Schlauncha
04-13-2010, 07:31 AM
Okay, for starters I will come clean that I am not only interested in getting to better-understand fuels, for the sake of my trikes ('85 ATC70, and a 2-stroke Suzuki TS185 converted from bike to trike), but also (maybe moreso) for some other power toys such as my 2002 HD Sportster 1200 (mostly stock engine), and my brother's 1993 Silverado street truck that he keeps bolting upgrades onto. But I figure a general discussion on fuel benefits all who use it, which is pretty much everyone here.
Being in Iowa, currently most of the pumps carry 87 regular, 89 ethanol (cheapest and guaranteed at every station practically), 91 regular, and 93 ethanol. There are some stations that carry E85 (which is 130 octane I've heard?) but the closest one is an hour away in the opposite direction of the towns we go to school and work at.
First observation is that 89 Ethanol is the cheapest. Therefore I run that in my daily driver, an '07 Cobalt with a manual trans. I have maybe ran 91 or 93 in there once, but noticed no difference. Slightly faster than slow is still pretty slow, i figure. But on my HD, I have established a very clear view of the effects of octane. If I hit my reserve level on fuel, it's pretty rare I'm in a position to pass a gas station for another one (only 2 stations along my normal commute home), so sometimes I end up with little choice but to put 89 Ethanol in there. The result is that the bike will start, idle, and cruise just fine, but accelerating is hugely affected, where I have to rely more on RPM's and less on torque, and overall give it less throttle or else it just feels like "BLEH". Putting 91 regular or 93 ethanol in there is the typical preference, but I can't perceive a difference in performance between the two. However, if I fill the tank up with 110 blue race fuel at the drag strip on a Test n Tune day, the really good smelling fuel, it sure feels like quite the opposite of 89, now the engine loves more throttle and being shifted earlier to stay in its torque band instead of rpm. For the mpg a bike gets, I would fill it with 110 every time given access to it.
On my ATC70, I have tried not to put Ethanol it in because of concerns regarding rumors I'd heard about Ethanol being bad for engines that were originally intended for leaded fuel. I don't recall when they stopped using leaded fuel, if my '85 is newer than that or not. But for as little as that goes through, I don't mind keeping a can of 91 regular in the garage. I put 87 regular in my JD lawnmower, having been told by my father in general not to put ethanol in any small engine such as mowers, a generator, or a power washer.
Ethanol is an alchohol sort of thing, and adding that to the fuels seems to have created a conflicting division between various types of motors, where now not only do I have to be mindful of whether an engine needs an expensive higher octane or can get by on cheaper low-octane fuel, but also now whether whatever octane I choose contains Ethanol in it, because some motors seem to just not be set up for that. I just don't know why these ethanol fuels that have crowded out non-ethanol fuels at the pump, like they are an equal substitution for them, can have such an effect on causing engine troubles for small engines, yet pretty much any modern car can switch between regular and ethanol blend fuels without any noticeable differences. I have a feeling that fuel injection may be a big factor here, as it seems like a clear trend that all my motors with carburetors need to run regular fuel, while those that are fuel-injected in our cars can run Ethanol blends. The EFI must be able to sense the way Ethanol burns differently, and so as it monitors the O2 sensor, the injection ECU keeps everything at a perfect balance to prevent fouling or poor performance, even if fuel attributes change between filling up with regular one time, ethanol blend the next. On the engines with carburetors, no such corrections are made, there is no feedback to the fuel input to let it know that the setting it had for regular fuel, is now fouling the engine up when running a different fuel. But this is all speculation on my part.
So what I'm wondering, looking for enlightenment here, how off are my perceptions on this all? My brother goes through a tank every other day at minimum in that Silverado, and he feels he needs to run 91 non-ethanol, absolutely no lower octane or with ethanol. While he has added headers, intake, bigger injectors, TBi spacer, fuel ECU chip upgrade, MSD 6AL ignition, higher ratio roller-tip rockers, and possibly a cam, I don't think he has done anything there that would push this motor into actually needing higher octane than 89, or even if it would be perceivably different. My HD doesn't NEED 91+, but it is definitely perceivable from how it acts on 89E that it doesn't like lower octanes.
I have heard that AvGas (110 low-lead I believe) burns much too slowly (as it is for the lower RPM motors aircraft use) and therefore in the engines of cars or bikes, it ends up melting the valves or causing destructive backfiring. Race gas, such as the blue stuff my buddy uses in his dirt oval cars, smells good and seems to run really good, but I have also heard that this is leaded fuel, and will quickly foul up the plug and eventually valves, if used on an engine for a length of time, instead of just briefly in race motors that get rebuilt frequently. The E85 they sell, that my father's 2007 Silverado can run (losing about 7% fuel efficiency), supposedly is around 130 octane and is dirt cheap thanks to subsidies. And that requires corn, which puts money in the farmers' pockets, to buy tractors, which supports the ag industry that employs pretty much everyone I know. Good or bad in a bigger picture, it's good for my picture. But there are no pumps nearby with that, so I can't see making a daily driver whose engine relies on using that fuel. I read in a car magazine about a guy in Minnesota with an old Vette he dropped a crate engine into, put twin turbos on it, and uses it as a daily driver with something like 1100hp under his foot, thanks to having E85 pumps nearby that let him afford to drive this all around. The motor and EFI were built specifically for E85, however, so it's not just "any race motor can be a daily driver if you have E85 to put in it".
