1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

E85

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Old 09-25-08, 11:33 PM
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E85

Will E85 Work with an RX7 its cheaper then unleaded gas so I was just wondering if anyones used it yet
Old 09-26-08, 12:33 AM
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Originally Posted by ps_rx7Rage
Will E85 Work with an RX7 its cheaper then unleaded gas so I was just wondering if anyones used it yet
From what I understand, ethanol is very corrosive and you would need to upgrade most of your fuel system. Pretty sure the motor would run on it fine though.
Old 09-26-08, 12:56 AM
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^ nice quote starfox, who said that anyway?

depending on how much power you are wanting to make would ultimately require bigger fuel lines anyways with E85. Thats the way I would justify the money spent for swapping lines, two birds-one stone. Clean the tank out, swap out fuel filter(s), larger lines, big injectors. If you were wanting to convert your 12a/carb car over and keep it pretty stock, I guess its possible with bigger jets. I wouldnt see the reason for converting over if its not making sick boost, the E85 would burn more fuel and cost of conversion wouldnt really be worth it. Possible slight loss in power over stock due to the colder nature of e85. If you did, get ready to wash the back bumper from all the carbon and soot that will jar loose.

Last edited by buldozr; 09-26-08 at 12:58 AM.
Old 09-26-08, 02:08 PM
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Originally Posted by buldozr
^ nice quote starfox, who said that anyway?

depending on how much power you are wanting to make would ultimately require bigger fuel lines anyways with E85. Possible slight loss in power over stock due to the colder nature of e85.
If tuned properly with the necesary upgrades should E85 not produce more power?
Old 09-26-08, 02:12 PM
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Its higher octane, but you won't get the gains unless you needed the octane (compression ratio, or turbo)
Old 09-26-08, 02:17 PM
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Originally Posted by Frostycrowd
Its higher octane, but you won't get the gains unless you needed the octane (compression ratio, or turbo)
ah, that makes sense.
Old 09-26-08, 02:28 PM
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Really depends on what is a better fuel I think. Octane is irrelevant to power output, its just that without it, the fuel will pre-ignite under compression. So, as stated its only necessary when combustion pressures are higher (aka boost or higher compression ratio) That's why if you run a car that is DESIGNED to run on 87 octane on 93 octane, it will make less power because there is less % combustible material by volume and more % octane (which isn't part of combustion) But I think ethanol is more volatile then gasoline, you might make more power?
Old 09-26-08, 03:56 PM
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Ethanol has a lower IC work output than gasoline per unit mass (and mass-wise, it's very close to gasoline).

Miles-per-gallon on equivalent, properly tuned engines is always lower with ethanol than with gasoline, mainly because the stoich air:fuel mix for ethanol is around 9:1, where gas is 14.7:1.

Alcohol burns hotter but slower.

Ethanol produces more BTUs per pound of fuel, but you have to burn 36% more of it by mass to get the mix right. Gas/air mixed produces more BTUs/lb than does Eth/air.

I'm fairly sure the "winter mix" "oxygenated" gas here in Cali runs as high as 10% ethanol.
Old 09-26-08, 04:07 PM
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unless you're wanting to make big power on cheap fuel, don't use it.......

or if you're wanting to keep your money in the USA, that's cool too

anyhow....... you can use E85 with your stock fuel lines and stock tank and aluminum ......... all of the earlier myths have been busted
Old 09-26-08, 04:37 PM
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I wish there was an E85 station around here. It'd be nice to have 100+ octane pump "gas".
Old 09-26-08, 07:01 PM
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Originally Posted by Viking War Hammer
unless you're wanting to make big power on cheap fuel, don't use it.......

