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setting a carb for e85?

36K views 30 replies 17 participants last post by  Yachtsman 
#1 ·
Ive read that e85 fuel has an octane rating of 105. This stuff is available everywhere now here in Missouri and sounds like it could be a great cheap race fuel. Does anyone have any tips on setting a carb to run it? are there any dangers to running it in a race motor? Whats the compression limit for 105 octane? thanks a lot, BF
 
#2 ·
You won't find a lot of info about this at your local racers club because those who know ain't talkin.

Essentially, you will need to rework the air bleeds, the metering block, PV restriction, the venturi's, and the N&S needs to be all metal. A big pump is needed as well.

If your under class sanction, talk to a specialty carb builder and listen to them. Your gonna pay for it though, I'll warn ya.

E85 on the street is pretty much pointless because of the mileage concerns. Even running 12:1 compression on E85 won't get your mileage back. It ends up costing a lot for little gains.
 
#3 ·
It takes about 30% more fuel to be the right mix, and it has a large percentage less BTUs per pound.

Car Craft or Hot Rod did a complete side-by-side test on gas vs. e85. They did an apples-to-apples test on the same motor set up with 9.5:1 on pump gas, and then 12.5:1 on E85. They burned 30% more fuel and made the same power.

So, race gas yes because it can handle high compression, but not race gas from the standpoint of super high performance.
 
#7 ·
curtis73 said:
Car Craft They burned 30% more fuel and made the same power.

So, race gas yes because it can handle high compression, but not race gas from the standpoint of super high performance.

Curtis, Perhaps you should go back and read the articles in the past two months of CARCRAFT. If you can't get the news stand copy, then go online to www.carcraft.com.

Uses more fuel, makes big power. E85 is great for the weekend racer.
 
#8 ·
alittle1 said:
Curtis, Perhaps you should go back and read the articles in the past two months of CARCRAFT. If you can't get the news stand copy, then go online to www.carcraft.com.

Uses more fuel, makes big power. E85 is great for the weekend racer.
The article to which I was referring made 6 more hp on the dyno. I'm not an expert, I was just quoting an article from a magazine. IIRC it was a 360-hp 355 that made 366 after the whole kit and caboodle. Proper timing, cooler plugs, the works.

The fact is, E85 has fewer BTUs than gasoline. Gasoline weighs in at 114,000 BTUs per US gallon, Ethanol comes in at 76,000. So, E85 would be around 81,700 BTUs if my head did the numbers right. E85 therefore has 28% less energy and requires about 30% more fuel. Sounds like a wash to me. The higher compression does tend to make better use of the BTUs in ethanol, which accounts for the modest gains in power in most of the apples-to-apples tests I have seen.

It CAN mean big power, but no more than gasoline if you're comparing apples to apples.
 
#9 ·
johnsongrass1 said:
No timing adjustment. Timing is based on head chamber config and not type of fuel.

Power gain were to had with E85 and compression, but not enough to warrent the $1000 your gonna spend on the carb alone and the mileage decreases.
Oh great. So I´ll just run on the same timing on low octane as on race fuel? Brilliant... :rolleyes:
Why would I wanna spend 1000$ on the carb when my buddys carb´s been runnig great with E85 for 3 years? Could it be broken but not knowing it? :drunk:
 
#10 · (Edited)
Yes exactly, the same timing.

Gas, alky, methonal, E85, nitro, whatever, I've have, or my buddies have used it all these at some point. 36' timing

If your using race gas then and moving timing your wasting money. Octane does NOT make power. Compression does.


Your from Sweden, and not here in the land of the free, so I can't tell you about your carb since your fuel requirement's are not the same as ours.

I can tell you that when you switch to our street gas to E85 my carb builder, I might he is the best in the buisiness, will charge you close to $1000 to convert.
 
#11 ·
johnsongrass1 said:
Yes exactly, the same timing.

Gas, alky, methonal, E85, nitro, whatever, I've have, or my buddies have used it all these at some point. 36' timing

If your using race gas then and moving timing your wasting money. Octane does NOT make power. Compression does.


Your from Sweden, and not here in the land of the free, so I can't tell you about your carb since your fuel requirement's are not the same as ours.

I can tell you that when you switch to our street gas to E85 my carb builder, I might he is the best in the buisiness, will charge you close to $1000 to convert.
Using high octane ALLOWS you to use more timing and possibly get more power.

if you are getting 400 hp with 32° of timing on 87 octane, then you add 104 octane unleaded race fuel and that race fuel allows you to run 36° of timing. if your setup makes more power with more timing, then you WILL make more power by advancing the timing.

I agree with you, higher octane fuel alone doesnt make more power, actually it makes less, but the extra slower burning high octane fuel allows you to advance timing to make more power. As well as using more compression, leaner a/f ratio etc etc.

peace
Hog
 
#14 ·
I think what he's getting at is that if you see a power gain from better fuel and more timing then your combination was poorly matched to start with. I agree with that.

As for E85, it alone does not make more power. It allows you to use a higher compression ratio/tolerate higher cylinder pressure. That combined with the proper combination of parts to suit will make more power. It's all relative to the combination and the type of fuel used is a part of the combination.


