318 MAX fuel economy builds?

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mpgmike said:
Since this is a thread on improving fuel efficiency, that's probably irrelevant. The discussion about vaporizing the fuel too soon relates to hurting Volumetric Efficiency due to the additional room vaporized fuel occupies. This was a major concern when the restrictor plates were first introduced to NASCAR. You have to consider "The Precious Commodity".

In an all-out performance application, the precious commodity is air. If you need more fuel, you can pour liquid fuel into an engine and drown it. Air, though, is limited by what can squeeze through the throttle blades, through the ports, and past the valves on the intake stroke. Thus, air is the precious commodity.

In a fuel economy application, fuel is the precious commodity. If you need more air, simply open the throttle a bit more. Vaporizing as much of the fuel as possible, as soon and quickly as possible improves Combustion Efficiency (perhaps at the expense of Volumetric Efficiency).
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I agree. But HOW you get that done is critical. You can vaporize the fuel the wrong way, at the wrong time and hurt power and fuel consumption, especially with pump gas.
 
Hysteric said:
Where does all that atomizing take place?.......Not only that you use a large port with a Large valve and Large carb with a Large runner intake manifold and couple that with a late intake valve closing point so you don't actually compress the mixture all that much. Where's all that over vaporization you're talking about happening?

In the Exhaust perhaps?


Great post. That said I've come across many "underheaded" engines combos that defy convention in regards to how much power they make for how much air they ingest.
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I‘m talking about heated intake manifolds and then over atomizing the fuel at the booster.

You know this. Why argue it?
 
Rat Bastid said:
I agree. But HOW you get that done is critical. You can vaporize the fuel the wrong way, at the wrong time and hurt power and fuel consumption, especially with pump gas.
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Could you provide an example of doing it right, and another example of doing it wrong?
Rat Bastid said:
I‘m talking about heated intake manifolds and then over atomizing the fuel at the booster.

You know this. Why argue it?
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Could you explain the detriment caused by over atomizing fuel at the booster?

I'm open to learning new stuff.
 
mpgmike said:
Could you provide an example of doing it right, and another example of doing it wrong?

Could you explain the detriment caused by over atomizing fuel at the booster?

I'm open to learning new stuff.
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I can give several examples of doing it wrong, but the best one is a Ford 460 in 1988. Last year for a carb.

I can’t remember the Holley list number any more, but Ford had so much heat moving under the carb it would coke the fuel in the manifold. The piece of **** would barely run after 20k miles.

I pulled the intake, blocked the heat crossover and it picked up 3-4 MPG when towing my race car. At one point it was down to TWO MPG. At best I got it to 10.

Straight junk. That’s what happens when you use heat and too much booster. It wastes fuel, loses power and is just garbage.

Of course, in about 10k it burned through the stainless steel block off plates and the fuel consumption went up and power went down.

I almost, ALMOST put an aftermarket manifold on it (would have been aluminum and I would have welded the cross over shut) but I hated that piece of **** so bad I traded it for a 1990 Dodge.

Thats just one example of not getting the fuel atomized and vaporized correctly.

There are certain people who believe that you MUST vaporize the fuel because of what someone wrote, and thinks it is THE factor in distribution (its not) and that you can never get the fuel too finely atomized and then vaporized too soon.

Ever wonder why most guys pick up when they switch to alcohol over gasoline? VAPORIZATION.

Its that simple. Guys run way too much engine temp on gasoline, which vaporizes the fuel too soon and kills some power. Alcohol loves engine temp. 2.5 times the fuel volume requires as much heat as you can get to vaporize the fuel or it just runs into the chamber and out the exhaust.


I tried everything from 6 or 7 different MFI nozzles to as high as 140 PSI at the nozzles and no matter what, you can’t get enough vaporization with alcohol without 180 plus degrees of coolant temp.

I‘m not certain that a water heated intake manifold wouldn’t benefit alcohol fueled engines.
 
