View source for CVCC

{{About|the engine trademark|the consonant-vowel-consonant-consonant syllable pattern|Syllable}}
{{Short description|Reduced-emissions engine by Honda}} 
[[File:CVCC.JPG|thumb|270px|A [[Honda Civic]] engine with CVCC]]

'''CVCC''', or {{Nihongo|2=複合渦流調整燃焼方式|'''Compound Vortex Controlled Combustion'''|3=''Fukugō Uzuryū Chōsei Nenshō Hōshiki''|lead=yes}}, is an [[internal combustion engine]] technology developed and [[trademark|trademarked]] by the [[Honda|Honda Motor Company]].<ref name=":0">{{Cite web|title=Honda Global {{!}} Introducing the CVCC / 1972|url=https://global.honda/heritage/episodes/1972introducingthecvcc.html|access-date=2020-12-15|website=global.honda|language=en}}</ref>

The technology's name refers to its primary features: '''Compound''' refers to the use of two combustion chambers; '''Vortex''' refers to the vortex generated in the main combustion chamber, increasing combustion speed, and '''Controlled Combustion''' refers to combustion occurring in a timely, controlled manner.<ref name=":0" />

The engine innovatively used a secondary, smaller auxiliary inlet [[valve]] to feed a richer air-fuel mixture to the [[combustion]] chamber around the spark plug, while the standard inlet valve fed a leaner [[air-fuel mixture]] to the remainder of the chamber, creating a more efficient and complete [[combustion]].<ref>{{cite journal |last1=Roeser |first = Justin |date=2022 |title=Milestones: The Journey of Honda in America.| url= https://images.squarespace-cdn.com/content/v1/583c9490be659429d110c269/1663197766454-U2WPYP6SW44BIP7T11BY/AVANTS~1.JPG |
journal=Avants |volume=3|issue= December 2022 |pages=29 |access-date=4 December 2022}}</ref>

== History ==
Following the establishment of an "[[Air pollution|Air Pollution]] Research Group" by Honda in 1965, its collection of emissions data from [[Automotive industry in the United States|American automakers]], and subsequent research into emissions control and [[Indirect injection|prechambers]], the first mention of CVCC technology was by [[Soichiro Honda]] on February 12, 1971, at the Federation of Economic Organizations Hall in Otemachi, Chiyoda-ku, Tokyo.<ref name=":0" />

On the advice of [[University of Tokyo]] professor Tsuyoshi Asanuma, then-Honda [[Research and development|R&D]] Director Tasuku Date, Engine-performance Research Block head Shizuo Yagi, and then-Engineering Design Chief Engineer Kazuo Nakagawa began research into [[Air–fuel ratio|lean combustion]]. After Date suggested the use of a prechamber, which some diesel engines utilized, the first engine to be installed with the CVCC approach for testing was a single-cylinder, 300&nbsp;cc version of [[Honda E engine#EA|Honda's EA engine]] installed in a modified [[Honda N360|Honda N600]] hatchback in January 1970.<ref name=":0" /> This technology allowed Honda's cars to meet [[Japan]]ese and [[United States|American]] [[Vehicle emission standard|emissions standards]] in the 1970s without the need for a [[catalytic converter]].

A type of [[stratified charge engine|stratified charge]] technology, it was publicized on October 11, 1972 and licensed to [[Toyota]] (as [[Toyota TTC|TTC-V]]), [[Ford Motor Company|Ford]], [[Chrysler]], and [[Isuzu]] before making its production debut in the 1975 ''[[Honda E engine#ED|ED1]]'' engine. As emission laws advanced and required more stringent admissible levels, CVCC was abandoned in favour of [[Programmed fuel injection|PGM-FI]] (Programmed Fuel Injection) on all Honda vehicles. Some Honda vehicles in Japan used electronically controlled "PGM-Carb" carburetors on transitional Honda D, E and ZC engines.

The 1981 amendments to the Clean Air Act made it increasingly difficult for CVCC to meet emissions and Honda joined the wider industry in using 3-way Catalysts.

In 2007, the Honda CVCC technology was added to Japan's [[Mechanical Engineering Heritage (Japan)|Mechanical Engineering Heritage]] list.

== Operation ==
Honda CVCC [[Internal combustion engine|engines]] have normal inlet and exhaust valves, plus a small auxiliary inlet valve. On the intake stroke a large amount of a very lean mixture is drawn into the main combustion chamber; at the same time a very small amount of rich mixture is pulled into the pre-chamber near the [[spark plug]]. The pre-chamber near the spark plug is contained by a small perforated metal plate. At the end of the compression stroke, the pre-chamber is rich in fuel, there is a moderately rich mixture in the main chamber near the pre-chamber outlet and the rest of the main chamber is quite lean.  On ignition, flame fronts emerge from the perforations and ignite the remainder of the air–fuel charge. When the sparkplug in the pre-chamber fires, the rich mixture ignites easily and the flame spreads from there into the main chamber, igniting a mixture so lean it wouldn't have fired satisfactorily with just a sparkplug. The remaining engine cycle is as per a standard [[four-stroke engine]].

