More ethanol = increased octane

Quote:
Originally Posted by Birdman
Adding ethanol to gasoline increases the octane number - a measure of the fuel's resistance to pre-ignition or engine "knock." As well, ethanol contains oxygen, which allows for cleaner and more complete combustion. So if you are getting better performance with higher octane, your car LIKES the ethanol. There is more ethanol in the high octane gas.

Birdman

Can we expand on this?

 

Dig is right.

Octanes are actually combustion retardants intended to momentarily inhibit combustion below a certain threshold with the goal of more complete combustion when the energy exceeds that threshold.

Please don't confuse octane with specific energy (the amount of molecular energy in a combustant).

Alcohol has less specific energy than the gasoline it is added to, and that makes it more expensive per volume to use.

 

More ethanol = increased octane?

Like, no... dude. When regular 87 octane (RON+MON)/2 and premium 91-94 octane (RON+MON)/2 were mandated to now include ethanol 116(RON+MON)/2, did you see the octane stickers change at the pumps? Refiner's are now able to use a lower octane base gasoline and with the higher ethanol still make the octane number needed. You didn't think they would give you extra octane for free did you?

As for the "If 10% ethanol is good, 20% must be better"..... How about this? Go find some E85 (85% ethanol & 15% gasoline) and let us know how it performs for you. Just make sure you have scheduled and appointment with you mechanic.

 

I dunno about octane stuff, I'm not a chemist, so I can only go by seat of the pant and observation, and then only in a car that's not smart enough to advance or retart the ignition based on octane. (Or whatever all those blackboxes do in my new fangled cars.)

So, Dino experience only.

The new 10% ethanol fuels SUCK. The octane isn't higher, JCR is correct, I'm sure they're knocking down the octane of the gasoline they're mixing with the ethanol to give us this hybrid crap.

My car doesn't run better on it. Doesn't "run" worse either, but boy it sure is A LOT harder to start my warmed up car with this ethanol blend in it. And I'm not the only one to observe that. My mechanic says he's sturggling with it in his high end motorcycles, and in his older cars, running and starting.

It's his belief that there's a higher solvent factor to the ethanol, and that it dissolves crud that spent years collecting in your lines, tank, etc and then re-introduces them into your fuel system.

We still don't know what other problems it might cause. If it has a higher solvent factor, what might it do to fuel lines?

Guess only time will tell.

DM

 

No Dave, you aren't the only one with these problems. Enthusiasts have been dealing with this since the 1980s. It was a regional problem, not a national one.

Gasohol (AKA gasoline + 10% ethanol) actually dates from the 1930s. Prodution ramped up during WWII and then declined after the war. Production rebounded when codified and subsidized in the Energy Tax Act of 1978. This stuff has been in use for over two decades in the Midwest. Unfortuneately now the entire country is now stuck with it.

Yes, gasohol eats old style hoses and can leach scale from old gas tanks. Gasolines have changed so much over the last 30 years that the new hose materials were developed. Ok, so the newer hoses don't look like that fabric braided crap that the concours types like. In that case if you want to keep your "old skool" hoses, bite the bullet and buy unleaded racing gas with no ethanol. No, you're not buying it for the 100 octane but for the fact it has no ethanol. Another major benefit to unleaded racing gas is a better distallation curve than street gasoline. Street gasolines are blended to perform best between idle and 3,000 RPM. The #1 priority for refiners is EPA compliance. Drivability, hot and cold weather running follow as well, performance, however is way down the list. Racing fuels are blended to perform better at higher RPMs independent of octane. If you can take advantage of the higher octane of racing fuel by using higher compression, all the better. The other option is to dilute the gasohol with racing fuel or avgas.

These article explains what is happening to our current gasolines.
http://www.idavette.net/hib/fuel/index.htm

Other articles: http://www.rockettbrand.com/technicals/bulletins.htm

 

Like, yes dude. Just do a google search and do a little reading.

That's flawed logic. At that mix, an engine designed to burn gasoline does not run right. Ethanol is not being used as the FUEL in gasoline, just as an octane enhancer. If you made Coca-Cola out of 85% sugar instead of 85% water it wouldn't work right either. But take out the 15% sugar and see how it tastes!

No offense but most people have a basic misunderstanding of what octane measures.

Gasoline has always had additives to increase octane. Octane is a measure of a fuel's resistance to pre-ignition. A fuel with higher octane actually does not burn as well as one with a lower octane. Most people do not get this right. They think that high octane fuel somehow has more energy than low octane fuel. Wrong. High octane gasoline just burns less well than low octane. Problem is that low octane fuel can burn well enough that it lights itself off before the spark plug fires, because of heat and pressure in the combustion chamber. (Think of a very low octane fuel: diesel. It is designed to ignite with no spark plug at all).

In a gasoline engine, pre-ignition is VERY bad for the engine. You put additives in the gas to reduce that. You need more additives in a high compression engine than a low compression engine because the higher the compression, the more pre-ignition you get.

