Can a stock 85 rx7 fb gsl run on E85
11-10-19, 10:25 PM
#1
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Can a stock 85 rx7 fb gsl run on E85
I've searched around here and cant find anything about E85 on first gens (mostly just other gens or personal problems). I know E85 requires more fuel so the chances of needing a larger carb could be probable but im not sure if the fuel lines or even the gas tank will be affected
11-11-19, 01:35 AM
#2
Full Member
I can't remember the exact figure, but I think you need something like a 1/3 more fuel to run E85 due to the lower calorific value.
I don't know how much flow the standard pump on your car produces but you may need a bigger fuel pump.
Also on a carbed car it makes less sense as you need to re-jet every time you switch between E85 & normal petrol, a car with EFI can just run a flex sensor & a map that can switch between the two fuels.
Additionally I've read that ethanol can have a corrosive effect on old rubber fuel lines & fuel pumps. I have no idea if this is an internet myth or true but it bears thinking about.
So the answer is not without modification & not easily. And if the cars stock, what's the point?
I don't know how much flow the standard pump on your car produces but you may need a bigger fuel pump.
Also on a carbed car it makes less sense as you need to re-jet every time you switch between E85 & normal petrol, a car with EFI can just run a flex sensor & a map that can switch between the two fuels.
Additionally I've read that ethanol can have a corrosive effect on old rubber fuel lines & fuel pumps. I have no idea if this is an internet myth or true but it bears thinking about.
So the answer is not without modification & not easily. And if the cars stock, what's the point?
11-11-19, 10:15 AM
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we did the conversion on a miata, and its a nice race fuel.
you need:
about 30% more fuel, Alcohol has less energy in it (CH12 vs CH18 for gas). this would require a complete re jetting of the carb. and you may run into an issue where you cannot buy jets that big, or the passages are too small.
you will need a larger fuel pump.
the alcohol will act like a solvent, so the first few tanks will clean out some junk, and you'll need to change filters a couple of times. any original 40 year old fuel line will probably die. fresh hose does fine.
you will need to premix, as the normal premix, and the metering pump oil is not compatible with alcohol.
in short, its probably not worth doing, unless you're actually racing.
you need:
about 30% more fuel, Alcohol has less energy in it (CH12 vs CH18 for gas). this would require a complete re jetting of the carb. and you may run into an issue where you cannot buy jets that big, or the passages are too small.
you will need a larger fuel pump.
the alcohol will act like a solvent, so the first few tanks will clean out some junk, and you'll need to change filters a couple of times. any original 40 year old fuel line will probably die. fresh hose does fine.
you will need to premix, as the normal premix, and the metering pump oil is not compatible with alcohol.
in short, its probably not worth doing, unless you're actually racing.
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11-18-19, 05:48 AM
#8
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we did the conversion on a miata, and its a nice race fuel.
you need:
about 30% more fuel, Alcohol has less energy in it (CH12 vs CH18 for gas). this would require a complete re jetting of the carb. and you may run into an issue where you cannot buy jets that big, or the passages are too small.
you need:
about 30% more fuel, Alcohol has less energy in it (CH12 vs CH18 for gas). this would require a complete re jetting of the carb. and you may run into an issue where you cannot buy jets that big, or the passages are too small.
you will need a larger fuel pump.
the alcohol will act like a solvent, so the first few tanks will clean out some junk, and you'll need to change filters a couple of times. any original 40 year old fuel line will probably die. fresh hose does fine.
you will need to premix, as the normal premix, and the metering pump oil is not compatible with alcohol.
in short, its probably not worth doing, unless you're actually racing.
in short, its probably not worth doing, unless you're actually racing.
So yes, maybe just fine for a drag engine or big single FD that might only see 1000-2000mi between engine teardowns, but not so good for anything else, and rather pointless too, since you don't need the additional cooling in a stock 12A.
11-18-19, 09:34 AM
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actually the stock pump is quite good, its does a decent volume at a rock steady pressure. the holley regulator made the flow worse, and pressure is all over the place
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