Formation of [[carbon monoxide]] and [[hydrocarbon]]s are minimized by the overall leanness of the mixture, and the stable and slow burning in the main combustion chamber keeps peak temperature low enough to suppress formation of oxides of nitrogen while keeping the mean temperature high enough long enough to give low hydrocarbon emissions. The design allowed the engine to burn less fuel more efficiently without the use of an [[exhaust gas recirculation]] valve or a catalytic converter, although those methods were installed subsequently to further improve emission reduction.

== Advantages ==
The most significant advantage with CVCC was that it allowed for [[carburetor|carbureted]] engines that did not rely on intake swirl. Previous [[stratified charge engine]]s needed costly [[fuel injection]] systems. Additionally, previous engines tried to increase the velocity and swirl of the intake charge to keep rich and lean mixtures separated; Honda was able to maintain separation via the shape of the combustion chamber.{{Citation needed|date=December 2020}}

The design of CVCC also allowed it to be adapted to existing engines, since only the cylinder head needed to be modified.<ref name=":0" />

== Early design flaw ==
Some early CVCC engines had problems with the auxiliary valves' retaining collars vibrating loose. Once unscrewed, [[Motor oil|oil]] would leak from the [[valvetrain]] into the prechamber, causing a sudden loss of power and large amounts of smoke to flow from the exhaust pipe. These symptoms usually indicated the failure of critical oil seals in the motor that would result in costly repairs. However, the solution was quite simple; Honda corrected the problem with metal retaining rings that slipped over the valves' retaining collars and prevented them from backing out of their threads.{{Citation needed|date=December 2020}}

==CVCC-II==
The 1983 [[Honda Prelude]] (the first year of the second generation of Preludes) used CVCC in combination with a catalytic converter to reduce emissions, along with two separate side draft carburetors (instead of a single, progressive twin-choke carburetor). This new system was called CVCC-II. The following year, a standard cylinder head design was used, and the center carburetor (providing the rich mixture) was removed. The [[Honda City (AA)|Honda City AA]], introduced in November 1981, also used a CVCC-II engine called the [[Honda E engine#ER|ER]].<ref name="WorldCars1985">{{cite book|title=World Cars 1985|publisher=The Automobile Club of Italy/Herald Books|year=1985|isbn=0-910714-17-7|location=Pelham, NY|pages=345–346}}</ref> Its use of CVCC was also known as COMBAX (COMpact Blazing-combustion AXiom).

==CVCC-equipped engines==
{| class="wikitable"
!Series
!Displacement
!Valvetrain
!Aspiration
!Power
!Torque
!Applications
|-
|ED
|{{Convert|1487|cc|L cuin|1|abbr=on}}
| rowspan="5" |[[Overhead camshaft engine|SOHC]] 12-valve
| rowspan="5" |3-barrel carburetor
|{{Convert|52|hp|kW|abbr=unit}} @ 5,000 rpm
|{{Convert|92|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm
|1975- [[Honda Civic]] CVCC (ED1)
1975- Honda Civic Wagon (ED2)

1976-1979 Honda Civic CVCC (ED3)

1976-1979 Honda Civic Wagon (ED4)
|-
|EF
|{{Convert|1598|cc|L cuin|1|abbr=on}}
|{{Convert|68|hp|kW|abbr=unit}} @ 5,000&nbsp;rpm
|{{Convert|115|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm
|1976-1978 [[United States domestic market|USDM]] [[Honda Accord]] CVCC<ref name="Tom Wilson 1985">How to Rebuild Your Honda Car Engine by Tom Wilson, copyright 1985, HP Books, {{ISBN|0-89586-256-5}}</ref>
|-
|EJ
|{{Convert|1335|cc|L cuin|1|abbr=on}}
|{{Convert|68|hp|kW|abbr=unit}} @ 5,000&nbsp;rpm
|{{Convert|104|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm
|1980- Honda Civic (EJ1)
1980- [[Honda Ballade]] (EJ1)

1980- [[Triumph Acclaim]] (EJ1)

1981-1983 Honda Civic CVCC (EJ1)
|-
|EK
|{{Convert|1751|cc|L cuin|1|abbr=on}}
|{{Convert|72|hp|kW|abbr=unit}} @ 4,500&nbsp;rpm (six-port cylinder head, 1979-1980)
{{Convert|75|hp|kW|abbr=unit}} @ 4,500&nbsp;rpm (eight-port cylinder head, 1980-1981)
|{{Convert|127|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm (six-port cylinder head, 1979-1980)
{{Convert|130|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm (eight-port cylinder head, 1980-1981)
|1979-1983 USDM Honda Accord CVCC

1979-1982 USDM Honda Prelude CVCC

1981-1985 [[Japanese domestic market|JDM]] Honda Vigor<ref name="Tom Wilson 1985" />
|-
|EM
|{{Convert|1487|cc|L cuin|1|abbr=on}}
|{{Convert|52|hp|kW|abbr=unit}} @ 5,000 rpm (1980)
{{Convert|63|hp|kW|abbr=unit}} @ 5,000 rpm (1981-1983)
|{{Convert|92|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm (1980)

