Premium fuel with ethanol - problem or not?
#21
09-15-2012, 04:25 PM
Veteran Member
It strikes me that if you really wanted to figure out what octane was "required" then the thing to do would be to monitor the spark advance while driving in various conditions. My suspicion is that what you'd see is that the 87 results in the car pulling out the advance, which has disadvantages with respect to efficiency.
I haven't tried it with the Jag (maybe I'll try it today for fun) but when I had a turbo VW I know that even with the 91 octane we can get in AZ the advance would get pulled back to 11 or 12 deg in hot weather. A buddy of mine who is from Ohio where 93 is common, grumbled about it while he was here.
On the topic of ethanol, cars built in the last 20 years or so shouldn't have a problem with 10% blends. In fact, I know some of those same VW guys who run E85 in non-approved cars.
These are the kind of crazies who squeeze 400hp out of a 1.8L turbo. What they told me was that the fuel systems can handle it but you have to be careful about the conversion. Their recommendation was to fill up with E85 a couple of times and then change the fuel filter, because it will clean out a bunch of junk in the fuel system.
On older cars it can be problematic because ethanol will attack natural rubber, PVC and some other materials, so all of the seals disintegrating in the 72 OTS isn't all that surprising given that most fuel these days has some amount of ethanol in it.
I can say that in my disassembly of the fuel pump from my 2003 (75k miles) all of the seals appear to be viton, which works just fine with ethanol. I also didn't see any signs of the plastic parts being brittle or having been chemically attacked. They were actually quite flexible considering their age.
What ethanol does do that plain gasoline doesn't is pick up water. Ethanol by itself isn't very corrosive, but ethanol plus a little water can be, especially at the interface with the air in a half full fuel tank.
The boat guys have it right. Fill the tank to the top and use the stabilizers if the car is going to sit for a long time.
I haven't tried it with the Jag (maybe I'll try it today for fun) but when I had a turbo VW I know that even with the 91 octane we can get in AZ the advance would get pulled back to 11 or 12 deg in hot weather. A buddy of mine who is from Ohio where 93 is common, grumbled about it while he was here.
On the topic of ethanol, cars built in the last 20 years or so shouldn't have a problem with 10% blends. In fact, I know some of those same VW guys who run E85 in non-approved cars.
These are the kind of crazies who squeeze 400hp out of a 1.8L turbo. What they told me was that the fuel systems can handle it but you have to be careful about the conversion. Their recommendation was to fill up with E85 a couple of times and then change the fuel filter, because it will clean out a bunch of junk in the fuel system.
On older cars it can be problematic because ethanol will attack natural rubber, PVC and some other materials, so all of the seals disintegrating in the 72 OTS isn't all that surprising given that most fuel these days has some amount of ethanol in it.
I can say that in my disassembly of the fuel pump from my 2003 (75k miles) all of the seals appear to be viton, which works just fine with ethanol. I also didn't see any signs of the plastic parts being brittle or having been chemically attacked. They were actually quite flexible considering their age.
What ethanol does do that plain gasoline doesn't is pick up water. Ethanol by itself isn't very corrosive, but ethanol plus a little water can be, especially at the interface with the air in a half full fuel tank.
The boat guys have it right. Fill the tank to the top and use the stabilizers if the car is going to sit for a long time.
#22
09-15-2012, 05:28 PM
Veteran Member
There are other sites where additional reliable or at least believable information can be found about ethanol and its effects.
There is at least one site that tracks the commodity pricing of ethanol and gasoline against retail pricing of blended/unblended fuels and their energy equivalence based on mpg. Their result is that the pricing spread between blended and unblended is carefully set by the vendors to maximize revenues versus cost.
There are multiple hypermiler sites focusing on the effect of ethanol on mileage. Many of the participants on those forums routinely log fuel consumption versus type and brand of fuel using full time OBD logging as well as manual calculations.
What can be easily and repeatably observed using OBD logging is the effect on LTFT. Ethanol has higher octane but lower energy content as well as a different stoichiometric ratio. The ECU responds to ethanol by increasing LTFT. The difference between unblended premium and 10 percent ethanol blended regular is about 7 percent depending on the vehicle. Some vehicles, depending on the programmed ECU strategy will take advantage of the increased octane by advancing spark ignition timing. The hypermilers do not track MPG, they track MP$. The result for them is that in some markets, depending on pricing, they get better MP$ on unblended premium. They also note better performance along with the better MP$. Sort of like having your cake and eating it too.
From another viewpoint, if someone is hunting down a persistently high but stable LTFT with STFT that looks ok on a pre-ethanol era vehicle, the first possibility might be to try a few tanks of premium unblended fuel containg no ethanol while logging fuel trims. There may be a big surprise in store around the 3rd or 4th tankful as the high LTFT disappears. This is perfectly sensible given the design of the ECU logic and the known effects of ethanol as noted above. Someone who did not suspect this could spend an awful lot of time and effort looking for a physical defect when the "defect" is sitting in the tank and changes with every fillup.
