[IamIan]

Originally Posted by mja1

higher temperatures are needed to 'vaporize' a higher pressure fluid.

Only if you want to vaporize the liquid under the high pressure ... as apposed to the whole world that uses the pressure difference between high and low pressure to kinetically vaporize the liquid.

If anything the fuel from a high pressure EFI system drops in temperature as it vaporizes in the kinetic vaporization when it moves to the lower pressure... and it still vaporizes just fine.

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I don't have to raise the temperature on a paint gun that vaporizes liquid paint despite it using higher pressures.

I don't have to use higher temperatures for the humidifier that I have that vaporizes water with pressure.

The world over and over again in a wide variety of applications vaporizes liquids by using higher pressure.

You seem to be claiming that those devices can't possibly work without some type of heater ... which they don't have.

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Also ... it doesn't stay higher pressure ... there is a pressure difference between the fuel and the combustion chamber it is going into ... that pressure difference is what causes the force that moves the fuel mass ... lower pressure difference means less mass moves ... try to see how much vaporization you get on a paint gun using your theory of lower pressure causes more vaporization ... hint it doesn't work that way.

Originally Posted by mja1

the cam grind and intake/exhaust lobes are the only timing is needed in a gas engine that has no spark.

Originally Posted by mja1

Concept to think about - the same volume of fuel either by carb or EFI. We don't want to control any fuel timing, therefore we want the fuel to vaporize as quickly as possible, carb is the key.

(bold added above)
You can't have it both ways.

We want timing or we don't ... hint ... to avoid fuel being used during the other 3 non-power strokes in a 4 stroke cycle ... yes you do want timing.

Additionally the combustion event is not instantaneous ... it takes time to happen during the power stroke ... which means we have other timing desires as well.

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Without your self contradictory statement on timing ... the only thing left is how fast we want the fuel to vaporize.

I'm not 100% sold on the idea that we always want it to vaporize as as quickly as possible ... we want the best combustion event ... that is not necessarily always from a uniform fuel / air mixture ... it is also not necessarily always from a specific degree/% of vaporization.

Can you at least provide one real world example that agrees with your claim of more vaporization from lower pressures? ... as of right now ... it disagrees with what I've seen in the real world from real world devices... low pressure liquid water coming out of a hose doesn't vaporize nearly as much as it does if the same liquid water at the same temperature is at a higher pressure... the low pressure water just kind of flows out as a liquid barely vaporizing at all.

Originally Posted by mja1

right because PV=nKbT, where the pressure of a gas has nothing to do with temperature. Or avg vel of gas <v^2> = or prop. to: KbT where KE depends only on temperature have nothing to do with eachother, and neither does pressure

roll your eyes all you like ... I'll take the side of proven thermodynamics ... and I think it's a solid position.

The maximum possible efficiency of any heat engine is = 1 - Tc/Th ... the Tc is the cold part of the cycle ... when you increased the engines Th you increased the difference between them and that alone increased the maximum possible efficiency.

The ideal gas law equation you quote is separate from the efficiency of the engine... although it also seems to disagrees with you previous claims on lower pressure vaporization.

Originally Posted by mja1

engine efficiency is not directly related to gas mileage. Top fuel or F1 engines are extremely efficient.

It can be once we know enough about the context the MPG was achieved... which is why the context is important.

For example the Fiero of your link has a known CdA so if we know the vehicle speed relative to the air , we can calculate the energy lost to wind resistance for given wind conditions... it has a known weight ... if we put on it tires with a known Crr we know how much energy it lost to rolling resistance... if we know the elevation is not changing than there is no energy spent on gravity ... etc.

So if in the link you provided we assume he averaged ~50 MPH on flat ground with no wind ... we know reasonably well how much energy it would take to accomplish that from gasoline ... gasoline has a known energy content per gallon ... which means we know he was no better than about ~24% efficient if those assumptions are true ... of course if he averaged a slower speed than that than he actually had a lower efficiency... I doubt he average much higher than that ... especially considering the language used of 'as high as' ... for all we know that 51MPG could have been his best case that he got under slow P&G conditions ... the kind of conditions that people got 164MPG for 2,254 Miles out of a Gen-1 Honda Insight... context always matters.

~24% efficiency is fairly good ... I congratulate his efforts ... but my OEM spark ignition EFI ICE does better than that... and supposedly he was running the complete system you are describing.

Originally Posted by mja1

hopefully we are both talking about gasoline engines, most of these are technical/research examples that we have.

There are gasoline fueled engines that run without sparks.

I'm fine with research examples ... especially is the technical details are well documented.

Originally Posted by mja1

It cannot be directly injected just previous to the intake runners, the fuel will be much too cool.

I didn't specify locations ... just that EFI and not using a spark are not mutually exclusive things.

Also ... I'm a bit fuzzy on what type of setup you are describing ... EFI can be put just about anywhere along the fuel delivery system ... although if you put it some places it isn't direct injection anymore... and of course some locations have certain advantages.

Originally Posted by mja1

There is nothing revolutionary about it, I said there wasn't, it has been done multiple times.

I didn't mean revolutionary as in not having been done ... I mean not revolutionary as in your links final result of about ~24% efficiency is above average maybe ... but not particularly high by modern standards.

Originally Posted by mja1

Using EFI as the main fueling source cannot be in any way beneficial if the intake valves control a vaporized intake charge of a specific volume of gas (fuel/air). In this example only.

What specific example are you referring to?
Your ~24% efficient Fiero example?

I don't agree with your absolute language ... but ... I'll digress on that for the moment... at least pending clarification on what example you are referring it to.