DIfference between Mobil 93 and Shell 93 with 10% Methonal
Nov 22, 2006, 03:56 PM
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Difference between Mobil 93 and Shell 93 with 10% Ethonal
Just to levelset I am running with 93 octane and Alky injection. I have been tuning the AFR's lately and noticed a .3 to .5 (lower) difference in AFR's when I filled up with Shell 93 with 10% Meth added. You can also see the difference in the Mid and High Fuel trims.
I have attached both logs to show the differnces. Both are 3rd gear pulls.
I never realized the difference the addittive could make. Of course, it could be the difference in gas, but not sure.
I have attached both logs to show the differnces. Both are 3rd gear pulls.
I never realized the difference the addittive could make. Of course, it could be the difference in gas, but not sure.
Last edited by fixem2; Nov 22, 2006 at 04:28 PM.
Nov 22, 2006, 04:11 PM
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So you're saying Shell 93 made you run richer than Mobil1 93octane. I wouldnt call that evidence until you consistently run shell for a few tanks, note the a/f and do the same for mobil1. too many inconsistent variables in the tests as well..
Nov 22, 2006, 04:26 PM
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Not really trying to test a theory. I have been tuning the Mobil 1 tank for the last 2 days. The first log was the morning and the second 4 hours later; after the Shell fillup. Just thought it was interesting since I didn't make any changes to the AFR Map and the AFR's changed that much with the new gas. Makes tuning that much more fun!!
Last edited by fixem2; Nov 23, 2006 at 12:32 AM.
Nov 23, 2006, 07:15 AM
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The specific gravity of the fuel is probably different. I too noticed a difference going from sunoco 94 to Exxon 93. Sunoco no longer carries 94 and that was a nice fuel.
Nov 23, 2006, 08:09 AM
#7
Most fuels are "Oxygenated" these days, some states are still allowed to use MTBE, but most have replaced it with 10%-30% ethanol..
I suspect he's referring to the Alcohol content in gas, Ethanol and not Methanol.
When I first got my Evo, New York was just switching from MTBE to Ethanol, running Ethanol in the winter, and MTBE in the summer (if I recall)
I always have had a wideband in my car, and the AFR never changed, however the fuel consumption rate did, therefore the value in the AFR gage still being calibrated from lambda to gasoline, will always read 14.7 However in reality, the different blends of fuels obviously had different specific gravity and different stoichiometric ratios.
This was obvious to me when I was averaging 315 miles to a tank, down to 275-290.. Obviously your consumng more fuel with ethanol content to maintain closed loop stoich balance.
Another thing I noticed was the Alcohol blends, although rated at the same octane level as MTBE, allowed me to run slightly more boost than the non alcohol blends. This is pretty obvious as early on, most people felt on 93 octane you could only safely tune for about 21psi on pump, and you are seeing 23psi pretty regularly, even at 91 octane..
I think what the original poster is describing is he is located in an area where both MTBE and Ethanol blend fuels are available. Most refineries aren't making different blends for different areas any longer, so its rare to see in most states.
I suspect he's referring to the Alcohol content in gas, Ethanol and not Methanol.
When I first got my Evo, New York was just switching from MTBE to Ethanol, running Ethanol in the winter, and MTBE in the summer (if I recall)
I always have had a wideband in my car, and the AFR never changed, however the fuel consumption rate did, therefore the value in the AFR gage still being calibrated from lambda to gasoline, will always read 14.7 However in reality, the different blends of fuels obviously had different specific gravity and different stoichiometric ratios.
This was obvious to me when I was averaging 315 miles to a tank, down to 275-290.. Obviously your consumng more fuel with ethanol content to maintain closed loop stoich balance.
Another thing I noticed was the Alcohol blends, although rated at the same octane level as MTBE, allowed me to run slightly more boost than the non alcohol blends. This is pretty obvious as early on, most people felt on 93 octane you could only safely tune for about 21psi on pump, and you are seeing 23psi pretty regularly, even at 91 octane..
I think what the original poster is describing is he is located in an area where both MTBE and Ethanol blend fuels are available. Most refineries aren't making different blends for different areas any longer, so its rare to see in most states.
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Nov 23, 2006, 10:00 AM
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Basically, I am just reinforcing the fact that if you change certain variables in your car the tuning will change with it. I now have to be more aware of the gas I put in the car. Mostly for information purposes not a true test.
Nov 24, 2006, 06:11 AM
#12
For me its driving stye.. with my GT35r, 280 cams and 1000cc injectors if I do all highway driving I'm still averaging 260-280 miles to the tank..
BTW if you want to log the load on the car while cruising, use the 1C RequestID value.. If you drive at 55, 65, 75 there will be a noticable increase in load at higher speeds due to drag.. the higher speeds will have an affect on your mileage as does wheel size, if you do/dont have a spoiler, wheel alignment, tire pressure, etc..
BTW if you want to log the load on the car while cruising, use the 1C RequestID value.. If you drive at 55, 65, 75 there will be a noticable increase in load at higher speeds due to drag.. the higher speeds will have an affect on your mileage as does wheel size, if you do/dont have a spoiler, wheel alignment, tire pressure, etc..
Last edited by MalibuJack; Nov 24, 2006 at 06:15 AM.
Nov 24, 2006, 08:25 AM
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MJ, the 1C RequestID is the ECULOAD correct, not the calculated load?
C6, Yes the first pull was much better according to DLL. I made 315/304 on the first pull and 299/282 on the second. Of course, this was due to not being tuned for the ethanol gas.
C6, Yes the first pull was much better according to DLL. I made 315/304 on the first pull and 299/282 on the second. Of course, this was due to not being tuned for the ethanol gas.
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