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Old 11-22-12, 0:37   #16 (permalink)
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My thoughts (and theoretical recipe) are as follows:

E-85 for relatively low (and homogenous) boiling point, high octane properties, long-term supply availablity, and convenient fuel density (ie, no pressure containers, cryogenic tanks, solid fuel hoppers, etc.)
High Compresson for efficient combustion
High Compression for maximum expansion during the power stroke
High Rod:Stroke Ratio to increase piston dwell at TDC, and reduce piston side load for longevity
Mild cam to produce peak torque at acceleration/cruising speeds, and turbo boost to also peak at same speeds/rpm range.
Carburetor for simple mechanical fuel induction
Non-Intercooled Draw-Through Turbocharger with LOW BOOST for simplicity of carburetion, pre-mixing and stirring of air-fuel mixture, HEATING OF THE AIR FUEL MIXTURE, and positive pressure front in the event of back-fire (think of a welding torch, and the fact that the flame doesn't usually burn fast enough to overcome the flow rate from the nozzle).

Overall Goal: to build a pick-up truck that gets better fuel economy than any NEW Car or Truck on the market, and that compares favorably with the economy of the older econmy cars; or, to turn my pick-up into a fuel sipper that would make GEO METRO DRIVERS JEALOUS. (ie, 50 MPG Highway, or as close as possible.)

THIS WILL NOT HAPPEN AS BUILT IN ANY STOCK MINI-TRUCK CONFIGURATION, OR MOST STOCK CAR CONFIGURATIONS.

Hence, the custom/performance/tech interest.

Is my logic, recipe, or goals fatally flawed, in anyone's experience (versus myths, old wives tales, or tradition) of ENGINE PERFORMANCE MODIFICATIONS?

and, what other typical 'recipes' are (or have been) used, and for what goals?
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Old 11-22-12, 3:19   #17 (permalink)

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most engines are using a shorter deck height these days to cut weight IMO.

There is another figure to consider; bore should be about 0.8 x stroke for maximum torque.
Once again this leads to other compromises like piston speeds at high RPM, valve sizes and deck height.
The Mazda MA is a good example of this dimension and its torque was good for a 2.0 litre engine of its day.

The other thing; you need to be careful of draw through applications as they dont transition well between throttle on/off changes due to the extra volume in the intake tract.
If you can get the turbo outlet as close as you can to the IM you can eliminate some of this, but why bother with carburetors when you can use the control you have over electronic injection, you can probably gain 5 MPG alone just by converting any 2.0 carbed engine to injection is well worth keeping this on your agenda.

The other trick is to start with a small undersized engine and boost the hell out of it. like a 1.0Litre, then there is the Atkinson cycle to think about... all of which has been tried by the manufacturers many times before.

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Old 11-22-12, 8:23   #18 (permalink)
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And, an article regarding a historical approach:

What Ever Happened To Smokey's Hot-Vapor Engine? - Hot Rod Magazine
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Old 11-22-12, 8:33   #19 (permalink)
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And another:

Georgia Fiero Club Official Website
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Old 11-22-12, 9:10   #20 (permalink)
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I am aware of the lag-issue, the compressor loading/failure potential for poorly mixed air/fuel & fuel droplets, and the potential for oil draw (into turbo) due to the very high vacuum present in the turbo on throttle close (can draw oil right through the turbo oil seal).

So, WHO ACTUALLY HAS PUT TOGETHER AN ENGINE WITH A 400 DEGREE AIR-FUEL INTAKE TEMPERATURE AND MADE IT RUN??

Anyone??

The only thing out there that I know of is historical footnotes, and possibly some tight-lipped (probably for very good reasons) experimentors.

In this project, 5 mpg improvement on CONVENTIONAL FREEZING COLD LIQUID DROPLET HIGH WASTE TECHNOLOGY is pocket change.
20% increase versus 120% increase, again. Not worth the effort and expense of a complete re-build and re-design, for a daily driver.

