Multi-valve: Difference between revisions

[[File:Nissan VQ35DE 005.jpg|250px|thumb|A [[cylinder head]] of a four [[Poppetpoppet valve|valve]] engine.<br />( [[Nissan VQ engine]] )engine]]

In [[automotive engineering]] aA '''multi-valve''' or '''multivalve''' [[engine]] is one where each [[Cylinder (engine)|cylinder]] has more than two [[poppet valve|valves]] (an intake, and an exhaust). A multi-valve engine has better breathing, and with more smaller valves (having less mass in motion) may be able to operate at higher [[revolutions per minute]] (RPM) than a two-valve engine, delivering more [[Powerpower (physics)|power]].<ref name="KevinClemensDOHC">{{cite web |url=http://www.europeancarweb.com/features/0209ec_twin_cam_analysis/index.html |title=An Echo of the Past: The history and evolution of twin-cam engines (European Car, February, 2009) |author=Kevin Clemens |access-date=2011-12-23 |url-status=dead |archive-url=https://wwwweb.webcitationarchive.org/6HoPOlzah?url=web/20140111045642/http://www.europeancarweb.com/features/0209ec_twin_cam_analysis/ |archive-date=20132014-0701-0211 }}</ref><ref name="DanMcCosh4valves">{{cite web |url= http://www.popsci.com/archive-viewer?id=1QAAAAAAMBAJ&pg=37&query=Quad+4 |title=Auto Tech 88: 4-valves (Popular Science, May 1988, pp. 24, 37-40) |author=Dan McCosh |access-date=2011-12-23 |archive-date=2013-06-02 |archive-url=https://web.archive.org/web/20130602151732/http://www.popsci.com/archive-viewer?id=1QAAAAAAMBAJ&pg=37&query=Quad+4 |url-status=dead }}</ref>

A multi-valve engine design has three, four, or five [[poppet valve|valves]] per cylinder to achieve improved performance. AnyIn [[automotive engineering]], any four-stroke [[internal combustion engine]] needs at least two valves per cylinder: one for ''intake'' of air (and often fuel<ref name=fuel/>), and another for ''exhaust'' of combustion gases. Adding more valves increases valve area and improves the flow of intake and exhaust gases, thereby enhancing [[combustion]], [[volumetric efficiency]], and [[Engine efficiency|power output]]. Multi-valve geometry allows the spark plug to be ideally located within the combustion chamber for optimal flame propagation. Multi-valve engines tend to have smaller valves that have lower [[reciprocating mass]], which can reduce wear on each cam lobe, and allow more power from higher [[revolutions per minute|RPM]] without the danger of [[Valvevalve float|valve bounce]]. Some engines are designed to open each intake valve at a slightly different time, which increases turbulence, improving the mixing of air and fuel at low engine speeds. More valves also provide additional cooling to the cylinder head. The disadvantages of multi-valve engines are an increase in manufacturing cost and a potential increase in oil consumption due to the greater number of valve stem seals. Some [[SOHC]] multi-valve engines (such as the [[Mazda B engine#B8|Mazda B8-ME]]) use a single fork-shaped rocker arm to drive two valves (generally the exhaust valves) so that fewer cam lobes will be needed in order to reduce manufacturing costs.{{citation needed|date=April 2014}}

This has a single large exhaust valve and two smaller intake valves. A three-valve layout allows better breathing than a two-valve head, but the large exhaust valve results in an RPM limit no higher than a two-valve head. The manufacturing cost for this design can be lower than for a four-valve design. The three-valve design was common in the late 1980s and early 1990s; and from 2004 the main valve arrangement used in [[Ford]] [[Ford F series|F-Series]] trucks, and Ford SUVs. The [[Ducati ST3]] [[V-twin]] had 3-valve heads.

