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Well Corey, you are still thinking gasoline terms, designs, limitations, and parameters. I want to keep the waste heat to a minimum, hence running the engine hotter and vaporizing the fuel. You simply cannot do what I am working on with gasoline, and very little if anything about gasoline will fit or work in an engine such as I am building. If it doesnt have ethanol, it will not be running, you cant limp it, or squeak by on even the best pump gas, and race gas will still have issues with vapor lock and boiling over the radiator or requiring a much larger radiator. If I can utilize the heat absorbed into the engine rather than shed it into the air, I am not losing as much energy. Its not just about the combustion event, there is more to it. The entire package matters, not just one small aspect. A Cello sounds nice on its own, but its usually rather boring by itself, with a symphony the experience is quite different.

 

As I have mentioned often before, the carb has limitations on how much heat you can put in it before the fuel simply boils out of the float bowls. Perhaps if the carb was encased in a plenum box such as Paxton uses for superchargers that encloses the vents and float bowls, then it could work, but as soon as you shut it off you have the issue of vapors trying to get back out of the intake tract. So the benefit from heating the fuel with a carb is much more difficult, but I am not only dealing with carbs, I just happen to have some old cars that have them, and that is where I am starting. The carbs are sort of a baseline, to show just what we can do with slightly altered EFI reconfigured to take advantage of the cooling effect of the fuel, even when it is heated substantially.

 

Remember that E85 is the absolute most gasoline I will be using, and I will have to make changes just to run it because of the limitations with the gas in it. There is much more than BTU, calories, and other measurements of energy, they are all mostly looking at one aspect, not at the benefits of the fuel. Its like using a hammer to attempt some surgery, sure you can cut with it but it is leaving a lot to be desired as a cutting tool. The cool part about ethanol is it will run in a lightly modified gasoline optimized engine and make more power, with the drawback of more fuel consumption. You cannot run pump gasoline in an engine optimized for ethanol, it will rattle itself to death quite quickly, I give it two or three runs at WOT. That is about how long a mild 400 Pontiac with 10.5:1 with iron heads lasted on pump gas in Nebraska. After that it had flattened the upper rod bearings in 4 holes. It would have limped around for a while longer if I never opened it up or put it under load, but what use is that? If it wont get out of its own way, why bother?

 

Also I was not referring to Biscaynes, Bel Aires, or any full size cars from the 50s and 60s. More along the lines of Falcons, Comets, Valiants, and early Tempests. They could be tuned quite easily to deliver well into the 20s mpg. They still are too. The big cars werent really intended to get good mileage, and in the 70s the big cars got worse with much lower compression, highway gears, and more weight for crash protection.

 

I have a 79 Trans Am with a 403 Oldsmobile, Qjet carb, and 2.73 gears with an auto. It would run mid 14s in the 1/4 and got 21mpg on I80, around town it used more because it wasnt geared for in town, and the 403 had a compression ratio around 7.7:1, not exactly lending itself to bottom end torque and efficiency. Actually I have two of those with the same engine and trans, a 10th Anniversary with all the bells and whistles, and a black Special Edition that had power windows, steering, AC and lots of heavy crash protection like the silver one. They are between 3750 for the black one and almost 4000 for the silver one, without me. Those cars are leaving lots on the table in stock form...  and especially on gasoline.

 

There are different ways to get to the same place, it just depends on what you are using to get there and how you are doing it.

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Measuring expired carbon molecules a good measure of burn efficiency, but not of productive work.  In general the goal to create max chamber pressure for the given quantity of fuel. That is if all else was constant. But, when the fuel changes all the optimal burning conditions change. Diesel fuel vs gas vs ethanol vs propane vs NG....etc. Compression, mechanical timing, ignition timing, ignition requirements, temperature, stroke, etc. Now these changes not only to optimize burn to 99.9% thermal efficiency, but to position forces to harvest max energy of the highest possible pressure gases. That's why torque so important to high mpg. Maximizing torque for the same quantity of fuel and designing high torque around most usable speed range.