or if you're wanting to keep your money in the USA, that's cool too

anyhow....... you can use E85 with your stock fuel lines and stock tank and aluminum ......... all of the earlier myths have been busted
My car's a lot closer to stock than yours, but I'm considering E85, too. Are you able to find it readily around STL?
Old 09-27-08, 02:44 AM
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so I can use it without any additions, Like say tomorrow i went and filled my car with E85 it would run just fine??
Old 09-27-08, 05:07 AM
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All cars built by 70-71 were designed to handle 10% ethanol. I used to run it in my 71 Road Runner occasionally. Just running 1 tankful did an amazing job of cleaning the plugs and carbon buildup in the engine. Our NA engines will run fine on a lower rated octane fuel. How much more fuel needs to be added to maintain the same performance level is yet to be determined as I've not seen anyone post any dyno testing.

If one were to go this route, I would use an aftermarket carb simply for the wider range of jets, emulsion tubes, etc., that aren't available for the Nikki.

My biggest concern with E85 is that with the increased fuel volume and alcohol is not petroleum based, it may wash down the pre-mix lube that's needed on the housings and iron faces, thereby increasing wear. Pre-mix volume may need to be increased or perhaps a synthetic pre-mix, i.e. Royal Purple, may be needed.
Old 02-04-09, 01:19 AM
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I've got a Mikuni in the SA. I'd just need bigger fuel jets? It'd be interesting! I have 190 air 200 fuel righti now with 52.5 idels. I have a set of 62.5 idles.

If this can be done with the stock system fuel system, that'd be good to know as E85 and I think E100 are available across the street. I could fairly easily increase the OMP, as I have a second setting on the wire attatched to it from the carb.
Old 02-04-09, 08:37 AM
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some guys were discussing this on rx8club and since i saw it here, figured i'd post some info found there in a post by howardteets :

"As far as E85 goes...
Keep in mind that there are a ton things to consider if you are going to run E85.
- Electrical corrosion - ethanol is a much more conductive fluid than regular gasoline, electric current can migrate through the fluid between terminals (not good). Make sure the Walbro pump you plan to use is E85 compatible, as pump manufacturers make specific design changes to pump for E85 use to prevent current migration. There are also specific design changes to electrical connectors inside the tank for the same reason.
- O-ring swell - O-rings will swell at a much larger rate in ethanol fuels, this is more from a module standpoint, than a pump but something to look out for. Orings will swell to the point where they swell out of their pocket. Then you'll have no pressure.
- Regulator - make sure the regulator you use is rated for E85. Some platings used on regulators will not make it in E85.

These are just a few examples. This is just in the fuel tank, injectors, fuel rail, etc... are another story.

As I typed this I'm not sure if an E85 conversion is really worth your while. If you do go ahead with it I wish you luck but there is quite a bit involved."
Old 02-04-09, 09:07 AM
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unless your runnig a power adder of soemsort it's a waste of time and money IMO. YOu don't save much if any money running it. Save your money and get a WB02 and adjust your highspeed air bleeds for leaner cruise. Money well spent!
Old 11-02-09, 12:43 PM
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right now e85 is 2.69 and normal 87 octane fuel is like 2.89 should i run it in my stock gslse?
Old 11-02-09, 12:47 PM
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No...
Old 11-02-09, 02:14 PM
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ok, sticking to 87 then
Old 11-02-09, 06:47 PM
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Originally Posted by elwood
My car's a lot closer to stock than yours, but I'm considering E85, too. Are you able to find it readily around STL?
Only a year late, but yes; it's pretty common in the STL metro area now.
Old 11-02-09, 06:51 PM
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Originally Posted by mazdaverx713b
some guys were discussing this on rx8club and since i saw it here, figured i'd post some info found there in a post by howardteets :

"As far as E85 goes...
Keep in mind that there are a ton things to consider if you are going to run E85.
- Electrical corrosion - ethanol is a much more conductive fluid than regular gasoline, electric current can migrate through the fluid between terminals (not good). Make sure the Walbro pump you plan to use is E85 compatible, as pump manufacturers make specific design changes to pump for E85 use to prevent current migration. There are also specific design changes to electrical connectors inside the tank for the same reason.
- O-ring swell - O-rings will swell at a much larger rate in ethanol fuels, this is more from a module standpoint, than a pump but something to look out for. Orings will swell to the point where they swell out of their pocket. Then you'll have no pressure.
- Regulator - make sure the regulator you use is rated for E85. Some platings used on regulators will not make it in E85.

