Surprised at Gasahol Result

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nm9stheham

nm9stheham

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My son and I had a surprising experience with some 'up to 10%' gasahol today. We have been running his new 340 around in the last few weeks, and using nothing but non-alcohol 93 octane fuel from a local no-name chain. Their pumps were out today, so we put in 5 gallons of Shell 93 octane gasahol with up to 10% alcohol. We drive 1.5 blocks and stopped for a red light, and looked at each other and said "Is this thing idling smoother?" We drove on home 5 miles up a 1000' foot climb, from 55-60 mph straights to a 30-40 mph twisty section, and commented at each phase how smoother the motor felt and sounded. Pulling into the driveway, I hopped out while it was idling in gear to listen to the exhaust note, and darned if it did not sound more even. (We have been tweaking on this thing for a few weeks so are really tuned into the sounds....)

FYI this 340 has 10:1 SCR, AL Edelbrock heads and intake, Crane Z-268 cam, and Spitfire headers. All I and figure is that the fuel volatility is better and making it fill and run more evenly, or the alcohol is effecting the combustion process. I expect this engine to be somewhat sensitive to fuel but this is something I have never seen. (The only more dramatic change I've experienced in my time was a load of really bad gas!)

If anyone has any other ideas why, I'd like to hear them and learn. I read this thread to glean the comments there:
http://www.forabodiesonly.com/mopar/showthread.php?t=327846&highlight=alcohol
 
Before I read the other thread, I would take a stabbing guess at the engines actual need for the gas you have been using. The cams timing events and the use of aluminum on a stated 10-1'engine may very well NOT need 93 octane by may actually get away with 89. Or less.
 
Yes, agreed; we just started out high to be safe while we dial things in. We have to work out advance and a lot of other bugs yet (some leftovers from the PO, some are new things).
 
Some actual testing that has been done on fuel has shown the alcohol content to usually be closer to 5% than 10%. The octain will still be 93 no mater 100% gas or a mix. Maybe the shell fuel was just better than the pump with 100% no name gas!!
 
The BIG issue I have with alky in gas is

the politics of it, that is, it doesn't seem to financially stand on it's own

and the "engine" industry, that is people manufacturing fuel handing products have not stepped up and designed compatible systems. This stuff has been used for HOW LONG now? Fuel systems of everything from chain saws, lawn mowers, to anything on a hot rod should by now be compatible, unless you have some fuel hose made in 1965 LOL
 
Just a thought, you've tuned to supposed pure 93 no alcohol. My thought is maybe, due to more alcohol required to produce the same btu's, that maybe your tune is a little "fat" with the pure gas and the blend is leaning it out a tad more? Just a guess. Or as stated the 93 pure isn't really 93.
 
Alcohol leans out A.F.R,in comparison to pump fuel. Depending on your pump gas blend,doesn't surprise me at all. My shop teacher( ex' S/S racer) 's quote: "lean is mean..."
 
EL5DEMON340 said:
Some actual testing that has been done on fuel has shown the alcohol content to usually be closer to 5% than 10%. The octain will still be 93 no mater 100% gas or a mix. Maybe the shell fuel was just better than the pump with 100% no name gas!!
Click to expand...

Our 'gasoline' is a mix of refined petroleum and other related fuels even when there is no eth added. Agree the Shell fuel might be better due to any number of things. Agree that the alcohol content is an unknown. Disagree that the R+M/2 octane will be the same when eth is added to the mix. Eth can raise the octane although obviously there are other ways to do it. When I was upstate NY all of the stations with an eth free option - its 91. Had to get premium with eth to get the 93. My undertanding is that the eth is mixed in close to the final distribution point. And I suspect most of the eth free is a result of not mixing it in.

Because of its vapor pressure and boiling point, I suspect that ethanol mostly effects the 'front end' of the gasoline and the Reid Vapor Pressure. Fuel companies are allowed to supply higher RVP gasoline in the winter months. Have that winter fuel in a carb on a hot day and its miserable because the easy to light portion is evaporating before it gets to the cylinders. I've got a datalog showing that.

The Shell fuel also might have an overall better fuel curve than the other gasoline for our engines. Most pump fuels today have components that require a lot more heat to ignite than the fuel of 1970 (or race fuel and av gas). These effect how the burn completes.

Some info on Summer RVP and fuel composition for the 48 states
http://www.eia.gov/todayinenergy/detail.cfm?id=11031

Interesting discussion on pump fuel specific gravity etc
http://speedtalk.com/forum/viewtopic.php?f=1&t=33517
 
There is little if any ethanol in fuel now. Gasoline price is low and adding more expensive ethanol cuts profit per gal of the distributor.
 
