The 100 mpg carb - Does it really exist?

[DavidVizard-GFN]

The 100 mpg Carb.

By
David Vizard

Finally here’s what gas companies have been hiding all these years!
Now you can forget rumors – here’s reality.

I’ll make a bet here that there is barley a performance enthusiast in the USA that has not heard of the rumored 100 mpg carb that the oil giants bought up so you would be forced to keep on buying lots of their gas.

Bet you have also heard arguments both for and against the existence of the 100 mpg carb - you may have heard that even movie star Steven Segal claim that it existed.

Well folks here is what could possible be the end of the controversy.

It’s going to take a little math toward the end but I have taken 99% of the pain out of that so here goes.

First off let me give you what I believe qualifies me to address this subject. In 1975 I was the lead engineer on an economy project. The subject was a 1275 Mini GT. That’s a direct relative of the original 1275 Mini Cooper.

The goal was to see if we could get this car to do 50 mpg at 50 mph. Once that had been achieved it would be taken on a 3 month round USA drive at normal highway speeds (not fuel economy test speeds which would take forever to go anywhere) and see if we could get 50 mpg.. An independent test at MIRA (Motor Industry Research Association) on a truly lousy wet and windy winter day recorded 55 mpg at 50 mph and 99 mpg at 30 mph. OK that 99 mpg is real close to 100 but do we all want to drive at no more than 30mph – no! Not only that but that 99 mpg was achieved with a 1600 lb car. The same size car today weighs in at over 2100 lbs and the average mid sized sedan at 2800 lbs plus.

I am not sure my team was the first to break the 50 mpg at 50 mph but we did it before Honda and all for less than $100,000 in today’s money. We failed to see that 50 mpg with our round USA trip but did record a close 49.88 mpg. But in all fairness this figure included full throttle road test by Road & Track plus 300 miles of snow drift bashing in 2nd and 3rd gear as we drove through one of the worst winter storms in Wyoming. Added to that the car saw a hurricane in the New Orleans area which we had to out run. But that’s not the end. The car had 'run flat' tires which were magazine tested by driving at 50 mph for about 50 miles plus it was also driven off road. How many economy drives include such? Answer - about none!

In addition to the fuel saving we added over 10 mph to the top speed and cut the 0-60 time by 1.5 seconds so we really did address Performance, Economy and Green (PEG) issues successfully.

Ok so now you all know where I’m coming from lets get technical. Unless you are really into carb design the inner workings of a carb look more like a collection of parts for executing a little black magic. Don’t feel bad about that – most of today’s top carb designers were there once. Those trick Barry Grant carbs you see are complex but not un-fathomable.

In reality the function of any carb can be reduced to two simple functions that it must perform. The first is to deliver a certain ratio of fuel and air to the engine. The second is to atomize that fuel so that a significant proportion is vaporized and the remaining wet fuel is sufficiently well atomized to turn to a vapor as the piston reaches Top Dead Center on the compression stroke.

OK so now we know what the carb has to do we no longer need worry about how it works so lets get down to the nitty gritty.

Any respectable carb can be calibrated to deliver whatever fuel air ratio you want to the extent that it will be either too rich (has too much fuel for the air) to burn or will be too lean (insufficient fuel for the air). However it’s not what you may want to see in the way of mixture ratio that counts - it’s what the engine wants to see. Most engines run into lean misfire at about 18/1 to 19/1 air/fuel ratios. Just for the record with some fine development details we managed to get the ‘Round USA Economin’ to run effectively at just over a 22/1 air/fuel ratio. Now consider this; if we can get any decent carb to deliver a fuel air ratio significantly leaner than say 30/1 the problem of finding fuel mileage is not constrained by that carbs ability to deliver a lean enough mixture. In other words any decent carb (and there are dozens out there) will deliver an economy mixture far leaner than any engine can burn.

Let’s move on to the other aspect – namely fuel atomization.

