93 Octane vs. Non-Ethanol w/ lower Octane
07-20-2021, 12:16 PM
#1
Burning Brakes
Thread Starter
93 Octane vs. Non-Ethanol w/ lower Octane
I've been running non-ethanol for the past couple of years in our 08 LS3. Lately the price for non-ethanol gas in this area is out of sight. What is everyone else doing? Opinions greatly appreciated!
Thanks!
Thanks!
Popular Reply
07-20-2021, 05:14 PM
Drifting
The problem with conspiracy theories is that they are almost impossible to counter with reason and facts. If you have some specific reason for favoring ethanol free gas, I can almost certainly give you scientific evidence that it is internet misinformation. The biggest known issue with E10 versus E0 is that E10 gets slightly less mileage, about 1 to at most 2mpg. It is also somewhat corrosive to fuel systems in cars built prior to the 1990’s that did not have upgraded materials to counter the slight increase in corrosion. But for most issues, there is simply no consequential difference.
Engine power is the same. The engine computer recognizes that energy content of the gas per gallon has dropped a bit and simply squirts a bit more fuel per pulse, which is why the mileage drops. But since a bit more fuel is being squirted, the energy content being squirted remains the same.
Most of the internet horror stories relate to the fact that if water is present, ethanol absorbs more of it than gas does. But in a practical sense, that has not proven to be a problem. The only condition under which there’s a smidgen more risk is for someone who stores his car over the winter. Even there, the difference is not night and day, it’s a small risk versus a slightly greater but still very small risk.
When I make these posts saying don’t waste your money or go out of your way to get ethanol free gas, I also point out for credibility that I don’t like ethanol in gas either. But my objection has nothing to do with performance, it’s simply economics. Ethanol is more expensive than gas, and requires some form of subsidy or forced use which costs us all. Contrary to what some on the pro-ethanol side believe, it does not offer significant environmental benefits. The only benefits are to corn farmers and ethanol plant owners in the form of dollars flowing their way. The great irony is that the ethanol boondoggle is one of the vanishingly few places where Republicans and Democrats cooperate. The Republicans do it to please their farm state voters, while the Democrats do it in the false belief that it is helping the environment.
You might finally ask, if ethanol is more expensive, why isn’t gas without ethanol cheaper? Several years ago there were direct subsidies. Those are now mostly gone, but they have been replaced with the so called ethanol mandate. That means a certain number of gallons of ethanol must be blended into the nations gas. The required ethanol gallons are high enough that if someone sells gas without ethanol, they will also need to sell more E15 or E85 to meet the mandate, and most people don’t want to buy those fuels. So supply and demand means selling ethanol free gas (which is actually cheaper to make than E10) ends up carrying a marketing penalty to pay for the undesirable side effect that higher E0 sales must be accompanied by higher sales of unwanted E15 and E85 to meet the mandate.
Engine power is the same. The engine computer recognizes that energy content of the gas per gallon has dropped a bit and simply squirts a bit more fuel per pulse, which is why the mileage drops. But since a bit more fuel is being squirted, the energy content being squirted remains the same.
Most of the internet horror stories relate to the fact that if water is present, ethanol absorbs more of it than gas does. But in a practical sense, that has not proven to be a problem. The only condition under which there’s a smidgen more risk is for someone who stores his car over the winter. Even there, the difference is not night and day, it’s a small risk versus a slightly greater but still very small risk.
When I make these posts saying don’t waste your money or go out of your way to get ethanol free gas, I also point out for credibility that I don’t like ethanol in gas either. But my objection has nothing to do with performance, it’s simply economics. Ethanol is more expensive than gas, and requires some form of subsidy or forced use which costs us all. Contrary to what some on the pro-ethanol side believe, it does not offer significant environmental benefits. The only benefits are to corn farmers and ethanol plant owners in the form of dollars flowing their way. The great irony is that the ethanol boondoggle is one of the vanishingly few places where Republicans and Democrats cooperate. The Republicans do it to please their farm state voters, while the Democrats do it in the false belief that it is helping the environment.