Thanks for the responses. My favorite reason is to think that the fuel volatility is better with the Shell fuel; the improved evenness of the cylinder firing is what makes me tend to think that. But it could be that the combustion speed is a bit different too. Whether due to actual alcohol, or to a different blending, I have no way to know at this point. We'll see if it starts and idles cool any differently this AM.

If fuel volatility is the reason, it may suggest that this engine would be better off wit a 195 t'stat. The all AL top end gets the heat out faster in the whole intake tract, and there is no heat crossover.

Either way, it may pay to try some different fuels in your area.
 
mderoy340 said:
There is little if any ethanol in fuel now. Gasoline price is low and adding more expensive ethanol cuts profit per gal of the distributor.
Click to expand...

But... In some places (like the insane state I live in) at least 5% ethanol in all gas is mandated by law.
 
10 percent ethanol in our state, MN, but you can buy BP 92 without ethanol for small engines and old cars.
 
Maybe the ethanol dispersed some water that was in your fuel tank. That would help a lot if water was the issue.
 
Fuel volatility is described as a distillation curve. Its not too hard to find info for race fuels and av gas. Pump fuel is harder of course, and its a moving target as its blended differently for different climates, regulations, and economics.

Here's an illustration of the volatility of some gasolines. Race Fuels are 260 GT (Sunoco), Vintage and C9 (VP). Notice how flat they are. 100LL is low lead Av Gas. The others are pump fuels mostly from tests done when oxygenated fuels were being pushed as a way to improve fuel economy. My recollection is that A & L are not fuel you and I could buy, but special formulation for testing and I included them on the graph to show the range possible.

GT is oxygenated (3.7%) and has 9.8% ethanol. The other two race fuels shown are not oxygenated or any eth.
Fuels A & L are from study called CRC-E67. A was the baseline, L was oxygenated to 3% and 10 % eth.
Tier 2 EEE is from tested sample used in the ACE Optimal Blend Study 2007
 

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My car runs messed up at idle and tries to stall if I get a high ethanol fuel. after checking my AFR it was going lean. I'd guess you are tuned on the rich side.
 
magnumdart said:
Maybe the ethanol dispersed some water that was in your fuel tank. That would help a lot if water was the issue.
Click to expand...
A good thought there.... but we pulled and dumped the fuel in the tank about 5 weeks ago just before initial fire up of the new engine, and have been putting fresh fuel in it every few days.
 
roccodart440 said:
My car runs messed up at idle and tries to stall if I get a high ethanol fuel. after checking my AFR it was going lean. I'd guess you are tuned on the rich side.
Click to expand...
Is that opposed to low ethanol fuel or no ethanol fuel? We had tuned the idle mixture all around and the jets are the standard for the Holley carb. The plugs have been almost scary clean, so nothing indicates being on the rich side. But what you say on the lean with high ethanol makes sense.

The firing "unevenness" that this helped is pretty subtle, and sounds like if a 1-2 hydraulic lifters were a bit 'lazy' , or 1-2 soilds were misadjusted by maybe .005" .
 
nm9stheham said:
Is that opposed to low ethanol fuel or no ethanol fuel? We had tuned the idle mixture all around and the jets are the standard for the Holley carb. The plugs have been almost scary clean, so nothing indicates being on the rich side. But what you say on the lean with high ethanol makes sense.

The firing "unevenness" that this helped is pretty subtle, and sounds like if a 1-2 hydraulic lifters were a bit 'lazy' , or 1-2 soilds were misadjusted by maybe .005" .
Click to expand...

Yes, car runs bad at idle on high ethanol vs. low or ethanol free. It took me a while to figure out what was going on. Car want to die at idle but then run fine going down the road. Finally brought it to my dyno guy and put it on the AFR and it was lean. He asked about fuel and it hit me, each time this happened it was on 93 or 94 ultra from the same place. Ran that gas out, problem went away. Put that places gas in it again, replicated the issue.
 
roccodart440 said:
Yes, car runs bad at idle on high ethanol vs. low or ethanol free. It took me a while to figure out what was going on. Car want to die at idle but then run fine going down the road. Finally brought it to my dyno guy and put it on the AFR and it was lean. He asked about fuel and it hit me, each time this happened it was on 93 or 94 ultra from the same place. Ran that gas out, problem went away. Put that places gas in it again, replicated the issue.
Click to expand...
Good detective work there. I'm kinda curious as to what SCR/DCR you have?
 