Rat Bastid, you make some excellent points. I can see how poorly atomizing the fuel at the carburetor, having very poor velocity through the induction system, dumping unreasonable amounts of exhaust gas into the plenum, then trying to band-aid it by super-heating the plenum floor could cause coking issues. I suspect the coking was the carbon particulate in the EGR blending with the gasoline aerosols first, then burnishing to the plenum floor. Also, gasoline is a blend of hydrocarbons that vaporize anywhere from 156 degrees F (Hexane) upwards of 420 degrees (dodecane). Alcohol, on the other hand, has a fairly consistent vapor point of a mere 180 degrees. The heavy elements in gasoline (decane, undecane, dodecane...) make consistent vaporization more challenging. We are painfully aware of the lousy engineering that sprang forth from the OEMs in the 1970's & 80's. Point well taken.
Rat Bastid said:
There are certain people who believe that you MUST vaporize the fuel because of what someone wrote, and thinks it is THE factor in distribution (its not) and that you can never get the fuel too finely atomized and then vaporized too soon.
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I believe in the case of your 1988 Ford, the fuel wasn't vaporized soon enough! Vaporized gasoline cannot possibly coke up the plenum floor, only liquids can.
Rat Bastid said:
Its that simple. Guys run way too much engine temp on gasoline, which vaporizes the fuel too soon and kills some power.
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Here I must differ in opinion (after all, both of us are merely espousing our opinions). Engine temperature will have a significantly greater impact on in-cylinder vaporization than "vaporizing the fuel too soon". "Too soon" could happen in the carburetor, but that isn't influenced by engine temperature. It could possibly happen in the intake manifold, which is somewhat influenced by engine temperature. However, the only reason "too soon" might be an issue here is if Volumetric Efficiency at WOT is the primary goal.

To run with what you stated, there is a right way and a wrong way of doing things. I have seen where folks have heard about a concept, attempted to make it happen their own special way, only to fail miserably. I guess that is what you were alluding to earlier.
 
Rat Bastid said:
There are certain people who believe that you MUST vaporize the fuel because of what someone wrote, and thinks it is THE factor in distribution (its not) and that you can never get the fuel too finely atomized and then vaporized too soon.
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You mean this guy:

"Unfortunately proper vaporization doesn't occur in most engines. The issue of vaporization is not fixable by any other means other than managing the energy input to the fuel prior to ignition. Firstly lets distinguish vaporization and atomization. Vaporization is liquid turning into gas, atomization is essential to achieve that in a short time period. I mentioned managing the energy input, the atomization achieved is essential to maximizing the energy input during the intake system and the energy exchange within the cylinder on intake and compression. The whole process of combustion relies upon vaporization.
Petrol or gasoline is a complex mixture of hundreds of different types of Hydrocarbons and some other chemicals in minor concentrations. The Hydrocarbons are the ones of interest. With pump grade sold for the street use unleaded fuels the boiling point of these Hydrocarbons varies from approx 110F to 430F depending on brands etc. Racing fuels boil from 120’s F to 220-260’s F as a general average across brands. Some brands are way different to this but most are similar. By observing some of the difference between street fuels and race fuels you can see that the race fuels are easier to vaporize, they boil completely away into gas at lower temperatures than street fuels. This is a desirable feature for maximum combustion efficiency. You can obtain the various distillation fractions for racing fuels from the manufacture’s websites. A distillation fraction of 10% at say 120F means that 10% of the mass of the fuel will be converted into a gas at the temperature of 120 degrees F. If the temperature to achieve 10% is higher, then that means that the particular fuel requires more energy to gas up the lightest HC’s of its makeup. The other side to this is considering a fuel that has a 90% distillation temperature of 350F and a second fuel with a 90% distillation temp of 230F. The first fuel is not going to be easy to convert the heavy HC’s into a gas for burning whereas the second fuel will be. The first thing to realize from all this is that different fuels achieve different vaporization % at the end of the process.
Unleaded street fuels are very hard to gas completely so why do people expect their hotrod engine with a short compression stroke because of the valve timing to have enough compression energy etc to vaporize unleaded street fuel?
 
