Editing Jaguar XK engine (section)

==Individual displacements==

===3.4-litre===

The first production use of the XK [[straight-6]] was in the 1948 [[Jaguar XK120]], which used the {{cvt|3441|cc|L cuin|1}} version with a [[Bore (engine)|bore]] x [[Stroke (engine)|stroke]] of {{convert|83x106|mm|2|abbr=on}}. It had an iron block without cylinder liners and aluminium [[cylinder head]]. It had a wider gap between cylinders 3 and 4 than between the other cylinders. The 3.4 was first rated at {{convert|160|bhp|PS kW|0|abbr=on}} [[Horsepower#SAE gross power|SAE gross]] at a [[compression ratio]] of 8:1, rising to {{convert|210|bhp|PS kW|0|abbr=on}} SAE gross with the C-type cylinder head (confusingly not the head from the C-Type as raced at Le Mans) all the way to {{convert|250|bhp|PS kW|0|abbr=on}} SAE gross with the "straight port" head at a compression ratio of 9:1 as fitted to the XK150SE.

Almost as soon as the new compact Jaguar [[Jaguar Mark 1|2.4-litre]] was released, there was pressure on Jaguar to fit the 3.4-litre engine to it. This was duly done in February 1957, the car being known as the Jaguar 3.4-litre. The designation "Mark 1" for these cars was applied retrospectively, after the release of the Mark 2 in 1959.

The original 3.4-litre XK was used in the following road cars:
* [[Jaguar XK120]] - 1948-53, "Standard (or "A type")" cylinder head, bare aluminium finish, 2 × [[SU Carburettor|SU H6 carburettors]]. The XK 120 C came with the C-type head (red) as an option from 1951 to 1952 with 2 × SU H8 carburettors. In 1953, the XK 120 C switched to a triple 40 DCOE [[Weber carburetor]] setup. The XK 120 SE and M came with the C-type head as an option with 2 × SU H6 carburettors (occasionally SU H8)
* [[Jaguar XK140]] - 1954-57, "Standard (or "A type")" cylinder head, 2 × SU H6 carburettors. The XK 140 SE or M came with the C-type head as an option, painted red with 2 × SU H6 or H8 carburettors
* [[Jaguar XK150|Jaguar XK 150 3.4]] - 1957-61, "B type" cylinder head, painted light blue-green, 2 × SU HD6 carburettors
* [[Jaguar XK150|Jaguar XK 150 3.4S]] - 1957-61, "Straight port" cylinder head, painted orange, 3 × SU HD8 carburettors
* [[Jaguar Mark VII]] - 1950-54, "A type" then "C type" (as option from April 1953) cylinder head, unpainted aluminium, 2 × SU H6 carburettors
* [[Jaguar Mark VII|Jaguar MkVIIM]] - 1954-57, "C type" cylinder head, 2 × SU H6 carburettors, some had high-lift cams
* [[Jaguar Mark VIII]] - 1956–1958, "B type" cylinder head, painted light blue-green, 2 × SU HD6 carburettors
* [[Jaguar Mark 1|Jaguar 3.4-litre 'Mark 1']] -<ref>''Jaguar Workshop Manual 2.4- and 3.4-litre Mks. I and II, 3.8-litre Mk. II with automatic transmission 1956 to 1961'', Scientific Publications, Australia</ref> 1957-59, "B type" cylinder head, painted light blue-green, 2 × SU HD6 carburettors
* [[Jaguar Mark 2|Jaguar 3.4-litre Mark 2]] - 1959-67, "B type" cylinder head, painted light blue-green, 2 × SU HD6 carburettors
* [[Jaguar Mark 2|Jaguar 340 Mark 2]] -<ref>''Jaguar Mk II Workshop Manual No.186'', InterEurope Ltd, {{ISBN|0-85666-020-5}}</ref> 1967-68, "B type" cylinder head, ribbed cam covers, 2 × SU HD6 carburettors
* [[Jaguar S-Type (1963)|Jaguar S-Type 3.4]] - 1963-68, "B type" cylinder head painted light blue-green, smooth cam covers, 2 × SU HD6 carburettors

===2.4-litre===
In the mid-1950s, Jaguar lacked a compact saloon of the type represented until 1949 by the Standard-engined 1½ litre. In choosing a power unit for its all new compact saloon, Jaguar could choose between the 1,995 cc four-cylinder XK prototype and a downsized version of the 3.4-litre six-cylinder XK.  The 4-cylinder was considered too low powered and unrefined. The 3.4 was already well "undersquare", which means that its bore was much less than its stroke, so a smaller bore version of the 3.4 was not seen as a realistic proposition.  Jaguar was therefore obliged to create a short-stroke version of the 6-cylinder XK with a shorter cylinder block, reducing it in height from {{convert|11.5|in|mm|0|abbr=on}} to {{convert|8.85|in|mm|0|abbr=on}}.