Less common is the five-valve head, with two exhaust valves and three inlet valves. All five valves are similar in size. This design allows excellent breathing, and, as every valve is small, high RPM and very high power outputs are theoretically available. Although, compared to a four-valve engine, a five-valve design should have a higher maximum RPM, and the three inlet ports should give efficient cylinder-filling and high gas turbulence (both desirable traits), it has been questioned whether a five-valve configuration gives a cost-effective benefit over four-valve designs. The rise of direct injection may also make five-valve heads more difficult to engineer, as the injector must take up some space on the head. After making five-valve [[Yamaha Genesis engine|Genesis engines]] for several years, [[Yamaha Motor Company|Yamaha]] has since reverted to the cheaper four-valve design, examples.

Examples of the five-valve engines are the various [[List of Volkswagen Group petrol engines#1.8 R4 20vT (EA113/EA827)|1.8L8 L 20vT engines]] manufactured by AUDI AG, the later versions of the [[Ferrari]] [[Ferrari Dino engine|Dino V8]], and the very rare 1.6L6 L [[Toyota A engine#4A-GE (20-valve)|20-valve 4A-GE]] engine ofmade by Toyota. in collaboration with Yamaha.

[[Turbocharging]] and [[Supercharger|supercharging]] are technologies that also improve engine breathing, and can be used instead of, or in conjunction with, multi-valve engines. The same applies to [[variable valve timing]] and [[Variablevariable-length intake manifold|variable-length intake manifolds]]s. [[Rotary valve#Use in engine design|Rotary valves]] also offer improved engine breathing and high rev performance but these were never very successful. [[Cylinder head porting]], as part of [[engine tuning]], is also used to improve engine performance.

In 1916 US automotive magazine ''Automobile Topics'' described a four-cylinder, four-valve-per-cylinder car engine made by Linthwaite-Hussey Motor Co. of Los Angeles, CA, USA: ''"Firm offers two models of high-speed motor with twin intakes and exhausts."''.<ref>{{cite book |url=https://books.google.com/books?id=_OMDAAAAMBAJ |title=Engines: A Century of Progress (Popular Mechanics, Jan 1985, pp. 95-97, 120, 122) |author=Mort Schultz |access-date=2011-12-26 |date=January 1985 }}</ref>

Early multi-valve engines in [[T-head engine|T-head]] configuration were the 1917 ''Stutz'' straight-4, White Motor Car Model GL 309327 CID Dual Valve Mononblock four, and 1919 ''Pierce-Arrow'' straight-6 engines. The standard [[Flathead engine|flathead]] engines of that day were not very efficient and designers tried to improve engine performance by using multiple valves. The [[Stutz Motor Company]] used a modified T-head with 16 valves, twin-spark ignition and aluminium pistons to produce 80&nbsp;bhp (59&nbsp;kW) at 2400 rpm from a 360.8 cid (5.8-liter) straight-4 (0.22&nbsp;bhp per cubic inch). Over 2300 of these powerful early multi-valve engines were built. Stutz not only used them in their famous [[Stutz Bearcat|Bearcat]] sportscar but in their standard touring cars as well.<ref>{{cite web |url=http://www.sportscarmarket.com/car-reviews/american/1500-1918-stutz-series-s-roadster |title=1918 Stutz Series S Roadster (Sportscarmarket.com, Friday, 31 March 2000) |author=Sports Car Market |access-date=2011-12-23 |archive-url=https://web.archive.org/web/20120116170520/http://www.sportscarmarket.com/car-reviews/american/1500-1918-stutz-series-s-roadster |archive-date=16 January 2012 |url-status=dead }}</ref><ref>{{cite web |url=http://classiccardatabase.com/specs.php?series=2885&year=1918&model=21969 |title=1918 Stutz S Series Roadster Standard Specifications (Classic Car Database) |author=Classic Car Database |access-date=2011-12-23 }}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=-DPE_yAlErU |archive-url=https://ghostarchive.org/varchive/youtube/20211222/-DPE_yAlErU |archive-date=2021-12-22 |url-status=live|title= 16-valve Stutz block (YouTube.com video, May 6, 2010) |author=PaulFreehill |website= [[YouTube]] |access-date=2011-12-23 }}{{cbignore}}</ref> The mono block White Motor Car engine developed 72 horsepower and less than 150 were built, only three are known to exist today. In 1919 [[Pierce-Arrow]] introduced its 524.8 cid (8.6-liter) straight-6 with 24 valves. The engine produced 48.6&nbsp;bhp (0.09&nbsp;bhp per cubic inch) and ran very quietly, which was an asset to the [[Prohibition in the United States|bootlegger]]s of that era.<ref>{{cite web |url=http://www.rmauctions.com/FeatureCars.cfm?SaleCode=AZ12&CarID=r198&fc=0 |title=1919 Pierce-Arrow Model 48 Dual-Valve Four-Passenger (RM Auctions, Phoenix, AZ, USA) |author=RM Auctions |access-date=2011-12-23 |archive-date=2012-01-12 |archive-url=https://web.archive.org/web/20120112023839/http://www.rmauctions.com/FeatureCars.cfm?SaleCode=AZ12&CarID=r198&fc=0 |url-status=dead }}</ref><ref>{{cite web |url=http://classiccardatabase.com/specs.php?series=2687&year=1919&model=16436 |title=1919 Pierce Arrow 48-B-5 Series Touring Standard Specifications (Classic Car Database) |author=Classic Car Database |access-date=2011-12-23 }}</ref><ref>{{cite web |url=http://www.conceptcarz.com/vehicle/default.aspx?carID=13542&i=2#menu |title=1919 Pierce Arrow Model 48 Specifications (Conceptcarz.com) |author=Conceptcarz.com |access-date=2011-12-23 }}</ref>

