Jay Honeck
Touchdown! Greaser!
Automotive 87 octane.Jay,
What is the octane of the fuel you are using?
Automotive 87 octane.Jay,
What is the octane of the fuel you are using?
Given how we fly, odds are we will never approach 100% mogas.I was going to post something similar. The 235 hp engine had 7.2:1 compression. The 180 hp engines have 8.5:1. Given that he lives in a very hot climate and at sea level, he's in the worst possible situation for damaging his engine using low octane fuel. If I was Jay, I'd religiously mix in at least 25% 100 LL to help with the octane issue. TEL is a tremendous octane booster and at that concentration might provide enough octane to keep his engine happy over the long term. (Also, it might not.)
RVP is another issue. I'd check it regularly to preclude vapor lock. Again, Jay is more at risk for vapor lock than many others because of the hot climate and his dark colored fuel tanks, which (compared to white tanks) will absorb more heat on a sunny ramp. Vapor lock is most likely following a quick turn-around on a hot day.
Saving $2/gallon is great when there is no downside. There are downsides in Jay's situation.
Yeah, I'm sure getting t-boned with 100 gallons of gas in back would make a nice explosion. Then again, I could fall in the shower.Just a word of caution.
I had a friend who got rear ended by a truck while he was pulling a gooseneck with a tool-and-tank with gasoline in it. The gooseneck broke loose and rammed into the tank and it was bye-bye friend. This is why I like diesel so much for transport. But that's another subject.
Point is, I wouldn't use my gas (fuel) truck as a family hauler ... especially pulling a gooseneck unless the buddy tank were empty and vented.
Given how we fly, odds are we will never approach 100% mogas.
Actually, with all the short flights lately (due to crappy weather) we are probably getting close to 75% mogas right now. Our low compression O- (not IO-) 360 is running wonderfully on it.
Also, remember that octane is measured differently in automotive applications than aviation applications. The differences mean your 87 octane fuel would likely register lower using the standard tests used in aviation.
you can find anecdotes to support any conclusion. fact is, many, many 180hp O-360's and 250hp O-540's in experimentals are burning mogas and it just hasn't been a big issue. There's plenty of discussion on vans, backcountry, etc forums if you're interested. Is it 100% proper per the engine manufacturer's intention, no it's not. But they seem to get away with it.Your Pathfinder had 7.2:1 compression. Your RV has 8.5:1. It is not a low compression engine. I suspect the dataplate on it mandates 90+ octane. There is a valid engineering reason for that - the marketing department would have loved it if it could have run on bilge water. The 200 hp engines are either 8.7 or 9.0:1 compression, IIRC. Do a Google search for the TCDS for your engine to confirm what I'm relating here...
Also, remember that octane is measured differently in automotive applications than aviation applications. The differences mean your 87 octane fuel would likely register lower using the standard tests used in aviation.
A friends' O-320 in his RV was routinely run on 87 octane fuel. That engine suffered broken piston skirts in the wrist pin area on two cylinders. No telling if there is a connection between the fuel and the piston problems, but...
Oh, and sorry for 'jacking your thread. The subject is very worthwhile, and I've been tempted several times to work out a fuel trailer for my own use (never have - too many irons in the fire already).
It may not be required, but putting an ERRONEOUS placard is probably not a good idea.no placards are required and DOT rules don't apply as long as the tank capacity is 119 gallons or less.
you can find anecdotes to support any conclusion. fact is, many, many 180hp O-360's and 250hp O-540's in experimentals are burning mogas and it just hasn't been a big issue. There's plenty of discussion on vans, backcountry, etc forums if you're interested. Is it 100% proper per the engine manufacturer's intention, no it's not. But they seem to get away with it.
At high altitude cruise? Probably not an issue.
We will never be running on pure mogas. It's simply not possible to obtain everywhere we go.No "probably" to it, do the math. At 5,000' there is not problem. At sea level, I don't know that there will be a problem but that is the only place it will happen. I suspect that just setting up the carb on the rich side at WOT will protect the engine but a little testing would figure that out real quick. If the engine has an engine monitor then the operator will know very quickly if there is a problem with the gas.