As for how Octane affects stuff, basically what I've been told is that it is a quality that resists knock, or detonation premature to the spark initiating it, and as you get to higher compression motors, the minimum amount of octane required to keep detonation from happening increases along with it. The big misconception is that higher octane equals higher power, through the fuel somehow containing more potential energy or a faster combustion rate. Dumping those expensive bottles of Octane Booster into my fuel tank will not make my grandma's Buick suddenly run more powerfully, the only time Octane Booster would be needed might be perhaps if you had a high(er) compression motor and were forced to fill it with 87 or 89 octane, then this bottle of stuff would (if it does its job) allow you to still give decent throttle to the motor without it knocking and pinging. For the rest of the world, just because the bottle has flashy performance catchwords on it, and logos of flaming tires implying potential power output results, doesn't mean it will make your stock engine run a single bit faster, other than your car being lighter weight by the amount of wasted cash.
One thing somebody suggested to me was mixing 1:1 ratio of gasoline and R/C nitromethane fuel. Unfortunately I don't feel like paying $30/gallon for r/c fuel, which is comprised of a vast amount of castor oil since it is generally for 2-stroke motors, so I can go and make $33/gallon "race fuel" to foul and/or burn up the rings and valves on whatever I put it in. Last I remember, it was only around $10 for a gallon, if not a whole motorcycle tank, of that blue 110 race fuel at the drag strip. But if what I'm reading in my searches indicates that this race fuel is "not in the best interests" of any motor I don't plan on rebuilding often/ever, it makes me wonder what fuels I can or should use in performance motors like that, if I'm basically stuck with 91 regular or 93 Ethanol. I figure you guys here will have a much wider set of experiences with fuels, and could give me your input on what are many assumptions on my part, as well as perhaps some advice on what fuels to use in things like my ATC70, small engines, Harley engine, or my brother's 350 he keeps bolting upgrades onto, yet uses as a daily driver.
Anyways, sorry for the long rant, meds make me talkative. Through my hands. Hopefully I stayed on topic enough that this thread is of value to those reading it, and will get responses from others which will make for a valuable source of info here on fuels.
Being in Iowa, currently most of the pumps carry 87 regular, 89 ethanol (cheapest and guaranteed at every station practically), 91 regular, and 93 ethanol. There are some stations that carry E85 (which is 130 octane I've heard?) but the closest one is an hour away in the opposite direction of the towns we go to school and work at.
First observation is that 89 Ethanol is the cheapest. Therefore I run that in my daily driver, an '07 Cobalt with a manual trans. I have maybe ran 91 or 93 in there once, but noticed no difference. Slightly faster than slow is still pretty slow, i figure. But on my HD, I have established a very clear view of the effects of octane. If I hit my reserve level on fuel, it's pretty rare I'm in a position to pass a gas station for another one (only 2 stations along my normal commute home), so sometimes I end up with little choice but to put 89 Ethanol in there. The result is that the bike will start, idle, and cruise just fine, but accelerating is hugely affected, where I have to rely more on RPM's and less on torque, and overall give it less throttle or else it just feels like "BLEH". Putting 91 regular or 93 ethanol in there is the typical preference, but I can't perceive a difference in performance between the two. However, if I fill the tank up with 110 blue race fuel at the drag strip on a Test n Tune day, the really good smelling fuel, it sure feels like quite the opposite of 89, now the engine loves more throttle and being shifted earlier to stay in its torque band instead of rpm. For the mpg a bike gets, I would fill it with 110 every time given access to it.
On my ATC70, I have tried not to put Ethanol it in because of concerns regarding rumors I'd heard about Ethanol being bad for engines that were originally intended for leaded fuel. I don't recall when they stopped using leaded fuel, if my '85 is newer than that or not. But for as little as that goes through, I don't mind keeping a can of 91 regular in the garage. I put 87 regular in my JD lawnmower, having been told by my father in general not to put ethanol in any small engine such as mowers, a generator, or a power washer.