There is much discussion about which was the first 'mass-produced' car to use aan engine with four valves per cylinder. For six cylinder engines, and considering special versions of mass-produced cars, the first appears to have been the 1969 [[Nissan Skyline]], using the Nissan [[Nissan S20 engine|S20]] six cylinder DOHC four-valve engine. This engine was also fitted to [[Nissan Fairlady]] Z432 racing edition.

For a four -cylinder engine, the first mass-produced car using a four valves per cylinder engine was the British [[Ford Escort RS1600]], this car used the Cosworth BDA engine which was a Ford 'Kent' block with a [[Cosworth]] 16 valve twin cam cylinder head. The car went on to become a rallying legend in the 1970s winning many domestic and World Championship events. Other cars claiming to be first are the [[Jensen Healey]], launched in 1972 which used a [[Lotus 907]] belt-driven DOHC 16-valve 2-liter straight-4 producing 140&nbsp;bhp (54.6&nbsp;kW/liter, 1.20&nbsp;bhp/cid). All of these, although mass-produced, are also of relatively limited production., so Theit is argued that the first widely available and popularly priced mass-production car with a four valve per cylinder engine was the 1973 [[Dolomite Sprint|Triumph Dolomite Sprint]]. This Triumph used an in-house developed SOHC 16-valve 1,998 cc (122 ci) straight-4 engine that produced 127&nbsp;bhp (47.6&nbsp;kW/liter, 1.10&nbsp;bhp/cid) at introduction.

The 1975 [[Chevrolet Cosworth Vega]] featured a DOHC multi-valve head designed by [[Cosworth|Cosworth Engineering]] in the UK. This 122-cubic-inch straight-4 produced {{Convert|110|bhp|kW PS|0|abbr=on}} at 5600 rpm (0.90&nbsp;bhp/cid; 41.0&nbsp;kW/liter) and {{Convert|107|lbft|Nm|abbr=on}} at 4800 rpm.<ref>{{cite web |url= http://upload.wikimedia.org/wikipedia/en/f/f4/1975_Cosworth_Vega_Ad.jpg |title=1975 Cosworth Vega advertisement (Motor Trend Magazine, 1975) |author=Wikimedia Commons |access-date=2011-12-23 }}{{dead link|date=January 2022|fix-attempted=yes}}</ref>

