarket turbo expert, but I've been working on cars for about 40 years, so, here it goes:

The aftermarket company would want to make the turbo installation as easy as possible. So, it is unlikely that extensive, expensive and difficult modifications were required.

The hot gas, exhaust, side of the plumbing would be the most difficult part of the installation. The cold, intake air, side could be done with flexible rubber or plastic hoses. The fuel system probably required either retuning/rejetting a carburetor, or reprogramming/rechipping a fuel injection system. A fuel injection modification may have also required installing different, larger injectors. I know that Bosch has a whole series of injectors that take the same electrical plug and look about the same, but they all have different fuel-flow ratings to allow leaning out or enriching the mixture by swapping the them out.


Replacing an existing piece of the exhaust system by simply bolting the turbo in its place would make sense. In that case, the original stock piping could go back in quickly. Again, find out if the hot rodder still has what he took out when he put the turbo in.

Or, it may be that cutting and welding the exhaust system was required to fit the turbo. That would require reversing those moves, and as in climbing, might be more difficult than when they were done in the first place.

A turbo acts a bit like a muffler, so the original muffler may have been replaced, or even discarded. What sort of noise pollution laws exist for snowmobiles?

Rejetting a carburetor, or reprogramming a fuel injection system could prove to be a real pain in the ass, if you're not used to doing things like that. A good MAF fuel injection system might not have needed any modifications, because it meters the fuel based on mass airflow. Denser, hotter air being forced through the intake could be accurately picked up by a hot-wire-type mass airflow sensor. A simpler fuel injection system may have required tricking the brain box to accommodate the higher density and temperature of the air coming off the turbo. A carburetor would certainly need adjustment to compensate, in the same way that they used to require adjustment for high altitude. That might have been as simple as adjusting a couple of mixture screws. Or, required replacing or reaming out the stock jets.





Here's something I just thought of: get an intercooler that has a high pressure drop as the air goes through it. A high-resistance air-to-air heat exchanger will have a high rate of heat exchange, with cooler air exiting it, compared to a low-resistance heat exchanger. Intercoolers for cars are big, because they need a lot of surface area to compensate for the relatively low pressure drop across them.

Much of the turbo boost pressure would be lost in the intercooler, so that lower pressure, cooler air was fed into the engine. That would reduce the effective compression ratio, and allow the use of lower octane gas. The engine would run more efficiently with cooler air coming in, too.

The intercooler would go between the turbo air outlet and the engine intake, and could be easily plumbed in with flexible hoses. Long hoses to and from the intercooler, providing additional flow resistance, might be beneficial, but turbo lag would probably increase. If you keep a steady throttle while cruising, turbo lag wouldn't be an issue.

An intercooler might be able to defang and domesticate that wild-assed snowmobile engine.


ß Î Ø T Ç H

Boulder climber
ne'er–do–well
Feb 28, 2018 - 10:52pm PT
Need help ASAP: Aviation fuel question!
[Click to View YouTube Video]
Tom

Big Wall climber
San Luis Obispo CA
Feb 28, 2018 - 11:28pm PT
^^^^^^^^^^^^

The guy who made that video is qualified to replace Hope Hicks as the next White House Director of Communications.


hooblie

climber
from out where the anecdotes roam
Mar 1, 2018 - 07:33am PT
octane technical issues aside, does the legal angle re: avgas involve highway use tax avoidance?
tradryan

Big Wall climber
San Diego
Mar 1, 2018 - 07:59am PT
Disclaimer: I don't know shite. But that said, I've heard you can add Toluene (available from a paint store) in a specific amount to boost octane from 91/93 to closer to 100. This was in the context of high performance twin turbo stock cars (e.g. Volvo S60/V70R, expensive machines and there are many that swear by this). My V60 generally runs pretty crappy on any CA gas but I've never poured toluene to try it myself. I say give er hell!
fear

Ice climber
hartford, ct
Mar 1, 2018 - 08:03am PT
octane technical issues aside, does the legal angle involve highway use tax avoidance?

If you were to use AvGas in a registered automobile on the road then yes... Same thing if you tried to use home-heating oil in a Diesel car/truck. Many people do though without any problems since who's going to really enforce this?

Since a snowmobile is essentially an unregistered off-road vehicle this would likely be a giant grey area that would again be very unlikely to ever be enforced.

But I wouldn't want to be the trial case either...
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