Ive been reading that to build an engine to take full advantage of e85 or LP that the compression should be bumped to 12-1 or so. So would it not make sense to use those two fuels instead of gasoline plus either?

Ive got a 72 351w going in a 64 f100. And dont want to run regular gas for many reasons. So would that be a better dual fuel setup? As far as the engine is conserned.

 

Interesting. In theory, I would have to say go for it. An old-tech carb'd engine could easily be modified. Up the compression with pistons and/or head work, jet the carb for E85 and install the LP setup on top. You will need to play with spark advance curves to optimize efficiency and detonation is a danger if you are actually going to work it hard, since there is no knock sensor and computer to control the timing. Combustion chamber shape with good quench area helps. Sorry, Im somewhat ignorant about 351W specifics in that area, but it is basically a stroked 302, which is better than a big-bore engine as far as detonation is concerned.

 

I have been thinking along the same lines for my highboys 390. lp here is sitting at 2.61 instead of 3.23 for gas. unfortunately all the info that is available isn't geared towards economy. and theres more to it that just octane numbers. gas, lp, and e85 are three very different fuels that have very different effects on the engine (IE: lp is already in gasous state and ethanol has a cooling effect)

however I fully agree that using them together instead of gas+another makes alot more sense.

 

i have david vizards "performance with economy" and not finding anything there either about specific changes (other than the carb) to the engine

 

AKI or "octane" is a valid test for detonation resistance valid for all. For maximum economy you want to run as high a compression ratio as possible without detonation, and not just use sloppy over rich jetting to protect the engine, but good spark advance control. LP is different in that you need to run in a narrower band of mixtures for it to light off. Misfire can be more of a problem if its not set up correctly.

 

thats why i started looking into the racing side of things. those guys are running e85/98 as cheap race gas, it has most of the same qualities as meth but not such a chemestry project. and they of course are looking to get the best bang every time. the better they use it the faster they go, on the same token the better we can use it the further we can go.

thats what irks me about the oem sector, they just get lazy, o you can run e85 but ha ha itll cost you in the long run.

forget that ... ok enough rant

good spark advance control? better than a stock distrubitor? as in msd brand good or just different than stock?

with higher compression does the major need for more fuel go away. allowing me to keep the little 2 barrel?

 

Its not that the OEMs are lazy, its just that "Flex Fuel" requires that the engine run flawlessly on 87AKI straight gasoline as well as E85. That means lower compression ratios than optimum.

I know little about stock Ford pre-computer distributors. My experiences with old VW's. Straight mechanical advance "high perfromance" distributors are terrible for mileage or part throttle drivability, let alone emissions. They are only good for race engines where the gas pedal is treated like an on-off switch. Combined mechanical and vacuum advance distributors have a basic mechanical advance to keep you safe from detonation if timed properly, then add extra vacuum advance at part throttle for economy.

MSD, I dont know. I suspect its more of a high rpm race setup.

If after economy, a small 2bbl is fine. It still has to be jetted for E85. All a 4bbl really does is combine two small 2bbl carbs in one housing, opening the second one only on demand.

 

OEM's also know that alot of people aren't gonna run the e85...

I have a little spark box that i got a while back called a megajolt jr. cost about 100 bucks, deletes the need for a distributor, and lets me put EDIS on pretty much anything I can mount the crank trigger on (the only other things that are needed are the edis module, coilpacks, 36-1 trigger wheel, crank sensor and wires). best thing is that its fully programmable, and that two different spark tables can be switched between with a switch on the dash. would be nice if you could hook it up to a TFI dizzy and have it control the curve like an eec-iv computer would.

with using a stock style distributor you would need to figure out beforehand about what you want your timing curve to be, buy a recurve kit and swap out the weights and springs until the mechanical advance curve was how you wanted it, maximum vacuum advance can be adjusted on alot of dizzy's. however when you want to tweak your curve, your going through the whole process again. there are a few shops out there that still have old sun distributor machines that can figure out what the curve is for you with the dizzy out of the car.

a bit hotter of a spark is needed since the compression makes it a bit tougher for the spark to jump the gap. and IIRC ethanol likes to blow out the spark a bit easier too, or something like that. but most of it is in the curve.

forgive me, but I don't think that your thinking for running a 2bbl carb is quite right. adding to what jimandmany said, regardless of how big the carb is, the engine is still going to need that 9.6:1 (or whatever it is) air/fuel ratio when running ethanol.what the higher compression does is increase the volumetric efficiency of the engine, making it a better air pump. technically if you could get it to run without detonation, it would run way better on gasoline.

so even though with each pound of air your engine is ingesting more ethanol than it would gas, the higher volumetric efficiency means that your not running the engine as hard to do the same amount of work, which is where it *should* even out.

what does matter with carbs is the actual throttle bore size. quadrajets have an underground following because their primaries are so small that air flows really, really fast through them, which means that the carb can be much more precise with how it gives the engine fuel. a quadrajets primaries look about the right size for the 144 in my falcon! but the secondaries are big enough to drive a mack through.

IIRC the biggest ford 2bbl flowed 434cfm and the the most common slightly small one flowed just more than 350cfm, and then think about what that 500cfm edelbrock is when you don't have your foot on the floor!

on another note, I had a 500 cfm holley 2bbl on my capri for a couple months. with it tuned to the best of my ability it run way to rich at idle (it would start flooding idling in denver traffic) but would get a lean misfire when i ran it hard, an got better fuel economy at 85 than it did at 45.

on yet another note, the MSII for my bronco can be hooked up the a gm style flex fuel sensor and can adjust fuel and spark for any mixture of gas and ethanol, however the compromise would still be the compression ratio.