You might finally ask, if ethanol is more expensive, why isn’t gas without ethanol cheaper? Several years ago there were direct subsidies. Those are now mostly gone, but they have been replaced with the so called ethanol mandate. That means a certain number of gallons of ethanol must be blended into the nations gas. The required ethanol gallons are high enough that if someone sells gas without ethanol, they will also need to sell more E15 or E85 to meet the mandate, and most people don’t want to buy those fuels. So supply and demand means selling ethanol free gas (which is actually cheaper to make than E10) ends up carrying a marketing penalty to pay for the undesirable side effect that higher E0 sales must be accompanied by higher sales of unwanted E15 and E85 to meet the mandate.
07-20-2021, 01:56 PM
#2
Le Mans Master
Member Since: Mar 2001
Location: Omaha
Posts: 6,614
Received 2,303 Likes
on
1,202 Posts
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
ALL US cars made since 2001 were designed to run on E10 (10% ethanol) from the factory. Running on non-ethanol may have given you a slight MPG gain as straight non-ethanol blend gas has more energy content (thus needing less gas to produce the same power), but it won't hurt the car any to switch to normal pump 93 (E10). Do not use E15 (15% ethanol blend) gas, however, as your car is not designed to run it. Ethanol has a higher octane rating than straight gasoline and it also runs cooler (both reasons why many of us with blower cars have them set up to run E85), however for E10 neither is really going to make much difference (they actually use a lower octane gas and the 10% ethanol to come up to 93 octane overall).
07-20-2021, 05:14 PM
#3
Drifting
The problem with conspiracy theories is that they are almost impossible to counter with reason and facts. If you have some specific reason for favoring ethanol free gas, I can almost certainly give you scientific evidence that it is internet misinformation. The biggest known issue with E10 versus E0 is that E10 gets slightly less mileage, about 1 to at most 2mpg. It is also somewhat corrosive to fuel systems in cars built prior to the 1990’s that did not have upgraded materials to counter the slight increase in corrosion. But for most issues, there is simply no consequential difference.
Engine power is the same. The engine computer recognizes that energy content of the gas per gallon has dropped a bit and simply squirts a bit more fuel per pulse, which is why the mileage drops. But since a bit more fuel is being squirted, the energy content being squirted remains the same.
Most of the internet horror stories relate to the fact that if water is present, ethanol absorbs more of it than gas does. But in a practical sense, that has not proven to be a problem. The only condition under which there’s a smidgen more risk is for someone who stores his car over the winter. Even there, the difference is not night and day, it’s a small risk versus a slightly greater but still very small risk.
When I make these posts saying don’t waste your money or go out of your way to get ethanol free gas, I also point out for credibility that I don’t like ethanol in gas either. But my objection has nothing to do with performance, it’s simply economics. Ethanol is more expensive than gas, and requires some form of subsidy or forced use which costs us all. Contrary to what some on the pro-ethanol side believe, it does not offer significant environmental benefits. The only benefits are to corn farmers and ethanol plant owners in the form of dollars flowing their way. The great irony is that the ethanol boondoggle is one of the vanishingly few places where Republicans and Democrats cooperate. The Republicans do it to please their farm state voters, while the Democrats do it in the false belief that it is helping the environment.
You might finally ask, if ethanol is more expensive, why isn’t gas without ethanol cheaper? Several years ago there were direct subsidies. Those are now mostly gone, but they have been replaced with the so called ethanol mandate. That means a certain number of gallons of ethanol must be blended into the nations gas. The required ethanol gallons are high enough that if someone sells gas without ethanol, they will also need to sell more E15 or E85 to meet the mandate, and most people don’t want to buy those fuels. So supply and demand means selling ethanol free gas (which is actually cheaper to make than E10) ends up carrying a marketing penalty to pay for the undesirable side effect that higher E0 sales must be accompanied by higher sales of unwanted E15 and E85 to meet the mandate.
Engine power is the same. The engine computer recognizes that energy content of the gas per gallon has dropped a bit and simply squirts a bit more fuel per pulse, which is why the mileage drops. But since a bit more fuel is being squirted, the energy content being squirted remains the same.
Most of the internet horror stories relate to the fact that if water is present, ethanol absorbs more of it than gas does. But in a practical sense, that has not proven to be a problem. The only condition under which there’s a smidgen more risk is for someone who stores his car over the winter. Even there, the difference is not night and day, it’s a small risk versus a slightly greater but still very small risk.