 

Ethanol needs more heat or higher state of excitation to ignite.  We attempt to meet this requirement mostly with dilution with more flammable gasoline and squirting more fuel, hoping to increase odds of combusting some molecules. This is not particularly efficient, but an easy solution to cold start. 

 

In general, as you know, ethanol burns slower and ignites harder. This surely would require an ethanol engine to run slower and have longer stroke, in general for optimum efficiency as compared to gasoline. The long slower speed longer stroke engine provides more time at tdc combustion and gaining high ultimate pressure for a slower burning fuel. Now all this counter intuitive for most high hp designs. If were about high mpg were not going to max the hp per cubic inch. The high mpg engine will be slower, bigger, high torque, and lower hp. Unfortunately, their is a compromise to this as well.....as the mechanical drag of cylinder (waste heat) is approximately the same for low hp or high hp. You are more efficient therefore with high hp. This is why large diameters so effective. For the drag surfaces, the biggest cubic inch displacement.

 

For the hp folks its all about cramming the most oxygen molecules into a cylinder to allow larger squirts of fuel. Burn more fuel = more hp.  You can do this easier with ethanol as it cools intake facilitating a slightly more dense gas.  Also, ethanol carries chemical oxygen that supports more fuel burn within the same air volume, another advantage to maximize hp. All of this not an advantage for high mpg.

 

Higher compression will promote high efficiency. Why? High compression = high temperature. High temperature excites fuel molecules to be more reactive....more explosive as the electrons almost ready for a change of state or combustion.  Compression with air is roughly proportional to compression ratio.  If you compress ambient air 2:1 you will double your chamber temperature. But, within reality, relative cold metal surfaces rob much of the heat. To minimize this go faster with rpm and have large cylinders. But, again, this is yet another formulation and compromise to efficiency. IOWs just part of the efficiency calculation. Also, high compression rates do increase cylinder drag/friction.  A test report of a  particular variable displacement test engine lost all gain of thermal efficiencies from higher compression with compression rates above 11:1. It was presented as a typical compromise. So, high compression diesels suffer with requirement of high compression mechanical drag efficiency loss to enable diesel operation. Now diesel operation as compare more efficient than Otto cycle even omitting the benefit of higher btu fuel.

 

Know the compression ratio directly multiples the gas heat.  So, starting with very cold air bad and cooling this air more with ethanol bad as were looking more to optimal burn temperatures and not really concerned of compression ratios. Compression is just a way to achieve optimal temperature.  This is why combustion so hard to manage with complex hydro carbon brew and the variability of intake air temps. This the reason Ford so effective with DI E85 as they squirt in ethanol to correct operating conditions and take some of the variability out. Effectively making gasoline operate more productive.

 

So, what am I getting at? We need a low compression high temperature diesel engine that warms up quickly to burn ethanol. We need the fuel to be at its maximum excitation to quickly flip to combustion. Enter in the low compression hot intake diesel with spark plug cold start. A air to air plate heat exchanger capable of heating intake to near exhaust temps and backing out the compression rate to achieve desired final combustion temps. Enter in the exhaust fuel boiler to heat fuel to near super critical vapor pressures to max out the ignition chemical power. 

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11:1 is the max for gasoline in a small cylinder before diminishing returns, some engines do better at 9.5:1 on gasoline, like my 455s with a 4.18 bore and a 4.21 stroke. Gasoline thinking is quite different than ethanol thinking, they overlap a bit but one will suffer the more its optimized towards the other. The most efficient static compression ratio (SCR) for ethanol is quite a bit higher and varies depending on the engine and its operating range, bore/stroke, and cam timing.

 

Not only do you get higher temperatures with higher compression, you also increase the force that pushes the piston back down the bore. With a very high compression ratio you have more force even at light throttle and cruise, its always there. Boost only comes with demand, if the load is low the boost is low thus you end up having reduced mechanical advantage from the lower SCR, and that works very well for gasoline because it doesnt like lots of pressure before it pings.

