okbeast Posted February 21, 2007 Report Share Posted February 21, 2007 Not to open up a big can of worms here but I'm planning on upping my compression in the near future. I can't get race gas around here for any cheaper than about $10/gal. so I'm trying to figure out other fuels to run. I was reading through the AVgas thread and haven't really been convinced whether or not it's good to use or not. I've heard of people mixing alky (methanol, which I can get free around here) with pump gas to up the octane. I was curious what some people's opinion (or hopefully someone that's actually knowledgeable in the subject, which Firehead seems to be based on the other thread) is on doing this. Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 21, 2007 Report Share Posted February 21, 2007 Not to open up a big can of worms here but I'm planning on upping my compression in the near future. I can't get race gas around here for any cheaper than about $10/gal. so I'm trying to figure out other fuels to run. I was reading through the AVgas thread and haven't really been convinced whether or not it's good to use or not. I've heard of people mixing alky (methanol, which I can get free around here) with pump gas to up the octane. I was curious what some people's opinion (or hopefully someone that's actually knowledgeable in the subject, which Firehead seems to be based on the other thread) is on doing this. While methonal is a fuel with a much higher flashpoint than gasoline, it only has about 2/3 the energy density of gasoline. You can blend it yourself or buy it blended. Anything with more alcohol than M20 (20% methanol) you will have to start dealing with the all of the parts of alcohol that are a pain in the ass. Methanol is a hydroscopic liquid meaning that it attracts water, which means that no matter how you blended it, you will need to purge your bike when you are done riding. Also because of this, the fuel has a very short shelf life. Some misinformation that is out there involves the term "alcohol." Alcohol tends to be used as a blanket term to desribe methanol. ethanol, and several other variants of the fuel. The main difference being that ethanol is a distilled fuel and methanol is a refined fuel. Fuels in this family are given a designation such as M80 or E80 which identifies the as being 80% methanol and 80% ethanol respectively. The remaining 20% of the fuel in this example would be made up of gasoline, additives, and chemical impurities from the manufacturing process (this sort of fuel designation is similair to the designation of biodiesel if you are familiar with that). If it were me making the decision, the biggest issue you have is that you all of a sudden have atleast 1/3 less range on a tank of fuel. If your ding area is small or you don't ride all day long then it might not be a big deal for you. This can be offset with an oversize fuel tank as well. This also means that you need to take alot more fuel with you when you go riding. Purging a fuel system isn't that big of deal if you allow for an easy connection of an external fuel source on your bike (BigRed350X had pictures up in the Images Forum a while back). You really only need to do this when you are done riding for the weekend. If you don't do this, all of the aluminum that was contacted by the fuel will corrode very badly, steel parts will rust, and rubber parts will become dry and brittle. Depending on the outside temperature your bike may also be hard to start. If the temperature drops much below freezing, you will never get your engine started without preheating it. To take full advantage for an alcohol type fuel you would be looking at specially tuned/modified carbs, very samll cylinder domes (15cc or so), and some sort of programmable ignition of PVL ignition. If I were going to run methanol I would run M80 and deal with the consequences as that would be the performance vs. maintenance trade off point for me. I am not going to go out on a limb and speak to the issue smaller percentage blended alcohol fuels raising the octane rating of gasoline as there are many variables involved. I will say that blending in alcohol with gasoline will raise the octane of the fuel, but how much isn't something I am prepared to provide an answer for. I were the one asking that question, I would be buying a preblended fuel from a race fuel company who publishes that sort of data for their product line. I have run alcohol in the past and it is certainly the way to get the most out of your motor in respect to fuel, but I am lazy and am not interested in all the maintenance required at this point. I have a large tank of it outside my building at work which I have free access to and it is apparently still too much work for me. I am sure that my triple will probably wind up running on alcohol once the bugs are out of it. In case anyone was wondering what I am actually a big fan of fuel-wise for my bikes is Sunnoco 110 blended with Propylene Oxide at about 1000 ppm. :thumbsup: Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted February 21, 2007 Report Share Posted February 21, 2007 Methanol also is corrosive to aluminum. Here is the quote from Wikpedia. Doesnt matter if it is mixed with gas or not it is still there. Wikpedia Methanol LINK One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminium. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminium from corrosion: Quote Link to comment Share on other sites More sharing options...
trueraiderfan Posted February 21, 2007 Report Share Posted February 21, 2007 Dude av gas works just fine. There are too many bikes that i have seen run around here for too long and never had a prolbem for it to be bad. I also use it. I have never used anything else Quote Link to comment Share on other sites More sharing options...