Some carbs such as the constant vacuum SU and Stromberg carbs can atomize fuel better than a 45 psi fuel injection nozzle so the question of whether or not fuel can be adequately atomized is - yes it can. But not all carbs are as good as these at doing the atomization deal. But there is a fix for that. It’s called intake manifold heat. If a carb fails to atomize the fuel well enough then a little manifold heat fixes the problem Also the fact that fuel economy driving takes place at part throttle also means that there is a lot of intake manifold vacuum present. This also has a strong influence on vaporization.

So where are we at now?

I’ll tell you - any decently designed and correctly sized carb can cover a far wider range of fuel mixture conditions than the engine needs so what is this supposedly 100 mpg carb going to do that the ones we currently have available cannot already do? Answer – Nothing! It’s the engine that is the limiting factor not the carb.

From the forgoing you can see the argument for the existence of a 100 mpg carb is starting to get somewhat tenuous. But I have not finished yet.


We don’t need to consider the 100 mpg carb in terms of a 50 cc moped as that is not in context with what is so often refer to. When the 100 mpg carb crops up in conversation it’s in connection with a reasonably sized sedan and speeds we could reasonable expect people to drive at. Let’s say such a vehicle is a typical 2300 lb sedan (and that’s on the small side) and the speed concerned is say 50 mph (and that’s on the slow side). By picking these conservative numbers I’m giving the benefit of the doubt to the 100 mpg carb. To power such a car at a steady 50 mph will typically take about 15 hp. With Brake Specific Fuel consumption figures being what they are at part throttle such a car would turn in right around 40 mpg at that speed. Also it would be utilizing the fuel’s energy at close to 25% (that is the engines thermal efficiency is 25%). If the engine could convert 100% of the fuels heat into mechanical energy the mileage would go up to about 160 mpg. Now that shows what room there is for improvement but the problem is it is the engines inability to convert the fuels total heat capability into power not the carbs ability to deliver a suitable mixture. It’s already doing its job near 100% so that 100 mpg is going to come from engine development not from fuel delivery development (i.e. the carb). This means that long ago carburetors had already reached near maximum potential and there is little room left for improvement. From the forgoing we can safely conclude that the 100 mpg carb never has existed and never will!


OK - by now I should have convinced you that 98% at least of any mileage improvements will come mostly from engine development and maybe a little extra from fuels. Of course you could drive more carefully by easing down on the gas pedal, avoid overtaking, drive 5 mph slower and back into the driveway at night. But if you are anything approaching a type ‘A’ personality like me the very fact there is a car in front means that some overtaking is due! I have to race something and the only way I have been able to consistently drive for economy is to race a trip computer that reads out in mileage to date and instantaneous mileage. The bottom line is I need to get there now not five minutes later. All this adds up to one thing for me – and that is the vehicle I drive better be able to go fast on next to no fuel!
As things stand as of now I can detail how you can increase the output of a typical Detroit built street V8 engine (and the principles apply across the board to all engines) by some 50% while improving mileage by some 40% That means if your vehicle is making 250 hp and doing 18 to the gallon now, I can show you how this can be bumped to 375 hp and 25.6 to the gallon.

You can continue to put money into the pockets of foreign oil cartels or lobby whoever in some attempt to get the cost of gas down – if you believe that will work that is. Personally I believe that the only way to stop the population at large squandering gas is to put the price up - but thats another story!

But there is a third alternative that really will benefit you and that is you can hop up your engine using the proven tech that I can supply you with. However it cost me a lot of time and a seven figure money number (not all my money might I add) to do the research and testing needed to verify what I am proposing. If I am going to give this info to you for free (I repeat for those who may be sight impaired – ‘for free’) I need you to do something in return. If I am going to spend about two months writing this all up and producing a lot of fancy artwork to boot I would, in return, appreciate you spending a few minutes of your time sending out a blanket email to all of your auto enthusiast friends informing them about this web site and what it has to offer. I simply want you to tell all your auto enthusiast friends about this web site. When I have a big enough audience I will spill all in great detail with extensive text, color drawings and a lot of top notch photo’s.