 

A naturally aspirated high compression engine gets the same advantage continuously, you dont have to add extra fuel because it is only ingesting air that falls in so it will use less fuel, when you start pushing more air in you have to add more fuel. Hence the thinking of a larger engine taking advantage of the SCR and dynamic compression ratio (DCR) rather than forcing the air in. It is already making more torque in the lower RPM range than the boosted engine, and even though the boosted engine will make more power, it will consume more fuel under load, it has to to avoid going lean and putting a hole in a piston. I like all the time rather than on demand for compression.

 

However a roots blower is all the time as it is slaved to the engine, but it has parasitic drag from the belt or gear drive, as well as from the rotors or lobes turning. So some of its power goes to turning the blower itself, an extreme example is a Top Fuel 14:71 blower, they require about 800-900hp to produce full boost at max RPM, which inst a problem since those engines are making 8000+ hp and torque on nitromethane, which has even more interesting qualities as a fuel.

 

I am not really concerned with HP as much as torque, because torque is what gets the mass moving. The actual twisting force of the engine measured in ftlbs as opposed to HP which is a mathematical equation of torque. TQ x RPM / 5252 = HP. So it will always more more HP over 5252 rpm than torque and less HP under 5252. So if an engine is making 400 hp at 2000 rpm it is making some SERIOUS TQ, right around 1050ftlbs. Conversely a small engine making 400hp at 9000 rpm isnt making much torque, only about 235ftlbs.

 

An engine making 500ftlbs from just off idle all the way to 5000 rpm is going to stomp a mudhole in an engine that is making 500hp at 8000 rpm provided the gearing is the same and the mass of the vehicle is similar. The larger TQ engine will also use less fuel than the high RPM engine to move the same mass as it doesnt have to work nearly as hard to move it.

 

We arent trying to go faster here in this thread though, so we want to maximize efficiency and minimize fuel consumption. So we want the engine to produce the maximum amount of work it can at all rpm ranges under all loads and throttle positions. If it is too small with inadequate TQ for the mass of the vehicle it will end up using more fuel than an engine with more than enough TQ to move the vehicle as it is working harder, and has a greater throttle angle allowing more air and requiring more fuel in.

 

If we can get the fuel to do more work by taking advantage of what it is capable of, then we can use less fuel. If the fuel limits us on how much TQ we can make in the usable RPM range then it limits us on efficiency. Having to rev an engine to 3000 rpm for a cruise will use roughly just as much fuel as an engine that can cruise at 1500 rpm but is twice as large. There are design considerations to that other than bore/stroke that play a part, but not as many revolutions means less fuel consumed per mile of operation. Because the low RPM engine can pull more gear than the one that needs 3000 rpm cruise, you can gear it more effectively so you reduce the revolutions per mile. For instance a 2.41 gear vs a 3.73 gear, the 500ftlb from idle to 5000rpm engine will run just as well if not faster and quicker with the 2.41 as the 500hp at 9000 engine with the 3.73s, and it will have far fewer revs per mile in doing so. It will be more than happy to loaf along at 1500 rpm at 80 mph where if the higher rpm engine tried to run at that low RPM with its diminished TQ it would be a dog, and use more fuel because it simply doesnt have the capacity to operate that low.

 

I dont always mean a 7.5L vs a 2.0L as that is pretty extreme, but even a 3.8L vs a 2.0L can have a large difference when the mass of each vehicle is the same. Once the smaller engine has the car moving it will use a bit less fuel under diminished load provided it isnt working against an inordinate amount of wind resistance, but the 3.8L will get the car moving easier thus requiring less throttle angle and fuel. Now the interesting part of this is if both the 2.0 and the 3.8 have the same bore size and only the stroke is different, the 3.8 will make much more torque at the lower RPM range than the 2.0 will with very similar flame travel and combustion efficiency.

