hubes

I seen some info about 94 octane gas at pumps in alberta but its 10% ethanol. From what Ive read its fine for newer cars, but it may cause problems on older cars because ethanol isnt good for rubber fuel system components. Is it ok for our C3s? Also, if I were to build a new carb'd engine would the ethanol blend be ok? Basically does ethanol blend work well with carbs? Im sure I could use an 11:1 CR with 94 octane, that'd be

gkull

At less than @23% or so ethanal and methanol stay suspended in gasoline and causes no problems other than your also running a slightly leaner A/F mixture.

alki in the fuel is good because it also removes any water from your tank and fuel system.

Great stuff for making your own higher octane blends.

Larry B.

Ethanol can eat the carb gaskets and some types of rubber parts. Some gasket sets for carbs have been on the shelves for years and while they are new, the material may be old, in which case the ethanol blend my eat them over time. I would not use ethanol fuels as a constant diet

Z-man

I agree w/Larry. Ethanol is pretty hard on older gaskets.

Plus, be ready for decreased performance and lower mileage from "oxygenated" gas. We are forced to use it here (10% ethanol minimum) and the difference is dramatic. Almost all states are moving that direction.

If you build a new engine, you'll probably be OK because most of the newer parts assume ethanol and MTBE gasoline.

hubes

Wouldnt the increase in octane improve performance if the compression ratio is raised for it? example, wouldnt the 94 octane with a 10%ethanol blend be better than 92 octane without ethanol?

marshrat99

with Larry & Z-man. Ethanol can be problematic on rubber parts. In addtion, ounce for ounce, alcohol produces less energy than gasoline. Think of it this way: alcohol has less calories than gasoline. Therefore, ethanol produces less HP.

A C

So why do Top Alcohol dragsters turn faster ET's than gas powered dragsters?

hubes

ok so theres 2 questions left to be answered.
1. is a 10% ethanol blend ok with carb'd cars?
2. what will make more power, an engine built to run on 94 octane with a 10% ethanol blend, or an engine built to run on 92 octane straight gas, assuming both are using the fule they were built for?
thanks

LiveandLetDrive

Which gas fueled dragsters are you referring to? I'm no expert in the field, but I don't think there's anything remotely comparable to top fuel that runs standard gas (high octane of course, but non mixed). With alcohol you can run much much higher compression ratios due to less heat, plus "ounce for ounce" gas makes more, but I can't imagine how fast a TF engine must go through fuel....

-Chris

Tele_Man

I purposely drive to the neighboring county to buy non-ethanol 93 octane. All the local Vette owners with older cars like mine suggested that.

Gordonm

Alcohol Gives off a lot less BTU (heat) when burned then does gas. If you look at a carb setup for alcohol the jets are almost twice as big. To make tha tkind of power more fuel is consumed. You can run much higher compression with alcohol. I'm no expert but I have seen how much BtUs are given off by alcohol and gas. Quite a difference. Nitro is a whole different ball game.

mandm1200

Alcohol has less potential energy than gasoline. The solution is quite simple. You just burm more alcohol by re-jetting the carb. Since most carburators are designed to burn gasoline, these carbs are reworked to be able to flow more fuel (more then just the jets). The gaskets are also made to handle the destructive properties of pure alcohol.

vettenoir

Doesn't the octane rating directly relate to the energy output of the fuel? Does 94 octane with 10% alcohol have any less energy output than 94 octane without it? If you want the highest energy output shouldn't you run 87 octane? Isn't the purpose of the alcohol to raise the octane to make the fuel burn slower for a high performance engine that would otherwise detonate? Lots of questions....

My car has had a steady diet of Sunoco Gold 94 octane 10% alcohol for 7 years, and even though it's had major problems, rotting rubber hasn't been one of them (yet anyway )

ZCR

Octane rating relates to the fuels resistance to burn. The higher the octane the more resistant it is. If you put very high octane fuel in a low compresion engine, it won't run very well at all.

Dalannex

We've had ethanol plants all over this state for over 10 years now and everybody has been burning the 10% blend for just as long. The stories about it eating rubber parts are nothing more than an urban legend. I probably haven't purchased more than 20 gallons of non-ethanol gas in the last 10 years and haven't had a problem. We run the stuff in everything from tractors built in the early 50's to brand new cars and pickups. (this included 5 Corvettes between 68 and 81, one of them a 69' 390 HP 427) Lawn mower's, weed eaters, motorcycles, snowmobiles all get ethanol blend and it works fine. Ethanol doesn't become a problem unless you start talking about running the 85% ethanol blend. At 10% you won't notice a single bit of difference.


-Justin

Paul L

I use Sunoco 94 in my 1967 Corvette with no problem. And PetroCanada 87 in my daily driver (2001 Impala). Both contain up to 10% ethanol (usually derived from corn, the "active" alcohol agent in beer and other spirits). The benefit in the winter is removal of water in the gas without the need to drop it in the tank as an additive.

Older winter gas-line anti-freeze additives used methanol (wood alcohol). It was hard on rubber but is not easy to find these days. When the manufacturers shifted to fuel injection it was found that methanol was hard on injector seals. Modern drop-in additives are iso-propyl (rubbing) alcohol as it is cheaper than ethanol but is just as safe for rubber components.

Z-man

Those cars are usually called "top-fuel" not "top alcohol". Ethanol is familiar to most of us - . Nitromethane (Nitro) is not really alcohol. Nitromethane's chemical formula is CH3NO2. For comparison, gasoline is typically C8H18. The oxygen in nitromethane's molecular structure means that nitromethane does not need as much atmospheric oxygen to burn -- part of the oxygen needed to burn nitromethane is carried in the fuel itself.

You need 14.6 kilograms of air to burn a kilogram of gasoline, and only 1.7 kilograms of air for the same amount of nitromethane to burn. A cylinder can only hold so much air on each stoke, and with that amount of air you can burn 8.7 times more nitromethane than gasoline. By pumping in 8.7 times as much nitromethane per stroke, you get about 2.4 times more power per stroke.

Z-man

I think this is a great comparison. Gasoline typically has 18,000 BTU (like calories) per lb and ethanol has 11,500.

Compare 10lb of gasoline (180,000BTU) with 10lb of 10%ethanol gasoline. Take away 10% of the regular gas and replace with ethanol and that 10lb of fuel now only has 173,500BTU. You will find yourself pressing the pedal harder to make the same power.

An added bonus is that most places charge more for the oxygenated stuff so you get a double whammy - less power at greater cost...

Russ Bellinis

You are half right. If you are talking about NHRA classes, Top Fuel and Funny cars run Nitro methane. The NHRA does have an alcohol class as well. At Pomona a few weeks ago John force won the Funny Car class and his daughter won the Alcohol Dragster class. It was the first time a father-daughter won two classes in a single national meet.
IHRA doesn't run top fuel classes. Their fastest dragster class is the Alcohol dragsters.

75 Hot One

Although different octane gasolines are blended a bit differently and probably have slightly different energy levels, the amount of energy is not related to octane. Octane is simply related to the ability of a blend to resist premature detonation and it's determined on what's called a "knock engine" that increases compression ratio until knocking occurs. Blending in alcohol increases the octane rating, but lowers the energy level. If you want max energy/ mileage, use a gasoline with no alcohol. Alcohol is blended in to reduce emissions because the oxygen it contains leads to a more complete combustion.