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Old 06-30-2022, 09:23 AM
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Originally Posted by w72 View Post
I should be able to tune for pump gas no problem. The combo I'm running has been scienced to the moon and back by people way smarter than me, and was assembled by a well-respected pro. I plan to run 93 non ethanol whenever possible. It won't need octane booster or race gas.

My question is if the good stuff is unavailable, will I be better off with 91 non-ethanol or 93 with ethanol?
My take on it is that I go for the octane rating and don't worry about the ethanol content. I've never noticed any real difference between ethanol and non ethanol gas as far as drivability. And since non ethanol fuel is about non existent where I live now, I've been using 10-15% ethanol fuel in the cars for a couple decades now with no ill affects. Now if it were higher in the 30% plus range I might be looking at other options.

If you have both easily available to you, you could switch back and forth to see for yourself.

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Old 06-30-2022, 09:47 AM
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Originally Posted by Formulajones View Post
... I've never noticed any real difference between ethanol and non ethanol gas as far as drivability ...
I will chime in on that last post;
Not to argue, or anything of the sort, but to just offer an opposing first hand opinion.

my car:
- engine rebuilt in 1998 (un-needed - because I was a kid, and wanted to do it!?!)
- YZ 400 (0.040 over)
- stock heads, only light cleaning - no port work
- 744 cam installed (installed because what I thought was the stock cam seemed really mild, so I wanted to upgrade to the one step bigger pre-1970 RAIII-MT cam)
- 7041264 carb (it was the best I could find at the time)

When I first learned of the "higher octane" ethanol blended fuel around here, I gave it a try;
I was nearing empty, and put in 1/2 or maybe 3/4 of a tank (because that's all this broke kid could afford).
My car ran like absolute turd with it.
It barely kept an idle, and was just generally unhappy.

So please mark me down as someone who definately could tell the difference when running ethanol blended, vs conventional premium unleaded gas.

It ran so bad that my cousin felt bad for me, and shared some of his av gas;
I topped up the tank with his av gas, and you could quite literally hear when the av gas mixture made it to the carb;
The idle smoothed out unlike I had ever heard it run.

Since that time, I have stayed away from Ethanol blends - if possible.
(I will add that it is possible that the ethanol blending has gotten better since 1999.)

It is probably easy enough to adjust the carburetor to run a bit richer for the ethanol, but at that time, I could not do that, and couldn't afford to pay a professional to fiddle with carb settings (I actually looked into it).

I live at, and mostly drove my car at an elevation between 2966-3435ft.

I had people time and again tell me that there was no way I could run my engine on pump gas - which is a factor of why I have been following this discussion.

When I got my car in 1995 it was 0.030 over, had a tiny "A" cam (which I still have in a box by the way), the engine was topped off with a crappy smog era Chev carb, and was driven in an area with an elevation of 764ft.

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1970 Formula 400
Carousel Red paint on Black standard interior
A no-engine, no-transmission, no-wheel option car.
Quite likely one of few '70 Muncie three speed Formula 400's left.


1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing)
2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs)

Last edited by unruhjonny; 06-30-2022 at 10:03 AM.
  #43  
Old 06-30-2022, 01:05 PM
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If folks tuned their engines ( along with altitude, temp, usage at their location) by BTU, instead on Octane, a real feeling for whats going on inside would make tuning more accurate if you are going for details.
Octane, like Cetane, is a Flame Retardant. This " Can" , with dense fuel , make more power.
Alcohol has a higher Octane, but its a puke on BTU, much less power. So in modern fuel with Alcohol it can be misleading when compared to Suncoast 260 of the past.
Octane doesn't always mean better, or more power in the case of Ethanol.

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  #44  
Old 06-30-2022, 01:12 PM
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Tuning with an air/fuel ratio meter is tuning by BTUs or energy content of the gas you are using.