The choice then becomes whether to go with high LTFT or higher fuel cost. Bear in mind the previous distinction between MPG and MP$ as the unblended premium may yield better MP$. There are multiple factors to consider including higher injector duty cycle, idle characteristics, and remaining available injector duty cycle under heavy acceleration. The last factor is especially important on the supercharged engines under boost. It is even more important *if* the strategy adopted by the ECU does not include LTFT adjustments in open loop mode. The engine will then be substantially underfueled under WOT.
On the matter of fact versus fiction, anyone who has a OBD logging tool can gather their own data, using the fuels in their market and see repeatable results. Just remember that it can take several tanks to clear out the old fuel and that the fuels being compared must each come from one station. The blending is done at the pump and can vary from brand to brand as well as station to station.
Finally, the E85 boost crowd are *very* careful to only use fuel pumps that are ethanol certified by the manufacturer. In their world of 800bhp 2.5 litre engines, leaning out due to pump failure equates to instant engine destruction. They won't buy fuel pumps that do not explicitly state that they are suitable for use with ethanol fuels.
There is at least one site that tracks the commodity pricing of ethanol and gasoline against retail pricing of blended/unblended fuels and their energy equivalence based on mpg. Their result is that the pricing spread between blended and unblended is carefully set by the vendors to maximize revenues versus cost.
There are multiple hypermiler sites focusing on the effect of ethanol on mileage. Many of the participants on those forums routinely log fuel consumption versus type and brand of fuel using full time OBD logging as well as manual calculations.
What can be easily and repeatably observed using OBD logging is the effect on LTFT. Ethanol has higher octane but lower energy content as well as a different stoichiometric ratio. The ECU responds to ethanol by increasing LTFT. The difference between unblended premium and 10 percent ethanol blended regular is about 7 percent depending on the vehicle. Some vehicles, depending on the programmed ECU strategy will take advantage of the increased octane by advancing spark ignition timing. The hypermilers do not track MPG, they track MP$. The result for them is that in some markets, depending on pricing, they get better MP$ on unblended premium. They also note better performance along with the better MP$. Sort of like having your cake and eating it too.
From another viewpoint, if someone is hunting down a persistently high but stable LTFT with STFT that looks ok on a pre-ethanol era vehicle, the first possibility might be to try a few tanks of premium unblended fuel containg no ethanol while logging fuel trims. There may be a big surprise in store around the 3rd or 4th tankful as the high LTFT disappears. This is perfectly sensible given the design of the ECU logic and the known effects of ethanol as noted above. Someone who did not suspect this could spend an awful lot of time and effort looking for a physical defect when the "defect" is sitting in the tank and changes with every fillup.
The choice then becomes whether to go with high LTFT or higher fuel cost. Bear in mind the previous distinction between MPG and MP$ as the unblended premium may yield better MP$. There are multiple factors to consider including higher injector duty cycle, idle characteristics, and remaining available injector duty cycle under heavy acceleration. The last factor is especially important on the supercharged engines under boost. It is even more important *if* the strategy adopted by the ECU does not include LTFT adjustments in open loop mode. The engine will then be substantially underfueled under WOT.
On the matter of fact versus fiction, anyone who has a OBD logging tool can gather their own data, using the fuels in their market and see repeatable results. Just remember that it can take several tanks to clear out the old fuel and that the fuels being compared must each come from one station. The blending is done at the pump and can vary from brand to brand as well as station to station.
Finally, the E85 boost crowd are *very* careful to only use fuel pumps that are ethanol certified by the manufacturer. In their world of 800bhp 2.5 litre engines, leaning out due to pump failure equates to instant engine destruction. They won't buy fuel pumps that do not explicitly state that they are suitable for use with ethanol fuels.
Last edited by plums; 09-15-2012 at 05:33 PM.
#23
09-15-2012, 05:53 PM
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I can speak first hand that this is true. My 72 OTS V12 is in the shop right now for this issue and it won't be cheap to get it fixed. Damage to the gasket at the fuel bowl (disintegrated in the mechanic's hand as he tried to remove it), 3 of 4 carbs are significantly fouled, choke/throttle linkages are gummed up. It is a mess.
And you're certain this is directly attributable to ethanol, and would not have happened without ethanol? If so, why?
How old were the carb gaskets? This would certainly enter in to the deterioration, and "gummed up" linkages were a problem long before E10 fuel. Heh heh....I can remember buying "GumOut" carb spray in the middle 70s. :-)
This happened when my battery died and I took longer than I should have to replace it. By the time I fired up the car again, Ethanol had done it's damage.