 

Its the same as running a 400 and a 455 in the same car geared the same with the same mass, a .030" over 400 has the same bore size as a 455 but the 400 has a 3.75" crank and the 455 has a 4.21" stroke. The 455 will move the vehicle much easier and can utilize less gear to achieve the same performance. That is a bit less than 1 liter difference, 6.6L vs 7.4L and it is noticeable in operation. The idea is to match the mass of the vehicle to the displacement of the engine so it can move it just as easy as a 3500lb car with a 455 with 500ftlbs from idle to 5000. Match the mass and wind resistance to the displacement and mileage will improve over too much CID or too little.

 

Add in that an engine that is making 500ftlbs just off idle isnt using much fuel to make that power, and it is making 500ftlbs at the max RPM too so it will be making quite a bit more torque at very low throttle angles compared to an engine that is laboring to move the vehicle, it doesnt need to be WOT to get the car moving as briskly as the much smaller engine.

 

One reason why people think bigger engines will always get worse mileage and smaller engines will always get better mileage is that when big car engines like the 455 came out just as lead was being removed from gasoline, and emissions limits/controls were put in place that hampered the technology of the day to be efficient. Very low compression, cams that were designed more for emissions than for efficiency, and choked up exhaust systems. A 1969 400 converted to ethanol with its high compression and better cam timing will get much better mileage than the 400 built in 1975 or 76 would because it is making more work of the same amount of fuel. That isnt theory for me, that is something I have done as is getting 455s into the low 20s, good luck doing that with a stock one that is hampered by cam timing and crappy exhausts choking it.

 

All of this plays into why I want to vaporize the fuel rather than atomize it as I get more work and less waste heat when I do that. Just because it is burning all of it doesnt mean it is using it to produce work, it could be just heating everything around it. I would rather it worked for me and made some torque rather than heat some water. :) The smaller particles of the vapor burn quicker than the large droplets and thus produce more usable power. That happens to work much better with ethanol than it does with gasoline, so designed correctly and tuned well an ethanol engine can get better mileage than a gas engine while being smaller to make the same power, or the same size to make more power. It has to be optimized for ethanol though, otherwise the vapor will only break even or just come close to the same mileage without the compression increase and cylinder pressure from camshaft timing.

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we have many cars, running on CNG or LPG fuel.

 

and there is no benefits of geseous fuel over liquid fuel.

 

there is last generation of LPG fuel systems, using stock gasoline fuel ramp and injectors for deliver liquid LPG fuel - and those systems are much better.

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Measuring expired carbon molecules a good measure of burn efficiency, but not of productive work.

 

Ya, I thought efficiency and economy was the whole topic of this thread.  In the original post, you ask, "May this be the better technology for better mpg? "  That is what led to my example of HC emissions to demonstrate combustion efficiency is already very high.  If you're looking for max power, that is a totally different beast.

 

In general the goal to create max chamber pressure for the given quantity of fuel. That is if all else was constant.

 

Well, if we're still talking about efficiency, I would say the goal is to create max pressure *from* a quantity of fuel, though I think we're talking about the same thing at this point. 

 

But you go on below to suggest "Higher compression will promote high efficiency" then "high compression rates do increase cylinder drag/friction.  A test report ...lost all gain of thermal efficiencies ... above 11:1" then a quote about high CR diesels (presumably much>11:1) being more efficient than lower CR gas even omitting the diesel btu and finally end up saying, "We need a low compression high temperature diesel"

 

I admittedly don't have the best reading comprehension, but I got lost on this one!

 

But, when the fuel changes all the optimal burning conditions change. Diesel fuel vs gas vs ethanol vs propane vs NG....etc. Compression, mechanical timing, ignition timing, ignition requirements, temperature, stroke, etc. Now these changes not only to optimize burn to 99.9% thermal efficiency, but to position forces to harvest max energy of the highest possible pressure gases.