I thought the issue was that you do not want a spark at the filler neck caused by static buildup during filling. That's why you want a constant connection between the tank and plane away from where you're filling.Thanks, guys. A few notes in reply:
Re: Grounding. The hose has a metal grounding mesh embedded in the rubber. This means every time you pump gas, the plane and truck are grounded, which is why I am 99% certain that the retractable grounding wire is unneeded. Still, belt and suspenders.
I thought the issue was that you do not want a spark at the filler neck caused by static buildup during filling. That's why you want a constant connection between the tank and plane away from where you're filling.
......
25% 100LL and 75% 87 octane pump gas (call it 80 octane aviation equivalent) would give you 95 octane fuel with just the right amount of lead.
http://en.wikipedia.org/wiki/List_of_Lycoming_O-360_variants
that's why a lot of people run blue gas in one tank and smelly gas in the othersThe question is "What mogas (87 octane, 91, or 93?), and in engines with what compression?" This isn't a one size fits all answer here.
As far as people "getting away with it", there were several ex-mogas users who posted in a discussion on VAF recently. In-flight vapor lock was their primary reason for moving back to Avgas.
As you say, there are plenty of anecdotes. Personally, I wouldn't run a slow turning, large combustion chamber, 8.5:1 compression engine on 87 R+M/2 octane fuel. At takeoff on a hot day at sea level, bad things could happen. At high altitude cruise? Probably not an issue.
As a side note, I have not found a source for unpolluted premium mogas here in Texas. The place I get it handles only regular.Lycoming revised their fuel requirements in 2013. 87 octane mogas might not work for an O-360, but 93 octane could (depending on model):
http://www.lycoming.com/Portals/0/Upload/SI1070S Specified Fuels.pdf
it's the opposite in IL, you can usually only find 91-93As a side note, I have not found a source for unpolluted premium mogas here in Texas. The place I get it handles only regular.
Which will work fine.
I thought the issue was that you do not want a spark at the filler neck caused by static buildup during filling. That's why you want a constant connection between the tank and plane away from where you're filling.
it's the opposite in IL, you can usually only find 91-93
there was one time i can think of that our local station ran out of 91 no-alcohol. I had promised the kids we'd go tubing and there is no way I'm putting alcohol in the fiberglass tank. So I topped the boat with 100LL. It was empty. As I watched the avgas gallons count up, it occurred to me that i could have siphoned the mogas from the farmall for part of it. I didn't calculate the hourly cost of tubing that day and even now I'm trying to think of other things so i don't cipher it in my head.Same here in MO. And it's still almost $2/gal cheaper than 100LL. I typically run a 75/25 blend.
All gasoline fuel pumps I have bought over the last 20 years came with a hose that had a grounding wire imbedded in it..... Just touch the plane somewhere before fueling, insert the nozzle with a decent metal to metal contact......
Easy Pleasy..... IMHO..
This works for cars where the nozzle mates with the filler neck. I can't claim to have seen all that many planes, but none of the ones of flown have a filler neck that's designed to have the nozzle rested in contact with it.
like playing "Operation" when we were kids. ;-)
Which part didn't you understand? Maybe I can clarify.
That seems very complicated compared to a fuel transfer tank installation. But if you found an easy way to do it, you could market a kit for it...So for those of us that have easy access to pure gas, why not just use the installed gas tank in your car/truck? I just need to figure out where to tap in a T in the line, and put in a quick connect with a cap to keep it clean. From there you just use an inexpensive facet fuel pump or find a way to trick the cars pump into running whenever you want it to, and then run a line from the car to the plane. And ground everything. And don't pump the car dry or you won't be having fun.
Too little capacity, too low a fill rateSo for those of us that have easy access to pure gas, why not just use the installed gas tank in your car/truck? I just need to figure out where to tap in a T in the line, and put in a quick connect with a cap to keep it clean. From there you just use an inexpensive facet fuel pump or find a way to trick the cars pump into running whenever you want it to, and then run a line from the car to the plane. And ground everything. And don't pump the car dry or you won't be having fun.
Too little capacity, too low a fill rate