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Hysteric said:
You mean this guy:

"Unfortunately proper vaporization doesn't occur in most engines. The issue of vaporization is not fixable by any other means other than managing the energy input to the fuel prior to ignition. Firstly lets distinguish vaporization and atomization. Vaporization is liquid turning into gas, atomization is essential to achieve that in a short time period. I mentioned managing the energy input, the atomization achieved is essential to maximizing the energy input during the intake system and the energy exchange within the cylinder on intake and compression. The whole process of combustion relies upon vaporization.
Petrol or gasoline is a complex mixture of hundreds of different types of Hydrocarbons and some other chemicals in minor concentrations. The Hydrocarbons are the ones of interest. With pump grade sold for the street use unleaded fuels the boiling point of these Hydrocarbons varies from approx 110F to 430F depending on brands etc. Racing fuels boil from 120’s F to 220-260’s F as a general average across brands. Some brands are way different to this but most are similar. By observing some of the difference between street fuels and race fuels you can see that the race fuels are easier to vaporize, they boil completely away into gas at lower temperatures than street fuels. This is a desirable feature for maximum combustion efficiency. You can obtain the various distillation fractions for racing fuels from the manufacture’s websites. A distillation fraction of 10% at say 120F means that 10% of the mass of the fuel will be converted into a gas at the temperature of 120 degrees F. If the temperature to achieve 10% is higher, then that means that the particular fuel requires more energy to gas up the lightest HC’s of its makeup. The other side to this is considering a fuel that has a 90% distillation temperature of 350F and a second fuel with a 90% distillation temp of 230F. The first fuel is not going to be easy to convert the heavy HC’s into a gas for burning whereas the second fuel will be. The first thing to realize from all this is that different fuels achieve different vaporization % at the end of the process.
Unleaded street fuels are very hard to gas completely so why do people expect their hotrod engine with a short compression stroke because of the valve timing to have enough compression energy etc to vaporize unleaded street fuel?
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I don’t disagree with ANY of that. But those aren’t YOUR words.

I’ll say it again. Just jamming a bunch of highly atomized fuel out of the booster and not considering the rest of the system is a bad policy.
 
mpgmike said:
Rat Bastid, you make some excellent points. I can see how poorly atomizing the fuel at the carburetor, having very poor velocity through the induction system, dumping unreasonable amounts of exhaust gas into the plenum, then trying to band-aid it by super-heating the plenum floor could cause coking issues. I suspect the coking was the carbon particulate in the EGR blending with the gasoline aerosols first, then burnishing to the plenum floor. Also, gasoline is a blend of hydrocarbons that vaporize anywhere from 156 degrees F (Hexane) upwards of 420 degrees (dodecane). Alcohol, on the other hand, has a fairly consistent vapor point of a mere 180 degrees. The heavy elements in gasoline (decane, undecane, dodecane...) make consistent vaporization more challenging. We are painfully aware of the lousy engineering that sprang forth from the OEMs in the 1970's & 80's. Point well taken.

I believe in the case of your 1988 Ford, the fuel wasn't vaporized soon enough! Vaporized gasoline cannot possibly coke up the plenum floor, only liquids can.

Here I must differ in opinion (after all, both of us are merely espousing our opinions). Engine temperature will have a significantly greater impact on in-cylinder vaporization than "vaporizing the fuel too soon". "Too soon" could happen in the carburetor, but that isn't influenced by engine temperature. It could possibly happen in the intake manifold, which is somewhat influenced by engine temperature. However, the only reason "too soon" might be an issue here is if Volumetric Efficiency at WOT is the primary goal.

To run with what you stated, there is a right way and a wrong way of doing things. I have seen where folks have heard about a concept, attempted to make it happen their own special way, only to fail miserably. I guess that is what you were alluding to earlier.
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Actually the coking was fuel that was being almost consumed in the plenum. And, the intake was so F’ing hot that the cast iron was bright blue AND engine oil was coked all across the crossover.

Just an idiot, stupid thing. There isn’t a carb in the world that could function like that.
 