Introduced in the Jaguar [[Jaguar Mark 1|2.4-litre]] in 1955, the engine had a stroke of {{convert|76.5|mm|in|1|abbr=on}} while retaining the bore of {{convert|83|mm|in|1|abbr=on}} to give a capacity of {{convert|2483|cc|abbr=on}}. Despite having a displacement of almost 2.5 litres, the new car was called the "Jaguar 2.4" to create an obvious separation from the old Standard 2½ litre and link it to the now familiar 3.4-litre XK engine.  The 2.4s produced were rated at 112&nbsp;bhp (nett) by the factory, using twin Solex downdraft carburettors.

In 1959 the engine was carried over into the new Mark 2, in which it produced {{Convert|120|hp|kW|0|abbr=on}} [[Horsepower#SAE gross power|SAE gross]], still with Solex carburettors. The [[Jaguar Mark 2|Jaguar 240]] was fitted with an uprated version of the engine, incorporating the straight-port cylinder head and twin SU carburettors delivering 133&nbsp;bhp [[Horsepower#SAE gross power|SAE gross]].

The 2.4-litre XK was used in the following cars:
* [[Jaguar Mark 1|Jaguar 2.4-litre 'Mark 1']] - 1955-59, "B type" cylinder head, unpainted, 2 × Solex B32PB15S carburettors, valve angles 30 degrees inlet, 45 degrees exhaust
* [[Jaguar Mark 2|Jaguar 2.4-litre Mark 2]] - 1959-67, "B type" cylinder head, unpainted, 2 × Solex B32PB15S carburettors, valve angles 45 degrees inlet and exhaust
* [[Jaguar Mark 2#240 and 340|Jaguar 240 Mark 2]] - 1967-69, "Straight port" cylinder head, unpainted, 2 × SU HD6 carburettors, valve angles 45 degrees inlet and exhaust

===3.8-litre===

The 3.8-litre version was released in 1958, initially for the last of the XK150s and the Mark IX saloon.  It retained the 3.4’s bore centres and {{convert|106|mm|in|1|abbr=on}} stroke but was bored out to {{convert|87|mm|in|1|abbr=on}} for a total displacement of (3,781 cc / 230.7 cu-in).  The distance between the cylinder bores was sufficiently small that it was decided to fit dry liners to the bores.  The 3.8 had a number of detail differences from the 3.4, particularly in its valve gear and carburetion.  The standard 3.8 produced {{Convert|220|hp|kW|0|abbr=on}} [[Horsepower#SAE gross power|SAE gross]] and up to {{Convert|265|hp|kW|0|abbr=on}} [[Horsepower#SAE gross power|SAE gross]] in the XK150SE with the straight port head.

The 3.8-litre XK was used in the following road cars:
* [[Jaguar XK150|Jaguar XK 150 3.8]] - 1958-61, "B type" cylinder head, painted dark blue metallic, 2 × SU HD6 carburettors
* [[Jaguar XK150|Jaguar XK150 3.8S]] - 1958-61, "Straight port" cylinder head, painted pumpkin orange, 3 × SU HD8 carburettors
* [[Jaguar Mark IX]] - 1958-61, "B type" cylinder head, painted dark blue metallic, 2 × SU HD6 carburettors
* [[Jaguar Mark X|Jaguar Mark X 3.8]] - 1961-64, "Straight port" cylinder head, painted gold, 3 × SU HD8 carburettors
* [[Jaguar Mark 2]] - 1959-67, "B type" cylinder head, painted dark blue metallic, 2 × SU HD6 carburettors
* [[Jaguar E-Type|Jaguar E-Type Series 1 3.8]] - 1961-64, "Straight port" cylinder head, painted orange then gold, 3 × SU HD8 carburettors
* [[Jaguar S-Type (1963)|Jaguar S-Type 3.8]] - 1963-68, "B type" cylinder head, dark blue metallic or later with smooth cam covers and unpainted, 2 × SU HD6 carburettors
* [[Panther J72|Panther J.72]]

===3.0-litre===

3-litre versions of the XK engine were built from 1959 onwards for [[FIA]] sports car racing with a 85 mm (3.35 in) bore and 88 mm (3.46 in) stroke.<ref>{{cite web |title=Guide: Jaguar E2A |url=https://supercarnostalgia.com/blog/jaguar-e2a |website=Supercar Nostalgia|date=16 October 2019 }}</ref> It was also popular with small race car manufacturers such as [[Lister Cars]] who could not afford to produce their own engines. As well as endurance racing, the engine was also used in [[Formula Libre]] racing.

