Ethanol

[Terry M.]

Re: Ethanol

Terry-----


Gasoline also attacks fiberglass over time. In fact, I would expect gasoline to be more of a problem in causing the deterioration of fiberglass than ethanol.

I am certain you are right Joe, but the rate of deterioration is substantially different. You and I will be long gone before gasoline will damage fiberglass tanks, not so with ethanol laced gasoline.

[Jim D.]

Re: Ethanol

I stand corrected. In the late 70's I bought a 1970 LS-6 Chevelle. Unfortunately the only fuel available was laced with that evil ethanol and you know what? The rear tires needed constant replacement. The front tires seemed to last forever. The motor ran great but I'm willing to bet that the ethanol was the reason the rears kept wearing out, not to mention the speeding tickets it caused.

[Clem Z.]

Re: Ethanol

Many boat fuel tanks are made from fiberglass, as are the larger Corvette fuel tanks. Ethanol will attack fiberglass over time (although I don't know how the new underground plastic tanks survive) as many boaters and large tank Corvette owners have found out. Thus the alcohol free gas for boaters.

The lower BTU content of ethanol causes me to wonder at the logic (I understand Richard Nixon's EPA does not have to follow logic) of adding a product to gasoline that in the end causes one to burn more gasoline to get from point A to point B. I understand why the oil companies would support this. And I can understand why farmers and alcohol producers would support such a system, but what about everyone else? Do we not understand we are burning more fuel in the name of clean air? It just seems to me burning less fuel would help the air and the economy, but WTFDIK.

you are correct about boat gas tanks as i have seen this in boat carbs i have rebuilt. i think you are correct it is a plan to sell more gasoline as my fuel mileage has dropped in mrs clem's 04 impala on trips to fla. about 2 MPG since they have 10 % all year round because before it was only in the summer months. also the plastic fuel lines in my weed eater disappeared over the winter a couple of years ago leaving only the fuel filter in the fuel tank. no wonder it was hard to start. i have seen the black neoprene accelerator pumps in older q jets swell up to where they were stuck in the pump well

[Clem Z.]

Re: Ethanol

I am certain you are right Joe, but the rate of deterioration is substantially different. You and I will be long gone before gasoline will damage fiberglass tanks, not so with ethanol laced gasoline.

the ethanol seems to soften or dissolve the resin in the fiber glass tanks and it get into the fuel filter in older boats.

[Duke W.]

Re: Ethanol

Lighting the fire of a quiescent mixture of fuel and air in a test vessel is a very different phenomenon than lighting the fire of the highly turbulent and chaotic mixture in a cylinder as the piston approaches TDC. You're comparing apples and oranges. You'll hear more about this in San Diego.

Peak cylinder pressure in vintage high compression engines is no more than, and likely less than 1000 psi. Modern engines probably have somewhat higher peak cylinder pressures than vintage engines because of more efficient combustion chambers. Peak cylinder pressure usually occurs at WOT near the torque peak.

Peak cylinder pressure for the isentropic Otto air cycle with heat addition at constant volume at 10:1 CR is about 2000 psi, but a real engine is about half of what we compute for this idealized Otto cycle.

Duke

[Steven B.]

Re: Ethanol

Thanks DOM

[Michael W.]

Re: Ethanol

If a person truly has a clear understanding of 'detonation' in a piston engine, it will become apparent that the speed at which a fuel burns can have no possible effect on this phenomena. The octane rating of a fuel has NO fixed relationship with the speed at which it burns, the amount of energy the fuel contains or how 'hot' it burns, or any of the other myths and misunderstandings that have floated around for decades.

Apparently this fuel manufacturer got tired of answering the same old questions time after time and issued this:

http://www.rockettbrand.com/techsupport/documents/TechBulletins/FlameSpeedOctaneAndHpRelationships.pdf

[Domenic T.]

Re: Ethanol

If a person truly has a clear understanding of 'detonation' in a piston engine, it will become apparent that the speed at which a fuel burns can have no possible effect on this phenomena. The octane rating of a fuel has NO fixed relationship with the speed at which it burns, the amount of energy the fuel contains or how 'hot' it burns, or any of the other myths and misunderstandings that have floated around for decades.

Apparently this fuel manufacturer got tired of answering the same old questions time after time and issued this:

http://www.rockettbrand.com/techsupp...ationships.pdf

Michael,
Thanks for this (rocket brand fuel) made by their ROCKET SCIENTIST.

Most likely if we use this racing fuel manufacturer's fuel the need to time our engines will be eliminated.

WOW can't wait for a station to open near by, especially near my beach front property I'm going to buy here in the desert. I'll look them on the net and see if it's sold by the pint.

Thanks, this strengthened what I said in my post about believing what one reads from the major oil companies that had class action lawsuits. Rocket brand racing fuel could teach them a thing or two.

DOM

[Clem Z.]

Re: Ethanol

i alway referred to combustion as "turning gasoline into noise"

[Michael W.]

Re: Ethanol

Michael,
Thanks for this (rocket brand fuel) made by their ROCKET SCIENTIST.

Most likely if we use this racing fuel manufacturer's fuel the need to time our engines will be eliminated.