THINK OUTSIDE OF THE BOX, FOLKS. I am planning for BIG. (improvements). Still data-mining, though. Will probably be building piece-meal, towards actually figuring a workable combination. I gueas thats called 'TUNING'.

My specific plans are as follows:

The engine runs, but the fuel pump is out (probably varnished). I will be driving this project for a stock baseline as soon as I get it put together.

Maybe, put a carb spacer / heater core derived coolant heat exhanger to pre-heat the air/fuel in NA mode.

Then, I will probably slap an earlier FET Exhaust manifold & Turbo on, and re-plumb the carb to get a second base-line, stock with non-intercooled intake temperature rise.

Next, plumb in a heater core underneath the carburetor plenum (where it is remotely mounted), to get a coolant-heated air/fuel mix baseline.

Tuning ho-hum stuff like plugs, cap, rotor, wires, oil, carburetor adjustment, ignition timing adjustment, and a little more aggressive stuff like cam timing adjustment & camshaft swap.

Last, Full Rebuild, balance, and drive for the next 200,000 miles.

R & D, FOLKS.

DETROIT AND WASHINGTON CAN'T (OR WON'T) ACCOMPLISH THIS GOAL.

I guess that the only way to obtain usefull information on this type of combination is to experiment.
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Old 11-22-12, 9:39   #21 (permalink)
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To chief tool: There is an approach being used with fuel-injection. I believe that it is called 'SUPERCRITICAL GASOLINE INJECTION' there is a laboratory in florida that is routinely DOUBLING the MPG on dyno runs of their test-mules.

The theory is as follows:

Vapor burns, liquid doesn't.

Hot liquid evaporates more readily than cold liquid.

Superheated Ligquid (ie, raised above atmospheric boiling temperature and maintained under positive pressure) will evaporate VERY RAPIDLY (Like the coolant spewing out of a hot radiator when you take the cap off, contrary to typical safety warnings, or when you (stupidly) remove the lid on a pressurized pressure cooker.

SUPERCRITICAL Fluids flow more freely than a superheated liquid, and will also rapidly change phase to vapor when pressure is suddenly reduced.

The experimental set-up involves a direct-point injection setup, with fuel rail temperatures something along the line of 800 degrees F, pressures accordingly, and injection into the cylinder IMMEDIATELY BEFORE SPARK IGNITION.

I'll let you retro-fit that system on your vehicle

I'm not real fond of boiler explosions with combustible working fluid.

You get a double whammy -

first, the pressure explosion (like the old-time steam locomotive),

then the fireball (as the too-rich-to-burn but way-above-the-auto-ignition-temperature gets diluted enough to burn, and spontaneously self-ignites.

Sweet.
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Old 11-22-12, 18:11   #22 (permalink)
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Hmm, interesting project, that Yunick's high-efficiency high performance engine. I think I'll do some otto cycle calculations with high input heat and pressure and high steam content when I'm in the mental state to do it (I'm minutes away from hitting the bed right now.) Might offer some insight on the process. It's not magic, if the observations are true. It must be terribly wearing on the engine, though.

The Fiero website isn't one to follow though. It seems he rephrased the text in the other linked article and misunderstood it. He begins by stating that 75% of fuel goes unburned, not acknowlidging it's the HEAT of combustion that goes mostly to waste. Such an assumption makes him very unreliable information source on the subject. Hot Rod article seems much more knowledgeable.

One of the best ways to harness the exhaust gas energy is a simple multi-stage turbine on a bendix clutch geared to the crank; even the regular F2T turbo has a few dozen SHP. Old radial engines used such a method a lot, though only with a single stage turbine. Taking the idea to it's logical extreme, there was a peculiar aircraft engine concept just before turbine jets made their final push into aviation; the Napier Nomad. In it's most complex form, it had a supercharger with axial and radial spools, and it was connected to both crank and the exhaust turbine; At low RPM the supercharger acted as a traditional crank driven one, but at high RPM the turbine actually powered both the supercharger AND gave extra power to the crank output. In a modern application, a large turbo connected to an electric generator would make an interesting hybrid project.

