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I've just read about Tom Ogle, an inventor who claims to have built an fuel injection system that can achieve 100+ mpg and has apparently proven it, before dying in suspicious circumstances.

From a technical point of view, is this even feasible? Does a gallon of fuel even have enough energy to achieve this?

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    I think you should flag this and ask for it to be migrated to Skeptics – Evan Carroll Mar 14 '18 at 3:36

10 Answers 10

5
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Looking at the market, VW has built the VW XL1 (EN, DE), a hybrid car with up to 260mpg. The german site says there was a test drive on the street where the car indeed consumed 0.89l diesel /100km, which equals 240mpg. But there are also many other confusing numbers, giving up to twice the consumption. I also find 1.82 l/100km with full and 1.94l/100km with empty battery. The last value is what you get when you feed the car by fuel only, and corresponds to 125mpg.

So yes, in general, it is possible to build a car with 100mpg or better.

But this car is only 1.6m wide and 1.1m high, with two seats one behind the other for best aerodynamics, weights just 750kg and 40hp. Oh, and it's a diesel, with an in general lower consumption.

A more reasonable car like the Tesla Model S weights about 2000kg, which is similar to the weight of Tom Ogle's Fort Galaxy. And it runs 260 miles on a 75kWh charge (EPA).
Gas contains 125MJ/gallon=34.7kWh/gallon of energy, so if the Tesla would burn gas to generate electricity at 100% efficiency, it would consume 75/34.7=2.61gallons for 260 miles, i.e. exactly 100mpg!

But a combustion motor has a theoretical maximum efficiency of 40-50%, because the exhaust gases are hot and still under pressure when leaving the cylinder. In reality, internal and drive train friction lower the efficiency even more.
Even electric cars with their >90% efficiency motor do a lot to increase their "milage". For example, the kinetic energy of the car is used to charge the battery when braking, instead of wasting it as heat.

Replacing the carburetor by a system which allows to add the fuel more controlled, more precisely and in a ways that allows a better, more complete combustion can increase milage a lot, but 100mpg by just this is far from realistic.

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The claim is suspicious, to say the least. Replacing just the fuel injection system only allows you to do so much.

A modern petrol engine has a peak efficiency of maybe 30% (and that's optimistic). I.e. 30% of the energy in the fuel is converted to motion. The rest is dissipated as heat by the cooling system and the exhaust.

Achieving 100 mpg would mean reducing those losses by a huge amount. Much of those losses are outside the control of the fuel injection: no fuel injection can ever prevent heat losses through the cylinder walls, for example. Fuel injection can't reduce friction in the drive train either.

Now, Ogle ran his experiments on a 1970's carburetted car. Efficiency on those was far less than 30%. The exhaust gases often contained unburned fuel. Replacing that with an injection system would increase efficiency considerably. Going from 15 to 30 mpg is believable.

Ogle claims his gains were due to evaporating the gasoline instead of letting the carburetor draw droplets of petrol into the engine. Let's compare this to LPG. Classical LPG systems evaporate the LPG. Some modern systems have switched to liquid LPG injection to increase efficiency. If Ogle were right, liquid LPG injection would be less efficient than a vapor system.

Ogle patented his invention. Patents contain a detailed description of how the invention works. Anyone can try and replicate his work. Ogle's is not the only claim, 100mpg carburetors are a popular urban legend.

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Not possible, a complete hoax and Fabrication. Tom Ogle swindled his investors. It is virtually impossible to get over 20 miles per gallon in a 7 liter V8 1970 Torino. And that configuration no matter how you vaporize the gas you could not possibly get over 20 miles per gallon. The car is an arid anomic brick. A 1970 also does not have an Overdrive. Thus as 60 miles an hour, that 7 liter V8 would be spinning at nearly 3,000 RPM. An engine must maintain at least a 15 to 1 air fuel ratio in order for the spark plug to ignite it. In a 4000 pound car with gas sucking bias-ply tires in a 7 L engine revving at 3000 RPM, I would be totally surprised if even 17 miles per gallon could be achieved

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Also at highway speeds of 50 to 60 miles per hour at which they claim Ogle's carburetor was tested, a standard carburetor and intake manifold are already working very efficiently. As the gas goes down the carburetor Venturi and it's the throttle plates it is further atomized, and then when it goes me intake manifold , it is subjected to a strong partial vacuum which makes it vaporize even further. What particles of fuel have not vaporized at Point hit the bottom of the intake manifold which is heated by engine coolant. From that point engine vacuum, heat and high airflow quickly vaporize any gasoline on the intake manifold floor. Intake manifold Runners are purposely left somewhat rough and are equal length, and run 10 to 12 in to the intake ports in the engine. They are vaporized on the way by the airflow and the heated runners. Your fuel mixture and goes through the heated ports in the heads of the engine, another 3 or 4 in. And when your intake valve is open that mixture then flows down and hits the intake valve. By the time Wallace has occurred just about every bit of liquid gasoline has been turned into a vapor. But even after the intake valve the air fuel mixture is drawn down into cylinder in a swirling motion, and then as the Piston comes up is further swirled compressed heated, and then finally ignited by the spark plug.... Tom Ogle's so-called invention is crap

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The reason for the higher efficiency is mostly due to the fact that the ogle carburettor runs the engine at full throttle. Vaporising the fuel using exhaust heat would increase efficiency by approximately 5% only.