OK, a combination of too much heat hitting the plenum floor, generous EGR (perhaps), and lots of heavy stuff coming through the PCV port. It helps to diagnose the cause of issues and not just band-aid them over. Would less heat in the cross-over have hit the sweet spot? Was there excessive blow-by where a PCV catch can would have resolved it? Could a better carburetor (look at the praise the T-Quad gets on this site) have made things better?? The outcome was obvious, but I'm curious about the diagnosis and fix.
 
mpgmike said:
OK, a combination of too much heat hitting the plenum floor, generous EGR (perhaps), and lots of heavy stuff coming through the PCV port. It helps to diagnose the cause of issues and not just band-aid them over. Would less heat in the cross-over have hit the sweet spot? Was there excessive blow-by where a PCV catch can would have resolved it? Could a better carburetor (look at the praise the T-Quad gets on this site) have made things better?? The outcome was obvious, but I'm curious about the diagnosis and fix.
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This was way before EGR and has nothing to do with the pcv system (which is just a closed crankcase vent system)
 
toolmanmike said:
This was way before EGR and has nothing to do with the pcv system (which is just a closed crankcase vent system)
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EGR wasn't used by 1988??? If PCV is a "closed system", where do the 2 ports on the valve covers connect to?

EGR certainly was used by 1988. PCV vents to the air cleaner, then the PCV valve draws blow-by gasses into the intake manifold at the base of the carb. What am I missing here??
 
I see it now, RB was talking about a coked up intake on a 88 460. I saw "Ford" and thought of something older and most of the ford v8's were coked beyond belief.
 
14 pages and the original poster still doesn't have much of an idea on how to improve his mileage.
 
Ceedawg said:
One other thing that happened to my van that had the millage up to 16 mpg. I was chasing a problem with the engine not running right, changed every part at least twice. It would buck jump under the slightest hill climb, regular hill no problem, maybe a 2% grade. Well by chance I changed the crank sensor, bam ran like a top but then after that came the 12 mpg. Still trying to figure how that sensor caused that difference because it’s only picking up a signal when to fire. Any ideas guys? Can’t find that dang sensor to retry.
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One thing that comes to mind is whether or not the replacement crank sensor is indexed to the crank in the same place.

If you want to play around with it you can slot the bolt holes in the crank sensor to move and it will advance(or retard) the timing signal that the computer sees.

If you choose to do this couple things to check- make sure whatever little paper cover on the end of the sensor is completely removed from the end. Also make sure the sensor isn't covered in oil.
 
Rat Bastid said:
Lets. Get off the atomize/vaporize the he’ll out of everything and calling it the only thing there is.
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Now that you've ruled out improving atomization and vaporization for improved combustion efficiency what are you suggestions for the Op to accomplish his goals?
 
Hysteric said:
Now that you've ruled out improving atomization and vaporization for improved combustion efficiency what are you suggestions for the Op to accomplish his goals?
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That’s NOT what I said. Not even close. You see, that’s YOUR issue. You read something and become fixated on it.
 
I believe all the simple & sensible things for better economy were mentioned earlier in this thread, with names &/or part numbers supplied:
- an efficient low rpm intake
- a small carb. If using a 4bbl, one with small primaries like the 800 TQ
- a specific mileage cam
- headers & dual exh
- etc
 
mpgmike said:
EGR wasn't used by 1988??? If PCV is a "closed system", where do the 2 ports on the valve covers connect to?

EGR certainly was used by 1988. PCV vents to the air cleaner, then the PCV valve draws blow-by gasses into the intake manifold at the base of the carb. What am I missing here??
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I’ll have to say my 1987 E350 Ford van with the 460 bought new and has 49,890 miles. Replaced the intake gaskets back 17 years ago, removed engine to replace some freeze plugs, removed the pumps and egr tubes at the same time. Rebuilt carb 3 months ago (sat for two years without starting) runs great and never saw any coke. Changed oil after 12 years, 9-10 mpg but it’s payed for itself a long time ago so I’m ahead of the game big time. Still has same trans fluid, rear fluid and brakes, I did change water pump a few years back. Hardest thing was finding the matching belts. Just put 6 new tires on, 23 years on that set, still great tread but dry rotted.
14’ utilmaster box van I deliver cabinets in to job site
 
mgoblue9798 said:
Ok, so what are your ideas on how the OP can improve the fuel mileage of his build?
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Go back and read the quote Hysteric posted. Read it VERY CLOSE. If you do that, you’ll see why I’m critical of him and how he uses other peoples words to try and make his pet theories sound plausible.

It pays to READ what Shrinker says, but use your God given brains and your logical thinking to correct the issue Shrinker is discussing.

I do NOT build for fuel consumption per se. It’s part of the build process of making horsepower. You can’t make horsepower without burning fuel.
 
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