STLBILL Posted February 1, 2006 Report Share Posted February 1, 2006 I know a bunch of you guys are running Avgas. Anyone ever looked into the numbers on gasoline? They say regular pump gas is based around a molecule called octane. Avgas is however based on the fuel's performance. They add lead to make stand up to higher compression engines, but nothing else for performance. I was surprised to read this. I found something that says avgas is usually expressed as two numbers lean mixture performance and rich mixture performance such as 100/130. So is Avgas really just modern pump gas with lead additives? I say modern day because old fashioned leaded gasoline was much lower octane. The lead additive brought it up to 85+ octane. These days they cannot use lead so the gasoline itself must be 85+. Adding lead then takes it up into the 100s. Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted February 1, 2006 Report Share Posted February 1, 2006 Race gas (unoxygenated) does not add performance, the engine does. By using the proper octane for your compression, your motor can produce more power without detonation. The two numbers for your av gas are your motor octane number (MON) and your research octane number (RON). These are based on the lower and upper levels of engine operation. Your octane number is based on a combination of the two (R+M/2). Your race fuels also have a lot less additives and impurities than pump gas. Quote Link to comment Share on other sites More sharing options...
Hulio-mv Posted February 1, 2006 Report Share Posted February 1, 2006 brad you amaze me with your infinate brain power if any ever leaks out send me some for real you seem like a smart guy Quote Link to comment Share on other sites More sharing options...
Old Two-Smoke Posted February 2, 2006 Report Share Posted February 2, 2006 (edited) There is quite a bit more to av gas than just lead. The vapor pressure is alot different than car gas. As well as the hydo carbons It also is final filtered much smaller than other fuel. 100LL is blue, how we tell if we have a contamination problem before takeoff is checking the color. If it is mixed with another fuel it turns clear. I love this feature for use in the banshee All my kids know if the jug is clear it has been mixed if its blue it hasnt. Also great for us old forgetful folks as well. And the best thing, it has to remain stable for 15 months. The last meeting I attended most car gas starts breaking down after only three weeks. Edited February 2, 2006 by Old Two-Smoke Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted February 2, 2006 Report Share Posted February 2, 2006 I run diesel in my banshee. I put everclear in my tank once with my old 87 shee. Ran great for that one tank. I don't know that I would try it again, but for that one tank, it did awesome. Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted February 2, 2006 Report Share Posted February 2, 2006 brad you amaze me with your infinate brain power if any ever leaks out send me some for real you seem like a smart guy 467422[/snapback] Thanks, but you forgot ass behind smart. Like old two smoke said, a lot of differences between av and pump gas. But one problems is when people use AV gas istead of race gas, when they assume it has the same octane or higher based on the octane numbers. Hopefully people that use AVgas know this, I dunno. . Most people run into problems with low octane on av gas since it is tested and rated for a different type of engine than a motor gasoline engine. A standard 110 octane race gas will score a 160 or better on the AV gas octane scale. Big difference so be careful to not subsitute AV gas for these high compression gasoline engines. It's a good substitute "generally" for pump gas. It definitly has better stability and a little higher octane than can be found at the pump. Quote Link to comment Share on other sites More sharing options...
thegroup Posted February 2, 2006 Report Share Posted February 2, 2006 I run diesel in my banshee. I put everclear in my tank once with my old 87 shee. Ran great for that one tank. I don't know that I would try it again, but for that one tank, it did awesome. 467787[/snapback] now thats fucked up, running everclear. i guess id work if u mixed it bet it had a nice smell to it burning Quote Link to comment Share on other sites More sharing options...
dawarriorman Posted February 2, 2006 Report Share Posted February 2, 2006 Thanks, but you forgot ass behind smart. Like old two smoke said, a lot of differences between av and pump gas. But one problems is when people use AV gas istead of race gas, when they assume it has the same octane or higher based on the octane numbers. Hopefully people that use AVgas know this, I dunno. . Most people run into problems with low octane on av gas since it is tested and rated for a different type of engine than a motor gasoline engine. A standard 110 octane race gas will score a 160 or better on the AV gas octane scale. Big difference so be careful to not subsitute AV gas for these high compression gasoline engines. It's a good substitute "generally" for pump gas. It definitly has better stability and a little higher octane than can be found at the pump. 467820[/snapback] Sorry, but you're wrong on that brad. The 100LL gas is 100 motor octane. Thats the lean mixture rating, ASTM D2700 (Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel). VP 110 is 107 motor octane. Its not quite as high as most race fuels sure, but it is a HUGE step above pump gas. Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted February 2, 2006 Report Share Posted February 2, 2006 Sorry, but you're wrong on that brad. Quote Link to comment Share on other sites More sharing options...