These are just a few examples. This is just in the fuel tank, injectors, fuel rail, etc... are another story.

As I typed this I'm not sure if an E85 conversion is really worth your while. If you do go ahead with it I wish you luck but there is quite a bit involved."
The majority of the myths have been busted.

Two things needed;

Enough fuel pump
Enough ignition
Old 11-03-09, 09:29 AM
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Any minimal savings in per-gallon cost will be thrown away in the higher fuel consumption to make the same power, so why bother?
Old 11-03-09, 11:59 AM
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i get near 50 mpg in my geo, the last tank was 350 miles and i still had 1 more gallon out of the 8 gallon fuel tank... if my rx7 made close to 25 on the street i'd drive it more often, but its more like 15 mpg city/ 25 mpg fwy (80-100 mph)
Old 11-03-09, 02:11 PM
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Originally Posted by DivinDriver
Any minimal savings in per-gallon cost will be thrown away in the higher fuel consumption to make the same power, so why bother?
If it's tuned correctly, it should make more power. Besides the greater cooling effects of alcohol-based fuels, a stoich mixture of ethanol contains more energy than a stoich mixture of gasoline (around 27% more for E85). It works miracles on boosted engines, but NA engines can still benefit.
Old 11-03-09, 02:58 PM
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Originally Posted by PercentSevenC
If it's tuned correctly, it should make more power. Besides the greater cooling effects of alcohol-based fuels, a stoich mixture of ethanol contains more energy than a stoich mixture of gasoline (around 27% more for E85). It works miracles on boosted engines, but NA engines can still benefit.

From much earlier:

Originally Posted by DivinDriver
Miles-per-gallon on equivalent properly tuned engines is always lower with ethanol than with gasoline, mainly because the stoich air:fuel mix for ethanol is around 9:1, where gas is 14.7:1.
...

Ethanol produces more BTUs per pound of fuel, but you have to burn 36% more of it by mass to get the mix right. Gas/air mixed produces more BTUs/lb than does Eth/air.
Ethanol is lighter (less mass per gallon) and requires almost twice as much fuel mass per air mass to be at stoich ratio.

E85 isn't pure ethanol, of course, but 85% of it is.

Since you need more more fuel mass per working charge, and your desired fuel is lower mass per unit volume than is gasoline, you end up burning a lot more gallons of ethanol to get the same amount of work as you do with gasoline.

Therefore, your cost per mile increases dramatically, and your range per tank drops significantly. You may, if set up properly, produce more net power at WOT.

The point of Thunkrd's question was about fuel cost. He can get E85 for 7% less cost per gallon, but will end up spending more on fuel because E85 is far more than 7% less efficient on a per-gallon basis.


Results from an Edmunds.com test using the same factory-prepped flex-fuel vehicle in a controlled road test, San Diego to Vegas and back:

Gas Result: From San Diego to Las Vegas and back, we used 36.5 gallons of regular gasoline and achieved an average fuel economy of 18.3 mpg.

Gas Cost: We spent $124.66 for gasoline for the trip. The average pump price was $3.42 per gallon.

E85 Result: From San Diego to Las Vegas and back we used 50 gallons of E85 and achieved an average fuel economy of 13.5 mpg.

E85 Cost: We spent $154.29 on E85 for the trip. The average pump price was $3.09 per gallon

Gas/E85 difference:The fuel economy of our Tahoe on E85, under these conditions, was 26.5 percent worse than it was when running on gas.
http://www.edmunds.com/advice/altern...3/article.html


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