The octane-enhancing additive used to be lead. (Think about it, high octane gasoline used to be made with lead. Does lead burn? Do you think lead would make a fuel burn BETTER? No.) Lead was bad for the environment, so they switched to methyl tertiary-butyl ether (MTBE). Now they have decided that is also bad for the environment and they are using Ethanol, which does the same thing as lead and MTBE--decreases knocking by increasing octane. It's anyone's guess why they are using ethanol, but I suspect it's to pump some money into farmers hands to grow corn. Ethanol may not be the ideal compound for octane enhancement, and clearly some cars don't seem to like it. I have not noticed any difference in any of my cars, including two Ferraris.

Since the 308 has a pretty low compression ratio (somewhere around 8.5:1) and doesn't need high octane fuel, I am wasting my money putting high octane gas into it. By using regular 87 octane, I save money, and put less Ethanol in the tank. I'm more concerned about the Ethanol eating away the deposits in my gas tank and clogging the jets in my carbs, frankly.

Here is a really good simple explanation. Seriously. I know it's in a kids encyclopedia, but read it:
http://encyclopedia.kids.net.au/page/ga/Gasoline

Here's a more technical explanation:
http://www.chevron.com/products/prodserv/fuels/bulletin/motorgas/8_q-a/

If you do a google search you will get thousands of references to octane and how it is measured, what it means and the fact that higher octane gasoline has MORE Ethanol in it. Google is your friend.

Birdman

 

Birdman, you haven't done your homework. In the modern emissions era, ethanol and MTBE were added because they are oxygenates, not because of their octane properties. Regular unleaded gasoline is 87 octane whether it has ethanol or not. And no, Premium Unleaded doesn't have more ethanol than Regular. My first post was mocking the "if 10% ethanol is good, 20% must be better" post because using large amounts of ethanol is a stupid way to raise octane in gasoline. BTW, it's detonation thats alot more common with too low of octane. Preignition is much less a problem in automobiles. You need better sources for your gasoline info. Here's one http://ferrarichat.com/forum/showpost.php?p=135786429&postcount=29

 

These are all very erudite and interesting comments, but they have absolutely NOTHING to do with the "206/246 Model Specific Discussion", and would be more appropriate for "Technical Q & A".

 

Feel better?

 

Well actually, my post is about my Dino, and the effect ethanol additives have had on it, so, I get a pass on this.

And, while perhaps this belongs in technical, I think it's important information for all of us Dino guys, and I suspect not all of us spend much time in the technical section.



DM

 

I'm certainly no expert on fuel, but about a zillion google references contradict what you are saying. BTW, pre-ignition and detonation are the same thing. It's also called knocking.

Birdman

 

Oh, yes. That's quite clear by your posts.

And I can find a zillion google references that "alternative medicine" and other such medical quackery can cure cancer.

No, they are not the same thing. Read and learn.

http://www.jandssafeguard.com/tech.html
http://www.sdsefi.com/meltdown.htm
http://www.rockettbrand.com/technicals/documents/TechBulletins/DetonationOrPreIgnition.pdf
http://www.streetrodstuff.com/Articles/Engine/Detonation/

 

Too many cooks. Too many theories. Not enough engineers and successful racers. Gasoline has higher energy potential per gram than alchohol. And per liter. Engines can be tuned to run either and it is possible to run many engines to a higher horsepower with alchohol. Change everything but displacement to do it. Mileage goes to hell but you can get more HP without blowing the engine immediately. This wins certain races within certain rules.

So What. Real cars on real roads burning fuels that are economically realistic run on gasoline. Higher octane allows engineers to use higher compression ratios. Most posters are not engineers and will not raise the compression ratio of their engine without changing parts. The fact that Green Idiots specify or push certain fuels has nothing to do with engineering, science or reality. Buy gasoline of the octane specified by the factory and live a life.

The rest of us have been doing this for years.

John

 

John
You are right of course, I think...My concern has always been loosing the beneficial effects of 101 octane leaded fuel, (for my dino246gts). Now if one is going to drive a few miles here and there or maybe even a few hundred miles nothing much will happen. But lets consider a 10,000 mile run, as in a lap of the USA. What can I expect, a loss of power, O.K no big deal, what about exhaust valve temperatures, does this stuff burn the same way? How does an engine designed 45 odd years ago handle modern fuels. I had read somewhere that a different kind of exhaust valve/guide/seat could be used, one more suited to lower octane, unleaded gas. What about higher compression good or bad? In reality, I do not believe that it is possible to run at near maximum revs for hours at a time as it once was, not for me at any rate, so maybe my dino will never get to the point where lower octane unleaded gas, or gas designed for different enviroments can harm it, right?

 

Right. Lead helps exhaust valve life. No other help anywhere. Quite frankly, who cares unless you are going to run over 50,000 miles. And if you are, are the exhaust valves your big worry. I am closing in on 200,000 miles and lead is pretty low on my worry list. Ran low lead for at least 60,000 of those miles. Exhaust valves were a problem in each head removal. 112,000 miles and 181,000 miles. I can live with that. Alcohol does nothing for anybody who cares about their car. Check compression and if all OK, all is OK.