BMW is experimenting a steam turbine with the boiler using surplus heat from the exhaust. That's an interesting idea too.

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Old 11-22-12, 21:57   #23 (permalink)
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cheif has a point about the draw through carby system.

If your only going to running low boost, then it should be fine with transitioning between 0 and +1psi.
The problem with carbies is that (besides very expensive items) they generally do not do a good job of atomising the fuel.
The better atomised your fuel the more rapidly the phase change will occur.
The trick is to then get that in the combustion chamber and burnt without it cooling too much to remain homogenous.

IMHO a turbo running such low boost wil not put a significant amount of heat into the charge air.
Certainly less than preheating the fuel, intake, intake piping, carb bowl, etc.

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Old 11-23-12, 8:39   #24 (permalink)
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On Yunick's layout, there is a fine lne. Intake charge gets too hot (and there is additional heating from the compression stroke, auto-ignition (dieseling) occurs. Too cool, condensation/drop-out occurs. stagnation, the same.

I think that the article is correct, if not in the percentages. There is only a certain amount of Jules / BTU's in a gallon of gasoline. 100% conversion to motive energy would be sufficient for ~ 300 miles, on level ground, according to some historical calculations.

You get inherrent heat losses with any engine. The number is usually 30-45% conversion to kinetic, the rest going to losses such as friction, or as exhaust discharge.

Of course, if you have a poor fuel utilization (burner set-up), you are not using all of the available BTU's out of the fuel to begin with. Less Total Heat input into the engine (x BTU's per gallon, Y BTU's combustion in Engine, Z BTU'S Combustion in exhaust system, or atmospheric oxidation afterwards.

so, you run from X - Z = Y (or, Total Chemical - Unutilized = Energy for your engine.

So, you still can get a theroetical range of ~ 100 mpg, with a 33% heat engine loss,
if you use all of the available BTU's to feed into the engine.

FYI, Leno's 193x Doble gets aroung 20ish mpg on STEAM, and meets modern CA emmissions, to boot. Not bad for 80 year old technology.

Not good for modern tech, either.
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Old 11-23-12, 13:31   #25 (permalink)
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Quote:
Originally Posted by troyjmueller View Post
I think that the article is correct, if not in the percentages. There is only a certain amount of Jules / BTU's in a gallon of gasoline. 100% conversion to motive energy would be sufficient for ~ 300 miles, on level ground, according to some historical calculations.
The Hot Rod article is on the money, the Fiero writeup talks about 75% of fuel going through the engine unburned. That's someone without a clue writing.

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Old 11-23-12, 21:00   #26 (permalink)

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I think you would need to think further outside the square than just using a conventional engine as a base.

First look at the inefficiencies in a conventional engine:

Mechanical losses: Parasitic mechanical valve train. bearing friction, piston friction, inertia. External mechanical losses like hydraulic power steering, conventional transmissions and torque converters.
Pumping losses: vacuum created by throttle plate and valves, port losses, exhaust back pressure
Thermal losses: heat lost into the cooling system and out the exhaust, low compression ratio.

How can we fix these things:
Mechanical: remove the valve train, poppet valves are horribly inefficient. Rotary or slider valves could be used or port valving. reduce the number of cylinders, switch to air bearings.

Pumping losses : remove the throttle plate completely and switch to two stroke, using an external air pump (no crank case compression) to pump in only enough air needed for the amount of fuel, using the spent gasses remaining in the chamber as a sort of EGR, to take up the unused displacement need to develop the power required. Two stroke engines also have the advantage of twice the power density for a given weight, no external valving need be used, although control over the timing on the intake could be advantageous.

