Effect of ethanol in car

cstreit · cstreit's Garage

Gang,

Can anyone point me to information regarding the use of ethanol as a partial mixture in gasoline? I know most places use about 10% these days, but what affect does it have?

Could you safely use 20%? What would this do to timing, heat, etc...

(Long story why, but might be worth my while to investigate)

sammyg2 · 04-08-2003, 09:23 AM

Alcohol (ethanol and methanol) actually burn cooler than gasoline due to a lower BTU content by volume/weight.
But...... alcohol also can make an engine burn leaner, raising combustion temperatures.
The effect of running 20% alcohol mix would be to reduce power output, raise effective octane rating (resistance to pre-ignition and pre-detonation) and effectively lean out the engine.

If you designed the engine to run alcohol (or a percentage) you could theoretically make more horsepower, but that would be done with extremely high compression ratios (16 to 1 or higher) and air/fuel ratios around 8 to one.
An engine designed optimally for gasoline suffers when alcohol is used. Efficiency falls off as the concentration increases. If the engine management system compensates for the leaner burning all you would probably notice would be an increase in consumption as more fuel is poured in.
If the engine management system was a "dumb" system like CIS or MFI it would just run a little leaner. On the street the drive would notice a reduction in mileage because he or she would be driving the car harder to get the same performance out of the engine.

Jim Sims · 04-08-2003, 09:32 AM

Alcohol also tends to attract water which can be bad for CIS and MFI and other fuel system metal parts due to increased internal corrosion. It is also hard on seals and elastomers (methanol is especially harsh) not forumulated for exposure to alcohol. The original gaskets and seals in early cars may suffer if exposed to fuels containing alcohol. Jim

cstreit · cstreit's Garage

So to run 10-20% ethanol in a race engine would require:

1. Richer mixture
2. Some dyno testing for power
3. Careful temperature monitoring for mixture
4. More fuel
5. Some decent development time...

juanbenae · juanbenae's Garage

on the fuel subject, i have been told by someone in the know that california has a "summer" and "winter" blend of gasoline. it has to do with emmisions the way i understand it. i have also noticed that since about three weeks ago the mileage in my commute car has deminished rather sharply. from about a 320 mile range to only about 280+. i could before go back and forth to work for four days on a tank, now only 3 1/2 and i gotta fill. anybody shed some light on this?

MotoSook · 04-08-2003, 10:44 AM

Ok, first off, I'm ignorant on the topic, but I have some questions.

On a carburated motor or MFI or CIS w/o exhaust gas monitoring, won't running 20% alcohol just decrease power and combustion temperature? I agree with Sam that gasoline mixed with ethanol and methanol have less Btu per volume than unmixed "gasoline", but on an engine that has no exhaust-gas-based feedback to control (vary) the rate of fuel into the combustion chamber, how do we get a leaner mixture? I always thought the term refered to a volume of fuel versus air.

I also thought the alcohol burning dragsters and CART cars burned more fuel than a "gasoline" car, because they had to make up for the decreased energy of the fuel, not because of an AF ratio issue.

So on an engine that can't change the AF ratio on the fly, won't the result of running higher alcohol percentage result just cooler temp and lower HP?

Perhaps, I'm over simplifying here

HarryD · 04-08-2003, 12:13 PM

This is an interesting discussion on Gasoline.

http://www.rennsportsystems.com/2a.html

sammyg2 · 04-08-2003, 12:24 PM

let's see. Yes, California does have a summer and winter blend, mostly it has to do with RVP (vapor pressure, the tendency to evaporate). During the winter (colder months) fuel can have a higher RVP and still be in compliance. During the summer months the RVP has to be lower to comply with government mandated specifications. In order to have a lower RVP and still work, the gasoline blend is actually more expensive to make. Without getting really complicated the loss of aromatics requires more reformate blend stocks.

yes, alcohol is hygroscopic and will absorb water. That isn't necessarily a bad thing in all cases, at least it helps to keep the water in suspension. If it settles out it can do more harm. I still don't like it and don't want alcohol in my gas tank though.