okbeast Posted February 21, 2007 Author Report Share Posted February 21, 2007 Damn man thanks for that. I didn't even think about the purging crap, and that is enough to make me not want to do it. I'll just check around to see if I can find some cheaper race fuel from some of the guys that drag race possibly. I'm guessing that mixing pump gas and race fuel is ok to do though, seeing as a ton of people do it. Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 21, 2007 Report Share Posted February 21, 2007 (edited) Methanol also is corrosive to aluminum. Here is the quote from Wikpedia. Doesnt matter if it is mixed with gas or not it is still there.Wikpedia Methanol LINK I hope I made that clear in the book I just wrote above. :thumbsup: As for the mixing of race gas with pump gas, it is perfectly fine to do. However if you want a quantifiable octane rating to identify the fuel mixture you have in your tank, the mixing the two won't get you that as it would have to go through an octane testing method to get that. What I am trying to say is that you can't add 110 octane unleaded to 92 octane unleaded in equal parts and get a fuel that 101 octane. Our fluid engineer at work would probably also verbally abuse me for saying that it is perfectly fine to mix pump gas with most race fuels as the race fuel is made from a different hydrocarbon string than pump gas. However, while may not chemically make sense to do so, it does work in practice and effectively raise a fuel mixtures propensity to detonate. Another fun fact that I came up with while I was writing the book of a post above is that if you are having a small detonation problem with premium pump gas (92 octane or better) than you may want to try some different two stroke oils. The oil effectively raises the flash point of the fuel, thus it gains a bit in octane rating. The Castor based oils tend to raise the flash point higher than some of the synthetcs that are out there. :thumbsup: Edited February 21, 2007 by FireHead Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted February 21, 2007 Report Share Posted February 21, 2007 Purging is NOT that big of a deal. Originally i thought it would be a huge headache, but if you get a purge valve from majicmike and make yourself some kinda purge tank system its NOT hard to do... - Jared Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 21, 2007 Report Share Posted February 21, 2007 Purging is NOT that big of a deal. Originally i thought it would be a huge headache, but if you get a purge valve from majicmike and make yourself some kinda purge tank system its NOT hard to do... - Jared I agree. :thumbsup: However, I will complain about it because I am a fat, lazy, bastard. :: Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted February 21, 2007 Report Share Posted February 21, 2007 I agree. :thumbsup: However, I will complain about it because I am a fat, lazy, bastard. :: Yeah I'm sure I will fuck myself one of these weekends when I get a lazy spell and decide not to purge before I load up and will forget when I get back to town and let it sit for a week or two with methanol in there... that will suck, and I'm sure I will do it one of these days. - Jared Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 21, 2007 Report Share Posted February 21, 2007 Yeah I'm sure I will fuck myself one of these weekends when I get a lazy spell and decide not to purge before I load up and will forget when I get back to town and let it sit for a week or two with methanol in there... that will suck, and I'm sure I will do it one of these days. - Jared I found that the amount of top ends and carburetors that I was rebuilding was directly proportionate to the amount of beer I was drinking when I was packing up the bike to go home. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted February 21, 2007 Report Share Posted February 21, 2007 I figure it can't be any worse than the number of top ends I end up going through in my normal ride season. Hitting the dunes a couple times a week after work and being there EVERY damn weekend I'm off all weekend long puts a lot of hours on my shit. - Jared Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 21, 2007 Report Share Posted February 21, 2007 I figure it can't be any worse than the number of top ends I end up going through in my normal ride season. Hitting the dunes a couple times a week after work and being there EVERY damn weekend I'm off all weekend long puts a lot of hours on my shit. - Jared In your case that is probably true. I am working on getting moved into a position where I can hit the dunes after work a few times a week. The only down side is that I will have to move............ :: Quote Link to comment Share on other sites More sharing options...
Mullet Man Posted February 21, 2007 Report Share Posted February 21, 2007 do you still need to purge even if it is a 50/50 or 60/40 mix? Quote Link to comment Share on other sites More sharing options...
nunyabinness Posted February 21, 2007 Report Share Posted February 21, 2007 hey Firehead, when do you go find out about that job? Quote Link to comment Share on other sites More sharing options...
okbeast Posted February 21, 2007 Author Report Share Posted February 21, 2007 do you still need to purge even if it is a 50/50 or 60/40 mix? W/o re-reading the post I believe he said if any amount of "alcohol" is used the system needs to be purged. Quote Link to comment Share on other sites More sharing options...
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