dawarriorman Posted February 2, 2006 Report Share Posted February 2, 2006 Here's a quote from Rich Rohrich. Motor Techniciain, writes articles for Hot Road, Off-Road mags, and atv mags. Contrary to popular belief this isn't 100-octane fuel. Aviation fuels are rated on an ASTM Lean/Rich performance number system. 100LL is rated at 91/96 By comparison; Unocal Leaded race gas that is used in lots of spec fuel racing classes has performance number of 112/160. 100LL is closer to 91 octane (MON); by comparison VP C12 is rated at 108 (MON). Opinion expressed by Sunoco Aircraft engines are also essentially low engine speed, constant throttle applications that must work well at very low atmospheric pressure and temperature. Aviation gasolines are blended to work well only under these very specific circumstances, and do not perform as well under high rpm and high load applications. For maximum engine performance, stability and power use race fuels with octane levels designed to mactch your engine specifications. Granted Av fuel is one the best refined fuels on the market, it's just tested different than motor gas. The ASTM uses different motors in testing AV and Motor gasolines. So when testing aviation fuel in the same motor that is used for the automobil test, it has a much lower antiknock rating. And yes the 100ll is 100 octane when tested in a single cylinder, fuel injected, supercharged air plane engine at 600 rpm or so rpm. Our race car race gas is not tested this way. 468012[/snapback] http://www.chevron.com/products/prodserv/f...ecsandtest.shtm http://www.astm.org/cgi-bin/SoftCart.exe/D...ystore+tbyb6426 The supercharged test is the rich mixture test, which is the aviation specific number. When 100LL is run through that test it scores 130, where a gasoline made up of entirely 100% isooctane would score a 100. 100LL scores 100 on the same motor octane test that is used for all gas motors. Which VP 110 scores a 107 on. Now sure, maybe it doesn't perform as well at higher rpms, but there aren't any industry standard tests that prove so. I don't think it matters too much though, we aren't running F1 motors, and there are aircraft engines that rev just as high as automotive motors. But it IS 100 MON gasoline. Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted February 3, 2006 Report Share Posted February 3, 2006 http://www.chevron.com/products/prodserv/f...ecsandtest.shtmhttp://www.astm.org/cgi-bin/SoftCart.exe/D...ystore+tbyb6426 The supercharged test is the rich mixture test, which is the aviation specific number. Quote Link to comment Share on other sites More sharing options...
dawarriorman Posted February 3, 2006 Report Share Posted February 3, 2006 Your correct on the 100 mon, that is probably the only significant number to compare race/auto fuels with avgas. 468072[/snapback] I will say that if you do plan on building a purpose built drag machine, race gas would be a better choice. But if you aren't going extreme, go with AV gas. I know of a couple people firsthand that use 100LL in their drag cars (all motor and nothing too extreme, but they turn 10s in the 1/4). And the guy at the airport says theres a bunch of people that come in every thursday night on their way to the track. Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted February 3, 2006 Report Share Posted February 3, 2006 I will say that if you do plan on building a purpose built drag machine, race gas would be a better choice. But if you aren't going extreme, go with AV gas. I know of a couple people firsthand that use 100LL in their drag cars (all motor and nothing too extreme, but they turn 10s in the 1/4). And the guy at the airport says theres a bunch of people that come in every thursday night on their way to the track. 468207[/snapback] Mentioning cars, this was interesting. Aviation gas is formulated for large-bore, long-stroke, low rpm engines which run at high altitude. While AvGas Quote Link to comment Share on other sites More sharing options...
dawarriorman Posted February 3, 2006 Report Share Posted February 3, 2006 (edited) Mentioning cars, this was interesting. Aviation gas is formulated for large-bore, long-stroke, low rpm engines which run at high altitude. While AvGas Edited February 3, 2006 by dawarriorman Quote Link to comment Share on other sites More sharing options...
pimpeinkc Posted February 3, 2006 Report Share Posted February 3, 2006 the mon test is to see how much compression it takes to detonate, right, which would make sence, high compression, more detonation unless rate for said compression Quote Link to comment Share on other sites More sharing options...
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