Now I know someone is going to say ‘what a cheap shot to advertise his books (heaven help me for actually wanting, as a professional writer, some form of re-imbursement for my work) and to get hits on this site’ but consider this. If each of you guys does your bit to reduce overall US fuel consumption the saving s you can bring about as an individual may only amount to some 5 gallons a week. What with my books and magazine articles I have about a million readers a month but this site is new. If I could get all my paper readers to follow just a few of the mods I propose and each one saves very conservatively just one gallon a week that means I will have brought about a saving, for the US as a whole, of 50,000,000 gallons a year. Yes that might be a drop in the ocean but it’s a hell of a lot bigger drop than most people can bring about.

So what will this power boosting fuel saving tech cover?
Here’s just a short list in alphabetical order, of some of the subjects:



Big bore short stroke or small bore long stroke.
Big valves or small?
Camshafts for mileage.
Carb Calibration.
Cold air intakes.
Effects of Compression Ratio
Exhaust system lengths and diameters.
Fuels.
Gearing.
Ignition timing.
Intake port dimensions
Intake port finish.
Intake to exhaust size ratio.
Internal friction,
Mixture preparation.
Nitrous – yes or no.
Oils and lubes (want to know how to go three quarters of a mil before a rebuild?)
Optimum valve sizes.
Piston speed for optimum mileage.
Rip offs.
Spark intensity
Swirl & tumble
Super chargers and turbo’s
Thermal Barriers
Two valve heads versus four valve heads - which is most fuel efficient.


Well if you read this far then you will probably be interested to know that the GoFastnews.com Power - Economy - Green (PEG) section has started in earnest. You can get there at: http://www.gofastnews.com/board/economy-green-forum/ Parts #1 and #2 are up and I am pulling no punches here. I think part #1 is pretty much a self analasis everyone needs to do to see where on the PEG scale they fall. Be warned - you might not like the conclusion you come to!

David Vizard

[beatr911]

Originally Posted by DavidVizard-GFN

[size="5"][font="Arial"][b][i][color="Red"]
As things stand as of now I can detail how you can increase the output of a typical Detroit built street V8 engine by some 50% while improving mileage by some 40% That means if your vehicle is making 250 hp and doing 18 to the gallon now, I can show you how this can be bumped to 375 hp and 25.6 to the gallon.

A 2005 Corvette can do 400hp and 30mpg real world on the freeway. So we know this is doable. Please do tell. How do we get these kind of efficiency gains for existing older vehicles? Transfer new tech to old?

I should introduce myself and where I came from. Rookie pointed us at gassavers.org to your 100mpg article because some people are already doing that, but with FI. I've driven 4 cyl cars and motorcycles for 27 years because they are light and fun, the good ones anyway, and they are typically inexpensive to operate on a daily basis. Fuel efficiency is desired, power is fun, both is what we're all after.

David, there are several growing communities, and finally an expanding awareness of the public at large, that sees that real gains are possible and just not put into production. Please contribute your extensive experience to this 'cause'. (Geez I sound like an activist.) No doubt it would be a huge benefit to us all.

Thanks for this site. I'll stay tuned for some good solid technical information, - and try to contrubute!

[automotivebreath]

David, 375 hp and 25.6 to the gallon is much needed to keep the grass roots
level of motor sports alive, let us know if we can help!

[Stubby]

Waiting for knowledge.

[rookie]

Originally Posted by beatr911

A 2005 Corvette can do 400hp and 30mpg real world on the freeway. So we know this is doable. Please do tell. How do we get these kind of efficiency gains for existing older vehicles? Transfer new tech to old?

I should introduce myself and where I came from. Rookie pointed us at gassavers.org to your 100mpg article because some people are already doing that, but with FI. I've driven 4 cyl cars and motorcycles for 27 years because they are light and fun, the good ones anyway, and they are typically inexpensive to operate on a daily basis. Fuel efficiency is desired, power is fun, both is what we're all after.