 

All too true.

 

That's why torque so important to high mpg. Maximizing torque for the same quantity of fuel and designing high torque around most usable speed range.

 

Well, in  a round-a-bout way, yes.  The engine puts out torque and HP is a mathematical construct of torque and time.  So maximum torque from minimum fuel is high efficiency.  The trick is not to mix efficiency with economy.  Engines are generally most 'efficient' (ie most power for least fuel) at or near the torque peak, which in turn is at or near full throttle.  But most 'economy' (best mpg) usually comes from very light throttle openings.

 

Edit - I see Thumpin added a response while I was in the middle of typing - so I would only add;

 

An engine which has a flat torque curve - while it may be fun to drive, is usually bad for economy.  It's generally accepted the BSFC (fuel consumption per power produced) follows the torque curve.  If you have a flat torque curve, it basically means you are burning nearly the same fuel at part throttle as you are near WOT.  Given the HP rises with increasing RPM, burning the same amount of fuel @ 2000 rpm / 190hp as you do @ 5000 rpm / 475hp (both instances of 500 ft lb torque), is generally pretty bad economy on the low end.

 

Ethanol needs more heat or higher state of excitation to ignite.  We attempt to meet this requirement mostly with dilution with more flammable gasoline and squirting more fuel, hoping to increase odds of combusting some molecules. This is not particularly efficient, but an easy solution to cold start. 

 

Yes, the cold start issues of ethanol are well known, but I would contend a fully warm engine at running speed has more than enough energy to ignite the ethanol. Heat of compression, turbulence in the chamber, optimizing chamber design all contribute to a very high degree of combustion with current technology.  Plus, all the exhaust gas heat exchangers you mention won't be functioning at a cold start, so you'd still need another system for that.

 

In general, as you know, ethanol burns slower and ignites harder. This surely would require an ethanol engine to run slower and have longer stroke, in general for optimum efficiency as compared to gasoline. The long slower speed longer stroke engine provides more time at tdc combustion and gaining high ultimate pressure for a slower burning fuel. Now all this counter intuitive for most high hp designs. If were about high mpg were not going to max the hp per cubic inch. The high mpg engine will be slower, bigger, high torque, and lower hp.

 

I've posted many times and several links showing ethanol burns faster than gas - this is part of the reason ethanol doesn't suffer the mpg penalty the btu's would seem to suggest.  A lot of factors change the burn speed, but all things being equal, ethanol is faster.  But I would agree larger, slower moving engines do extract max economy from the fuel.  The large crosshead engines in container ships have pistons several feet in diameter and turn a couple hundred RPM max - they are some of the most efficient piston engines in the world.

 

Unfortunately, their is a compromise to this as well.....as the mechanical drag of cylinder (waste heat) is approximately the same for low hp or high hp. You are more efficient therefore with high hp. This is why large diameters so effective. For the drag surfaces, the biggest cubic inch displacement.

 

For the hp folks its all about cramming the most oxygen molecules into a cylinder to allow larger squirts of fuel. Burn more fuel = more hp.  You can do this easier with ethanol as it cools intake facilitating a slightly more dense gas.  Also, ethanol carries chemical oxygen that supports more fuel burn within the same air volume, another advantage to maximize hp. All of this not an advantage for high mpg.

 

I don't know the hp necessarily equates to efficiency.  I guess if you limit it to the exact same engine making low hp vs high hp, then within reason the high hp may be more efficient.  Though to get very high hp, you generally need to make some sacrifice in efficiency – and you also get hurt in economy because the higher HP engine is run at a smaller throttle opening for the same power – which causes even more pumping losses, lower dynamic compression, etc.

 

But again, you originally ask about 'mpg' implying what would be most economic.  For that, you'd need a small engine running at or near the torque peak at a speed where you spend most of your driving time.  The trouble then becomes if you are using max torque just to cruise down the highway, there isn't a lot of extra power for passing, hills, etc.