I'll step down now, I had a bit more time this evening!

 

Well sounds like the 2100 is not easy, if possible, to convert. At least i havent found anyone thats done it. Is there an oem option that i may find in a junk yard, since ill be moddifing it anyway. Not to picky on 2/4 barrel, never messed with 4 bbl. Im assuming they can be more finely tuned. Which means more options, and i can find whats best for my drive style. Correct?

Dosnt the carb shut down to a minimal flow no matter what the max flow is? I thought there was a bigger variation (0-500cfm) not a higher range (200-500cfm).

Please excuse my ignorance. I want this to work but cant/ dont want to buy super expensive specialty parts.

As usuall thanks for the words of wisdom!

 

haven't ever heard of any oem carbs for ethanol, but pretty much any carb can be modified to do so. here's a link thats covers modifications: Adapting your engine for ethanol

the nice thing about aftermarket 4bbl carbs is that there are parts available, if not a complete carb available if your gonna buy a new one, for it to be ready for alcohol. half of it is more flow needed, the other half is that ethanol will destroy regular rubber hoses, float needles, etc.

not sure if i get what you are referring to on you second statement...

 

you made it sound like the bigger carb was always flowing strong. like the idle was too high beacuse it was to big to flow the lesser amount.

i thought a small carb would flow from 0 to 350 cfm and a large would flow 0 to 550. i know its not 0 but close.

your post sounded like a samll carb would flow 0 to 350 and a large would flow 200 to 550. there by running rich in traffic and part throtle.

i feel there is a good chance my youth is showing through. please correct if i'm wrong.

 

no, no you are right. sorry about that, i'm horrible at English!

any and every carb will only flow what the engine needs. a 1000cfm carb on an engine that can only flow 500 will only flow 500 with the throttle wide open. for example, your 351 will have to spin faster than 6000rpm in order to flow 600cfm.

that little holley 500 I had just flowed way more fuel than it should have through the idle circuit.

the problem with a bigger carb is that it doesn't flow that strong. there is so much more area that the same amount of air is flowing through, that air is moving alot slower. if the air is moving too slow, the carburetor can't meter the fuel well enough.

on another note, have you ever drove a vehicle with a really touchy throttle? a smaller carb (or smaller primaries) is less likely to be like that.

i'm not sure if that was any better in all honesty...

don't worry about being young, its just good that your asking questions. i'm actually probably not much older!

 

That was much better! And it agrees with what an engine builder told me yesterday. For torque on the 351w i want a little fuel flowing very rapidly through the system. Unfortunatly he dosnt like the idea of e85 for street use and seems very reluctant to touch such a project. Seeing as im not looking to take 600* hp 1/4 mile at a time he didnt see any benefit to e85. And if ill just be burning 30-40% more fuel to do the same work then i may not bother either. Not even from a financial view, this truck has a small tank already and dropping the mileage that much means id have to strap a drum in the bed to get anywhere.

Needless to say that kinda took the wind out of my sails. But im not done yet!!!

Also this guy said i should drop compression to run ethanol????? That statement alone made me think i should keep looking for a builder.

Any thoughts, thanks for your help and paitence with me.

 

That last statement also puzzles me about E85 compression. He doesnt understand something. He is right about burning more fuel. I doubt if hiring an engine builder would ever pay off. This is more of a home tinkerer-experimenter type of project. Use outside resources only when absolutely necessary. If the engine is shot, then just get an ultra high compression rebuild, without all the other race stuff. You want stock cam and valves with small ports for maximum velocity. Going for maximum volumetric efficiency is a waste if you are not running wide open throttle most of the time.

Maybe I misunderstood your goal. I thought is was to run LP most of the time and E85 in a pinch, but eliminate the ability to run E10 in order to gain full benefit from LP. Both should have an AKI of 101+. Since no E85 is sold near me I have no idea what is costs or the posted AKI. E85 energy content per gallon (71% of gasoline), Propane (74% of gasoline). Straight ethanol is about the same as CNG. (66% of gasoline). You need to do the math on costs.

You really need to read this in order to understand the basics of different fuels. Shorter range is a tradeoff with alternative fuels, thats why long haul fleets still use diesel. CNG, LNG, LP and electric are only used inside a factory or around town.

Propane Facts & Comparison Charts

 

originaly lp was the #1 goal, it kinda shifted though. now, in order, i'm thinking build the engine to run the dual setup, run e85 for now and when funds and parts become avaliable put the propane system on.

in any case the more i think about the shop, he was a jerk and didn't seem to want to do it. which sounds like lots of problems if i hand him my block.

i mentioned range beacuse the shop said i'd lose 50% milage. which means if i want to take it to work and back, the tank would have to be filled in morning before going. and theres only a 50 cent difference at the pump. between gas and e85. leaving me wondering why anyone would use it. the wondering continues on to he must be wrong, not understand, never attempted to try, or just be stupid. beacuse people are using it, and it's working. sooooooo i'm trying to pretty much ignore what he said besides the 351w oiling issues.

in any case if i'm going to tear the engine down it'll have to be machined, i've got a 302 that smokes and over heats and a 351 junkyard engine.

which leads to a good question. with e85/ lp in mind, for a '64 truck that'll mainly be used for crusing and menards runs. in stockish form 302 vs 351 and t18 (basicly 3 speed 2x4) vs m5r2 (5 speed 4x4). which combo would benifit most?

as i'm sure you can tell, i just ran in a mental circle