Chris, if you really want to build a race motor to run 20% alcohol in additio to the changes you alreadystated you would want to bump up the compression ratio in order to take advantage if the ethanol's properties. I can't say how much, that would take some digging and calcumaltions :-) With a higher compression ratio you could get back the lost energy, UNLESS the oil company selling the stuff compensated for the difference and used a lower quality blend to capitalize on the anti-knock properties of alcohol. I don't know if they do that or not, I could make some phone calls.

Souk, you are correct in your post. When I refered to "lean" I was talking about the actual burn ratio compared to optimum. With alcohol the mixture is "lean" because it is leaner than the ratio that would produce a compromise between complete combustion and maximum power. I am not absolutely sure if this would raise combustion temperatures or not. I was told by Jerry Darrien (JD, an alcohol engine buiding guru) that it would but he was talking about a blown alky hydro, might be apples to oranges.

In California the replacement of MTBE (at 10% by volume, also a type of alcohol blend) by ethanol (at around 5%) shouldn't make much difference in the way an engine runs.
But if some places are blending 20%, I would keep an eye on the plugs and if I was running CIS or carbs I'd richen it up a bit on the top.
Oh, one more thing: alcohol additives make it harder to correctly read plugs because they color more slowly. As if everything else wasn't enough.

Superman · 04-08-2003, 01:13 PM

The scary thing about alcohol for most of us is that there is a pool of water at the bottoms of our gas tanks, with rust suspended in it. Water will not mix with gas, but ethanol will, and will also mix with water. So now, teh water and rust have a way to become suspended in the gasoline, and for CIS guys, this is not good. Chris' car probably does not have this to worry about.

Recently I had a chance to chat with a Chevron delivery truck driver. He said that the "regular" gasoline they use (before additives which are mixed in the truck) is the same gasoline that everyone else uses. But other brands mix ethanol to it to make "premium" (remember when we used to call this "ethyl?"), while Chevron just starts with premium grade high octane gas (to make "premium").

HarryD · 04-08-2003, 01:17 PM

Quote:

Originally posted by Superman
The scary thing about alcohol for most of us is that there is a pool of water at the bottoms of our gas tanks, with rust suspended in it. Water will not mix with gas, but ethanol will, and will also mix with water. So now, teh water and rust have a way to become suspended in the gasoline, and for CIS guys, this is not good. Chris' car probably does not have this to worry about.

Recently I had a chance to chat with a Chevron delivery truck driver. He said that the "regular" gasoline they use (before additives which are mixed in the truck) is the same gasoline that everyone else uses. But other brands mix ethanol to it to make "premium" (remember when we used to call this "ethyl?"), while Chevron just starts with premium grade high octane gas (to make "premium").

.... and another reason to buy Chevron, Techron and real Premium fuel!

sammyg2 · 04-08-2003, 01:42 PM

I can't say what they do in other parts of the country, but in the peoples republic of Kalifornia, premium is premium, right out of the refinery.
Chevron gas might be made by chevron, or exxon-mobil, or equilon, or anyone else out there. The difference is in the additives like was already posted.

MotoSook · 04-08-2003, 01:43 PM

Harry, are you sure you're an "unemployed Chem E", and not a saleman for Chevron

..sorry had to poke fun at ya.

MotoSook · 01:58 PM

I have two buddies that use to enginerd for Marathon. There comment on differences between gasoline at the pump is, "they all get the stuff from the same terminal!" Perhaps Chevron is more on top of their QC, but I tend to agree that Shell, Mobile and Phillips (who else) gasoline are marginally different from a technical aspect.

I ran a test loop at a Mobil terminal a while back, and they delivered to everyone who wanted their gas. And it all came out of the same tanks!

My only concern when buying gas is to stay away from the stations that seem to lack care for their pumps and store. If they are in poor shape, think about what's sitting at the bottom of their underground tanks..yuck!

Also, when I drive by and see a tanker off loading, I make a mental note of what that tanker looks like and where it came from (company).

But we are getting of topic......

Chris, Why are you asking? Do you think you got some bad gas? Or did you pour the Bourbon in you tank in desperation to get Feebee (

) on the trailer?

pwd72s · 04-08-2003, 01:53 PM

Super, hate to correct you on this, but this old timer remembers buying "ethyl". Ahhhh, for a tankfull of 1967 "white pump" Chevron "ethyl" today...if memory serves, it was 105 octane! Anyway, the "ethyl" we referred to then wasn't ethenol...it was tetraETHYL lead.
BTW,if you find yourself in Oregon, stick to the major brands, but avoid ARCO brand gas...it is very heavily "oxegenated", meaning more gasahol than the others...it's cheaper because of the tax break the state offers, but you get what you pay for.