A 3.0-litre XK was used in the following road cars:
*Jaguar E2A prototype sports racer (1960)
*[[Jaguar E-type]] lightweight sports racer (1961)
*[[Jaguar D-type]] (non-works) sports racer (1959)
*[[Lister Cars]] endurance and formula racers
*[[Hersham and Walton Motors]] (HWM) endurance and formula racers
*[[Cooper Car Company]] endurance and formula racers
*[[John Tojeiro]] endurance and formula racers

===4.2-litre===
A bored-out 4.2-litre version of the XK was officially released in 1964, although racers had been boring the 3.8 out to 4.2 litres for years. The factory 4.2-litre block was a new siamesed sleeve design which used respaced cylinders set evenly along the length of the block with new main bearing spacings and a new crankshaft. The middle two cylinders were moved closer together and the outer two moved further apart but the overall length of the block remained unchanged. This enabled the cylinder bores to be taken out to {{convert|92.08|mm|in|2|abbr=on}} whilst retaining the familiar long stroke of {{convert|106|mm|in|2|abbr=on}} for a total displacement of {{convert|4235|cc|L cuin|1|abbr=on}}.

Despite the re-spacing of the cylinder bores, the cylinder head castings remained unchanged. As a result, the centrelines of the combustion chambers in the head no longer aligned precisely with the centrelines of the cylinders but this did not matter greatly as the combustion chamber diameters in the head were smaller than the cylinder diameters. The 3.8 and 4.2-litre cylinder heads and cams are therefore interchangeable. The 4.2-litre engine from the factory had unsmoothed steps between the inlet manifold and head, and the manifold gaskets were not a good match for the inlet ports. These engines therefore make excellent bases for some modification, achieving approx. {{convert|220|bhp|kW PS|0|abbr=on}} [[Horsepower#SAE net power|SAE net]] and increased torque merely by "flowing" the head.

Published horsepower ratings of the various versions of the 4.2-litre are complicated by the switch from gross to net horsepower systems during its lifetime. For example, in 1965 the 4.2-litre with triple [[SU carburettor|SU HD8]] [[carburetor]]s fitted to the US-specification E-Type was rated at {{convert|265|hp|PS kW|0|abbr=on}} @ 5400 rpm [[Horsepower#SAE gross power|SAE gross]] and a maximum [[torque]] of {{convert|384|Nm|lbft|0|abbr=on}} @ 4000 rpm <ref>{{cite web|url=https://www.ultimatecarpage.com/spec/6397/Jaguar-E-Type-4.2-Roadster.html|title=1964 - 1968 Jaguar E-Type 4.2 Roadster specifications|website=ultimatecarpage.com|language=en-US|access-date=2018-06-10}}</ref><ref>{{cite web|url=https://www.carfolio.com/specifications/models/car/?car=58399|title=1966 Jaguar E-Type 2+2 specifications|website=carfolio.com|language=en-US|access-date=2018-06-10}}</ref><ref>{{cite web|url=http://www.automobile-catalog.com/car/1966/1277165/jaguar_4_2_xk-e_roadster_3_31_opt__axle.html|title=1966 Jaguar 4.2 XK-E Roadster (3.31 opt. axle) detailed specifications|website=automobile-catalog.com|language=en-US|access-date=2018-06-10}}</ref><ref>"Jaguar XK-E 4.2", ''Car and Driver'', Feb. 1965</ref> whereas by 1969, now with twin [[Zenith Carburettor Company (British)|Zenith-Stromberg]] [[carburetor]]s, this had fallen to {{convert|246|hp|kW|0|abbr=on}} [[Horsepower#SAE gross power|SAE gross]].<ref>"Jaguar 4.2 XK-E", ''Road Test'', Feb. 1969</ref> The difference indicates the effect of the revised carburetion and other changes made to reduce exhaust emissions from US specification engines.  Jeff Daniels' reference states that the similar twin Zenith-Stromberg version fitted to a US specification XJ6 was rated by Jaguar at {{convert|170|PS|kW hp|0|abbr=on}} using the [[Horsepower#Deutsches Institut für Normung 70020 (DIN 70020)|DIN net]] horsepower system, the difference being largely due to the effect of the gross versus net horsepower rating systems.

