Crimson KING
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I'm no instructor by any means, but I have been trained by some of the best so I'm going to do my best to explain some common misconceptions about which fuel we use in our engines these days.
First off I have to explain what fuel is, and what it does.
So we all know when the low fuel light comes on we go to the pump and fill up. But what is fuel? Well fuel is energy. And with all types of energy, it was created by none other than our sun. But the sun didn't create all things equal. No we have many different types of fuels to choose from. We have 100% gas. We have different blends of 100% gas. We have different octane ratings. We have Compressed natural gas and diesel and more.
But what is 87,89,91,93 and so on? Yeah it's the octane rating of the gas, but what does it mean? Well let me give you this...
Fuel - Liquid, US Gallons GGE GGE % BTU/Gal kWh/Gal
Gasoline (base)[2] 1.0000 100.00% 114,000 33.41
Gasoline (conventional, summer)[2] 0.9960 100.40% 114,500 33.56
Gasoline (conventional, winter)[2] 1.0130 98.72% 112,500 32.97
Gasoline (reformulated gasoline, ethanol)[2] 1.0190 98.14% 111,836 32.78
Gasoline (reformulated gasoline, ETBE)[2] 1.0190 98.14% 111,811 32.77
Gasoline (reformulated gasoline, MTBE)[2] 1.0200 98.04% 111,745 32.75
Gasoline (10% MBTE)[3] 1.0200 98.04% 112,000 32.83
Gasoline (regular unleaded)[4] 1.0000 100.00% 114,100 33.44
Diesel #2[4] 0.8800 113.64% 129,500 37.95
Biodiesel (B100)[4] 0.9600 104.17% 118,300 34.80
Bio Diesel (B20)[4] 0.9000 111.11% 127,250 37.12
Liquid natural gas (LNG)[4] 1.5362 65.10% 75,000 21.75
Liquefied petroleum gas (propane) (LPG)[4] 1.3500 74.04% 84,300 24.75
Methanol fuel (M100)[4] 2.0100 49.75% 56,800 16.62
Ethanol fuel (E100)[4] 1.5000 66.67% 76,100 22.27
Ethanol (E85)[4] 1.3900 71.94% 81,800 24.04
Jet fuel (naphtha)[5] 0.9700 103.09% 118,700 34.44
Jet fuel (kerosene)[5] 0.9000 111.11% 128,100 37.12
What are we looking for in fuel? The British thermal unit per gallon, or BTU.
As the chart shows each type of fuel has different BTU ratings, in other words, how long it takes to burn.
Without getting too in depth to the science of it all(there's not enough time in the day), we will explain it like this;
in the US we use basically 86-87 Octane... 89-90 octane.. and 90-94 octane.
For argument purposes lets say these gases burn in....
87 Octane burns in .87 of a second
89 Octane burns in .89 of a second
93 Octane burns in .93 of a second
So obviously 87 octane burns the quickest, and 93 burns the slowest.
Now what does this mean for you?
Well cars nowadays are all engineered and designed to use a certain type of gas. A car that recommends 87 octane runs best on 87 octane. A car that recommends 93 octane runs best on .... 93 octane!
But why? Why not just use 93 in everything? If it burns slower than 87 that must mean I get better economy right? Wrong. This is why.
We all know our motors are timed to do everything in a certain order. We have chains and belts to keep all that good stuff working together and in time as designed.
Yeah fuel trims change as our O2 sensors read the exhaust and they increase or decrease our injectors pulse width, or time that they spray fuel.
But in each of our cars there's a little box with lots of gadgets and processors and capacitors and such. That little box keeps everything in motion. It's the boss. It tells everything what to do. But what we're worried about is timing.
Say our imaginary motor here is set to detonate its fuel at 10 degrees after top dead center. Why not 0 degrees before top dead center or right at top dead center? Well if the fuel was being detonated before the piston reached the top, you probably wouldn't get very far, since the piston would be coming up, or at its peak, rather than going down. But anyway, so our motor is set to detonate at 10 ATDC. Now in this motor the engineers have told us that we should use 87 octane gasoline. Why? Because the motor is timed that at a certain RPM, this fuel is going to burn most efficiently, and most complete at 10 Degrees ATDC.
So what happens when you use 93 octane gas in the same motor? It's simple, this motor is timed to burn it's fuel in .87 seconds at 10 degrees ATDC. But now that we have 93 octane, our fuel is burning at .93 of a second.... but where does that leave your timing? You can't burn both 87 octane and 93 octane at the same amount of time... 93 octane burns slower right? So now we're throwing our timing off, because we are taking longer to burn our fuel. Instead of 10 degrees like we had with 87 octane... we're now at 12-14 degrees ATDC.
But why don't our knock sensors adjust our timing to correct this? Well it's not pinging. There's no engine knock. The Computer still sees everything is working, and technically evrything is working. But you're not completely burning that fuel. You have nothing to gain by upping your octane rating. You're just burning dollars. You've shot unburnt fuel right into the exhaust. No economy gains, no power gains.... nothing.
Long term effects of using the wrong octane? More hydro carbons. What do HCs do? Break stuff. Had a gummed up EGR? How about a p0420 Catalyst code? Maybe you have maybe you haven't. If you're lucky enough to say you haven't, count your luck. Cause I've seen it happen many times. Years go by and people still use the wrong type of gas.
Do yourself a favor and use what your manufacturer recommends. There's a reason why they put that number in your owners manual.