This was not E86 fuel. This was the regular unleaded mixture that includes some Ethanol that many stations now sell. Be careful. Very careful.
This was not E86 fuel. This was the regular unleaded mixture that includes some Ethanol that many stations now sell. Be careful. Very careful.
Besides my own I have fours Jags in my care: E-type Ser I, XK120, XK140, and XJ220. Of the first three I find than the fuel evaporates out of the bowls in just a few days so the direct exposure to ethanol isn't very long in duration. Whether or not evaporation of E10 fuel leaves a damaging residue inside the bowls, I can't say.
Anyhow, all three have leak-free carbs and run well....although the the float bowls do at times need a few taps to free-up the floats. But, as we all know, float bowl tapping to free up stuck floats pre-dates E10 fuel by decades....so I don't draw anything conclusive from that!
I just had the XJ220 out a couple weekends ago. It started easily and ran fine on the nearly year old old E10 fuel that was in the tank. Again, if there is some sort of damage taking place, I haven't experienced any manifestations of it.
Cheers
DD
#24
09-16-2012, 04:26 AM
#25
09-16-2012, 04:33 PM
You are clearly way off track, the topic at hand is:
Premium fuel with ethanol - problem or not?
You are the one who tried to drag it into your own pet peeve.
Nice try, but no cigar.
OK, now, I know that you will respond very shortly, but I will be the bigger man and just let it go.
#26
09-18-2012, 01:35 AM
Veteran Member
You are clearly way off track, the topic at hand is:
Premium fuel with ethanol - problem or not?
You are the one who tried to drag it into your own pet peeve.
Nice try, but no cigar.
OK, now, I know that you will respond very shortly, but I will be the bigger man and just let it go.
Premium fuel with ethanol - problem or not?
You are the one who tried to drag it into your own pet peeve.
Nice try, but no cigar.
OK, now, I know that you will respond very shortly, but I will be the bigger man and just let it go.
As a consequence, the off-topic posts have been removed and the thread is being monitored.
#27
09-18-2012, 03:50 AM
EU is changing the direction and go back to max 5% ethanol fuel. I have never used the 95E10 we have here in Finland. Always 98E5 or Shell V-Power, which is nowdays very close to regular 98.
I have similar suspicions.
From what I read about US fuel in the forum, it's generally 10% Ethanol. I also read regular reports of fuel pump failures. It may not be to the level where the pump(s) won't last the life of the vehicle but must be a high proportion.
In the UK we currently have 5% Ethanol in our fuel. It's not widely publicised and many motorists are unaware there's any content! The big difference is fuel pump failures are much rarer. My last three Jaguars all went well over the 100K miles without any pump issues. I can't recall the last time a friend or colleague had a pump issue with any of their vehicles.
We are due to adopt the Euro standard of 10% Ethanol and it will be interesting to see if fuel pump failures begin to rise.
The only other difference I can think to account for the disparity in pump failure could be ambient temperature. In many parts of the US the fuel in your tank will always be warmer that over here. Perhaps pumps operating constantly at higher temperatures fail faster?
Graham
From what I read about US fuel in the forum, it's generally 10% Ethanol. I also read regular reports of fuel pump failures. It may not be to the level where the pump(s) won't last the life of the vehicle but must be a high proportion.
In the UK we currently have 5% Ethanol in our fuel. It's not widely publicised and many motorists are unaware there's any content! The big difference is fuel pump failures are much rarer. My last three Jaguars all went well over the 100K miles without any pump issues. I can't recall the last time a friend or colleague had a pump issue with any of their vehicles.
We are due to adopt the Euro standard of 10% Ethanol and it will be interesting to see if fuel pump failures begin to rise.
The only other difference I can think to account for the disparity in pump failure could be ambient temperature. In many parts of the US the fuel in your tank will always be warmer that over here. Perhaps pumps operating constantly at higher temperatures fail faster?
Graham
#28
09-18-2012, 09:19 AM
Join Date: Oct 2009
Location: Perth Ontario Canada
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+1 on this although my 'collection' is much much smaller. I've used E10 for 20ish years- never once had a problem traceable to ethanol.
I'd like to chime in, briefly :-)
First let me say that I'm not a chemist, engineer, metalurgist, or forensic examiner. I'm just a guy. :-)
I work for a family that owns a large collection of classic/specialty/exotic cars. The major part of my job is to keep the cars roadworthy and in good running condition. Storage periods range from weeks to months....or even years.
Briefly, I have no problem starting/running/driving cars that have been sitting for months with E10 fuel in the tanks. Or, frankly, even longer. There may be a degradation of performance if the cars are driven agreessively but I usually don't thrash 'em too hard when they come out for exercise.