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Old 06-30-2022, 01:15 PM
78w72 78w72 is offline
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Originally Posted by Formulabruce View Post
If folks tuned their engines ( along with altitude, temp, usage at their location) by BTU, instead on Octane, a real feeling for whats going on inside would make tuning more accurate if you are going for details.
Octane, like Cetane, is a Flame Retardant. This " Can" , with dense fuel , make more power.
Alcohol has a higher Octane, but its a puke on BTU, much less power. So in modern fuel with Alcohol it can be misleading when compared to Suncoast 260 of the past.
Octane doesn't always mean better, or more power in the case of Ethanol.
thats very true. but what happens when you increase the volume of ethanol to compensate for the lower BTU? i have never had an engine set up for that but i know some people that do & most say ethanol has some benefits like cooler & cleaner burning etc. for high compression or turbo/forced induction engines the higher octane E85 is what lots of guys use. plus its cheaper than any comparable octane fuel.

as you mentioned, i have never really noticed a difference in 91 straight gas vs 93 with 10%E in 3 different pontiac engine cars, the higher HP one at the drag strip or driving any of them around town. i try to stick with straight 91 but will get the 89 or 93 ethanol if its cheaper.

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  #46  
Old 06-30-2022, 01:36 PM
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Originally Posted by unruhjonny View Post
I will chime in on that last post;
Not to argue, or anything of the sort, but to just offer an opposing first hand opinion.

my car:
- engine rebuilt in 1998 (un-needed - because I was a kid, and wanted to do it!?!)
- YZ 400 (0.040 over)
- stock heads, only light cleaning - no port work
- 744 cam installed (installed because what I thought was the stock cam seemed really mild, so I wanted to upgrade to the one step bigger pre-1970 RAIII-MT cam)
- 7041264 carb (it was the best I could find at the time)

When I first learned of the "higher octane" ethanol blended fuel around here, I gave it a try;
I was nearing empty, and put in 1/2 or maybe 3/4 of a tank (because that's all this broke kid could afford).
My car ran like absolute turd with it.
It barely kept an idle, and was just generally unhappy.

So please mark me down as someone who definately could tell the difference when running ethanol blended, vs conventional premium unleaded gas.

It ran so bad that my cousin felt bad for me, and shared some of his av gas;
I topped up the tank with his av gas, and you could quite literally hear when the av gas mixture made it to the carb;
The idle smoothed out unlike I had ever heard it run.

Since that time, I have stayed away from Ethanol blends - if possible.
(I will add that it is possible that the ethanol blending has gotten better since 1999.)

It is probably easy enough to adjust the carburetor to run a bit richer for the ethanol, but at that time, I could not do that, and couldn't afford to pay a professional to fiddle with carb settings (I actually looked into it).

I live at, and mostly drove my car at an elevation between 2966-3435ft.

I had people time and again tell me that there was no way I could run my engine on pump gas - which is a factor of why I have been following this discussion.

When I got my car in 1995 it was 0.030 over, had a tiny "A" cam (which I still have in a box by the way), the engine was topped off with a crappy smog era Chev carb, and was driven in an area with an elevation of 764ft.
Most likely it was running too lean to begin with and ethanol exaggerated that problem.

One thing you have to do with ethanol, even just 10% blend, is richen the idle circuit. More than just adjusting screws, usually requires going in and opening the idle restrictions.
Never a problem for me because I was never one to try and run a super duper lean idle on any of the cars anyway even when I was running real gas. I always shoot for best drivability in all conditions and that generally ends up with a mid 13's AFR for idle conditions. Especially anything with a decent camshaft in it, it's just going to require more idle fuel anyway.

People have to keep in mind stoich for real gas is 14.7 10% ethanol is 14. I've had cars come in here where people have leaned out the idle circuit to the extreme looking for gas mileage only to find out that doesn't work too well when you start throwing ethanol in the mix.

It's all in the tune up. None of it makes a difference if the car is setup properly. I use it at sea level and 6000 feet, daily drive them, and we drag race with it. Not just one car, but several. No issues to report.

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Last edited by Formulajones; 06-30-2022 at 01:48 PM.
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  #47  
Old 06-30-2022, 01:47 PM
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For sure ethanol has properties that allow an engine to make more power without detonating, when tuned for it. Higher detonation resistance, and an extra cooling property that helps prevent heat buildup. On a Buick turbo V6, we can run some absolutely insane boost on E85, but it requires as much as 50% more fueling than with regular gas. That's a pretty dramatic increase. We also have the benefit of an ECU that can run different injection and ignition tables depending on what fuel is in the tank. None of that is easily achievable on a Pontiac V8.

