Carbureted V8 From the 1970s Gets 40+ MPG. Did Big Oil Really Rob Us For Decades?

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Everyone has heard some version of this story: your grandma’s best friend’s sister’s boyfriend’s brother’s girlfriend heard from this guy who knows this kid whose dad was a garage genius. He worked some non-technical desk job, but experimented with engines on evenings and weekends. After much trial and error, he invented a special carburetor and his car got amazing miles per gallon. When he went to commercialize it, he suddenly had a bunch of money, and was like, “What carburetor?” Big oil had gotten to him, bought his design for big bucks, and promptly threw the design in the trash.

Of course, there are many wild variations. Sometimes the guy died mysteriously because he refused to sell his design. Other times, a malfunctioning car would get amazing mileage, and auto mechanics (who were in on it somehow) “fixed” the car and it went back to getting 10 miles per gallon.

But now I’ve come across a really cool series of YouTube videos that has me wondering if maybe a few of these stories were real. A YouTuber used a 3D printer to make a custom intake adapter for his Ford Maverick (not the truck, but the old car), and used it to install a carburetor from a lawnmower onto the 302 cubic inch V8 engine.

If you know anything about older cars, this sounds like a dumb idea. A big engine needs a big carburetor to put in a bunch of air and fuel so that it can achieve a good fuel to air ratio and run right. But, ThunderHead289 knows his stuff a lot more than the average garage tinkerer, and figured out how to make it actually work and run right. The key? Advancing timing to put a spark to the less dense (but not lean) air-fuel mixture that the little carburetor would supply. Keep in mind that air-fuel ratios are a ratio, and don’t tell you how dense the mixture itself is overall.

The video itself goes into much deeper explanations, so be sure to check it out below (article continues below):

Electronics Not Needed

To be fair, this setup does use electronic injection, but not for fuel. He basically creates a controlled air leak to let in extra air as needed to prevent the little carburetor from creating an overly-rich mixture. This technology didn’t really exist in the 1970s, but normal 2- and 4-barrel carburetors were a lot more complex and used what I’d call “vacuum computing” to do everything, even if the “programming” was really simple.

In other words, electronic computers aren’t needed to perform every complex automated task. Older automatic transmissions used varying fluid pressure going through a complex set of valves and passages to control things. Old telescopes used complex clockwork-like gears to follow the movements of a star on long exposures. We don’t really know exactly what the Greeks used the Antikythera Mechanism for in the 2nd century BCE, but we do know that it was an analog computer, over 2,000 years before the invention of the transistor.

So, it’s entirely possible that something like this could have been pulled off in the 1960s-70s. Even if a garage inventor with limited technical skills couldn’t have pulled it off, automakers probably could have used their much greater resources to make a Maverick get 40-45 MPG on the highway.

This Isn’t The Only High MPG Old Engine We Know Of

It turns out that there are some verifiable automotive experiments that got amazing mileage over the years, and with far better horsepower than the project above.

One great example was Smokey Yunick’s hot vapor engines. He didn’t use a computer or anything else that didn’t exist in the mid-20th century, but managed to get a Pontiac Fiero with a 4-cylinder engine to produce 250 horsepower and 250 lb-ft of torque, while also getting over 50 miles per gallon on the highway. This wasn’t revolutionary, as the same vehicle got 35 MPG in stock form, but it was a gutless turd with 92 horsepower and very tall gear ratios.

His innovation? He used the engine’s waste heat to get the air-fuel mixture very, very hot and used a turbocharger to homogenize the mixture to very high degrees. This cleaner mixture could be run at much leaner air to fuel ratios without producing detonation, which meant a lot more power with far less fuel.

Like the above video, it was all done with a carburetor and with no computers running anything. Perhaps more importantly, he had been experimenting with hot vapor engines for three decades, and claims that he produced a milder engine that outperformed the Corvettes of the 1950s and used a small carburetor, so clearly doing things like he did didn’t even require 1980s technology.

With more digging, you can find a variety of other projects people have done over the years to get higher efficiency out of gas-powered cars. There’s an engineer who proposed adding a smaller engine to cars so that you’d get good power but have amazing highway mileage, even with a Mazda rotary engine (they’re known for poor mileage). There’s the AeroCivic, a modified 90s Honda Civic that got almost 100 MPG just by cleaning up the car’s drag coefficient with ugly DIY modifications. That rivals the efficiency of some EVs.

Why Didn’t Automakers Make Super Efficient Cars?

Obviously, the whole industry has moved on. Electrification, especially full BEVs, are far more efficient than any of these cool ICE projects. So, we can’t go back to yesteryear and go for ICE again. But that still leaves us with the question of why the industry didn’t create highly efficient vehicles after things like the oil crisis of 1973. There would have been plenty of customer demand for a 50 MPG vehicle, and even more demand for a car that got better figures.

We know that oil companies haven’t been afraid to stop automotive companies from building efficient vehicles, with one more modern and well-documented example being the patent issues with large automotive nickel metal hydride (NiMH) batteries. Texaco and then Chevron bought the patents, and wouldn’t let automakers build cars using the technology unless it was a hybrid. This likely held EVs back for a decade.

The reasons better automotive technology didn’t happen earlier in automotive history have been buried and lost to time, but we would be wise to not accept that it wasn’t technologically or economically feasible.

Featured image: Screenshot from the ThunderHead289 YouTube Channel.

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Jennifer Sensiba

Jennifer Sensiba is a long time efficient vehicle enthusiast, writer, and photographer. She grew up around a transmission shop, and has been experimenting with vehicle efficiency since she was 16 and drove a Pontiac Fiero. She likes to get off the beaten path in her "Bolt EAV" and any other EVs she can get behind the wheel or handlebars of with her wife and kids. You can find her on Twitter here, Facebook here, and YouTube here.

Jennifer Sensiba has 1984 posts and counting. See all posts by Jennifer Sensiba