When I make these posts saying don’t waste your money or go out of your way to get ethanol free gas, I also point out for credibility that I don’t like ethanol in gas either. But my objection has nothing to do with performance, it’s simply economics. Ethanol is more expensive than gas, and requires some form of subsidy or forced use which costs us all. Contrary to what some on the pro-ethanol side believe, it does not offer significant environmental benefits. The only benefits are to corn farmers and ethanol plant owners in the form of dollars flowing their way. The great irony is that the ethanol boondoggle is one of the vanishingly few places where Republicans and Democrats cooperate. The Republicans do it to please their farm state voters, while the Democrats do it in the false belief that it is helping the environment.
You might finally ask, if ethanol is more expensive, why isn’t gas without ethanol cheaper? Several years ago there were direct subsidies. Those are now mostly gone, but they have been replaced with the so called ethanol mandate. That means a certain number of gallons of ethanol must be blended into the nations gas. The required ethanol gallons are high enough that if someone sells gas without ethanol, they will also need to sell more E15 or E85 to meet the mandate, and most people don’t want to buy those fuels. So supply and demand means selling ethanol free gas (which is actually cheaper to make than E10) ends up carrying a marketing penalty to pay for the undesirable side effect that higher E0 sales must be accompanied by higher sales of unwanted E15 and E85 to meet the mandate.
The following 6 users liked this post by LDB:
cgladish (07-23-2021),
dryadsdad (07-24-2021),
Geoff13IOM6GS (07-27-2021),
jrose7004 (07-25-2021),
sd45t2 (07-20-2021),
and 1 others liked this post.
07-20-2021, 05:48 PM
#4
Safety Car
^^^Nice post but you failed to mention the biggest drawback of E10.... which is why I have nothing but problems when running it in my hot rods and classics...
The vapor pressure of Ethanol is much lower than the vapor pressure of Gasoline. Therefore a critical vapor liquid ratio, which can cause vapor lock, will be reached at lower temperatures with Gasoline-Ethanol blends than with regular Gasoline.
Not much of an issue when running it in a C6. But it causes problems with most carburetorated engines.
The vapor pressure of Ethanol is much lower than the vapor pressure of Gasoline. Therefore a critical vapor liquid ratio, which can cause vapor lock, will be reached at lower temperatures with Gasoline-Ethanol blends than with regular Gasoline.
Not much of an issue when running it in a C6. But it causes problems with most carburetorated engines.
07-20-2021, 06:16 PM
#5
Drifting
^^^Nice post but you failed to mention the biggest drawback of E10.... which is why I have nothing but problems when running it in my hot rods and classics...
The vapor pressure of Ethanol is much lower than the vapor pressure of Gasoline. Therefore a critical vapor liquid ratio, which can cause vapor lock, will be reached at lower temperatures with Gasoline-Ethanol blends than with regular Gasoline.
Not much of an issue when running it in a C6. But it causes problems with most carburetorated engines.
The vapor pressure of Ethanol is much lower than the vapor pressure of Gasoline. Therefore a critical vapor liquid ratio, which can cause vapor lock, will be reached at lower temperatures with Gasoline-Ethanol blends than with regular Gasoline.
Not much of an issue when running it in a C6. But it causes problems with most carburetorated engines.
As for your vapor lock input, I don’t have enough experience with ethanol in carbureted cars to comment intelligently. But assuming you are correct (and I have no reason to think you aren’t), it wouldn’t apply to a fuel injected car, which means essentially all cars built since the 1990’s.
The following users liked this post:
JJLovell (07-23-2021)
07-20-2021, 06:36 PM
#6
Safety Car
I think the main issue is one of principles. The forced addition of ethanol which is an industry that cannot produce profits on its own without massive subsidies based on a false premise of carbon dioxide caused climate change and the burning of this ethanol that supposedly pollutes less is for me the main issue.
But I will gladly burn E85 in my car for a nice HP/TQ increase.
07-21-2021, 05:43 AM
#7
Burning Brakes
......Engine power is the same. The engine computer recognizes that energy content of the gas per gallon has dropped a bit and simply squirts a bit more fuel per pulse, which is why the mileage drops. But since a bit more fuel is being squirted, the energy content being squirted remains the same........
A flex fuel enabled car has a sensor to measure the alcohol content which it sends to the ECM. The ECM uses a different fueling table.
How does "The engine computer recognizes that energy content of the gas per gallon has dropped a bit" happen? What measures that?