Right now, you'll find blends with up to 15% ethanol at the pump, though 10% is most common. The biggest issue with that is the swelling it'll cause on some seals and floats if they're not ethanol-tolerant. If the carb is tuned right, it shouldn't affect idle quality enough to be noticeable.

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Old 06-30-2022, 05:32 PM
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Boost for sure works well with E85.

I had a couple friends about 15 years back that was building N/A engines using E85. Knowing that was the fuel to be used these engines were purposely built with a lot of compression. I think they were 12:1 or a little more if I remember correctly, pretty radical camshafts, carbs setup for E85 and ran strictly an E85 diet.

They ran extremely strong but the problem was E85 availability. It wasn't everywhere then and it's still not everywhere now. That really limited the distance these cars could travel and basically remained around the town where the E85 pumps were, because regular pump gas for these engines at that point wasn't an option anymore.

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Old 06-30-2022, 05:42 PM
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Originally Posted by GoreMaker View Post
. If the carb is tuned right, it shouldn't affect idle quality enough to be noticeable.
Yep, In the grand scheme of things 10% really isn't all that much anyway.

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  #50  
Old 06-30-2022, 06:11 PM
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Originally Posted by Formulajones View Post
Most likely it was running too lean to begin with and ethanol exaggerated that problem.

...
That's possible, and I did try to touch on it.

But as I also mentioned, back then I wouldn't have known what needed to be done to actually richen it up at all.

I don't think that the 1971 Quadrajet would have been what we might consider lean - and that carb was bone stock jetting ect.

I will say that it made for some fun "testing" with my cousin and his '71 TA;
Him: bone stock, all correct; TH400 w/3.08:1(?)
Me: as mentioned with a slight mismatch of an M22 in front of 3.55:1 gears
I had him out of the hole pretty good, but somewhere down the road, he reeled me in, probably on the merits of having taller gears.

My real take away from the ethanol blended gas (other than it being terrible for these older engines) is how shockingly smooth my car ran with 100+ octane leaded fuel - I had never heard it idle so smooth and quiet before, or since.

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1970 Formula 400
Carousel Red paint on Black standard interior
A no-engine, no-transmission, no-wheel option car.
Quite likely one of few '70 Muncie three speed Formula 400's left.


1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing)
2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs)
  #51  
Old 06-30-2022, 06:14 PM
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[QUOTE=GoreMaker;6353234]For sure ethanol has properties that allow an engine to make more power without detonating, when tuned for it. Higher detonation resistance, and an extra cooling property that helps prevent heat buildup. On a Buick turbo V6, we can run some absolutely insane boost on E85, but it requires as much as 50% more fueling than with regular gas. That's a pretty dramatic increase. We also have the benefit of an ECU that can run different injection and ignition tables depending on what fuel is in the tank. None of that is easily achievable on a Pontiac V8."
It's not easy, but it can be done. I'm happy to be able to mix E85 and regular unleaded with gas prices through the roof...

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Old 06-30-2022, 07:32 PM
TRADERMIKE 2012 TRADERMIKE 2012 is offline
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Quote:
Originally Posted by 78w72 View Post
thats very true. but what happens when you increase the volume of ethanol to compensate for the lower BTU? i have never had an engine set up for that but i know some people that do & most say ethanol has some benefits like cooler & cleaner burning etc. for high compression or turbo/forced induction engines the higher octane E85 is what lots of guys use. plus its cheaper than any comparable octane fuel.

as you mentioned, i have never really noticed a difference in 91 straight gas vs 93 with 10%E in 3 different pontiac engine cars, the higher HP one at the drag strip or driving any of them around town. i try to stick with straight 91 but will get the 89 or 93 ethanol if its cheaper.
Mikes Reply:

Living in south Florida on a cool night in the winter the 1967 428 HO loves the higher 93 octane with 10 % Alcohol but the next day it is 90 degrees and the Alcohol takes affect and starts vapor lock issues. Then I have to go to the Rec- 89-90 fuel, less Alcohol.


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Old 06-30-2022, 07:57 PM
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Yep, In the grand scheme of things 10% really isn't all that much anyway.
Mikes Reply:

10% Alcohol in the fuel is all the difference in the world in my case, any Alcohol in my fuel on a hot day will cause my engine to vapor lock.