 

This is one benefit to hybrids, you can run a smaller engine closer to the torque peak but still have a little electric 'oomph' (technical term) for extra power.

 

Higher compression will promote high efficiency. Why? High compression = high temperature. High temperature excites fuel molecules to be more reactive....more explosive as the electrons almost ready for a change of state or combustion.  Compression with air is roughly proportional to compression ratio.  If you compress ambient air 2:1 you will double your chamber temperature. But, within reality, relative cold metal surfaces rob much of the heat. To minimize this go faster with rpm and have large cylinders. But, again, this is yet another formulation and compromise to efficiency. IOWs just part of the efficiency calculation.

 

Yes, the higher temperature / reactivity is part of the efficiency equation.  The expanding combustion also has more time to act on the piston with higher compression ratios and acts with a higher pressure for a longer time, so that is a 'win-win-win' for higher compression.

 

Also, high compression rates do increase cylinder drag/friction.  A test report of a  particular variable displacement test engine lost all gain of thermal efficiencies from higher compression with compression rates above 11:1. It was presented as a typical compromise.

 

Do you have a link to that report?  It would be some interesting reading.  Did they give any specifics?  Gasoline engine?  E85?  Did they indicate if the compression limitation was specific to the fuel and/or engine design?  Was it limited to thermal efficiency or the total BSFC of the engine?  I know a 'law of diminishing returns' applies to compression ratio, but didn't think there was necessarily a 'wall' at 11:1.

 

So, high compression diesels suffer with requirement of high compression mechanical drag efficiency loss to enable diesel operation. Now diesel operation as compare more efficient than Otto cycle even omitting the benefit of higher btu fuel.

 

Yeah, what you said!  The best I can make out - there is a limit to efficiency at a compression 11:1 - from the paragraph above, but diesel engines (which I would expect compression of 18-22:1 or more) are more efficient even omitting the higher btu fuel?  So maybe there isn't a limit at 11:1?

 

Know the compression ratio directly multiples the gas heat.  So, starting with very cold air bad and cooling this air more with ethanol bad as were looking more to optimal burn temperatures and not really concerned of compression ratios. Compression is just a way to achieve optimal temperature.  This is why combustion so hard to manage with complex hydro carbon brew and the variability of intake air temps. This the reason Ford so effective with DI E85 as they squirt in ethanol to correct operating conditions and take some of the variability out. Effectively making gasoline operate more productive.

 

So now we're not concerned with compression at all?? I think there is more to compression than you give credit.  It's not just about optimal temperature, but getting the gas in a small enough space / high enough density to react quickly, minimal exposure to heat sucking (another technical term) cylinder walls, and also to give a mechanical advantage when extracting work from the expanding gas.

 

I would contend the two main benefits from direct injection are:

 

1)  The cylinder is completely closed when the fuel is injected.  Absolutely no fuel can leak through the exhaust valve during valve overlap.  So the overlap can be optimized for best scavenging and reduced pumping losses.  You even minimize the fuel leaking past the rings in the blow-by gas – the fuel should be burning by the time it gets near the rings.

 

2)  You can create a stratified charge with an optimal mixture near the spark plug and a lean mix near the edges of the chamber.  This tricks the engine into thinking the CR is even higher because the fuel is in a smaller space / higher density than it normally would be.  Plus, the burn can be started even earlier allowing more time for complete combustion and power extraction.

 

So, what am I getting at? We need a low compression high temperature diesel engine that warms up quickly to burn ethanol. We need the fuel to be at its maximum excitation to quickly flip to combustion. Enter in the low compression hot intake diesel with spark plug cold start. A air to air plate heat exchanger capable of heating intake to near exhaust temps and backing out the compression rate to achieve desired final combustion temps. Enter in the exhaust fuel boiler to heat fuel to near super critical vapor pressures to max out the ignition chemical power. 

