Fuel

[smelly$cat]

I have a 440ex with a 12.5:1 CP piston in it.

I have been running "Trick" 114 octane fuel in it. This fuel costs ~6.50 per gallon at a station about 10 miles from my house.

I recently found out that there is a air field much closer to my house that sells aviation fuel to the public. It is 100 octane "low lead". This fuel is currently 4.00 per gallon.

I'm not terribly concerned with the cost, as I don't get to ride that often.

It would be nice to be able to go buy fuel much closer to my house though.

I'm curious if anyone has had any experience running 100 octane "low lead" fuel in a 12.5 to 1 set up.

Not sure if this octane is going to be high enough. Not sure if "low lead" is a concern.

For all I know, the Trick fuel I have been running might be low lead as well. I need to call that station to ask them.

I'm interesting in hearing back from people that have had experience with this.

Thanks!

[sprayedgt]

Aviation fuel is designed to be used at high altitudes, not at ground level. It will only hurt performance, not increase it. A well tuned 12.5cr engine should be able to run on a lot less than 100 octane. And finally you have no need for any lead at all with your combo.

[ae13291]

Originally posted by sprayedgt
Aviation fuel is designed to be used at high altitudes, not at ground level. It will only hurt performance, not increase it. A well tuned 12.5cr engine should be able to run on a lot less than 100 octane. And finally you have no need for any lead at all with your combo.


lol my brother is a aircraft mechanic, leaded fuel is used in aircraft because it increases power and lubricates all the parts of the piston engines better, those motors are always running at high rpm in the sky thats why you dont see much lead deposits in the combustion chamber except on the spark plug. they try not to idle the engines alot because it will form lead inside the cylinders.


but for my 400ex, i use leaded octane combined with other crap i mix with it, my fuel color turns from yellow to red from the lead. i use a lead additive i add to 91 unleaded fuel, it runs real good with the mixture, but the spark plugs dont last as long, thats why im using a iradium IX plug on mine.

[sprayedgt]

Originally posted by ae13291
lol my brother is a aircraft mechanic, leaded fuel is used in aircraft because it increases power and lubricates all the parts of the piston engines better, those motors are always running at high rpm in the sky thats why you dont see much lead deposits in the combustion chamber except on the spark plug. they try not to idle the engines alot because it will form lead inside the cylinders.


Leaded aviation fuel is formulated to work in extremely cold environments such as high altitude. It's vapor pressure keeps it in the liquid state at high-altitude preventing vapor lock. Certain airplanes can use automotive fuel, but most can not. This is coming from my neighbor who is an Aeronautical Engineer for Lockheed Martin.

[ae13291]

Originally posted by sprayedgt
Leaded aviation fuel is formulated to work in extremely cold environments such as high altitude. It's vapor pressure keeps it in the liquid state at high-altitude preventing vapor lock. Certain airplanes can use automotive fuel, but most can not. This is coming from my neighbor who is an Aeronautical Engineer for Lockheed Martin.

what you say makes alot of sense, but the low lead fuel is used in single engine aircrafts, so they wont be flying too high to have problems with fuel turning into vapor, i have seen experimental airplanes that use the subaru wrx water cooled motors that dont have problems with the coolent freezing in the air. so the low lead fuel should be fine on the ex, i have used it b4 and i think my motor runs great and responds better with that fuel.

[GPracer2500]

Don't get hung up on lead content. Yes, lead reduces plug life by some amount. But I've never found it enough to worry about--at all. Even halving the life of a plug still leaves you with a plug that will last a hellva long time--especially in a four stroke. Most performance and maintenance oriented powersport enthusiast probably change their machines' plug(s) often enough to negate lead's impact on plug life. Who cares anyway. Plugs are pretty cheap.

Trick 114 probably has twice as much lead in it as 100LL (i.e. ~4g/gal vs ~2g/gal). Not that it matters much, in and of itself. Although lead promotes valve and valve seat life, the metals used in modern engine components don't need it for decent lifespan like many engines of old. My preference for leaded gasolines mostly concerns the freedom lead allows a gasoline's designer in choosing the blend of hydrocarbons used. Lead has such strong anti-knock properties that hydrocarbons (the stuff gasoline is made of) can be chosen for reasons other than their contribution to octane rating. For this reason, I just assume avoid unleaded powersport gasolines. They're too likely to make sacrifices in the blend of hydrocarbons used in order to achieve their octane rating, IMO.

About vapor pressures....100LL has a spec of 5.5psi to 7.1psi. Compare that to Trick 114's spec of 6.7psi. Summer blends of pump gas range from around 7psi to 9psi. Most racing gasolines are gonna be somewhere between maybe 4psi and 12psi.

In other words, forget about vapor pressure. Unless the fuel you've chosen is giving your machine vapor lock issues (which is more closely related to fuel temperature than vapor pressure anyway), forget about it. There's plenty of reasons to choose one fuel over another that matter more than vapor pressure (distillation curve anyone?). The idea that 100LL is only for high altitude operation is nonsense. Compare actual fuel specifications for pump gasolines, common racing gasolines, and 100LL and stop listening to third hand information from (I'm sure well intentioned) people who probably got their info from someone else who didn't really have their facts straight. There's more misinformation out there about gasoline properties than there is real information, IMO. [see Twain quote below]

While I'm at it....Trick 114 has an octane rating of 106 MON. 100LL has a minimum spec of 99.5 MON (typical samples might be a point or three higher). Pump gas who's yellow pump sticker says 93 will be around 88 MON. Don't try comparing octane ratings unless you're actually talking about the same type of rating (there's 3 common types of octane rating--MON, RON, and the average of the two).

Bottom line: 100LL probably compares ok to Trick 114 unless those last few points of MON are necessary to keep engine knock at bay. The way to find out is to get some 100LL, jet for it (if necessary) and test for knock. If none is detected under conditions that promote knock, you're good to go.



$0.02

[smelly$cat]

GPracer2500, that is the sort of response I was looking for and it jives with other info I've found on the net since posting this. Thank you.

I purchased 5 gal of 100LL last night for $20. Heading to the dunes this Saturday to see how it runs.

I have no plans to change the jetting at this point, unless I end up needing to. If it happens to knock, honestly, I'll probably just go back to running Trick since it doesn't knock with that fuel. Curious what jetting changes you would normally need to make if it does knock though. Go richer I'm guessing? I have a Dial A Jet. So, I might be able to play with that on this trip if needed to overcome the potential knock.

Thanks again!

[smelly$cat]

Just to cap off this thread.

I ran on 100LL avgas this weekend and it ran great. No pinging and had excellent power.

Paid $4 per gallon.

Mean while, my buddy paid over $8 per gallon for Trick.....

I'm a happy camper!

[Wheelie]

I ran 100LL in my quad for several years, no negative effects whatsoever.

Smellycat--

Just a thought, have you thought about switching to E-85? It's 105 octane and in most areas it's cheaper than 87.

E-85 is 1.60/gal in my area right now. Sure is a nice change of pace from the $6 gal I used to pay for 110.

[smelly$cat]

Good to hear :)

I haven't given any thought to switching to e85. I like the sound of that price though :)

I just read a thread on here today about someone switching to e85.

First thing I'd have to check is where the nearest e85 station is. Heck, apparently my suburban will run e85, but I've never looked to see who sells it. I guess I should! duh

[sprayedgt]

I believe E85 will be gone soon. The benefits are outweighed by the cost to produce and fuel economy. It's about 15% cheaper but nets 20% reduction in gas mileage. Where I am you used to be able to get it at every station. Now it's no where to be found.