[[Ferrari]] developed their ''[[Ferrari Dino engine#Quattrovalvole|Quattrovalvole]]'' (or QV) engines in the 80s. Four valves per cylinder were added for the 1982 [[Ferrari 308 GTB|308]] and [[Ferrari Mondial|Mondial]] ''Quattrovalvole'', bringing power back up to the pre-[[fuel injection|FI]] high of {{Convert|245|hp|kW|0|abbr=on}} . A very unusual Dino Quattrovalvole was used in the 1986 [[Lancia Thema|Lancia Thema 8.32]]. It was based on the 308 QV's engine, but used a split-plane crankshaft rather than the Ferrari-type flat-plane. The engine was constructed by [[Ducati]] rather than Ferrari, and was produced from 1986 through 1991. The Quattrovalvole was also used by Lancia for their attempt at the [[World Sportscar Championship]] with the [[Lancia LC2|LC2]]. The engine was twin-turbocharged and destroked to 2.65&nbsp;litres, but produced {{Convert|720|hp|kW|0|abbr=on}} in qualifying trim. The engine was later increased to 3.0&nbsp;litres and increased power output to {{Convert|828|hp|kW|0|abbr=on}}. The 1984 [[Ferrari Testarossa]] had a 4.9-liter [[flat-12]] with four valves per cylinder. Almost 7,200 Testarossa were produced between 1984 and 1991.

Following Nissan's lead, Toyota released the 1.6-liter (1,587 cc) Toyota [[4AGE|4A-GE Toyota engine]] was releasedengine in 1983. The cylinder head was developed by [[Yamaha Motor Corporation]] and was built at Toyota's Shimayama plant. While originally conceived of as a two-valve design, Toyota and Yamaha changed the 4A-GE to a four-valve after a year of evaluation. It produced 115-140&nbsp;bhp/ (86-104&nbsp;kW@) at 6,600 rpm (54.2-65.5&nbsp;kW/liter) and 148 Nm/{{Convert|109 |lbft@|Nm|abbr=on}} at 5,800 rpm. To compensate for the reduced air speed of a multi-valve engine at low rpmrpms, the first-to-second generation engines included the [[T-VIS]] featureintake system.

The [[GM Quad-4 engine|GM Quad 4]] multi-valve engine family debuted early 1987. The Quad 4 was the first mainstream multi-valve engine to be produced by GM after the [[Chevrolet Cosworth Vega]]. The NA Quad 4 achieved {{Convert|1.08|bhp|kW PS|0|abbr=on}} per cubic inch (49.1&nbsp;kW/liter).<ref name="DanMcCosh4valves"/><ref>{{cite book |url= https://books.google.com/books?id=HOQDAAAAMBAJ |title=Quad 4: The Inside Story (Popular Mechanics, February 1988, pp.62-65) |author=Mike Allen |access-date=2011-12-23 |date=February 1988 }}</ref> Such engines soon became common as Japanese manufacturers adopted the multi-valve concept.

The 1975 [[Honda Civic]] introduced Honda's 1.5-liter SOHC 12-valve straight-4 engines. Nissan's 1988–1992 SOHC [[Nissan KA engine|KA24E]] engine had three valves per cylinder (two intakes, one exhaust) as well. Nissan upgraded to the DOHC after 1992 for some of thetheir sports cars, including the [[Nissan 240SX|240SX]].

Mercedes and Ford produceproduced three-valve V6 and V8 engines, Ford claiming an 80% improvement in high RPM breathing without the added cost of a DOHC [[valve train]]. The Ford design uses one spark plug per cylinder located in the centre, but the Mercedes design uses two spark plugs per cylinder located on opposite sides, leaving the centre free to add a direct-to-cylinder fuel injector at a later date.

Examples of SOHC four-valve engines include: the [[Honda]] [[Honda F engine|F-series]] engines, [[Honda D engine|D-series]] engines, all [[Honda J engine|J-series]] engines, the [[Honda R engine|R-series]] engines, the [[Mazda]] B engine#B8|Mazda B8-ME]], and the [[Chrysler SOHC V6 engine|Chrysler 3.5&nbsp;L V6 engine]].

