Same old Ethanol question

[Rich G.]

Re: Same old Ethanol question

Doncha think that any fuel system elastomer that's been in service for 60 years might be a little suspicious regardless of the type of gasoline it's been exposed to?

Duke

Agreed. But there is a reason FAA rescinded the approval to use auto fuel in airplanes once ethanol was added. The initial testing that was done before ethanol showed up was extensive and resulted in supplemental type certificates issued to at least two organizations that accomplished the testing to satisfy the Feds. It was mostly around worries about how auto fuel would react to rapid changes in altitude among other things. These STCs covered a range of normally aspirated older design aircraft engines like the 300 CI Continental in my airplane. The aviation community ran auto fuel with no negative effects for many years. Then ethanol came along. After a number of engine failures due to negative reactions to components in the fuel systems (not the least of which was the swelling of neoprene tips on needle valves causing the affected airplanes to become gliders unexpectedly,) the FAA said the STC no longer applies to ethanol gas.

By this time the neoprene tips are gone but the Feds realized there are too many older airplanes out there with fuel systems that could be compromised. And you just can’t change a component in a certified airplane with something else even if it fixes a potential problem without FAA approval. Too much work.

The sad fact is, my engine runs better on auto fuel. There’s too much lead in 100LL. Plugs foul and valves stick. These engines were designed to run on 80/87 octane Avgas. That went away years ago. 100LL was supposed to replace that and the 100 octane that was used by higher performance engines. Unfortunately 100LL has eight times the lead that 80/87 had. So we use FAA approved TCP to help scavenge the lead. It’s like chicken soup “It couldn’t hurt”. If it does any good is anybody’s guess.

Rich

[David K.]

www.race-gas.com

[Duke W.]

Re: Same old Ethanol question

When "gasohol" was introduced here in the Peoples Republik of Kalifornia back in the '80s, I was keeping meticulous fuel economy records for my S10 Blazer with the puny 2.8L V6. I calculated an immediate and verifiable 2 MPG reduction in fuel economy without a commensurate reduction in fuel cost.

E10 has about 3 percent less energy than straight gasoline. On a 20 MPG car that's 0.6 MPG.

Ethanol wasn't mandated in California until the early 2000s due to the phase out of MTBE. I don't recall the impact MTBE had on energy content, but I think it was less than ethanol.

https://www.energy.ca.gov/data-repor...%20that%20year.

Ethanol was required in all mogas by federal legislation a few years later.

https://apnews.com/general-news-4ef599997c1f4a7db5283c14d25de7b4

I also keep accurate fuel consumption data, but any difference was likely within the range of tank to tank variation due to trip length and driving conditions. It just wasn't obvious in the data. I don't think most people noticed a difference, but few track fuel consumption with much precision.

Duke

[Duke W.]

Re: Same old Ethanol question

Duke, the octane booster I’m using is the 105 formula at www.race-gas.com

Most of the verbiage is typical marketing BS. At least they claim "no lead".

I'm not aware of any hydrocarbons, a quart of which will raise the octane of 10-20 gallons of any gasoline blend by more than a few tenths of a point. (I couldn't find the blending chart that was mentioned.) Two excellent octane enhancers are are toluene and xylene, which are aromatics most of which have been eliminated from commercial mogas because aromatics are believed to be carcinogenic, and a gallon of either in 10 gallons of gasoline will raise the octane a couple of points. I don't think gallon cans of these chemicals are sold at hardware stores, anymore, at least in California.

Over the past few years I helped a friend get his '67 L-71 Coupe through the judging process to a Duntov Award. It was a real deal documented 15K mile car that Reggie Jackson had in his collection for ten years, and my my friend bought it from Canadian drag racer Dale Armstrong's widow.

He spent five years documenting the car and correcting a few deviations from OE correct and in the process only drove it about 1000 miles.

Since the heads had never been off he thought he had to use race gas or avgas. He had a connection at a local FSS and was able to buy avgas in five gallon jerry cans, but it was a hassle. The initial timing was at 4 deg. BTC, one degree less than recommended and with 30 total centrifugal total WOT advance was only 34, which is below the 36-40 recommended in the Chevrolet Power Manuals.

After the Duntov I convinced him to try 91 PON E10, which is the highest octane available in California. The first step was to convert the vacuum advance from ported to full time that reduces EGT and combustion chamber boundary temperatures at light load, which reduces the propensity to detonate at low revs at moderate to heavy load.

Then with the tank near empty we added two gallons of 91 PON, and lugged it up hills in 4th gear at 1500 RPM and got some light detonation. We did a couple of more cycles of this and still had slight detonation, so we reduced the timing by 2 degrees and the detonation ceased even trying our best to make it detonate by loading it up at low revs, and subsequent WOT tests up to 5500 did not cause any detonation.