 

Well, as I always say, give it a shot.  I never want to step on anyones toes for running an experiment.  But conventional wisdom is pushing for higher compression ratios, direct fuel injection combined with very precise timing over injection and/or spark events.  Ethanol auto ignites about 800F so we are capable of nearing the limit with conventional compression and injection techniques already.  A 'hot gas' intake could get you back up to these temps, but then you'd still have a low compression ratio, large volume of gas, slow burn time and less efficient power extraction from the expanding gas.  Plus, as I said earlier, if it isn't at least sequential injection or better yet, direct injection, then some of the fuel flows through the engine during valve overlap.

 

Anyway, I guess we're just talking in circles now, ...high compression...low compression...high compression....power...economy...power...etc.  And these epic posts aren't much fun to type or for many people to read, I'm sure.  So I'll probably bow out of the vapor fuel thread, but if either of you build this beast be sure to keep us informed of the progress and results.

 

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but if either of you build this beast be sure to keep us informed of the progress and results.

 

 

More of a when, but no worries I will be 100% honest and immediate with it. :)

 

Obormot, LPG and CNG is not the same as ethanol, extremely different fuels with very different qualities and parameters.  Its not just about the vapor, its about the fuel and the engine it is running in. :) If all fuels were the same, we wouldnt be having this discussion. :)

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i mean that gaseous fuel is harder to dose correctly, for proper air/fuel mixture.

espesially if it has to be pre-evaporated.

you have to control many parameters, much more, than with liquid fuel.

 

also, if you want to make mixture before cylinder, you will need big intake collector, filled with well-mixed air and fuel. it can blow, and that accidents happends very often with CNG and LPG cars, usually becouse of wrong settings on fuel equipment, or wrong sparc while valve is opened, or becouse of hot wire in MAF sensor. old and small metal collectors not very suffering, but new, big and plastic mainfolds usually brokes into pieces, and MAF and other sensor can be damaged too. this happends pretty often.

 

so, big "tank" with premixed air and fuel is very dangerous.

 

all fuel systems for CNG or LPG fuels that i saw, install and repair, was worse than stock systems for liquid fuels. (but CNG and LPG almost twice cheaper, so no one is relly upset)

 

we can call LPG as "pre-evaporated fuel" - in tank it liquid, than it evaporates in evaporatr and supply to engine in gaseous state. so, gasoline-like systems with usual "liquid" fuel rail, usual injectors and without evaporator is much better - on same fuel.

 

also we will loose cooling effect of ethanol, this efect is very good for turbocharged engines and for engines with high compression ratio.

 

CNG, LPG, gasoline and ethanol not so different - near the same energy, near the same burning speed, near the same range from "too lean" to "too reach".

 

that is why we can burn all those fuels in same engine without significant modifications.

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455 is posting to an carb large bore engine modified to run best on E85. Can't see, but he will have a better engine with better mileage. Higher CR,  benefiting from warm intake, etc. This all aligns to solve problems of ethanol. No penalty even with hot engine.

 

It does amaze me that more manifold explosions don't occur? Gas vapor and air mix, next to fire. Ethanol vapor should be safer.

 

The efficiency vs mpg, wasn't exactly posting a technical brief. Corey's post, pretty much in alignment with my thinking. However, I'm not convinced of ethanol is a fast burn as compared to gasoline. This is not settled science for me. I read mostly of slower burning ethanol responsible for the cooler combustion temps. Also, the ethanol burn in conventional gas engine misses the ultimate possible pressure because engines designed for fast burn of gasoline.  WOT efficiencies so high because they negate the advantages of diesel cycle. No vacuum and all the fuel mix is combusted and harvested for energy.