In April 1988 an [[Audi Quattro100|Audi 200 Turbo Quattro]] powered by an experimental 2.2-liter turbocharged 25-valve straight-5 rated at 478&nbsp;kW/650 PS@6,200 rpm (217.3&nbsp;kW/liter) set two world speed records at [[Nardo]], Italy: 326.403&nbsp;km/h (202.8&nbsp;mph) for 1,000&nbsp;km (625 miles) and 324.509&nbsp;km/h (201.6&nbsp;mph) for 500 miles.<ref>{{cite book |url=https://books.google.com/books?id=8odMlvCz19IC |title=Five valves for Audi (Popular Science, Jan 1990, pp. 35, 37) |author=D. Sherman |access-date=2011-12-30 |date=January 1990 }}</ref><ref>{{cite web |url=http://www.brunnracing.info/projects/audi_200_turbo_quattro/audi_200_turbo_quattro.html |title=AUDI 200 N6000 - WORLD RECORD PROTOTYPE (Brunnracing.com, Dec 2011) |author=Brunn Racing |access-date=2011-12-30 }}</ref>

[[Yamaha Motor Company|Yamaha]] designed the five-valve cylinder head for the [[Toyota A engine#4A-GE (20-valve)|Toyota20-valve 4A-GE]] 20Vengines 1991made Silvertopby andToyota 1995for Blacktop]] engine useduse in some [[Toyota Corolla]] models in Japan in 1991. Yamaha also developed five-valve Formula One engines, the 1989 [[V8Yamaha F1 engine#Yamaha|OX88]] V8, 1991 [[Jordan 192|OX99]] V12, 1993 [[Judd (engine)#Yamaha partnership|OX10]] V10 and 1996 [[Judd (engine)#Yamaha partnership|OX11]] V10, but none of these were very successful.

Although most multi-valve engines have [[overhead camshaft]]s, either SOHC or [[DOHC]], a multivalve engine may be a pushrod [[overhead valve engine]] (OHV) design. [[ChevroletGeneral Motors|GM]] has revealed a three-valve version of its [[GM LS engine|Generation IV V8]] which uses [[pushrod]]s to actuate forked rockers, and all Duramax V8 engines have four valves per cylinder with pushrods. Moreover, [[Cummins]] makes a four-valve OHV [[straight-six engine|straight six]] [[Diesel engine|diesel]], the [[Cummins B Series engine|Cummins B Series]] (now known as ISB). Ford also uses pushrods in its 6.7L Power Stroke

engine using four pushrods, four rockers and four valves per cylinder. The 6.0 and 6.4 Powerstroke engine built by Navistar also used pushrods with four-valve heads. Pushrod multi-valve systems are common on diesels because they need to be able to meet emissions standards, but also produce more low-end torque. The Harley-Davidson ''Milwaukee Eight'' engine, introduced in 2016, uses four-valves per cylinder driven by pushrods and a single in-block camshaft.<ref>{{cite web|last1=Bennett|first1=Jay|title=Milwaukee Eight Multi-Valve|url=http://www.popularmechanics.com/cars/motorcycles/a22601/harley-davidson-new-engine-milwaukee-eight/|website=Popular Mechanics|publisher=HEARST DIGITAL MEDIA|access-date=16 August 2017|date=2016-08-29}}</ref><ref>{{cite web|last1=Cook|first1=Marc|title=HD Pushrods|url=http://www.motorcyclistonline.com/harleys-all-new-milwaukee-eight-big-twin#page-4|website=Motorcyclist Online|publisher=Bonnier Corporation|access-date=16 August 2017}}</ref>

* 1915 [[Indian (motorcycle)|Indian]] [[Board track racing|board track racer]], 61-cid (1.0-liter) OHV 8-valve V-twin.<ref>{{cite web |url=https://www.youtube.com/watch?v=TfEZyCccKTs |archive-url=https://ghostarchive.org/varchive/youtube/20211222/TfEZyCccKTs |archive-date=2021-12-22 |url-status=live|title=1915 Indian 8 Valve Boardtrack Racer (YouTube.com video, Mar 18, 2010) |author=Yesterdays.nl |website=[[YouTube]] |access-date=2011-12-27 }}{{cbignore}}</ref>