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Old 06-30-2022, 08:41 PM
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I live 350ft above sea level, hoping to have no issues anywhere east of the Rocky Mtns. If I do head out west with the car, it should be easy to reprogram the Sniper to compensate. I can usually get 93 non-ethanol at a local gas station, but sometimes they get a truck of 91. At least they re-label the pump when that happens, pretty much everyone in Memphis with a cool car fuels up there.
Mikes Reply:

I was at MSU in 1976-77 on a Gymnastics scholarship, in the summer it got really humid. When I was there an earthquake tremor occurred, while I was in the dorm, I could see the water in the water pitcher moving. Later, I was told that the railroad track was built on a nice flat ground that turned out to be a fault line.

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Old 07-01-2022, 02:09 AM
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Mike, I live a half mile from that same train track. It's an unspoken rule in Memphis that we never discuss the fault line, and if we accidentally think about, we drink till we forget about it.

  #56  
Old 07-01-2022, 02:23 AM
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You have not been through a earthquake until you see chunks of firewood bouncing 4" in the air and flipping over in your backyard. I was at work one time when we had three 7.2s in one day. The chain on the green chain was clacking, catching a little air when the first one hit. That night there was a light post outside my bedroom window. You seen it, then you did not see it, over and over.
Makes you feel like a insect.

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Old 07-01-2022, 04:04 AM
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[QUOTE=Scott65;6353303]
Quote:
Originally Posted by GoreMaker View Post
For sure ethanol has properties that allow an engine to make more power without detonating, when tuned for it. Higher detonation resistance, and an extra cooling property that helps prevent heat buildup. On a Buick turbo V6, we can run some absolutely insane boost on E85, but it requires as much as 50% more fueling than with regular gas. That's a pretty dramatic increase. We also have the benefit of an ECU that can run different injection and ignition tables depending on what fuel is in the tank. None of that is easily achievable on a Pontiac V8."
It's not easy, but it can be done. I'm happy to be able to mix E85 and regular unleaded with gas prices through the roof...
The price IS deceiving. Ethanol has just POOR fuel economy. Engines work harder to do the same work, which means more rpms, and more heat ( in a street engine). Also consider that its subsidized by the taxpayers, so while it may seem cheaper, it just may not be.... Look at a EPA sticker on a new car. Cruising ranges are listed with E10 and then E85... Its a real eye opener. Almost has "Range anxiety"

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  #58  
Old 07-01-2022, 08:02 AM
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FYI - There are no federal subsidies or tax incentives for ethanol. There are federal mandates for required volume of renewable fuels which does force the oil companies to use ethanol since it seems to be the best solution.

There are long standing tax incentives for petroleum production which to some degree does affect taxes or the national debt and inflation.


Last edited by Nobuddy; 07-01-2022 at 08:02 AM. Reason: X
  #59  
Old 07-01-2022, 08:08 AM
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There's farm subsidies for growing corn that gets used for ethanol. From research over the years, ethanol corn wouldn't be profitable to grow without those subsidies. So because of those subsidies (which are entirely funded through taxes) farmers grow that instead of actual food.

But that's neither here nor there. That's a completely different discussion.

As far as E85 giving worse mileage, that's entirely true. If you're injecting 35 to 50% more fuel, then you'll get 35 to 50% worse mileage. In the turbo V6 community, we usually do it for racing purposes, then we switch back to regular fuel for street driving. Basically the same way some people will run AVgas for a day of drag racing

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Old 07-01-2022, 08:10 AM
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[QUOTE=Formulabruce;6353396]
Quote:
Originally Posted by Scott65 View Post

The price IS deceiving. Ethanol has just POOR fuel economy. Engines work harder to do the same work, which means more rpms, and more heat ( in a street engine). Also consider that its subsidized by the taxpayers, so while it may seem cheaper, it just may not be.... Look at a EPA sticker on a new car. Cruising ranges are listed with E10 and then E85... Its a real eye opener. Almost has "Range anxiety"
Yep, stoich for E85 is 9.7:1 so it's an extremely rich mixture, plus it takes a fair amount of compression to take advantage of it, which new cars really don't have enough of anyway making them even less efficient on that stuff.

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