The high heating value (HHV) for gasoline approx 47MJ/Kg.
The density (ρ) for gasoline varies approx between 0.71-0.77Kg/L; assuming 0.74 Kg/L would yield roughly 35MJ/L.

100mpg is equivalent to 42.5km/L. To keep numbers simple assume the car is travelling at 42.5km/hr, which means 1 litre (35MJ) will be used in 3600 seconds, ie 35,000kJ/3600s => 9.7kW is the power being fed into the engine (as fuel).

Power (kW) input at other speeds (km/hr) = 9.7*speed/42.5

i.e. PowerIn = speed/4.38

Assuming 75% of power is lost due to engine inefficiencies, driveline losses and rolling resistance. This leaves only 25% of input power to overcome wind resistance.
i.e. to achieve 100mpg (42.5L/km) average losses (in kW) must be less than (speed in km/hr)/17.53.

These is doable at lower speeds, however, at higher speeds it won’t be achievable because loses increase faster than speed does. Even rolling resistance and driveline loses are not quite linear, as assumed above.

It is much easier to achieve high fuel efficiency at lower road speeds because aerodynamic losses are proportional to speed squared, regardless of aerodynamic friction coefficient.

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I've read the patent abstract, which does talk about what he does, and is addressed in the above responses. So what? My off the lot 20013 Mazda 3 does 50 mpg at 65 mpg on the highway. The Society of Automotive Engineers sponsors a mileage competition every year for colleges and high schools. The vehicle must carry one person, achieve an average of at least 15 mph. Latest figures: over 3,000 mpg. Three THOUSAND miles per gallon! There was a video I saw someplace (This is now THIRD-hand information - reliability low) about Ogles car, which also claimed ZERO carbon emissions. Well, yes. it emits no carbon. Just carbon dioxide! (Here I suspect they were claiming that the complete combustion prevented any carbon particulates - smoke - emission.)

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    Welcome to Motor Vehicle Maintenance & Repair! I'm glad you can participate on the site. I would hope you'd be able to take The Tour so you can understand how the site works. With claims as you've made, it goes a long way on the site to back what you're stating with links and references. Enjoy your stay here at the site and I hope to see more input! – Pᴀᴜʟsᴛᴇʀ2 Sep 17 '18 at 13:51
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Ok, I would be sceptical but my dad's best freid (an engineer at FAA) modified a 351C in a 69 mustang fast back. Not sure of the engine exhaust mods, but there many, and designed an built a fuel injection system. It took two gallons of fuel additive per tank which about doubled the price per tank full 1977 prices. We drove from Oklahoma City to Padre Island and back (had to refill in Purcell or Norman) on a 20-21gallon tank. He got a patten on the injection system and was working on one for the engine when he promptly stopped. He had sold the patten to an oil company and had been paid extra to stop the SEC and patten. We got just over 60 mpg.

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There is only one flaw in your argument is that Tom Ogle was offered large sums of money for his invention they would not have offered him money if his invention did not work. Has anybody tried his invention and there are many inventions which were bought up by Big Oil and Buried and in some cases, inventors have died in mysterious circumstances? I f anyone had duplicated his invention since he died?

  • If you hear things like this how do you explain it. Enter the experiment known as OPERA (Oscillation Project with three sciencey words that aren't Earned Run Average). In September of 2011, scientists at CERN (Europe's particle-physics lab near Geneva in Switzerland) shot a beam of particles 730 kilometers away to the Gran Sasso National Laboratory in Gran Sasso, Italy. The problem was that they showed up 60 nanoseconds early, which doesn't sound like a big margin until you understand that in order for this to happen they would have to have traveled faster than the speed of light. – Ben Boyle Apr 19 at 8:28
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    Didn't further research show they had made an error.... – Solar Mike Apr 19 at 8:58
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I will just post this link, the author claims that an efficiency of around 80mpg should be a realistic maximum.

  • Please include some actual information in the post. Not just a link which may die any day. The answer should be able to stand on its own even after that link-rot. – Hennes Oct 10 '16 at 13:01
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As i understand the theory behind ogles claims, his adaptation heated the gasoline into a vapour. And it was that which was ignited not the liquid. As gas would take up less volume and provide a more explosive spark in the cylinder. Effectively more bang for your buck. 100mpg though?

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    Sorry but I think your theory is wrong. Fuel(or anything for that matter) can only burn when in gas phase, gas takes up more volume, not less, and you don't want explosions but gradual expansion of the combusting gas in your engine. Better atomisation, as Ogle is probably trying to achieve, does give better results though. – Bart Jan 21 '18 at 17:58

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