Ethanol fuels vs. FD injectors
03-07-11 | 12:28 AM
#1
Ethanol fuels vs. FD injectors
I ran into a dispute on a local car tuner forum of fuel types.
Where I live, we can get a 91 octane fuel without ethanol or a 94 octane fuel blended with ethanol. The controversy is that ethanol blends can actually harm injectors and on older vehicles, can severely reduce gas milage. My question is if it's okay to use an ethanol blend on a stock fd. Currently, I use th 94 octane ethanol blend and haven't noticed any ill effects. Obviously gas milage isn't great but hey.. it's an FD. My philosophy behind that is I'd rather just use the higher octane to have the peace of mind that I'm doing everything I can to prevent detonation. However, if the ethanol blend is harmful in any way, I wouldn't be reluctant to opt for the 91 octane.
Another quick question, people from the afformentionned site are saying their vehicles run alot better on fuel from a certain gas station but run like crap on fuel from another. I don't fully understand what "run like crap" might mean. I thought maybe knocking but that's a pretty severe consequence for simply using a different brand of fuel. Would they maybe mean fuel economy / power / AFR wise (according to their tune)? Do any of you notice anything like this?
I tried using the search function as well as google as this topic seems like it would have been covered time and time again but I really didn't find a difinitive answer, only opinions. Input anyone?
Where I live, we can get a 91 octane fuel without ethanol or a 94 octane fuel blended with ethanol. The controversy is that ethanol blends can actually harm injectors and on older vehicles, can severely reduce gas milage. My question is if it's okay to use an ethanol blend on a stock fd. Currently, I use th 94 octane ethanol blend and haven't noticed any ill effects. Obviously gas milage isn't great but hey.. it's an FD. My philosophy behind that is I'd rather just use the higher octane to have the peace of mind that I'm doing everything I can to prevent detonation. However, if the ethanol blend is harmful in any way, I wouldn't be reluctant to opt for the 91 octane.
Another quick question, people from the afformentionned site are saying their vehicles run alot better on fuel from a certain gas station but run like crap on fuel from another. I don't fully understand what "run like crap" might mean. I thought maybe knocking but that's a pretty severe consequence for simply using a different brand of fuel. Would they maybe mean fuel economy / power / AFR wise (according to their tune)? Do any of you notice anything like this?
I tried using the search function as well as google as this topic seems like it would have been covered time and time again but I really didn't find a difinitive answer, only opinions. Input anyone?
03-07-11 | 06:25 AM
#2
If its a bone stock FD with no mods, just use Shell 91 which will give you the most bang for your buck (gas mileage and power). Putting 94 in serves no benefit except taking money out of your wallet and can actually decrease power. If its a modded/tuned FD, use 94 generally for the octane. I'm assuming we are talking about Petro 94 (old Sunoco).
The reason you will get better gas mileage out of SHELL 91 is because Shell 91 is pure gas. Since ethanol has less btu's per volume, any fuel mix using it will provide worse gas mileage. And also less power is possible unless your tuned for the higher octane that 94 provides. That is why on a bone stock FD putting 94 in your tank is just a waste of money as it provides no benefit. The whole reassurance thing is mute, if it was going to blow, it would blow on either fuel (keep in mind I'm referring to completely stock FD's).
Having said that, don't worry about damaging your fuel system in using ethanol based fuels. Don't believe everything you read on the internet. Take everything you read with a grain of salt.
On a side note with my RX-8 I have tested using both Shell 91 and Petro/Sunoco 94. What I learned using the Cobb Accessport was that when I used the 94, the ECU kept adding fuel via the fuel trims. When 91 was used, fuel would be subtracted via the fuel trims. About 2% each each both ways which is a 4% difference (according to the Cobb anyway). This just proved/emphasized the whole fuel mileage and btu per volume thing.
As for the run like crap, people generally exaggerate. I notice when I'm running 87 in the RX-8, that it will idle a little different. Basically not as smooth as it does with the 91 but otherwise runs fine. Most people probably wouldn't even notice the difference to be honest, I just have the habit of always paying attention to how a car idles, especially a rotary. That still doesn't stop me from using 87 in the winter since I don't drive the car hard anyway. It still pulls fine all the way to 9k even with the 87. Actually pulls harder due to the cold, the opening of the ports is much more pronounced, almost feels like the sequential twins transition.
thewird
The reason you will get better gas mileage out of SHELL 91 is because Shell 91 is pure gas. Since ethanol has less btu's per volume, any fuel mix using it will provide worse gas mileage. And also less power is possible unless your tuned for the higher octane that 94 provides. That is why on a bone stock FD putting 94 in your tank is just a waste of money as it provides no benefit. The whole reassurance thing is mute, if it was going to blow, it would blow on either fuel (keep in mind I'm referring to completely stock FD's).
Having said that, don't worry about damaging your fuel system in using ethanol based fuels. Don't believe everything you read on the internet. Take everything you read with a grain of salt.
On a side note with my RX-8 I have tested using both Shell 91 and Petro/Sunoco 94. What I learned using the Cobb Accessport was that when I used the 94, the ECU kept adding fuel via the fuel trims. When 91 was used, fuel would be subtracted via the fuel trims. About 2% each each both ways which is a 4% difference (according to the Cobb anyway). This just proved/emphasized the whole fuel mileage and btu per volume thing.
As for the run like crap, people generally exaggerate. I notice when I'm running 87 in the RX-8, that it will idle a little different. Basically not as smooth as it does with the 91 but otherwise runs fine. Most people probably wouldn't even notice the difference to be honest, I just have the habit of always paying attention to how a car idles, especially a rotary. That still doesn't stop me from using 87 in the winter since I don't drive the car hard anyway. It still pulls fine all the way to 9k even with the 87. Actually pulls harder due to the cold, the opening of the ports is much more pronounced, almost feels like the sequential twins transition.
thewird
03-07-11 | 11:42 PM
#3
1993 Owners Manual section 3 page 2
Canadian government mandates a minimum 5% ethanol content for total fuels produced.
Husky Mohawk is E10 for all fuels.
PetroCanada is E10-regular, E5-Mid, 0 Premium
Shell Premium should also be ethanol free like stated above.
I personally use only Petro Canada 91 or Shell 91 since they're both ethanol free and close to my place. If I was in a pinch I wouldn't worry about filling up on premium with ethanol.
Overall there is point buying Husky 94 on a stock tune and you'll end up losing gas mileage too.
Fuel Requirements:
Your Mazda will perform best with premium unleaded fuel having an octane rating (antiknock index) of at least 91 [(R+M)/2 method].
You may use a regular unleaded gasoline with a rating from 87 to 90; this will slightly reduce performance.
Caution- Don't use gasohol, a mixture of gasoline and ethanol (also known as grain alcohol) containing more than 10% ethanol.
Your Mazda will perform best with premium unleaded fuel having an octane rating (antiknock index) of at least 91 [(R+M)/2 method].
You may use a regular unleaded gasoline with a rating from 87 to 90; this will slightly reduce performance.
Caution- Don't use gasohol, a mixture of gasoline and ethanol (also known as grain alcohol) containing more than 10% ethanol.
Husky Mohawk is E10 for all fuels.
PetroCanada is E10-regular, E5-Mid, 0 Premium
Shell Premium should also be ethanol free like stated above.
I personally use only Petro Canada 91 or Shell 91 since they're both ethanol free and close to my place. If I was in a pinch I wouldn't worry about filling up on premium with ethanol.
Overall there is point buying Husky 94 on a stock tune and you'll end up losing gas mileage too.
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