Ethanol is an alchohol sort of thing, and adding that to the fuels seems to have created a conflicting division between various types of motors, where now not only do I have to be mindful of whether an engine needs an expensive higher octane or can get by on cheaper low-octane fuel, but also now whether whatever octane I choose contains Ethanol in it, because some motors seem to just not be set up for that. I just don't know why these ethanol fuels that have crowded out non-ethanol fuels at the pump, like they are an equal substitution for them, can have such an effect on causing engine troubles for small engines, yet pretty much any modern car can switch between regular and ethanol blend fuels without any noticeable differences. I have a feeling that fuel injection may be a big factor here, as it seems like a clear trend that all my motors with carburetors need to run regular fuel, while those that are fuel-injected in our cars can run Ethanol blends. The EFI must be able to sense the way Ethanol burns differently, and so as it monitors the O2 sensor, the injection ECU keeps everything at a perfect balance to prevent fouling or poor performance, even if fuel attributes change between filling up with regular one time, ethanol blend the next. On the engines with carburetors, no such corrections are made, there is no feedback to the fuel input to let it know that the setting it had for regular fuel, is now fouling the engine up when running a different fuel. But this is all speculation on my part.
So what I'm wondering, looking for enlightenment here, how off are my perceptions on this all? My brother goes through a tank every other day at minimum in that Silverado, and he feels he needs to run 91 non-ethanol, absolutely no lower octane or with ethanol. While he has added headers, intake, bigger injectors, TBi spacer, fuel ECU chip upgrade, MSD 6AL ignition, higher ratio roller-tip rockers, and possibly a cam, I don't think he has done anything there that would push this motor into actually needing higher octane than 89, or even if it would be perceivably different. My HD doesn't NEED 91+, but it is definitely perceivable from how it acts on 89E that it doesn't like lower octanes.
I have heard that AvGas (110 low-lead I believe) burns much too slowly (as it is for the lower RPM motors aircraft use) and therefore in the engines of cars or bikes, it ends up melting the valves or causing destructive backfiring. Race gas, such as the blue stuff my buddy uses in his dirt oval cars, smells good and seems to run really good, but I have also heard that this is leaded fuel, and will quickly foul up the plug and eventually valves, if used on an engine for a length of time, instead of just briefly in race motors that get rebuilt frequently. The E85 they sell, that my father's 2007 Silverado can run (losing about 7% fuel efficiency), supposedly is around 130 octane and is dirt cheap thanks to subsidies. And that requires corn, which puts money in the farmers' pockets, to buy tractors, which supports the ag industry that employs pretty much everyone I know. Good or bad in a bigger picture, it's good for my picture. But there are no pumps nearby with that, so I can't see making a daily driver whose engine relies on using that fuel. I read in a car magazine about a guy in Minnesota with an old Vette he dropped a crate engine into, put twin turbos on it, and uses it as a daily driver with something like 1100hp under his foot, thanks to having E85 pumps nearby that let him afford to drive this all around. The motor and EFI were built specifically for E85, however, so it's not just "any race motor can be a daily driver if you have E85 to put in it".
As for how Octane affects stuff, basically what I've been told is that it is a quality that resists knock, or detonation premature to the spark initiating it, and as you get to higher compression motors, the minimum amount of octane required to keep detonation from happening increases along with it. The big misconception is that higher octane equals higher power, through the fuel somehow containing more potential energy or a faster combustion rate. Dumping those expensive bottles of Octane Booster into my fuel tank will not make my grandma's Buick suddenly run more powerfully, the only time Octane Booster would be needed might be perhaps if you had a high(er) compression motor and were forced to fill it with 87 or 89 octane, then this bottle of stuff would (if it does its job) allow you to still give decent throttle to the motor without it knocking and pinging. For the rest of the world, just because the bottle has flashy performance catchwords on it, and logos of flaming tires implying potential power output results, doesn't mean it will make your stock engine run a single bit faster, other than your car being lighter weight by the amount of wasted cash.
One thing somebody suggested to me was mixing 1:1 ratio of gasoline and R/C nitromethane fuel. Unfortunately I don't feel like paying $30/gallon for r/c fuel, which is comprised of a vast amount of castor oil since it is generally for 2-stroke motors, so I can go and make $33/gallon "race fuel" to foul and/or burn up the rings and valves on whatever I put it in. Last I remember, it was only around $10 for a gallon, if not a whole motorcycle tank, of that blue 110 race fuel at the drag strip. But if what I'm reading in my searches indicates that this race fuel is "not in the best interests" of any motor I don't plan on rebuilding often/ever, it makes me wonder what fuels I can or should use in performance motors like that, if I'm basically stuck with 91 regular or 93 Ethanol. I figure you guys here will have a much wider set of experiences with fuels, and could give me your input on what are many assumptions on my part, as well as perhaps some advice on what fuels to use in things like my ATC70, small engines, Harley engine, or my brother's 350 he keeps bolting upgrades onto, yet uses as a daily driver.
Anyways, sorry for the long rant, meds make me talkative. Through my hands. Hopefully I stayed on topic enough that this thread is of value to those reading it, and will get responses from others which will make for a valuable source of info here on fuels.