David, there are several growing communities, and finally an expanding awareness of the public at large, that sees that real gains are possible and just not put into production. Please contribute your extensive experience to this 'cause'. (Geez I sound like an activist.) No doubt it would be a huge benefit to us all.

Thanks for this site. I'll stay tuned for some good solid technical information, - and try to contrubute!

Good! keep sounding out, we need activists today like never before, not only to keep auto hobbies alive but to push auto makers and performance parts manufacturers to keep looking at better ways to create efficiency.
I was one of the dummies at the beginning crying about how fuel inj. And emissions would kill performance for ever, boy was I wrong I think clean air is good and efficiency has been one of the great power boosters maybe the single greatest.
I don’t think that means it should have to come at the hands of state or government control, so we need SEMA and originations alike, plus anyone willing to do their part.
Keep up the good work guys keep asking questions and pushing for answers.

[DavidVizard-GFN]

Thanks for the support fella's.

Beatr911 This is a big subject - anything you can bring over from your learnings at gassavers.org would be good. What this means is we are all ready for your input!! Looking forward to your postings.
DV

[Cammer]

California and a number of states have passed legislation requiring carmakers to achieve higher MPGs within a certain number of years.

The carmakers told California they can not meet demands and that they did not answer to individual states. The courts have ruled otherwise!

California needs approval from the feds and this may not happen. Is the federal government in the pocket of the carmakers? You decide.

________________________________________

Please be careful upon entering the men's room!

[UlfArens]

My first post in this great place.
Great post about this 100 MPG technology.

Lean burn has always be one way of getting the millage increased but several limiting factors have held this technology back from normal street cars.

1. The atomization of the fuel was never perfect enough
2. The Spark Power was too little.

The realization is twofold, either to atomize the fuel better OR to increase the spark power.

My experience is largely in the area of Spark Power and I have created many ignition systems over the years, to actually increase spark power dramatically.

A typical ignition system has around 50 Watt of raw spark power, of which usually only 5% to 10% is used to ignite the mixture. The most powerful ignition systems I have worked with, created close to 1 Million Watt.

If you look at the newest BMW engines with direct injection, they kept a low wattage ignition, but increase the atomization of the fuel through direct injection. With this system they are able to run stable and efficient at Lambda 1.4 or even higher.

Increasing the ignition power on these cars will even allow for more efficiency.

Ulf

[Rabiedmushroom]

Originally Posted by DavidVizard-GFN

In 1975 I was the lead engineer on an economy project. The subject was a 1275 Mini GT.

Some of us still drive 1970's Mini 1275GT's... but I don't suppose that's the modern solution!!

Economy is a very important issue. If sensible steps are not taken now, there will a very real problem with owning a fossil fueled car in the future. I can't even think what it would be like to not drive my classics because they'd either be banned or no suitable fuel available.

[BMac]

Hi DavidV,
I've got two of your books on Horsepower Vol. I & II. My thinking since I was about 14 or 16 was that the intake tract was one of THE most important areas to modify in making horsepower... and also mpg.
One book I have is called "Secrets of the 200 MPG Carburetor". In there an obvious drawing sticks in my head. It shows a carburetor on an intake pipe stuffed with ...steel wool of sorts, a distance to the intake manifold then the engine. This is one of THE most important things to observe. You have to heat the fuel to bring it closer to a vaporizing temp, screen it to break up the fuel droplets, then give is "time" to mix with the incoming air. "Time" = "Distance". "Distance" = longer Intake Runners. Longer Intake Runner = More "Torque". More "Torque" = an engine that doesn't have to work as hard to more the car.
One of Charles Nelson Pogue's carburetors was installed in a car up in Winnepeg, Alberta in the winter. He ran it there and said it had no less power and maybe a bit more. His carburetor heated the fuel and the engine would only suck the vapors. Any liquid left would stay in the bottom on the carb til it turned to vapor. If we do this now we will end up with sludge plugging up the system with todays crapoline.

BMac