Thermal losses: use turbo charging to capture wasted energy out the exhaust, or a second stage of pistons connected to the crank; refer to mechanical efficiency trade off above and pumping loss compromise.
Raise the temperature of the cooling system to reduce heat loss into it. Switch to ceramic components that dont need any cooling at all.
Change to compression ignition so as to eliminate the compression ratio limit with spark ignition engines.

Others: Propane could be used as a its octane rating is high and is a gas at STP meaning no vapourisation phase needed and better mixing.

Water injection to allow high compression ratios with lower octane fuels.


So, what is the end result:

A 3 cylinder air cooled ceramic two stroke engine with air bearings, compound supercharged and turbocharged running on diesel fuel.
Connected to the wheels via a CVT transmission.

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Old 11-24-12, 21:38   #27 (permalink)
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On current techonogy, NOTHING does a good job of atomizing the fuel; or rather, achiving the IDEAL of maximum dispersion of the fuel into the air.

Carburetors suffer from liquid droplets, momentary lean conditions, vaccum lag, and a host of other tuning compromises.

Fuel Injection also suffers from liquid droplets, and other unique problems, in addition to the potential liability of requiring a sophisticated and nearly impossible to adjust 'black box' to make the whole rube-goldberg contraption work.

The problem isn't in the 'atomization' of the fuel; it is in the limitations of the tecnique.

Carburetion is basically utilizing pressure differentials to 'suck' liquid fuel into the air-stream, and relies on turbulance and reduced pressure to 'atomize' (or break up large droplets into small droplets). The idea is to reduce the fuel into a very fine mist, which makes the chemical reaction happen more quickly and thoroughly.

The IDEAL is to divide the fuel portion into indidual moleculess, and then disperse those molecules evenly through the air volume (plenum, intake runner, cylinder, etc.)

With Gas-Gas mixing, this condition will happen (Diffusion).
Liquid-Liquid mixing, in like liquids (polar versus non-polar) the same will happen.
Solid-Solid also happens, though very, very slowly.

Stirring, turbulence, accelaerates the mixing process.

The problem with achieving the IDEAL mixture isn't in the nozzle, jet, pressures, or whatever else might be part of the system.

The problem is that we are mixing cold (below boiling point) heavy, dense, Liquids, with surface tension and other liquid properties, with a light, not-very-dense gas,
so we get liquid droplets in a stable form, being pulled out of the mixture from gravity, and condensation of any fuel vapor at the first oportunity.

The goal is to maximize the division of the fuel.

it is the vapor, not the liquid, which burns and makes power.

Liquid fuel into the engine is wasted fuel into the engine.

If the liquid fuel inside the engine is not able to evaporate, locate available oxygen, and combust inside the cylinder, it does not provide power.

and, more specifically, if it is not able to do so in the early stages of the power stroke, it does not provide power.

I'm pretty sure that you don't set up a carburetor (or injection rail) to squirt raw fuel directly into the exhaust manifold or catalytic converter, do you?

Combustion in the exhaust is waste. The energy being released by that combustion is not being used.

And that is what I (and nearly every other person interested in VAPORIZED FUEL, HEATED FUEL OR SUPERHEATED FUEL INDUCTION TECHNOLOGIES) is trying to elminate,

the wasted portion of the fuel which may or may not combust, but wich does not contribute to the heat input of the engine.

Another thought - where does the energy to make the catalytic converter glow red-hot come from? I know that that cherry red barbeque isn't making the car go.

I think it comes from the gasoline that goes into the carburetor (or injectors), goes through the engine (without giving up all of the energy it can to power the engine). This is the same HC Emissons that the smog people are worried about, and the same un-used fuel that makes flames shoot out of the exhaust ports and/or manifold.

(I'm sure that those of you who've ran an engine on a stand or on the floor know what i'm talking about)
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Old 11-24-12, 21:58   #28 (permalink)
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As for pumping losses, that has more to do with the plumbing, the inertia of the air, etc, than the mechanism for the control of inlet/exhaust events.