07-21-2021, 07:53 AM
#8
Le Mans Master
Member Since: Mar 2001
Location: Omaha
Posts: 6,614
Received 2,303 Likes
on
1,202 Posts
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
If I remember correctly, there are tables in the ECM for both short and long term fuel adjustments. These adjust how much fuel is used based on the A/F the ECM sees. Combined with the knock sensors, and the ability to advance/retard timing, this will let the ECM have a pretty significant capability to adjust for various fuels. You could for example, even run 87 octane in an emergency and the ECM would adjust for it (although I personally wouldn’t hammer on it while doing so).
07-21-2021, 07:59 AM
#9
^^^Nice post but you failed to mention the biggest drawback of E10.... which is why I have nothing but problems when running it in my hot rods and classics...
The vapor pressure of Ethanol is much lower than the vapor pressure of Gasoline. Therefore a critical vapor liquid ratio, which can cause vapor lock, will be reached at lower temperatures with Gasoline-Ethanol blends than with regular Gasoline.
Not much of an issue when running it in a C6. But it causes problems with most carburetorated engines.
The vapor pressure of Ethanol is much lower than the vapor pressure of Gasoline. Therefore a critical vapor liquid ratio, which can cause vapor lock, will be reached at lower temperatures with Gasoline-Ethanol blends than with regular Gasoline.
Not much of an issue when running it in a C6. But it causes problems with most carburetorated engines.
As for your vapor lock input, I don’t have enough experience with ethanol in carbureted cars to comment intelligently. But assuming you are correct (and I have no reason to think you aren’t), it wouldn’t apply to a fuel injected car, which means essentially all cars built since the 1990’s.
Carbureted cars also most often suck the gasoline from the tank using a fuel pump in the engine compartment so you have negative pressure in most of the fuel line, where FI cars almost always have fuel pumps in the tank.
.
Last edited by dmk0210; 07-21-2021 at 08:07 AM.
07-21-2021, 10:39 AM
#10
Drifting
I would be interested to hear how that is accomplished.
A flex fuel enabled car has a sensor to measure the alcohol content which it sends to the ECM. The ECM uses a different fueling table.
How does "The engine computer recognizes that energy content of the gas per gallon has dropped a bit" happen? What measures that?
A flex fuel enabled car has a sensor to measure the alcohol content which it sends to the ECM. The ECM uses a different fueling table.
How does "The engine computer recognizes that energy content of the gas per gallon has dropped a bit" happen? What measures that?
If I remember correctly, there are tables in the ECM for both short and long term fuel adjustments. These adjust how much fuel is used based on the A/F the ECM sees. Combined with the knock sensors, and the ability to advance/retard timing, this will let the ECM have a pretty significant capability to adjust for various fuels. You could for example, even run 87 octane in an emergency and the ECM would adjust for it (although I personally wouldn’t hammer on it while doing so).
Let’s start with the simplifying assumptions that the engine is hot, the O2 sensors are working properly, and the proper fuel trim has been calculated. If those conditions are met, there will be a smidgen of excess O2 in exhaust gas. You then stop for gas and switch from E0 to E10. When you start driving again, since ethanol doesn’t have as much energy content and thus doesn’t use as much O2 to burn per gallon, more than the usual smidgen of excess O2 will show up in exhaust gas, and that is sensed by the O2 sensors. The ECM will then increase the fuel trim which causes a bit more fuel to be squirted to use up that excess O2. If you go the other way, from E10 to E0, it will cause the excess O2 in exhaust gas to go from the proper “smidgen” to zero, the O2 sensors will see that, and the ECM will decrease fuel trim until the proper smidgen of excess O2 again shows up in exhaust gas. Things get messier in cold starts, at high power settings, or with malfunctions of various sensors, but that’s another discussion which I’ll ignore here.
Flex fuel ECM’s have both a gasoline and an E85 table. Early flex fuel vehicles did not have sensors to measure ethanol content in the fuel. The mechanism in the prior paragraph is capable of resetting fuel flow all the way from E0 to E85 without ever having direct measurement of ethanol content. It can do that by inferring the ethanol content from the A/F ratio required to give the proper “smidgen” of excess O2 in exhaust gas as in the prior paragraph. That allows it both to interpolate between its gasoline and E85 tables, and to fine tune things once it has itself in the right ballpark on ethanol content. Trouble is, it can take a minute or two to settle down after the big swings caused by such a large ethanol change, and operation can be rough during that period. Thus to aid in the first minute or two after a fuel switch, most flex fuel vehicles now have a direct sensor for ethanol content of the fuel. That sensor commands an immediate shift in the ratio of gasoline table and E85 table after a fuel switch, but the route in the prior paragraph still does the fine tuning. When the biggest swing is from E0 to E10 like in a normal vehicle, the prior paragraph can take care of things fast enough, so the direct ethanol sensor is not needed.
