Honda's CVCC - Honda vs GM #Blogpost

A story about a rivalry between GM and honda, and a great innovation that had boosted honda’s sucess, and gave the world new standarts.

The average internal combustion engines from the early 1970’s were not what we call today ‘high tech’ in today’s standarts. Loud, inefficiant and often ‘unnecessarily’ sized. Such examples like the massive 5.7 litres Impala V8, it looked as if oil grows on trees.
But then, in 1973, America was shocked by the oil embargo. The price of oil had been quadrupled. Suddenly, running a v8 was an issue. This was the right place, and the right time for an economobile.

Honda started developing a prototype somewhere in the early 70’s. “Compound Vortex Controlled Combustion” it was called. The idea was to meet Japan’s and the US’s new emissions standarts without using a catalitic converter, which was a significant add to the cost of the car. A small, cheap and efficiant engine from accross the ocean, had the benefits like impressive low emissions and offered great fuel economy, some would say it was the 1970’s Toyota Prius (althoug envy Toyota tried mimicing the idea later that decade). Timing was perfect as the oil was costly and americans were starting to look for alternatives.
While power was still a factor in the average american’s list of what a car needs to have, it’s a rather difficult choce, because either you have power OR economy. But worry not because Honda has a solution.

How it works

To understand how the mechanism works, you need to know few basics -
To get a good fuel-air mixture there should be just enough air to add to x amount of fuel, too much or too little and the efficiancy is damaged. While the maximum power (and minimum emissions) is in a rather rich but balanced point, However, a richer fuel-air mix is harder to egnite.
On the other hand, a leaner mixture is dirtier, and not powerful.

So here’s the dilema - Either you put a mixture for power and low emissions that is rich - but inefficiant, or a mixture for economy that is lean- but is dirty and not powerfull. Honda’s engineerong was ground-breaking and featured both!

Like most carburettored engined, usual inlet and exhaust valves had been placed as normal. However, the idea was to add another auxilary inlet valve which had a leaner air-fuel mix to a ‘pre-chaber’ infront of the spark plug. The rest of the inlet would be forced inside the combustion chamber normaly. In the power stroke, the pre-ignition flames would start the leaner fuel-air mixture, creating a fireball that is just big enough and would then egnite the actual combustion chamber.

(In basic terms - The spark plug would egnite a little lean and easily egnited fuel-air mixture, that would then egnite the main, richer and harder to egnite fuel-air mixture.)

With that technology it was both clean and efficiant which wasn’t so obvious at the time. Honda achived great reliability and low emissions as well as super impressive fuel economy while still having decent power. But also reduced prices by not having to add the catalitic converter and not rely on intake swirl. Also, carburettor were much cheaper than fuel injection systems.

Back to the fight with GM now - Chysler and Ford went right up to license the technology. But rather suprisingly General Motors refused to accept the future of small and efficiant motoring. (Classic Americans with their big engines.)

General Motor’s, CEO was qouted -

"Well, I have looked at this design, and while it might work on some little toy motorcycle engine…I see no potential for it on one of our GM car engines."

Of course, very controversial words. But Soichiro Honda, Honda’s founder and a gifted engineer had heard GM’s words and decided to have a go on what would shock GM and would force them to rethink their steps. Soichiro bought a ‘73 Impala with the 5.7 litre v8 and brought it to japan where he told his engineers to add a CVCC system to the motor. After that was quickly done he shipped it back to the USA with the new motor and the EPA tested it.

GM was absloutly shocked! Emissions were reduced to nothing!
78% reduction in hydrocarbons, 95% in carbon monoxide and 91% reduction in NOx.
And it is still 5.7 litre’s.
That was a massive punch by Honda that sent honda to the major global market and shocked General Motors for many years. Honda had their new standarts followed by other companies and the economobiles revolution had began. GM of course had to do something about it and in 1975 featured HEI electric egnition and catalitic converters and an ‘Econominder gauge package’ as an optional extra. And in 1977 the 6th generation was interduced being much smaller then the 5th.

Overall Honda has a quite impact over the global car market surfing the shockwave of the oil crisis. Japan is known today for reliability, economy, low prices and low emissions. It’s not that honda has bent japan motor industry path - japan was buliding economy cars before the oil crisis, but it has definatly proven superior engineering over the rivals from across the pacific. Radical engineering is still developed in japan like the ‘variable compression ratio’ from infiniti, and there are plenty of other examples. Japan, to me at least, is one of the leading countries in development of technology in the car business.. But untill the next time you hear a japanese car manufactorer developing a strange new technology.. Let the ‘Vtec kicked in’ puns roll..


CVCC on wikipedia
1973 oil crisis on wikipedia
Honda vs GM on Jalopnik
Air-Fuel Ratio
Chevrolet Impala
wheeler dealers (10:13) - if you haven’t understood how the mechanism works you should definatly watch this.



I was just thinking I’ll mention the Wheeler Dealers episode on it and…. there it is!

10/06/2016 - 10:51 |
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In reply to by Anonymous (not verified)

That’s what inspired me to write this article, when I came across that interesting story. Figured I’ll combine them

10/06/2016 - 10:52 |
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10/06/2016 - 11:38 |
2 | 0

Well did not work well for Dat rice

10/06/2016 - 11:42 |
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10/06/2016 - 13:07 |
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Now Honda and GM are developing hydrogen fuel cell technology together XD

10/06/2016 - 13:19 |
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In reply to by Anonymous (not verified)


10/06/2016 - 14:57 |
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Ikhtiar Pradana

Take my proud Honda!

10/06/2016 - 15:22 |
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Carter (FirebirdSquad)

Clearly if you think 5.7 liters is huge, you’ve never heard of a 409, 427, 440, 454, or even the legendary 572

10/07/2016 - 00:07 |
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I have. But even 5.7 is pretty damn big

10/07/2016 - 05:29 |
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