You'll really be doing yourself a favor by doing a similar octane sensitivity tests with your cars.

Duke

[David K.]

[James G.]

Re: Same old Ethanol question

IIRC the ZERO LEAD 100 octane AVIATION is being introduced into larger general aviation fields this year (2023) and should be WIDELY available through out the united states by 2024. It is supposed to be in the larger fields with flight schools on the west coast first.

meanwhile I mix about 10-15% 110 Sunoco with 87 nonethanol, however I would like to eliminate the lead 100%.
It runs much better than straight 93 non ethanol (which I have to go out of the way to purchase) and the cost is about the same.

Does anyone know why the total BTUs of gasoloine per gallon went from 124 in the late 80's to iirc 114 currently?
Did they lean the fuel out in the 1990's?

[Duke W.]

Re: Same old Ethanol question

Run on is easy to tame... simply shut off the engine with the transmission in gear and ease out the clutch.

But it's best to determine the cause and correct it. Run-on was common on early emission controlled engines because of the ported vacuum advance that denied vacuum advance at idle and higher than necessary idle speeds, which reduced emissions. The ideal total idle advance is in the range of low 20s to low 30s for small blocks (and maybe a bit less for big blocks). High overlap cams should be at the high end and low overlap cams in the low end range. This ideal total idle advance is obtained by the combination of initial timing, full vacuum advance, and maybe a couple of degrees centrifugal if it starts at below the minimum acceptable idle speed, which is the case of your L-76.

The OE vacuum advance for your L-76 is stamped 236 16 and provides 16 degs. max at 8" Hg. The modern aftermarket replacement is stamped B28, and typical idle behavior is 10" @ 900.

I believe the OE '67 L-36 VAC is stamped 360 12 that provides a maximum of 12 degs. at 12". The current replacement is B26 although it provides 16 degs. @ 12". I assume yours has a manual transmission, and typical idle behavior in neutral is 600 at 15".

Both of the above VACs meet the Two-Inch Rule, but if your measured idle behaviors aren't close to the above, then the camshafts may not be OE equivalent, and you will have to use the Two-Inch Rule to select a functionally correct VAC.

The complete centrifugal and vacuum specs are in your 1965 Corvette Shop Manual Supplement and '67 CSM and the "vehicle information packages" you can download from the GM Heritage Web site.

The first thing you need to do is verify that the VAC ID data is correct and then use a vacuum pump to make sure they meet the start and stop vacuum specs.

Then use a dial back timing light to measure the centrifugal curves. (The VAC must be disconnected and plugged for this test.) It is virtually impossible to measure initial timing on a L-76 because the centrifugal starts at 700 and the engine will not idle long enough below 700 before stalling to get a reading.

The solution is to use the "total WOT advance" method. (With the VAC disconnected, free revving the engine yields the same total spark advance curve as at WOT because at WOT vacuum advance is zero across the range.) This is easy because the OE centrifugal is all in at 2350, so rev the engine to a bit over 2500 and set the total WOT advance in the range of 36-40, as high in that range as the engine will tolerate without detonation.

Then connect the VAC and read total idle advance, which should be in the 30-34 range.

You should be able to set initial on the L-36 at 600 (OE centrifugal starts at 900) and since total centrifugal is 32 initial should be in the range of 4-8. Connect the VAC and you should see 20 +/- a few degrees total idle advance. Also, the L-36 curve is very lazy, so it should tolerate lighter springs to bring centrifugal in earlier.

The bottom line is know the OE spark advance map from the service literature and then TEST to see if your engines have an altered map or out of spec components.

Once you have the spark advance maps dialed in you can progress to doing octane tolerance testing.

You may not understand some terms I've used above like "Two-Inch Rule" and "spark advance map". All is explained in my tuning seminar, which can be found in the next to the last "sticky thread" restoration documents. Scroll down to keyword tuning and timing.

Duke

[Duke W.]

Re: Same old Ethanol question

Does anyone know why the total BTUs of gasoloine per gallon went from 124 in the late 80's to iirc 114 currently?
Did they lean the fuel out in the 1990's?

Are you talking about the lower or higher heating heating value? I recall that typical straight gasoline blends have about 19,000 BTUs per pound lower heating value and gasoline specific gravity averages about 0.72 so that's about 112K per gallon.

E10 has about 3 percent less energy, so figure about 109.

Maybe you're talking about higher heating value, but IC engines can't expand expand the hot combustion gas enough to even convert all of the lower heating value to useful work much less the higher heating value that would require expanding the gas to less than the boiling temperature of water.

Typical full load EGT is 1500F, which is why about one-third of the available energy goes out the exhaust.

Here's a useful Web site that has good heating values for most common fuels, and explains the lower and upper heating values.

https://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html

Duke

[Tom R.]