Some of the cars have years-old fuel in the tanks. When gas gets that old I'm not sure how to differentiate between an supposed ethanol problem versus plain, old fashioned "stale gas".
As for actual damage caused by ethanol, again, I'm not sure how to identify an ethanol problem. I spend plenty of time replacing leaky carb gaskets, dried-out seals, rotten fuel hoses and the like but I'm not convinced that 10-20-30 year old hoses and gaskets can be expected to be leak free with or without ethanol.
There's lots of conversation about corrosion-like damage. Maybe so. I haven't open up fuel tanks to examine them.
I dunno...maybe I'm just not seeing it but in the end I'm not at all convinced that ethanol is as bad as many say.
Additionally, as we all know, ethanol has become a political football. IMHO that immediatley puts into question the veracity and motivation of what I read and hear, either pro or con.
Just my puny 2-cents :-)
Cheers
DD
First let me say that I'm not a chemist, engineer, metalurgist, or forensic examiner. I'm just a guy. :-)
I work for a family that owns a large collection of classic/specialty/exotic cars. The major part of my job is to keep the cars roadworthy and in good running condition. Storage periods range from weeks to months....or even years.
Briefly, I have no problem starting/running/driving cars that have been sitting for months with E10 fuel in the tanks. Or, frankly, even longer. There may be a degradation of performance if the cars are driven agreessively but I usually don't thrash 'em too hard when they come out for exercise.
Some of the cars have years-old fuel in the tanks. When gas gets that old I'm not sure how to differentiate between an supposed ethanol problem versus plain, old fashioned "stale gas".
As for actual damage caused by ethanol, again, I'm not sure how to identify an ethanol problem. I spend plenty of time replacing leaky carb gaskets, dried-out seals, rotten fuel hoses and the like but I'm not convinced that 10-20-30 year old hoses and gaskets can be expected to be leak free with or without ethanol.
There's lots of conversation about corrosion-like damage. Maybe so. I haven't open up fuel tanks to examine them.
I dunno...maybe I'm just not seeing it but in the end I'm not at all convinced that ethanol is as bad as many say.
Additionally, as we all know, ethanol has become a political football. IMHO that immediatley puts into question the veracity and motivation of what I read and hear, either pro or con.
Just my puny 2-cents :-)
Cheers
DD
#29
09-18-2012, 10:47 PM
Senior Member
First of all let me apologize for getting this thread off track. It has been the typical 18 hr day. I am charged with the responsibility of maintaining a fleet of equipment that must respond to emergencies when needed. No we are not fire, police or ems. I superintendent for a utility that provides water, wastewater and power. I order to provide these services 24 hours a day this fleet must run and operate on a moments notice. Some of this equipment is designed for specific tasks and is only needed in extreme situations. It is not cost effective for my customers to upgrade this equipment on a regular basics. I know that we all have budget restrains professionally and personally. I have been in this environment for 30 plus years. Have i seen issues with fuels, your would not believe. It is almost impossible to fight a fire if you do not have water!! Will i continue to use additives, you better believe it. What is $15 when my customer are with out services.
When I am able to spend time with my beautiful wife, children and grandson my toys will start and run as needed.
As far as the mom and pop stations, we have all heard of the trans Continental pipe line. We do not have refineries in South Carolina fuel is shipped from the refineries in the gulf coast, 1000 plus miles. Do we honestly believe that BP, Exxon, Shell have their own private lines, or it shipped by truck to their private stations. Its transferred to these distribution point via these lines with a pig or plug separating these products to the proper storage or bulk tanks. Are these fuels commingled you better believe it. Are mom or pops stations worse that BP its called additives. premium is premium.
Please remember the next time you go thru a work zone and you are inconvenienced for a short period of time these maybe your services that these folks are trying to improve or restored. Give them the nice wave, I know they would rather be at home with family and friends. Sorry still have crews working on water main breaks!!!!
Jim
When I am able to spend time with my beautiful wife, children and grandson my toys will start and run as needed.
As far as the mom and pop stations, we have all heard of the trans Continental pipe line. We do not have refineries in South Carolina fuel is shipped from the refineries in the gulf coast, 1000 plus miles. Do we honestly believe that BP, Exxon, Shell have their own private lines, or it shipped by truck to their private stations. Its transferred to these distribution point via these lines with a pig or plug separating these products to the proper storage or bulk tanks. Are these fuels commingled you better believe it. Are mom or pops stations worse that BP its called additives. premium is premium.
Please remember the next time you go thru a work zone and you are inconvenienced for a short period of time these maybe your services that these folks are trying to improve or restored. Give them the nice wave, I know they would rather be at home with family and friends. Sorry still have crews working on water main breaks!!!!
Jim
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