Mattax said:
Fuel volatility is described as a distillation curve. Its not too hard to find info for race fuels and av gas. Pump fuel is harder of course, and its a moving target as its blended differently for different climates, regulations, and economics.

Here's an illustration of the volatility of some gasolines. Race Fuels are 260 GT (Sunoco), Vintage and C9 (VP). Notice how flat they are. 100LL is low lead Av Gas. The others are pump fuels mostly from tests done when oxygenated fuels were being pushed as a way to improve fuel economy. My recollection is that A & L are not fuel you and I could buy, but special formulation for testing and I included them on the graph to show the range possible.

GT is oxygenated (3.7%) and has 9.8% ethanol. The other two race fuels shown are not oxygenated or any eth.
Fuels A & L are from study called CRC-E67. A was the baseline, L was oxygenated to 3% and 10 % eth.
Tier 2 EEE is from tested sample used in the ACE Optimal Blend Study 2007
Click to expand...
Thanks for posting this; it sure shows a lot of variability. Where the fuels we have used in this case land on that graph is anyone's guess. But I'll be checking whatever links I can to look at Shell's premium.

This is an interesting analysis of some Shell premium gas that showed the RON octane to actually be 98 RON for some 93 (R+M/2)octane Shell premium. (Which I think are pretty much equal.) It is a few years old:

http://www.bimmerfest.com/forums/showthread.php?t=411398
 
ethanol???? how much they add to gas now, I don't know, ... but price of corn in bout $3.70'bu. way down from some previous years.
 
Research Octane is always higher. Motor Octane comes from a diffent test. The average is what they post on the pump in the USA. This average is also called AKI, Anti-knock index.

Yes pump gas has a range of variables although there are some regulatory requirements and industry standards. I had some Tier EEE high/low specs from one of those reports but didn't graph it. Av Gas is requirements are pretty tightly specified so less variablility there.

One reason for using race fuel is to eliminate the variability when serious about winning. Race gas is expected to be consistant. You can go to VP Racing, Sunoco Race Fuels or any other brand and find all the specs relevant for engine building and tuning; Specific Gravity, Oxygenation, RVP, along with the distillation curve points. Which one will provide the most power depends on the engine and is a subject beyond my knowledge. Perusing speedtalk and racingfuelsystems forums (and probably YB) will turn up posts that will give you a better idea than I could.

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Here's the graph with just pump fuels. The Tier 2 EEE high and low specs are added here. I only plotted 4-5 distillation points so the curves are approximate. Notice how the older Premium fuel didn't evaporate as much at ambient temperatures as the future looking fuels A,L and Tier 2 EEE. Interesting, huh?


Octane Ratings - Motor, AKI, Research
07? Prem 88.5 91.8
Fuel A: 84.0 88.0 92.0
Fuel L: 85.2 89.9 94.5
Tier 2: 88.0 92.3 96.6

Sources: ACE Optimal Blend Study 2007, Durbin et al CRC-E67
 
This Energy And Fuel research paper is on ethanol, methanol and other alcohols impact on the curve and other characteristics.
https://www.researchgate.net/publication/231274703_Distillation_Curves_for_Alcohol-Gasoline_Blends
It explains EEE is a test fuel for Federal emmissions testing of vehicles. I forgot that. It has no additives and so is not quite what we buy at the pump.

An easy to read color graph and more info at this webpage promoting the company's EF fuel additive as an alternative to ethanol.
 
Actually, it looks like the Chevron Premium evaporated better than most others at a given temp.
 
Maybe I didn't phrase or explain that well. Agree that from 40% to 95% the Chevron evaporates more easily. It was the other end I thought was interesting as it represents the conditions while the fuel is sitting in the gas tank or the carb bowls.

The light components in the Tier 2 EEE sample start evaporating at 74 F. 10% of that sample evaporated at 124 F.
In contrast it took 154 F to lose 10% of the Chevron sample to evaporation.

There seems to be some correlation between RVP and how easily the light end of the fuel evaporates.
RVP for the tested samples above
Chevron 6.7
Fuel A 7.74
Fuel L 7.6
Tier 2 EEE 9.07

Density for the tested samples above
Chevron ?
Fuel A .731
Fuel L .761
Tier 2 EEE .74

Based on the EPA page and Bimmer link you posted, it would seem the Benzene is one of the main components effecting the light end of the fuel and the RVP.
 
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