The Valve-Train is a MECHANICAL SYSTEMS LOSS, with factors such as inertia, friction, deformation, contributing to a reduction in useable power from the total power produced
(ie, from the 30-45% of the total btu content in the fuel)

And, for the prototype ceramic diesel 2-stroke, I don't have that kind of R&D Budget.

Try the TESLA TURBINE for a simple, efficient heat engine. One valve (or 'valvular conduit' (inlet pumping losses), a continous burn zone (like a ram-jet, or bunsen-burner), a high-velocity exhaust stream (heat-to pressure-to-kinnetic motion),
and a very efficient transfer of linear momentum (fast moving fluid stream) to angular momemtum and torque (by means of the fluid stream and the turbine 'runner' temporarily adhering to one-another and achieving a common momentim), and relatively cool exhaust with nearly zero velocity.

FIENDISHLY SIMPLE, yet no-one comercially has really utilized the concept. I wonder why?

I think that the second option is more in line with the DIY experimenter's budget.

My budget does not allow for machine-from-scratch engine components, exotic materials, or any of the other VERY EXPENSIVE CUBIC DOLLARS options which may very well exceed what you or I can discover and use for ourselves, with what is available. I just want to make that which I've got work the best that I can (and I happen to think the the OEM'S either cut corners, or weren't really trying very hard) on the economy front.
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Old 11-25-12, 0:44   #29 (permalink)

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Originally Posted by troyjmueller View Post
I happen to think the the OEM'S either cut corners, or weren't really trying very hard on the economy front.
No arguments there.

If fuel was $20 per gallon they might, but there would be rioting in the street before they would get a chance to change their ways.

Just a couple of points, catalytic converters need to operate on the stoichometric point so as to convert the oxides of Nitrogen back to Nitrogen and Oxygen, the reaction is endothermic so the heat has to come from unburned fuel in the exhaust. Not enough heat and too much oxygen and they dont work.
An unfortunate trade off for a clean exhaust.

Use of propane fueled cars in Australia has noted the improvement in exhaust emissions which could be attributed to better mixing of the fuel, but the improvement isn't a lot, I cant quantify by how much.

You could try raising the fuel pressure substantially to improve atomisation, a trick used on diesels. Once again its hard to quantify the amount of improvement this represents.
In the diesel world; as most diesels went to direct injection at same time as raising fuel pressure. The associated deletion of the pre chamber represents a gain in thermal efficiency and combustion chamber shape also represented an improvement in volumetric efficiency.
Typical unitary direct injection gave a 10-15% efficiency improvement over pre chambers. IMO most of that would be the lack of a pre chamber which has a high surface are to volume ratio.

Other tricks like using propane as a supplementary fuel on diesels were meant to improve fuel burn, actual results indicated the associated efficiency gain was less than 10%

It would be an interesting experiment, sure....however I think there would be too many trade offs using things like carburetors to improve atomisation.
You might be able to come up with a good system that would work on a constant speed stationary engine. The variable speed and power output of most car engines needs the accurate control of electronics to ensure the fuel delivery amount is more accurate.

I think the manufacturers could have discovered that on a cost efficiency basis is was cheaper to control the fuel injection timing and amount (in gasoline engines) than it has been to attempt to make it vapourise any better
Gasoline Direct injection uses a higher pressure (not sure how much) which would lead to better atomisation although the exposure time is much less.
If the particulate emissions are anything to go by maybe the mixing is much worse than port fuel injection.

Its probably still more about emissions control than fuel efficiency.

As I said, could be interesting; if it were me I would start with propane as you are most of the way there as it would be injectable as a gas and something you could control with electronics. You could mathematically compensate for the lower energy density and this would give you a clue how much improvement you could expect from Gasoline if it was fully atomised when it entered the engine.

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