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FlexFuel Conversions

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Rambler Mexicano View Drop Down
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    Posted: Jan/23/2018 at 2:48pm
Does anyone know if it is possible to convert AMC inline six cylinders into "FlexFuel" type engines running on a mixture of ethanol and gasoline?

I have been experimenting on using ethanol on my cars since a local supplier was established in my area.

He tells me that using ethanol in a car has other benefits aside from a lower price per liter. The engine runs with less heat, less pollution, smog emission is reduced partially, it's easier to pass emissions and it boosts general fuel octane from 92 to 113.

First is my 1981 VAM Rally GT (Spirit GT). 

I was told that since this is a carbureted engine without computerized controls, the top amount of ethanol I can use is 20% out a full amount of fuel (20% ethanol 80% gasoline). That would be 60 liters of gasoline plus 15 liters of ethanol (15 gallons of gas plus 3.75 gallons of ethanol). 75 liters total (18.75 gallons).

The question here is if the engine can be converted to accept a higher percentage of ethanol han 20%. To make that somewhere around 40%-50%, that would not just be helpful to our finances but also to get more octane since in my case I have above-stock compression ratio in my engine.

My daily driver, a 1999 GM Chevy (Opel Corsa), a four-cylinder TBI car with computerized engine controls can take from 20% to 50% ethanol mixed with gas.

New cars with FlexFuel engines from the factory can take up to 80% ethanol mixed with just 20% gasoline to run.

Has anyone experimented with this?
Mauricio Jordán

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1970390amx Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 12:16am
A carburetor can be modified to run 100% alcohol if desired. Bigger jets, bigger passageways. It is somewhat corrosive I dont know how well a carb would last. Even at 20% I think you should have bigger jets. Around here we have E85, seems like it would be a good fuel to run a high compression engine on. But the content is not always 85% alcohol, making it hard to jet a carburetor if the fuel is not consistent. it takes more than 1 gallon of alcohol to do the same work as 1 gallon of gas.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lyle Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 7:05am
I believe you would have to convert the whole fuel supply system. Ethanol is not friendly to some aluminum components, hoses, plastics, coatings in steel fuel lines.
Nylon fuel lines work, as well many automotive shops sell ethanol hoses.
The old carburetor will spald/corrode over time so as you mentioned a TBI, a new aftermarket carburetor rated for 85% or EFI system.
The fuel pump will also have to be changed, likely a new electric pump will be the best option.
The fuel octane goes up but the volume of fuel required also changes.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 7:36am
On pure ethanol it takes about 1.5 gallons to go the same distance as 1 gallon of gas, and at a loss of power too. You can regain some gas mileage and power by upping the compression ratio since ethanol burns a lot cooler -- you can easily raise compression a full point. If you have 8.5:1 on gasoline and raise to 10.0:1 and run ethanol, you should have close to the same power and get 10-15% better mileage. E85 will have a similar result, maybe only raise compression to 9.5:1.

See http://www.hho4free.com/gasoline_vs_ethanol.html and https://www.fueleconomy.gov/feg/ethanol.shtml. Note that the second link says you can only run E85 in Flex Fuel vehicles. Not entirely true -- but you can only run it in a vehicle tuned for E85. Flex Fuel vehicles are EFI with 10:1 or so compression. The computers are calibrated to have enough range to "tune" the engine to pure E85 or any blend of E85 and regular gasoline. Most EFI computers don't have the range to do that. You can tune an engine (including carbed engines -- different fuel system -- bigger carb, injectors, and whatever else is needed) to run only E85 easy enough, but switching between E85 and regular gasoline is a different story. Some drag racers are using E85 instead of racing fuel.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dbltrbl Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 3:16pm
Regular 4 barrel 600 cfm holley is easy to convert to E85, i would think 350/500 2 barrel is the same. Just build the engine with enough compression and it wont use any more ethanol than it did use gas.

Ofcourse it wont be "flex fuel", it just for E85 then. On my Amx i switched to E85 and it has worked fine with 12.4 comp ratio. Fuel consumption is 11.7 mpg both city and highway.

Here in europe some have modded their Volvos with 2.3 litre aluminium head fours and raised the comp ratio to 15:1 without pinging problems.





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Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 3:59pm
The only way to go truly "flex fuel" would be a computerized fuel delivery system with an O2 sensor because of the very different burn properties of gasoline vs. ethanol.  You can convert a carb to burn ethanol, but then it would not run right on gasoline.

Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6768rogues Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 6:57pm
I agree with Tufcj. You can use gas or modify it to burn whatever mixture you want. Then only that specific mixture or something close will work well. You asked about flex fuel, which I interpret to mean any gas/ethanol mixture you happen to put in. The only way to do that is with a computerized system that will change engine parameters based on fuel provided.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jan/24/2018 at 7:50pm
My 1936 Farmall F20 was flex fuel - it started on gasoline then when warmed up you shut off the gas valve and opened the valve on the kerosene tank and ran kero all day.
I could use almost any gasoline mix in it. 
But then the tank was steel, the fuel lines steel and the carb was cast iron.......   

Wink

Correct in that you can convert to run E85 or ethanol but not flip back and forth without a computerized system, injection, etc.

The local NASCAR track features ethanol powered races - the cars are built for it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jan/25/2018 at 7:01am
Similar to Jeepers experience in Australia and New Zealand where CNG is much cheaper. They build 11:1 or so engines to keep close to the same power as 8.5:1 gasoline engines. Still burns a bit more -- but not as much as 8.5:1 would.

To convert to true Flex Fuel you'd need the EFI system from a FlexFuel vehicle. No aftermarket EFI system has the tuning/adjustment range to run E85 or gasoline -- but can be tuned for one or the other.

The problem in the US is that you can't find E85 just anywhere. TomJ used to run LPG in his Rambler, did so for over 10 years IIRC. He had the same issue -- couldn't get LPG (for road use) just anywhere. It was available enough in the LA vicinity where he lives, but he still had to keep a list of stations and hours, as many LPG stations only operated close to regular business hours. If taking a long trip he had to plan ahead. I seem to recall that he had a connector for a regular 20# grill size tank for emergencies, but I may be mistaken on that.  The point is you have to plan and make sure you have enough fuel between stations. You can usually find E85 in most cities in the US, but need to know just where they are. In small towns and rural areas you may be out of luck. I would think the same applies to Mexico...
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lyle Quote  Post ReplyReply Direct Link To This Post Posted: Jan/25/2018 at 8:01am
Just talking last night with a local gentleman that converted his drag car from AVgas to Ethanol. He was running low 9's with AVgas but now is in the higher 8's with Ethanol. Both blown, nitro boost.
He went a little through the conversion and is pumping twice the Ethanol through the motor then AVgas.
Now this isn't by any means a street vehicle but, if you need twice the fuel for his application, I have to wonder what the mileage would be on a street vehicle. I read 15% to 20% less MPG?
Frank may have a very good point on how far you could drive and find your fuel as conversion once done is just that. Going back would be converting components back.

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