Last edited by LDB; 07-21-2021 at 10:44 AM.
07-22-2021, 03:42 AM
#11
Short version, the compression on the LS3 was dropped down (from the LS2) to run its best fuel at least 91 octane.
The ls2/ls7 with its higher compression, runs is best of on at least octane of 93 isntead.
Note, higher that stated octane on these motors will not increase HP, and if the octane rating is too high than needed, will decrease HP instead.
As for E10, lowers the emissions of the motor, but also reduces fuel mileage as well.
Hence car on E85, instead of run on petrol, will burn 30% more fuel for the same gas mileage.
As for ethanol, does collect water over time, and if left in the system long enough to separate from the petrol (think car in storage), can cause problems in the fuel system as well.
So really, we can say all we want on how the ethanol in the fuel is helping to lower emissions from the car, but is really goes back to the surplus of corn crop/it's falling prices that got the ball rolling on ethanol as fuel/HFCS to replace natural sugar's to help stabilize corn crop falling prices instead.
The ls2/ls7 with its higher compression, runs is best of on at least octane of 93 isntead.
Note, higher that stated octane on these motors will not increase HP, and if the octane rating is too high than needed, will decrease HP instead.
As for E10, lowers the emissions of the motor, but also reduces fuel mileage as well.
Hence car on E85, instead of run on petrol, will burn 30% more fuel for the same gas mileage.
As for ethanol, does collect water over time, and if left in the system long enough to separate from the petrol (think car in storage), can cause problems in the fuel system as well.
So really, we can say all we want on how the ethanol in the fuel is helping to lower emissions from the car, but is really goes back to the surplus of corn crop/it's falling prices that got the ball rolling on ethanol as fuel/HFCS to replace natural sugar's to help stabilize corn crop falling prices instead.
07-23-2021, 06:05 AM
#12
Advanced
If you drive your beauty often no issue with e10 however if you do not get to then there is the issue. E10 will begin phase separation within 60 days where ethanol free will take about two years to turn to varnish. Certainly some of you have boats and use a fuel stabilizer to prevent some of these issues. Octane is also lost in the process with the fuel absorbing moisture from the air. Performance with 93 e10 is great unless your car is a garage queen like so many typically have become. The reason ethanol free is so much more costly is because the ethanol is subsidized by the government for the farmers to grow the corn. Ethanol free gas os the worst thing that has ever happened to internal combustion engine for creating issues. Definitely more with carburetors but also can with fuel injected engines. Sure the systems can handle a small amount of water in fuel but water does not combust so enough in the cylinders can bend rods and all kinds of other issues but it would take a lot and at a higher rpm to do so.
07-23-2021, 09:05 AM
#13
Le Mans Master
Member Since: Mar 2001
Location: Omaha
Posts: 6,614
Received 2,303 Likes
on
1,202 Posts
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
Phase separation doesn't happen as fast as the critics like to believe, a lot of that comes from additive companies trying to sell you stabilizer products (which don't actually do anything about phase separation anyway). The NREL (National Renewable Energy Laboratory) did a research study on this back in 2016 and found that in a really hot & humid environment (the worst case, something similar to Houston or Orlando), it took at least 3 months for phase separation to occur on E10 in a small tank (i.e. lawn mower), a bigger tank is going to be much longer.
And here's the conclusion from a chemical engineer doing a study for the EPA:
Additionally, I've actually seen some boating sites that believe E10 fuels are better than non-ethanol gas as the E10 blend will keep low levels of water moving through the system instead of letting it build up in the tank.
Here's one final quote:
And here's the conclusion from a chemical engineer doing a study for the EPA:
Water phase separation in any gasoline is most likely to occur when liquid water comes in contact with the fuel. (Water in the form of moisture in the air will generally not cause phase separation.) Water which is in solution with gasoline is not a problem in any engine, but as a separate phase it can prevent an engine from running or even cause damage. Since oxygenated gasolines, however, can hold more water than conventional gasoline, phase separation is less likely to occur with oxygenates present.