{{Convert|104|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm (1981-1983)
|1980-1983 Honda Civic (EM1)
|-
|EP
|{{Convert|1601|cc|L cuin|1|abbr=on}}
|SOHC 8-valve
|2-barrel carburetor
|{{Convert|89|hp|kW|abbr=unit}} @ 5,500 rpm
|{{Convert|129|Nm|lbft|abbr=unit|order=flip}} @ 3,500&nbsp;rpm
|1980-1985 [[Honda Quint]]

1980-1981 Honda Accord
|-
|ER (CVCC-II)
|{{Convert|1231|cc|L cuin|1|abbr=on}}
| rowspan="5" |SOHC 12-valve
|1-barrel carburetor

2-barrel carburetor
|{{Convert|44|hp|kW|abbr=unit}} @ 4,500 rpm (1-barrel carb, EU)
{{Convert|55|hp|kW|abbr=unit}} @ 5,000 rpm (1-barrel carb, EU, super fuel)

{{Convert|60|hp|kW|abbr=unit}} @ 5,000 rpm (2-barrel carb, JDM, Pro versions)

{{Convert|62|hp|kW|abbr=unit}} @ 5,000 rpm (2-barrel carb, JDM)

{{Convert|66|hp|kW|abbr=unit}} @ 5,000 rpm (2-barrel carb, JDM, manual R and Cabriolet)
|{{Convert|82|Nm|lbft|abbr=unit|order=flip}} @ 2,500&nbsp;rpm (1-barrel carb, EU)
{{Convert|93|Nm|lbft|abbr=unit|order=flip}} @ 3,500&nbsp;rpm (1-barrel carb, EU, super fuel)

{{Convert|96|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm (2-barrel carb, JDM, Pro versions)

{{Convert|98|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm (2-barrel carb, JDM)

{{Convert|98|Nm|lbft|abbr=unit|order=flip}} @ 3,000&nbsp;rpm (2-barrel carb, JDM, manual R and Cabriolet)
|1981-1986 [[Honda City (AA)|Honda City]]<ref name="WorldCars1985" /><ref name="hoikusha">{{cite book|author=Koichi Inouye|title=World Class Cars Volume 2: Honda, from S600 to City|publisher=Hoikusha|year=1985|isbn=4-586-53302-1|location=Tokyo|pages=120–125}}</ref>
|-
|ES (CVCC-II)
|{{Convert|1829|cc|L cuin|1|abbr=on}}
|Dual side draft carburetors (ES1)
3-barrel carburetor (ES2)
|{{Convert|100|hp|kW|abbr=unit}} @ 5,500 rpm (ES1)
{{Convert|86|hp|kW|abbr=unit}} @ 5,800 rpm (ES2)
|{{Convert|141|Nm|lbft|abbr=unit|order=flip}} @ 4,000 rpm (ES1)
{{Convert|134|Nm|lbft|abbr=unit|order=flip}} @ 3,500 rpm (ES2)
|1983-1984 [[Honda Prelude]] (ES1)
1984-1985 Honda Accord (ES2)
|-
|EV
|{{Convert|1342|cc|L cuin|1|abbr=on}}
|3-barrel carburetor
|{{Convert|60|hp|kW|abbr=unit}} @ 5,500 rpm (USDM)
{{Convert|79|hp|kW|abbr=unit}} @ 6,000 rpm (JDM)

{{Convert|70|hp|kW|abbr=unit}} @ 6,000 rpm (Rover 213)
|{{Convert|99|Nm|lbft|abbr=unit|order=flip}} @ 3,500 rpm (USDM)
{{Convert|111|Nm|lbft|abbr=unit|order=flip}} @ 3,500 rpm (JDM)
|1983-1986 Honda Civic (EV1)<ref>''World Cars 1985'', pp. 346–348</ref>

1983-1986 [[Honda CR-X]] (EV1)

1984-1990 [[Rover 200 Series|Rover 213]] (EV2)
|-
|EW
|{{Convert|1488|cc|L cuin|1|abbr=on}}
|3-barrel carburetor
|{{Convert|58-76|hp|kW|abbr=unit}}
|{{Convert|108-114|Nm|lbft|abbr=unit|order=flip}}
|1984-1985 [[Honda Civic (third generation)|Honda Civic]]/CR-X DX (EW1)

1984-1986 Honda Civic (EW1)

1984-1986 [[Honda Civic (third generation)|Honda Shuttle]] (EW1)
|-
|EY
|{{Convert|1598|cc|L cuin|1|abbr=on}}
|Carburetor
|{{Convert|93|hp|kW|abbr=unit}} @ 5,800 rpm
|{{Convert|133|Nm|lbft|abbr=unit|order=flip}} @ 3,500 rpm
|1983 Honda Accord 1600 E-AC
|}

==References==
{{Reflist}}
* Setright, L. J. K. (1975). Some Unusual Engines. London: Mechanical Engineering Publications Limited.
* [http://www.carsandracingstuff.com/library/reports/402.pdf An Evaluation of a 350 CID Compound Vortex Controlled Combustion (CVCC) Powered Chevrolet Impala]
{{Honda}}

{{DEFAULTSORT:Cvcc}}
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[[Category:Automotive technology tradenames]]
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