 

We all know diesel cycle engines more efficient, by far. This is my promotion, to allow diesel cycle. An Otto cycle engine for warm up, converting to diesel cycle. Ford Ecco-boost engineers working on to do this under proper conditions.  Hot air mix the ignition for fuel.  Scandia bus company has modified diesel engines to ethanol for years. They need to kick up compression to burn ethanol 28:1 and put in a ignition enhancer. They have a trade protected fuel E95 for diesel.  This 5% ignition enhancer needed to support diesel cycle and not only to denature a food grade fuel.  Knowing the diesel ignition problem with ethanol, the motivation to heat and energize the fuel. Make the fuel more capable to support diesel cycle. Heating ethanol fuel a common practice to support combustion. Ethanol loves heat.

 

The mechanical friction drag upon higher CR. That was reported early on in tests for modifying IC for ethanol. Am sure a moving target and not all engines constant. But, we know the compression ring designed to accept pressure upon top side to push outward with more force. Like "O" ring gland design.  More pressure more force, more drag. I would guess, the piston travel the biggest friction waste?

 

The original link to VFIS patent paper, mentioned the ability to lean burn. I would think this is accurate. But in diesel cycle this is not as important as we squirt in the desired hp.  Analogy of wot throttle and coasting with engine off of Otto cycle. IYKWIM.

 

Ya, I'm suggesting a small DI heated fuel/heated intake diesel operating at constant speed (max torque). A long stroke, big bore, (maybe turbo), diesel  run as hybrid. That would be attractive and more cost effective if used for home and auto needs.  The engine module hooked up co-gen heat use for home heating needs and power.  Probably a V twin with 25-50 hp.

 

Utilize the cooling water and exhaust for co-gen hot water home heating needs such as the "Polar" company design. A PTO for powering a heat pump and hopefully a catalytic converter to harvest some chemical heat. Should be very cost effective.

 

Farm and industrial engines may be a good application of this technology, such as a non hybrid neat ethanol diesel? Farmers need a ethanol diesel tractor fueled by their own farm scale (pallet class) ethanol plant.

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I love listening to you guys "talk shop"... just wish that there was some way to fund hard core experimentation into these ideas, get them off the forum board, into the shop, and out on the street...  eventually into the factories and in production cars... 8)

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Innovation, the life blood of countries future. We should promote that as much as possible. I hear you.

 

Another thought. All this combustion engineering technology stuff really a few pay grades above us all. The real titans of this technology have PHDs and only a few practicing ones out there. Ricardo was able to snag a few from the auto companies. But, having said that, many a breakthrough demonstrated upon test stand with out the enormous R&D simulation efforts. The heat and thermal guys often appear to be using data generated from past technology. They seem to be handicapped when reaching for the rule book, like driving a car forward only viewing the rear view mirror.  Interesting that the MIT professors had an idea and relatively quickly strapped on twin turbos and modified a conventional engine to DI of ethanol. Why wouldn’t they merely reach for thermal book rulebook and convince everyone of their superior solution? No test stand needed. Note it took Ford how many man years of development to make the technology practical, cost efficient, reliable and meet pollution standards?  Can only imagine. Actually, the real challenge is pollution control. The technology is more concerned of this. Conversely, they could produce big gains in performance and/or mileage with unacceptable pollution.  Wildcatters of engine modification don’t concern themselves of pollution. They can get good results, but the technology wouldn’t ever be commercial.

 

You have read the technology of auto, more advanced than computing of NASA moon adventure. Not to long ago, the technology for mass flow meter was undiscovered. This developed into oxygen sensor and accurate measuring of exhaust gas upon molecular size. Currently, R&D upon sub molecular science. They understand the science better at this level. Appears the nano carbon particles to impact even IC engines.

 

A thought on pollution control. The EPA doesn’t concern itself with quantity of pollution.  Meaning you could have a locomotive engine in your car using buckets of fuel, that’s all right if the pollution stream is dilute. But the EPA would never approve a puny model air plane engine, using a thimble of fuel if it was a breakthrough technology capable of doing so….if the engine  had higher concentration of pollution upon waste stream. Does this sound a bit nutty way to minimize the countries pollution? I guess the government agencies never worry of cost effective or practical….only rules and politics.   

 

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