John

 

Then this should be a good question. Dino's, as well as other Ferrari's of the 70's and back have carbs, and can be rejetted faily easily. Disregarding for a moment all the potential trouble of loosed up scale in fuel tanks, swelling fuel lines, poorer fuel economy, etc... if these cars were jetted to run on E-85, would there be any potential performance gain? I mean, we could be approaching a time where the regular fuels we are burning dont work very well in our old motors. Maybe E-85 could offer something?

 

dignini, most Ferrari's never needed high octane leaded gasonline. In the USA we have had unleaded for 30 years. Remember the octane scales in the the USA are different than the rest of the world. RON vs. (RON+MON)/2 in the USA. Dino engines are not high compression.

As for unleaded gasoline, the EU has been playing "catch up" with the USA. 10 years ago, I remember in the classic car mags from the UK all the articles talking about valve seat recession. It's mostly B.S. Valve seat recession is a problem on older cars that driven under load with unleaded gasoline. Examples would be older racecars at WOT, or commmercial vehicles carrying a load.

Your fair weather weekend car should not count. The engine only needs 30-40 horsepower to maintain highway speed. Therefore it's only under partial throttle. The day you finally have to rebuild the heads, yes, you should install harder valve seats than what was installed originally. See here: http://www.aa1car.com/library/2005/eb050538.htm And also install better valves.

There have been alot of materials changes over the last 30 years to cope with the newer fuels. You can use them on your older car. So, if you want to run at max revs for hours, yes, you should consider upgrading now. It will all depend how you use your Dino. Don't fix it if it ain't broke.

 

Reading this: http://en.wikipedia.org/wiki/E85, I would seem that E-85 offers no performance gains.

 

John, JCR
thank you for your posts, points well taken.

Now would you bother with stainless steel fuel lines if you were at my stage in the rebuild?

 

One practical problem I see with the alcohol enhanced fuels is the boiling point. The carbed cars go into vapor lock at a much lower temp due to the lower boiling temp of alcohol. Real world experience shows us at this altitude that the summer mix of fuels here will boil in the float bowls when the engine is still cold enough to hold your hand on the exhaust headers. When alcohol fuel concentrations are high (summer) we have to bring the cars to emissions testing when they are stone cold. As the fuel in the bowls starts boiling the HC will sky rocket.
There is a debate in Colorado just how energy efficient the new E-85 really is. The energy content of this high alcohol content fuel is so low that the realized mileage doesn't make up for its low cost at the pump. This, let alone the fact the cars using it are unable to climb the mountains without revving the engine to uncomfortable levels is making it hard to sell the idea.
Back in the late 70's / early 80's when the "unleaded scare" was first upon us I built a race engine for a Triumph TR-3 I was road racing at the time. Engine spec's were 14.1:1 comp, unheard of valve spring rates and enormous valve lifts. In the TR engine no valve seats are used, simply a steel valve against a cast iron head. The head was left that way purposely to find the effects of valve seat recession with only unleaded fuel being used. Three years using that combination in race applications only (8000 RPM shift point on that old tractor engine) with zero recession. I did this at the time because there was a big fright in the Vintage car circles in Mpls. at that time with many owners highly limiting the use of their cars worried about expensive engine failures.
The new alcohol blended fuels are here to stay. The new cars can be made to use it effectively but mileage and power will suffer. Using it in the old cars will be an on going problem for some time (look at the 550's dissolving the rubber fuel pump boots in the fuel tanks). New rubber components will have to be used that can tolerate the new blends (try finding a fuel pump diaphragm for a 330 right now). Fuel tanks will have to be cleaned...... I have had to take the oil cooler duct hose on the Dino's and reroute it to blow cool air into the valley under the carbs just to control carb temps and resulting vapor lock in warm weather.
No matter which theory one uses justifying its existence (helping the farmers, helping save the oil reserves, reducing emissions, raising octane........) we will be challenged to find a way to make the older cars use it, as it is here to stay.

Dave

 

The concern over unleaded in our cars would be valves, valve guides and valve seats.

Since the guides and seats are hard metal (brass, right?) that's not really a concern here.

I also think the whole thing is a bunch of BS anyway. My Triumph TR6 ran on unleaded for 20 years before I bought it, and there were no discernable problems with the top end of the motor when we rebuilt it about 5 yrs ago.

As an aside, I've been adding race gas to my car (100 octane Sunoco) about 50/50 with 94 octane. So, my car is about 5% ethanol now and starts better hot than before I started to use it. Pricey, $7.99 a gallon, but I'm gonna experiment with adding less until I see where the starting problems come back.

I think Dave's right about the boiling point of the gasahol. Sure explains some of the warm starting issues I've had.

DM

 

I would be far more concerned with valve seats falling out of the heads. Run those engines cool...

Dave

 

http://www.exxon.com/USA-English/Files/US%20Gasoline%20Map%20100102.pdf

 

RFG? What's that? apart from regular fargin gas?

 

RFG = Reformulated Gasoline

http://www.epa.gov/OMS/rfg.htm