Here's one final quote:
Water absorption: No doubt that ethanol emulsifies and holds water. Yay!! That’s a good thing! In fact, “holding” / suspending /emulsifying water is an ethanol ASSET — not a detriment — as gas tanks actually run dryer after the transition from E0 to E10. Mercury Marine — the boat engine manufacturer — states this fact. Specifically, with regard to moisture, a gallon of ethanol suspends FOUR (4) TEASPOONS of water per gallon of fuel before phase separation. On the other hand, gasoline suspends only POINT ONE FIVE (.15) TEASPOON (that’s LESS than ONE teaspoon) of water per gallon before phase separation. So PHASE SEPARATION WILL OCCUR 26 TIMES MORE RAPIDLY WITH GASOLINE THAN WITH ETHANOL! This has been demonstrated hundreds of times (including one demonstration I recently saw by Dr. Andrew Randolph, technical director of Earnhardt-Childress Racing), clearly substantiating that gasoline does NOT effectively hold (suspend) water. So with straight gasoline, whatever water is in any tank or atmosphere “phase separates” and falls to the bottom of the tank. In contrast in ethanol-blended fuel, the ethanol will suspend that water during the driving of the vehicle; then, harmlessly carry it through the system to be vaporized by the engine without affecting the engine in the least. The suspended water, vaporized by the engine, produces NO harmful emissions. And one more point: at 70 degrees Fahrenheit and 70 percent relative humidity, it takes more than two months for even gasoline to absorb water. Since ethanol has 26 times the suspension capability of gasoline, it would take literally months and months before any phase separation could possibly take place. I can state categorically that I own a Classic 1980 Limited Edition Weissach Porsche 911 and have driven it three times in the past three years … to buy fresh gas. I start this vehicle (about every three months) and let it run for no less than ½ hour to circulate the E10 gas.
The following users liked this post:
LDB (07-23-2021)
07-23-2021, 01:34 PM
#14
Drifting
I agree with EvanZR1’s post #13. It’s pretty easy to dream up some bench scale test to illustrate some dire risk which some additive or other product will cure. But frequently, if not usually, the “huge risk” shown in the lab test doesn’t actually occur in the real world because some aspect of the real world does not match the conditions in the lab test. So when you hear internet lore about some huge risk, you ought to ask yourself some reality check questions. If the problem is really so big, why is it only known to a few internet bloggers, and why aren’t the auto companies screaming about crappy E10 gas driving up their warranty costs? Yeah, yeah, conspiracy XYZ means that somehow, somebody is kicking back money under the table to screw the little guy. Riiiiiiight.
Even internet testimonials that initially sound sensible turn out to have easy explanations. My favorite such example relating to E10 is that a guy’s boat which had an old 327 Chevy inboard engine ran slower on E10, which in his mind proved that E10 was less powerful and probably harmed the engine. In reality, his engine had a fixed jet carburetor with no O2 sensors to see and correct for the lower energy content of the E10. So when the guy put E10 in his boat, since the carb was fixed jetted for E0, it ran lean on E10. Guess what? Running lean loses power, and the boat runs slower. No mystery. Easy solution, rejet the carb for E10. But that example is utterly and totally irrelevant to a modern car, since as described in post #10, the fuel injection system adjusts for that automatically.
Even internet testimonials that initially sound sensible turn out to have easy explanations. My favorite such example relating to E10 is that a guy’s boat which had an old 327 Chevy inboard engine ran slower on E10, which in his mind proved that E10 was less powerful and probably harmed the engine. In reality, his engine had a fixed jet carburetor with no O2 sensors to see and correct for the lower energy content of the E10. So when the guy put E10 in his boat, since the carb was fixed jetted for E0, it ran lean on E10. Guess what? Running lean loses power, and the boat runs slower. No mystery. Easy solution, rejet the carb for E10. But that example is utterly and totally irrelevant to a modern car, since as described in post #10, the fuel injection system adjusts for that automatically.
07-23-2021, 07:47 PM
#15
Racer
I just got back from a 5,000 round trip adventure with my 2006 convertible. I tried 89, 91 and 93 octane. What I learned is that I got better mileage on 91 octane. The car seemed happier too.