* 1973 [[Yamaha TX500]] "pent-roof" 500cc DOHC 8-valve parallel-twin (the first mass-produced DOHC 4-valve per cylinder motorcycle)<ref>{{cite web |url=http://www.tobyfolwick.com/tx750/textual/cm1289.php |title=YAMAHA TX500/750: A QUESTION OF BALANCE |publisher=Tobyfolwick.com |access-date=2015-12-23 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304134437/http://www.tobyfolwick.com/tx750/textual/cm1289.php |url-status=dead }}</ref>

* 1978 [[Honda CX series|Honda CX500]], a 498 cc SOHC, pushrod actuated OHV, 4-valve per cylinder V-twin; 1982 [[Honda CX500#CX500 Turbo|CX500 Turbo]] was the first factory multi-valve [[Turbochargerturbocharger|turbocharged]] motorcycle.

Long after the King-Bugatti "U-16" aviation engine used them, shortly before World War II, the [[Junkers]] aviation firm began production of the Third Reich's most-produced military aviation engine (68,000+ produced), the 1936-designed, 35-litre displacement, inverted-V12, liquid-cooled [[Junkers Jumo 211]], which used a three-valve cylinder head design<ref>[http://www.enginehistory.org/German/Jumo%20211/j26.jpg German language illistrationillustration of Jumo 211 three-valve design]</ref> inherited from Junkers' first inverted V12 design, the 1932-origin [[Junkers Jumo 210]]<ref>{{cite web |url=https://www.flightglobal.com/pdfarchive/view/1937/1937%20-%202509.html?search=three%20valve |title=Flight Magazine, September 9, 1937 |author=<!--Not stated--> |date=September 9, 1937 |page=265 |website=flightglobal.com |publisher=Flightglobal Archive |access-date=March 15, 2017 |quote=At the recent international meeting at Zürich, several of the successful German machines were fitted with the new Junkers 210 petrol engine...'''Three valves per cylinder are provided, two inlets and one exhaust,''' operated by push rods and rockers from a single camshaft.}}</ref> — this was carried through into the later, more powerful 1940-origin [[Junkers Jumo 213]], produced through 1945, the production versions of which (the Jumo 213A and -E subtypes) retained the Jumo 211's three-valve cylinder head design.<ref>{{cite web |url=http://www.enginehistory.org/German/Jumo213/Jumo213.shtml |title=The Junkers Jumo 213 Engine |last=Culy |first=Doug |date=April 4, 2012 |website=enginehistory.org |publisher=Aircraft Engine Historical Society |access-date=March 15, 2017 |quote=The Jumo 213 had a three-valve head, but a four-valve head was in development for the “J” version. However, the Jumo 213A is documented as itself having superior high altitude performance at that particular point in time, although the DB 603 was later developed with equal or better features. |url-status=dead |archive-url=https://web.archive.org/web/20161221130406/http://www.enginehistory.org/German/Jumo213/Jumo213.shtml |archive-date=December 21, 2016 }}</ref>

In 1905 car builder [[Delahaye]] had experimented with a [[DOHC]] marine racing engine with six valves per cylinder. This Delahaye '''Titan''' engine was a massive 5190 cid (85.0-liter) four-cylinder that produced 350&nbsp;bhp (0.07&nbsp;bhp/cid). It allowed the motor boat ''Le Dubonnet'' piloted by [[Emile Dubonnet]] to set a new world's speed record on water, reaching {{Convert|33.80|mi/h|km/h|abbr=on}} on the lake at [[Juvisy]], near [[Paris]], [[France]].<ref>{{cite book |url=https://books.google.com/books?id=w07kz8QiXygC |title=Classic Speedboats 1916–1939 (Motorbooks International, 1997, p.16, ISBN 0-7603-0464-5) |author=Gérald Guétat |access-date=2011-12-23 |isbn=9780760304648 |date=1998-01-10 }}</ref>

<ref name=fuel>In direct injection engines - such as diesels and later petrol engines - fuel is delivered to the chamber directly via the injector rather than through a valve. In carburetted engines and indirect-injection engines the fuel is mixed with the air outside of the cylinder and both enter together via the intake valve. </ref>