Please comment and ask questions if you're unclear about anything, as I said earlier, I'm no professor, just a tech tryin to spread the wealth.
First off I have to explain what fuel is, and what it does.
So we all know when the low fuel light comes on we go to the pump and fill up. But what is fuel? Well fuel is energy. And with all types of energy, it was created by none other than our sun. But the sun didn't create all things equal. No we have many different types of fuels to choose from. We have 100% gas. We have different blends of 100% gas. We have different octane ratings. We have Compressed natural gas and diesel and more.
But what is 87,89,91,93 and so on? Yeah it's the octane rating of the gas, but what does it mean? Well let me give you this...
Fuel - Liquid, US Gallons GGE GGE % BTU/Gal kWh/Gal
Gasoline (base)[2] 1.0000 100.00% 114,000 33.41
Gasoline (conventional, summer)[2] 0.9960 100.40% 114,500 33.56
Gasoline (conventional, winter)[2] 1.0130 98.72% 112,500 32.97
Gasoline (reformulated gasoline, ethanol)[2] 1.0190 98.14% 111,836 32.78
Gasoline (reformulated gasoline, ETBE)[2] 1.0190 98.14% 111,811 32.77
Gasoline (reformulated gasoline, MTBE)[2] 1.0200 98.04% 111,745 32.75
Gasoline (10% MBTE)[3] 1.0200 98.04% 112,000 32.83
Gasoline (regular unleaded)[4] 1.0000 100.00% 114,100 33.44
Diesel #2[4] 0.8800 113.64% 129,500 37.95
Biodiesel (B100)[4] 0.9600 104.17% 118,300 34.80
Bio Diesel (B20)[4] 0.9000 111.11% 127,250 37.12
Liquid natural gas (LNG)[4] 1.5362 65.10% 75,000 21.75
Liquefied petroleum gas (propane) (LPG)[4] 1.3500 74.04% 84,300 24.75
Methanol fuel (M100)[4] 2.0100 49.75% 56,800 16.62
Ethanol fuel (E100)[4] 1.5000 66.67% 76,100 22.27
Ethanol (E85)[4] 1.3900 71.94% 81,800 24.04
Jet fuel (naphtha)[5] 0.9700 103.09% 118,700 34.44
Jet fuel (kerosene)[5] 0.9000 111.11% 128,100 37.12
What are we looking for in fuel? The British thermal unit per gallon, or BTU.
As the chart shows each type of fuel has different BTU ratings, in other words, how long it takes to burn.
Without getting too in depth to the science of it all(there's not enough time in the day), we will explain it like this;
in the US we use basically 86-87 Octane... 89-90 octane.. and 90-94 octane.
For argument purposes lets say these gases burn in....
87 Octane burns in .87 of a second
89 Octane burns in .89 of a second
93 Octane burns in .93 of a second
So obviously 87 octane burns the quickest, and 93 burns the slowest.
Now what does this mean for you?
Well cars nowadays are all engineered and designed to use a certain type of gas. A car that recommends 87 octane runs best on 87 octane. A car that recommends 93 octane runs best on .... 93 octane!
But why? Why not just use 93 in everything? If it burns slower than 87 that must mean I get better economy right? Wrong. This is why.
We all know our motors are timed to do everything in a certain order. We have chains and belts to keep all that good stuff working together and in time as designed.
Yeah fuel trims change as our O2 sensors read the exhaust and they increase or decrease our injectors pulse width, or time that they spray fuel.
But in each of our cars there's a little box with lots of gadgets and processors and capacitors and such. That little box keeps everything in motion. It's the boss. It tells everything what to do. But what we're worried about is timing.
Say our imaginary motor here is set to detonate its fuel at 10 degrees after top dead center. Why not 0 degrees before top dead center or right at top dead center? Well if the fuel was being detonated before the piston reached the top, you probably wouldn't get very far, since the piston would be coming up, or at its peak, rather than going down. But anyway, so our motor is set to detonate at 10 ATDC. Now in this motor the engineers have told us that we should use 87 octane gasoline. Why? Because the motor is timed that at a certain RPM, this fuel is going to burn most efficiently, and most complete at 10 Degrees ATDC.
So what happens when you use 93 octane gas in the same motor? It's simple, this motor is timed to burn it's fuel in .87 seconds at 10 degrees ATDC. But now that we have 93 octane, our fuel is burning at .93 of a second.... but where does that leave your timing? You can't burn both 87 octane and 93 octane at the same amount of time... 93 octane burns slower right? So now we're throwing our timing off, because we are taking longer to burn our fuel. Instead of 10 degrees like we had with 87 octane... we're now at 12-14 degrees ATDC.
But why don't our knock sensors adjust our timing to correct this? Well it's not pinging. There's no engine knock. The Computer still sees everything is working, and technically evrything is working. But you're not completely burning that fuel. You have nothing to gain by upping your octane rating. You're just burning dollars. You've shot unburnt fuel right into the exhaust. No economy gains, no power gains.... nothing.
Long term effects of using the wrong octane? More hydro carbons. What do HCs do? Break stuff. Had a gummed up EGR? How about a p0420 Catalyst code? Maybe you have maybe you haven't. If you're lucky enough to say you haven't, count your luck. Cause I've seen it happen many times. Years go by and people still use the wrong type of gas.
Do yourself a favor and use what your manufacturer recommends. There's a reason why they put that number in your owners manual.
Please comment and ask questions if you're unclear about anything, as I said earlier, I'm no professor, just a tech tryin to spread the wealth.