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Post by the light works on May 11, 2017 2:04:20 GMT
I did put in an explanatory statement. the thread is about myths that aircraft fuel is more potent than automotive fuel, including whether it is more dangerous in a crash, whether it has more energy, whether it will make an engine perform better with no other modification, whether it catches fire easier or not, etc. So we get back to the fact that avgas is exactly the same as the fuel you would put in a gasoline powered auto except for the higher octane rating. And we all know that there is no benefit to higher octane rating unless you have a higher compression engine that requires it. You can put aviation gas in a conventional automobile and it will run just like it had 87 octane auto fuel in it. If you put 87 octane auto fuel in an aircraft, it will eventually ruin the engine from preignition. (knocking) when compared with other fuels, it is exactly the same. there are small differences - it vaporizes slightly easier, but it takes slightly more heat to ignite it.
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Post by silverdragon on May 11, 2017 7:18:32 GMT
I did put in an explanatory statement. the thread is about myths that aircraft fuel is more potent than automotive fuel, including whether it is more dangerous in a crash, whether it has more energy, whether it will make an engine perform better with no other modification, whether it catches fire easier or not, etc. So we get back to the fact that avgas is exactly the same as the fuel you would put in a gasoline powered auto except for the higher octane rating. And we all know that there is no benefit to higher octane rating unless you have a higher compression engine that requires it. You can put aviation gas in a conventional automobile and it will run just like it had 87 octane auto fuel in it. If you put 87 octane auto fuel in an aircraft, it will eventually ruin the engine from preignition. (knocking) .. I was just about to get to the earlier mentioned point of putting a high octane fuel in a "normal" car, or even Av-Gas fuel, wont result in any real difference, unless your engine is built to take it, because these days, we all got limiters on RPM, and even if you can teach a modern EFI command module to accept higher octane fuel, its a whole new engine map to get the best out of it anyway. You may accelerate slightly faster, but as the gear ratio's are set, your top speed may be limited to aerodynamics and the engines limitations, all modern euro-box cars are limited to 155 mph, well, a lot of BMW/Merc/etc are anyway, so, you would need to do a lot of fettling and a tinkering underneath to make use of a different grade of fuel. So the question is, if you flush the fuel lines to remove any car grade fuel, will a modern engine [not designed to take higher grade fuel] even start on Av-Gas?. Is the engine map that different?. I believe my older Toyota "may" start, eventually, because its "map" is self learning, and the engine block is designed and built in a country that sort of uses any available fuel.. maybe not diesel heavy fuel, but any "petrol" type fuel?.. How many other modern engines are built like that these days?. they all expect "Clean burn unleaded" fuel..
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Post by GTCGreg on May 11, 2017 14:38:00 GMT
So we get back to the fact that avgas is exactly the same as the fuel you would put in a gasoline powered auto except for the higher octane rating. And we all know that there is no benefit to higher octane rating unless you have a higher compression engine that requires it. You can put aviation gas in a conventional automobile and it will run just like it had 87 octane auto fuel in it. If you put 87 octane auto fuel in an aircraft, it will eventually ruin the engine from preignition. (knocking) .. I was just about to get to the earlier mentioned point of putting a high octane fuel in a "normal" car, or even Av-Gas fuel, wont result in any real difference, unless your engine is built to take it, because these days, we all got limiters on RPM, and even if you can teach a modern EFI command module to accept higher octane fuel, its a whole new engine map to get the best out of it anyway. You may accelerate slightly faster, but as the gear ratio's are set, your top speed may be limited to aerodynamics and the engines limitations, all modern euro-box cars are limited to 155 mph, well, a lot of BMW/Merc/etc are anyway, so, you would need to do a lot of fettling and a tinkering underneath to make use of a different grade of fuel. So the question is, if you flush the fuel lines to remove any car grade fuel, will a modern engine [not designed to take higher grade fuel] even start on Av-Gas?. Is the engine map that different?. I believe my older Toyota "may" start, eventually, because its "map" is self learning, and the engine block is designed and built in a country that sort of uses any available fuel.. maybe not diesel heavy fuel, but any "petrol" type fuel?.. How many other modern engines are built like that these days?. they all expect "Clean burn unleaded" fuel.. Putting higher octane (avgas) in a modern, computerized engine automobile will have almost no effect on performance. I say "almost" because if the engine has knock sensors and retards the timing if preignition is detected, the avgas may allow the computer to keep the spark advanced a little bit further into the power curve. But the result would be very minimal, if at all. Beyond that, I doubt the computer would even detect the avgas was in the tank. If you read the owners manual of most new cars, they give you the minimum octane rating gas you should use. They don't specify a maximum. It makes no sense to use a higher octane rating than you need to. Not because it damages anything, but because you end up paying more with no gain in performance.