Re: Same old Ethanol question

NCRS gets a lot of knocks from other forums for being "original-centric" but here's a great discussion that is applicable to any old-school car guy and how to deal with modern gasoline formulations...especially when dealing with pre-unleaded fuel configured motors. I think dues is what $55 a year, probably the cost for a family of four at McDonalds (I don't have a clue) but the technical insights of working with these new fuel formulas is well worth it.

Thanks all for your contributions here...a most interesting read.

[Thomas S.]

Re: Same old Ethanol question

I buy my fuel from https://petroleumservicecompany.com/...8aAhXqEALw_wcB

[James G.]

Re: Same old Ethanol question

Duke,
Thank you for that explanation. I remember reading years ago about the mid 90's and formulations being changed - at the same time the BTU/gallon fell - it was the government reported EPA BTU number iirc.

regarding running E10 - does ethanol do anything which would leave a white-ish powder residue in fuel bowls?
I constantly clean customer carbs that have a powdery residue in the fuel bowls - sometimes with fuel systems flushed and cleaned, two years later, drop a fuel bowl and it is a whitegrey powder covering the bottom, enough to tap out.

I have assumed this was due to something with ethanol laced fuel - based on the fact that none of our vehicles have the powdery residue when dropping a dry fuel bowl and our family runs nonethanol in antiques and tractors etc.

[Duke W.]

Re: Same old Ethanol question

NCRS gets a lot of knocks from other forums for being "original-centric" but here's a great discussion that is applicable to any old-school car guy and how to deal with modern gasoline formulations...especially when dealing with pre-unleaded fuel configured motors. I think dues is what $55 a year, probably the cost for a family of four at McDonalds (I don't have a clue) but the technical insights of working with these new fuel formulas is well worth it.

Thanks all for your contributions here...a most interesting read.

Hey Tom... does that mean you'll pay my dues next year?

If Mike Ingham is watching he will for sure correct any errors I might have made. Mike has a PhD from the U. of Wisconsin Engine Research Center and spent his career at Chevron in fuels research and politics. I just have a MS from the UW ERC.

Duke

[Duke W.]

Re: Same old Ethanol question

Duke,


regarding running E10 - does ethanol do anything which would leave a white-ish powder residue in fuel bowls?
I constantly clean customer carbs that have a powdery residue in the fuel bowls - sometimes with fuel systems flushed and cleaned, two years later, drop a fuel bowl and it is a whitegrey powder covering the bottom, enough to tap out.

I have assumed this was due to something with ethanol laced fuel - based on the fact that none of our vehicles have the powdery residue when dropping a dry fuel bowl and our family runs nonethanol in antiques and tractors etc.

I'm not sure what that white powdery residue is, but it might be aluminum oxide (corrosion) or an oxide of the "pot metal" that makes up some carburetor parts.

My understanding from research is that E10 is not significantly corrosive, but it will absorb moisture when exposed to air, and this can cause corrosion problems on older cars that do not have sealed fuel systems, which includes most vintage Corvettes prior to the adoption of EFI that is essentially a closed fuel system. Ethanol acts as a co-solvent that allows more water, about 25 times, to mix homogeneously with E10 than with straight gasoline, but over a certain amount of water, about 0.5% by volume at 60F, a water-ethanol blend will come out of solution and drop to the bottom of the tank or fuel bowl, and that will significantly increase the rate of corrosion. Also, the lower the temperature the less water E10 will hold in solution.

This is why it's important to keep these older cars in a non-condensing humidity environment much as possible, and I also recommend driving them enough to consume at least one full tank of fuel per year and to fill the tank prior to winter storage to minimize the "vapor dome" that "breathes", which means filling up to at least the bottom of the filler neck on C2s. The same can be said for gasoline powered equipment like chain saws, but it's easy and best to drain all the fuel if you don't know how long it will be before using the equipment again.

Back in the day of straight gasoline, water would collect at the bottom of the tank, and it can freeze in subfreezing temperatures. It happened to my SWC, circa '64 during a Seattle winter cold snap when I had to park the SWC outside for a few months. The car would not start. After it warmed up to above freezing temperature for a day it started. I'm pretty sure the no-start condition was due to a slug of water at the bottom of the tank.

I added and can of Heet, which is basically ethanol, to cause the water to absorb into the gasoline allowing it to be purged as the fuel was consumed. The problem never occured again.

If that fuel in the SWCs tank was E10 the problem might not have occurred because the ethanol may have allowed the moisture to remain mixed with gasoline and be consumed with the fuel.

Duke

[Jim L.]

Re: Same old Ethanol question

E10 has about 3 percent less energy than straight gasoline. On a 20 MPG car that's 0.6 MPG.

Duke

I've seen claimed numbers in that range previously. I don't believe them.

I know how to do the MPG arithmetic. I stand by the fuel economy impact I noted when I kept records.