More questions re: autogas

Cmercado said:
Why change the timing back??
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Because auto fuel has no real standards it has to meet and there is no testing of the actual octane rating.. ie.. The supplier can say it is 91 octane and sell you 85 octane.. And they know you cannot prove it without a VERY expensive testing machine and protocol..

With 100LL, it has to meet higher standards and the testing process in very rigorous...

Ps... 2-3 degrees will not effect performance much at all .. BUT,, it will buy you a good margin of protection against detonation... IMHO.. YMMV..;)
 
N801BH said:
Because auto fuel has no real standards it has to meet and there is no testing of the actual octane rating.. ie.. The supplier can say it is 91 octane and sell you 85 octane.. And they know you cannot prove it without a VERY expensive testing machine and protocol..

With 100LL, it has to meet higher standards and the testing process in very rigorous...

Ps... 2-3 degrees will not effect performance much at all .. BUT,, it will buy you a good margin of protection against detonation... IMHO.. YMMV..;)
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What about using 30% Avgas - 70% Mogas mix? Do I have to change the timing?
 
Cmercado said:
What about using 30% Avgas - 70% Mogas mix? Do I have to change the timing?
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Personally I run 75% auto fuel and 25% 100LL....

I have a 10.5-1 compression water cooled V-8 so it is more tolerant then aircooled motors to detonation...

If it were me I would to run your cocktail of 70 /30 and not change the timing at all.. ..

You don't want your pistons to look like this though... :nono::nono::nono:
 

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Timing changes can do the job, but there is a cost in power. Don't know how much but static timing changes for detonation margin isn't the right way. I'm thinking of mounting a detonation detector on the case and trying to capture that with an aftermarket knock sensing unit and adjusting timing based on knock detection. It works for all car engine makers well, so it should work for an aviation engine as long as I can get the knock sensor mounted right on the case to reject all the other harmonics and vibrations of a opposed 4 cyl air cooled engine.
 
N801BH said:
Personally I run 75% auto fuel and 25% 100LL....

I have a 10.5-1 compression water cooled V-8 so it is more tolerant then aircooled motors to detonation...

If it were me I would to run your cocktail of 70 /30 and not change the timing at all.. ..

You don't want your pistons to look like this though... :nono::nono::nono:
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You might not be getting the change in AKI you expect with that mixture, but you are probably getting a disproportionate improvement in RVP. It doesn't take much avgas mixed-in to cure a vapor lock problem. We did something similar when fighting gas bubble issues in engine test cells at elevated temperatures. The benefit you see in practice with a mix is much more than what you'd predict looking at the paper properties of the 2 fuels.
 
N801BH said:
Because auto fuel has no real standards it has to meet and there is no testing of the actual octane rating.. ie.. The supplier can say it is 91 octane and sell you 85 octane.. And they know you cannot prove it without a VERY expensive testing machine and protocol..

With 100LL, it has to meet higher standards and the testing process in very rigorous...
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The standard for automotive gasoline is ASTM D-4814.

From Petersen:

"The following states require compliance with D-4814 in whole or in part or require critical specifications values per ASTM D-4814: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Maryland, Minnesota, Mississippi, Montana, Nevada, New Mexico, North Carolina, North Dakota, Oklahoma, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Virginia, Wisconsin, and Wyoming.


"Only eight states require compliance with the aviation fuel spec D-910.

There is no federal requirement for aviation fuel to meet the spec. Therefore control of auto fuel is tighter than it is for avgas."

There are only about 150 refineries in the US (and not all produce gasoline). They test every batch of fuel for octane rating, and the fine for delivering falsely labeled fuel is HUGE. Since it's no harder to produce one grade than another, why would anyone take the risk?

BTW, state and local Depts of Weights and Measures make surprise visits to gas stations (and answer consumer complaints), where they test samples of fuel for octane, lead, etc., so a station operator is as unlikely to risk the fine as a refinery operator.

Think about this -- if autogas were REALLY as variable as you believe, why would the FAA have approved it for Cessnas, Pipers, etc . . ?
 
SoloEqs said:
T
BTW, state and local Depts of Weights and Measures make surprise visits to gas stations (and answer consumer complaints), where they test samples of fuel for octane, lead, etc., so a station operator is as unlikely to risk the fine as a refinery operator.
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When I was 17 (1969) I was pumping gas at an all-night gas station. A guy pulled up in a State of Ga pickup and took out 3 Five gallon containers. They were rather tall and narrow and had markings up the side. He had me pump 5 gallons EXACTLY into each container (Hi test, regular and unleaded I think). While doing this he explained he was a State inspector. I got nervous because even though my pumps said 5.0 gallons, his tanks all read low. But he got out a pencil and notebook and thermometer and some other gauges and did some calculations. He said we we passed but were on the borderline and he suggested I tell my boss to have the pumps calibrated. We did and he came back a few weeks later and we were right on the money. My boss had those pumps calibrated every year after that. Another station was put out of business because of the size of the fine they got for being too far off.

I don't remember if he checked octane that time or not, but they do that too.
 