HarryD · 02:34 PM

Quote:

Originally posted by pwd72s
Super, hate to correct you on this, but this old timer remembers buying "ethyl". Ahhhh, for a tankfull of 1967 "white pump" Chevron "ethyl" today...if memory serves, it was 105 octane! Anyway, the "ethyl" we referred to then wasn't ethenol...it was tetraETHYL lead.
BTW,if you find yourself in Oregon, stick to the major brands, but avoid ARCO brand gas...it is very heavily "oxegenated", meaning more gasahol than the others...it's cheaper because of the tax break the state offers, but you get what you pay for.

Very true and also, in Orygun at least, all gasoline is delivered via a single pipeline. To separate the grades, they put a plug of water between each load. Guess where the first flush of gasoline goes? The low price, off brand fellows.

Also, in Orygun, it is my understanding that only 33% of the fuel at a branded station needs to be from the Brand

, the balance can be from anywhere.

Finally, it is also my understanding that Orygun has the most lax gasoline standards in the nation for contaminants such as sulfur. Want to hazard a guess where the off spec stuff goes?

I suspect the above is true as several years ago, my Windstar suddenly was very hard to start, and when it finally got going it ran very rough. The check engine light came on and I brought it to my wrench. His first question was where I bought my gas. I told my my wife buys it at the "cheap" places sonce it doesn't matter anyway. He just smiled and after cleaning the gunk out of my manifolds suggested I stick with the quality vendors. He told me he had a stream of these coming in recently so something bad is going on. I have used branded (Chevron, Texaco, 76) ever since, and all my problems seem to have ended.

As far as real ethyl, I want to know if Amoco premium is still clear. The story goes that they made av gas during WWII and bought hte plant for pennies on the dollar. It used a diferent process to make gasoline and did not need lead to boost octane.

Superman · 04-08-2003, 02:51 PM

I hear you, Paul, and was not connecting "ethyl" with "ethanol,' but rather just noting that this is name we used for "premium."

But I'm not backing off my previous observation. The guy who drives the Chevron truck provided some good firsthand information and I'm passing that on. He said the base gasoline is the same regardless of brand. They all draw from the same "regular grade" tank. Chevron then adds Techroline into the truck, where it mixes with the generic gas.

The other thing he said is even more important. Other brands add ethanol to regular gas to make "premium." Chevron starts with premium and adds no alcohol. There is no alcohol in our local Chevron Supreme gasoline. So, I use it exclusively.

HarryD · 04-08-2003, 02:56 PM

Quote:

Originally posted by Superman
I hear you, Paul, and was not connecting "ethyl" with "ethanol,' but rather just noting that this is name we used for "premium."

But I'm not backing off my previous observation. The guy who drives the Chevron truck provided some good firsthand information and I'm passing that on. He said the base gasoline is the same regardless of brand. They all draw from the same "regular grade" tank. Chevron then adds Techroline into the truck, where it mixes with the generic gas.

The other thing he said is even more important. Other brands add ethanol to regular gas to make "premium." Chevron starts with premium and adds no alcohol. There is no alcohol in our local Chevron Supreme gasoline. So, I use it exclusively.

If that's the case, to state the obvious, then Chevron Premium is always direct from Chevron not "sumdudes gasoline" with Chevron additives. Regular, on the other hand can be "sumdudes".

David Ceruti · 04-10-2003, 01:32 AM

Getting this thread back nearer the original topic!

Here in Sunny SA we had a bit of a fuss a few years ago (late 80's as I remember) when they started adding Alchohol to our fuel. Aside from the problems already mentioned - absorbing the water in the tank, messing with the rubber in some seals - there was also a problem with increases metal corrosion on the insides of carburettors and jets etc that became unuseable. If I remember correctly, the big problems were with some of the German cars - Something about the alloys they were using at the time.

Also, car paint that is gas resistant is not always alchohol resistant so we had quite a few cars with a faded stripe below their fuel filler caps.

So just a few words of caution before you go for it

David