WOW can't wait for a station to open near by, especially near my beach front property I'm going to buy here in the desert. I'll look them on the net and see if it's sold by the pint.

Thanks, this strengthened what I said in my post about believing what one reads from the major oil companies that had class action lawsuits. Rocket brand racing fuel could teach them a thing or two.

DOM

Dom-

Rather than hurtling insults, why not contact your local dealer (listed here

http://www.rockettbrand.com/dealernetwork/network.html#california

and see if they can put you into contact with one of their engineering staff or chemists that can help you overcome your confusion on the matter.

[William F.]

Re: Ethanol

Michael,
In WW2, Allies' aero engines could run more compression without detonation, and therefore produce more horsepower than Axis because Shell, with help from Gen. Jimmy Doolittle, developed 130 octane aviation fuel. That's a fact.Same true for auto engined in 20's being able to develop more power when Ethyl Corp. and GM found adding tetraethy lead ("ethyl"grade gasoline) raised octane and cut down on detonation.

[Domenic T.]

Re: Ethanol

Michael,
In WW2, Allies' aero engines could run more compression without detonation, and therefore produce more horsepower than Axis because Shell, with help from Gen. Jimmy Doolittle, developed 130 octane aviation fuel. That's a fact.Same true for auto engined in 20's being able to develop more power when Ethyl Corp. and GM found adding tetraethy lead ("ethyl"grade gasoline) raised octane and cut down on detonation.

William,
That's a good point and the WWII aircraft racing today at reno had to make some changes because the purple 130/145 fuel is gone.

Also a old timer that was in the motor pool said that the guys would put the high octane fuel (130/145 in the jeeps that had lower compression and lower octane requirements and found that they would burn the valves.

His explanation was that the higher octane (130/145) was not completely burned as it went past the exhaust valve & seat because it burned much slower than the fuel the jeep was supposed to burn. He said that advancing the timing would start the burn sooner and somewhat solve the problem but if they put the lower octane in without retarding the timing again the detonation would eventually ruin the engine.


DOM

[Michael W.]

Re: Ethanol

Michael,
In WW2, Allies' aero engines could run more compression without detonation, and therefore produce more horsepower than Axis because Shell, with help from Gen. Jimmy Doolittle, developed 130 octane aviation fuel. That's a fact.Same true for auto engined in 20's being able to develop more power when Ethyl Corp. and GM found adding tetraethy lead ("ethyl"grade gasoline) raised octane and cut down on detonation.

Yes- there's no dispute that higher octane gas can allow more advanced ignition timing which will produce more power without inducing detonation. That's not in dispute. The additional power comes from the advanced timing, not from the fuel itself.

[Duke W.]

Re: Ethanol

The old avgas ratings of 100/130 and 115/145 were not really "octane" ratings. They were "Army Navy Performance Numbers". Rather than use higher compression to determine detonation resistance, higher boost pressure was used with relatively low CR of about 7:1, which was typical for the big supercharged recips.

The first number referred to the "lean rating" - near stoichiometric - and the second number was the "rich" rating with something on the order of 50 percent excess fuel.

Taylor's book has a nomograph comparing the AN Performance number with MON. By defiinition 100 MON equals 100 PN.
A PN of 130 is about 110 MON.

In any reasonably designed engine, combustion is complete well before the exhaust valve opens, but matter, when hot enough, will emit in the visible spectrum. Supercharged engines have higher EGT than naturally aspirated engines. If the mixture is excessively rich, hot carbon can glow orange and the other exhaust products can glow blue. A blue flame is sometimes called a "stoichiometric flame". WW II aircraft used for night missions usually had some kind of shroud over the exhaust ports to cover the flame and allow it to cool to below where it emitted in the visible spectrum. There were a number of different designs used on Spitfires.

If the octane rating is high enough to allow sufficient spark advance to achieve peak output under all operating conditions, higher octane or additional spark advance will not improve performance. This was the general philosophy for sixties vintage engines. The manufacturer specified a high enough octane to keep the engine out of detonation - even in extreme conditions.

Many modern engines have higher true compression ratios than sixties vintage engines, and they can be higher than available fuel octane can support under all conditions. The octane ratings are okay for most driving conditions, and under those conditions that yield detonation, the knock sensor and engine management electronics retard the spark sufficiently to keep it on the ragged edge.

High compression is essential to obtain maximum output and low fuel consumption, but the limiting factor is detonation. Straight run gasoline from atmospheric distillation was all that was avaialble 100 years ago, and it is about 70 RON, but researchers were aware that higher compression ratios than the 4-5 that would run without detonation on 70 RON fuel were critical to improving output and efficiency. Thus the race was on to find something that increased detonation resistance, and that was tetraethyl lead that was discovered in the 1920s.

Modern refining processes can create much higher octane hydrocarbons, so, nowadays, we can economically produce octane ratings nearly equal to the sixties with no TEL.

Duke

[George J.]

Re: Ethanol

Duke,
why do you continually try to rebuff old wives tales with facts? It's really becoming instructional for some of us.
That was a great history lesson above. Keep it coming!

George