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Post by the light works on May 11, 2017 15:02:36 GMT
So we get back to the fact that avgas is exactly the same as the fuel you would put in a gasoline powered auto except for the higher octane rating. And we all know that there is no benefit to higher octane rating unless you have a higher compression engine that requires it. You can put aviation gas in a conventional automobile and it will run just like it had 87 octane auto fuel in it. If you put 87 octane auto fuel in an aircraft, it will eventually ruin the engine from preignition. (knocking) .. I was just about to get to the earlier mentioned point of putting a high octane fuel in a "normal" car, or even Av-Gas fuel, wont result in any real difference, unless your engine is built to take it, because these days, we all got limiters on RPM, and even if you can teach a modern EFI command module to accept higher octane fuel, its a whole new engine map to get the best out of it anyway. You may accelerate slightly faster, but as the gear ratio's are set, your top speed may be limited to aerodynamics and the engines limitations, all modern euro-box cars are limited to 155 mph, well, a lot of BMW/Merc/etc are anyway, so, you would need to do a lot of fettling and a tinkering underneath to make use of a different grade of fuel. So the question is, if you flush the fuel lines to remove any car grade fuel, will a modern engine [not designed to take higher grade fuel] even start on Av-Gas?. Is the engine map that different?. I believe my older Toyota "may" start, eventually, because its "map" is self learning, and the engine block is designed and built in a country that sort of uses any available fuel.. maybe not diesel heavy fuel, but any "petrol" type fuel?.. How many other modern engines are built like that these days?. they all expect "Clean burn unleaded" fuel.. here, a car badged for "flex fuel" is designed to recognize ethanol by products in the sensors and adapt for efficient burning with ethanol. most cars are now designed to adapt to lower octane fuel, but probably aren't programmed to expect extra high octane. part of my reasoning behind calling for a carburated car is because that way you know the car won't be adapting to higher octane; thus you get only the difference in fuel. as for whether it will even start; there shouldn't be enough difference to stop a modern engine from running. it will just run like it still has to worry about knock.
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Post by silverdragon on May 12, 2017 6:50:09 GMT
Conflicting opinions.... The only way is to test.
However, may I draw attention to the fact we do need the engine map to "sense" and react to the higher octane... We want to squeeze every last bit of performance out of the fuel to see just how bad*** it is?.. otherwise, you may as well just put a limiter on the higher octane and say "we dont want the extra thanks"... Therefore, isnt having a carburettor that ignores the extra ability of the fuel sort of counter intuitive on that?.
Also, "I have been told" by someone who seeks to be an expert, I sort of remember it being a top gear or fifth gear [Rival car show] presenter, that buying the higher octane rating fuel in a "normal" car wont see extra benefits because the engines are not built to get the extra performance out of the fuel in the first place, and you need high compression "sports" type engines to get that extra performance.. Therefore, may I suggest, someone read "The book of words" on how the car in question may react to the fuel, because, the presentation I remember watching sad that maybe it would increase performance slightly over a full tank, maybe you may get one or two extra miles per tank, but for the extra price you pay for it at the pump, the lower octane works out better in gallons per mile, and the majority of cars would see no particular change. Unless it was a higher tune "Sports" engine that is. And not may of us own one of them. We may drive like we do, but we dont.
They also went on to say that the average [xx] octane fuel is "what is expected" and did you really think they would go the extra mile and put extra's on an engine "Just in case" you used a higher octane fuel in your average "Economy plus" family car....
Now I have said "Mine May notice the difference.." Why do I claim that?.. I have the larger than your average bear engine in mine.. I didnt chose it, it just came that way, 10 month old when I bought it, it promised in the book of words to be the better higher power engine. But beggars choice, I couldn't afford "New" so went for second hand, this was the best they could offer in 5 seat 5 door cars.
Flex Fuel engines, yes, go for one of those. ANY multi-gruel engine will have the extra fuel maps, we hope... Any engine that says it will "Automatically" sense and adapt to fuels of all types, except heavy fuel oil, go for one of those. I am just mentioning that when it comes to testing, we need the car that has the ability to make use of a bigger faster more powerful bang to get the results we want, and that may not be "ALL" cars, so the choice of engine is paramount?.
Therefore, having a Carburettor engine with a "set" timing response.... [most cars from back when I first started to drive were like that..] probably wont get any different result in the fuels, even if they manage to start and stay running.
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Post by the light works on May 12, 2017 14:14:36 GMT
and we want the set engine, because one of the myths is that putting avgas in your daily driver will make it perform like a race car.
we want the ton/mile/time per gallon test, with tuned engines, to show whether you get more power out of the higher octane gas or just have the ability to run more of it through the engine.
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Post by silverdragon on May 13, 2017 6:33:47 GMT
and we want the set engine, because one of the myths is that putting avgas in your daily driver will make it perform like a race car. we want the ton/mile/time per gallon test, with tuned engines, to show whether you get more power out of the higher octane gas or just have the ability to run more of it through the engine. Good point, they need an engine that cant react to the change in fuel to show why it wont turn into a general lee overnight...
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Post by the light works on May 13, 2017 6:41:10 GMT
and we want the set engine, because one of the myths is that putting avgas in your daily driver will make it perform like a race car. we want the ton/mile/time per gallon test, with tuned engines, to show whether you get more power out of the higher octane gas or just have the ability to run more of it through the engine. Good point, they need an engine that cant react to the change in fuel to show why it wont turn into a general lee overnight... yes.
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