JOhnH said:
When I was 17 (1969) I was pumping gas at an all-night gas station. A guy pulled up in a State of Ga pickup and took out 3 Five gallon containers. They were rather tall and narrow and had markings up the side. He had me pump 5 gallons EXACTLY into each container (Hi test, regular and unleaded I think). While doing this he explained he was a State inspector. I got nervous because even though my pumps said 5.0 gallons, his tanks all read low. But he got out a pencil and notebook and thermometer and some other gauges and did some calculations. He said we we passed but were on the borderline and he suggested I tell my boss to have the pumps calibrated. We did and he came back a few weeks later and we were right on the money. My boss had those pumps calibrated every year after that. Another station was put out of business because of the size of the fine they got for being too far off.

I don't remember if he checked octane that time or not, but they do that too.
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Yep, there are guys running around with "knock engines" that they put your fuel in and squeeze the pocket until they get detonation.
 
SoloEqs said:
The standard for automotive gasoline is ASTM D-4814.

From Petersen:

"The following states require compliance with D-4814 in whole or in part or require critical specifications values per ASTM D-4814: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Maryland, Minnesota, Mississippi, Montana, Nevada, New Mexico, North Carolina, North Dakota, Oklahoma, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Virginia, Wisconsin, and Wyoming.


"Only eight states require compliance with the aviation fuel spec D-910.

There is no federal requirement for aviation fuel to meet the spec. Therefore control of auto fuel is tighter than it is for avgas."

There are only about 150 refineries in the US (and not all produce gasoline). They test every batch of fuel for octane rating, and the fine for delivering falsely labeled fuel is HUGE. Since it's no harder to produce one grade than another, why would anyone take the risk?

BTW, state and local Depts of Weights and Measures make surprise visits to gas stations (and answer consumer complaints), where they test samples of fuel for octane, lead, etc., so a station operator is as unlikely to risk the fine as a refinery operator.

Think about this -- if autogas were REALLY as variable as you believe, why would the FAA have approved it for Cessnas, Pipers, etc . . ?
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That is not entirely correct......

Back in the 70's, my room mate was a driver of tanker trucks for Texaco in the Miami / Ft Lauderdale area.... The tank farm was in Port Everglades and all the fuel was delivered by barges... The farm operators would keep all the huge tanks evenly topped off and when he would pull in to fill up his over the road tanker they would direct him to the storage tank they wanted him to fill from.... he would then top off and then drive over to the Texaco area and ADD the Texaco approved additive and octane booster to each compartment of his tanker.. So he was actually custom blending a generic base stock gas all other brands used with the Texaco additive.... Till he told me that, I had NO idea how gasoline distribution worked... The only brand that did NOT participate in that was Amoco, as they had their own tanks and barges..... ..

I am not saying refineries didn't test for octane... but I bet they tested for the minimum they could get away with for the base stock fuel... YMMV..
 
They were able to do that because the base fuel met the (earlier) ASTM standard. The standards have changed, but gasoline is gasoline.

It doesn't matter what "minimum" they tested for, if the gas MEETS STANDARDS.
 
SoloEqs said:
They were able to do that because the base fuel met the (earlier) ASTM standard. The standards have changed, but gasoline is gasoline.

It doesn't matter what "minimum" they tested for, if the gas MEETS STANDARDS.
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I feel so much better that the guv is monitoring the quality of all the gas being shipped out of all the refineries.....:no::nonod:....
 
N801BH said:
I feel so much better that the guv is monitoring the quality of all the gas being shipped out of all the refineries.....:no::nonod:....
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I doubt that the government does, but if the refinery were caught faking the numbers, you know that the Feds would be there at the speed of heat with their hands out for money. Just think of all the departments that would have their own cash registers ringing! Not only would they get got for "consumer fraud," but the EPA would get them for violating pollution standards (which the company couldn't prove hadn't happened), the department which buys fuel would get them if a single drop of that gas got into a government vehicle . . .by the time all was said and done, the government would get a couple of hundred dollars per gallon -- and THEN the LAWSUITS would begin, as hundreds of lawyers ran to the courthouse on behalf of everyone who had ever even heard the word "gasoline" . . .

You're not going to find a refinery operator willing to take that chance.
 
SoloEqs said:
I doubt that the government does, but if the refinery were caught faking the numbers, you know that the Feds would be there at the speed of heat .......
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Hmmm.. So who is going to be doing spot checks of the fuel coming out of refineries :dunno::dunno:...
 
N801BH said:
I feel so much better that the guv is monitoring the quality of all the gas being shipped out of all the refineries.....:no::nonod:....
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The auto companies also sample fuel from stations around the country every once in a while so they know what they are up against out in the field (the car gets the blame, not the gas). Lower than expected octane was not a problem that had to be dealt with like the lower vapor pressures with summer premium and the effect of ambient humidity on knock.
 
N801BH said:
Hmmm.. So who is going to be doing spot checks of the fuel coming out of refineries :dunno::dunno:...
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The guys doing the Weights and Measures inspections at gas stations, for car gas.

For airplane gas, well, you've never watched an NTSB accident board work, have you?

But, again, let me point out that if this were something to worry about, the FAA wouldn't approve autogas STCs. I can't think of a single incident in which autogas was a factor in any engine which is STC approved for autogas.
 
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