Larry
 
#15 ·
I do not want to sound cocky,but I am writing from the land where ethanol has being available at the pumps since late 70s.In the 80s more than 70% of new cars sold here by Chevrolet,Ford,VW,Fiat were alky burners.We do have quite an experience with this fuel.

Power: An engine can be tuned to duplicate and sometimes exceed the power of the gasoline version.

Driveability: Expect 3 times the warm-up time necessary until you can drive it.Use a hotter thermostat.Partially block the radiator if the engine runs too cool.

Cold start: It will not start bellow 60 F,unless you have the help of gasoline.Without heat rise ,will freeze the induction bellow the venturis.

Corrosion: Sending units,tanks,pumps,lines,carbs have to be protected by nickel.Will not corrode cylinders,pistons,rings,valves etc.

Pollution: Can be made to pollute less on HC and CO.Will release uncommon pollutants like acetone.Overall it is a clean fuel.

Timing: All engines respond better to more static advance and less total.Flame front velocity is slower.Could use cooler spark plugs if compression is raised.Same gap.

Rule of a thumb to modify existing carb:All calibrated fuel passages should be enlarged about 35%.Accelerator pump must squirt for a longer time.All calibrated air passages must also be enlarged around 15%.If the oil becomes
milky it is too rich.Use the same fuel bow level and fuel pressure.

If your line of work involves physical contact with fuel you will never want to deal with gasoline again.It is a fun fuel.Good luck.
 
#16 ·
I think johnsongrass is talking about TOTAL timing (initial plus advance), not just initial.

Thanks Paulo -- a word from the experienced always helps a lot! We have some "dual fuel" cars over here that burn gasoline or E85 (85% ethanol, 15% gasoline). That runs better in cooler climates, but is still a problem in winters with freezing and lower temperatures. Dual fuel cars have fuel injection -- the electronics sense the fuel and adjust accordingly. You can mix more gasoline in if you like. right now E-85 costs about the same as regular gasoline, and you have to burn more of it to go the same distance. there is no cost advantage, but that will change. I know that in Brazil the government made a large investment in ethanol as a fuel -- tax incentives and such for producers and sugar cane growers. It's easier to produce ethanol from suga cane (or beets) than from corn -- costs less. Our government is just now making incentives for auto makers and fuel producers. It will take us at least 10 years to catch up to Brazil -- 20 or more unless a real big effort is made (20 is more likely from what I've seen). Our goevernment and auto industry is more willing to bet on hydrogen power, which is still 10-20 years from practical production and use, maybe more. Until gasoline prices get up to $5 or so a gallon, alternate fuels don't make much economic sense because they cost more per mile (like E-85 now). That time is coming soon!
 
#18 ·
It is a lot for a street car but not for a circle track car where throttle response and drivability are paramount to whether you win or lose. Winning means you get to eat something besides Ramon Noodles tomorrow.

It's entirely possible to see a 40hp gain on a honest 600hp with better mileage and response with a custom carb built specific to your needs.

My carb builder is always within one jet size of dyno perfect after we play "twenty questions". It's hard to do that on a engine you've never even seen.
 
#26 ·
I have.
I currently have a 13:1 street car that runs E85 on a carb that I built, 750 holley DP. It took some time tuning it, had an annoying lean hesitation off idle but I finally cured that when my shop slowed up a bit and I could finally put a little effort into working on it.
I have no choke on mine, it could certainly use it on the cooler mornings though.
Right now I'm driving it nearly every day. Not sure what the mileage is, that's simply not a concern when running a motor like I am in this car. I assume it's crappy though, and would be about as crappy as gas. The nice thing is the price. An iron head SBC with 13:1 is going to need either race gas or some sort of alcohol. I last paid $3.35/gallon for E85 from a local gas station, compared to the $7.50 from a local gas station selling turbo blue.

If anyone needs help, I'd be happy to try to point you in the right direction.
Mine is a converted gas carb, no fancy billet metering blocks for mine. More an exercise in learning the carbs, the billet stuff is nice.

Regarding some of the older posts about timing......
I have extensive dyno time with alcohol (methanol and E85) vs. gas, and particularly on the lower compression stuff, you need more timing. The slow burn rates necessitate a longer lead to fully burn the fuel, simple chemistry and math there.
 
#25 · (Edited)
Setting up an engine for E85

Is it stupid to want 10hp per whole digit increase in compression? You can easily get that with E85. Pump fuel too, no putting in octane enhancer. Forget the green credentials of the fuel IT'S POWERFUL!!! :pimp: I'm currently rebuilding a British Ford Essex engine putting Mustang 200 cid pistons on V8 Mustang Con-rods. :sweat: The Essex block is heavily built it was designed to be diesel and petrol just by building it with different pistons manifolds and fuel system. Good idea but for petrol the engine is heavy 50lbs too heavy. The body is a Glass-Fibre Reliant Scimitar GTE weighs like 2500lbs.:D
 
#27 ·
Re: Setting up an engine for E85

Sounds like you had accelerator pump issues! 13 to 1 compression on on your current machine. What kind of mileage do you get? Would it be worth you making a still and making your own? Pure ethanol and a little bio-diesel will boost the energy density of the blend and the lubricity. You can get most of the makings from any Supermarket they might even give it to you.
 
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