The 1987 [[Jaguar XJ6]] was the last [[Jaguar (car)|Jaguar]] car fitted with the XK engine. In 1992 the last [[Daimler Company|Daimler]] DS420 Limousine was produced. Like all other DS420 limousines, it was equipped with a 4.2-litre XK engine. The 4.2 variant was also used in some military vehicles with relatively few modifications. The XK engine has the rare accolade of having been in production and service in cars spanning six consecutive decades.

All of the 4.2-litre XK engines used the straight port head. After the arrival of the ribbed cam covers in 1967 the heads normally remained unpainted, which some sources describe as "silver".

The 4.2-litre XK was used in the following cars:
* [[Jaguar Mark X|Jaguar Mark X 4.2]] - 1964-66, "straight port" cylinder head, painted gold, 3 × SU HD8 carburettors
* [[Jaguar 420]] - 1966-68, 2 × SU HD8 carburettors
* [[Daimler Sovereign]] - 1966-69, 2 × SU HD8 carburettors
* [[Jaguar Mark X|Jaguar 420G]] - 1966-70, painted gold, 3 × SU HD8 carburettors
* [[Jaguar E-Type|Jaguar E-Type Series 1 4.2]] - 1964-68, painted gold, 3 × SU HD8 carburettors (from 1967 US specification E-Types used 2 × Zenith-Stromberg 175 CDSE carburettors for reduced emissions)
* [[Jaguar E-Type|Jaguar E-Type Series 2]] - 1968-70, 3 × SU HD8 carburettors (US specification E-Types used 2 × Zenith-Stromberg 175 CDSE carburettors for reduced emissions)
* [[Jaguar XJ6#Series 1 (1968–1973)|Jaguar XJ6 4.2 Series 1]] - 1968-73, 2 × SU HD8 carburettors (North American specification XJ6 used 2 × Zenith-Stromberg 175 CDSE carburettors for reduced emissions)
* [[Daimler Sovereign|Daimler Sovereign 4.2 'XJ6' Series 1]] - 1969-73, 2 × SU HD8 carburettors
* [[Jaguar XJ6|Jaguar XJ6 4.2 Series 2]] - 1973-74, 2 × SU HS8 carburettors (North American specification XJ6 used 2 × Zenith-Stromberg 175 CDSE carburettors for reduced emissions)
* [[Daimler Sovereign|Daimler Sovereign 4.2 'XJ6' Series 2]] - 1973-74, 2 × SU HS8 carburettors
* [[Jaguar XJ6|Jaguar XJ6 L 4.2 Series 2]] - 1973-79, 2 × SU HS8 carburettors. From 1977, 2 × SU HIF7 carburettors, US market from May 1978 Bosch-Lucas L-Jetronic electronic injection
* [[Daimler Sovereign|Daimler Sovereign LWB 4.2 'XJ6' Series 2]] - 1973-79 (and Daimler Vanden Plas 1975-79), 2 × SU HS8 carburettors. From 1977, 2 × SU HIF7 carburettors, US market (VDP only) from May 1978 Bosch-Lucas L-Jetronic
* [[Jaguar XJ6|Jaguar XJ6 4.2 Series 3]] - 1979-87, 2 × SU carburettors or Bosch-Lucas L-Jetronic electronic injection
* [[Daimler Sovereign|Daimler 4.2 'XJ6' Series 3]] - 1979-86, 2 × SU carburettors or Bosch-Lucas L-Jetronic electronic injection
* [[Daimler DS420|Daimler DS420 Limousine]] - 1968-92, 2 × SU HD8 carburettors. From 1985 Bosch-Lucas L-Jetronic electronic injection
* [[Panther J72|Panther J.72]]
* [[Panther De Ville]]

It was also used in the [[Combat Vehicle Reconnaissance (Tracked)]] - CVR(T) - family of military vehicles: e.g.,
* [[FV101 Scorpion]], a light tank
* [[FV107 Scimitar]], an armoured [[reconnaissance vehicle]]

and the corresponding [[Combat Vehicle Reconnaissance (Wheeled)]] - CVR(W) - family: e.g., [[Fox armoured reconnaissance vehicle]]
plus the [[Dennis Specialist Vehicles|Dennis]] D600 fire engine.

===2.8-litre===

A 2.8-litre version of the XK was introduced for the entry-level XJ6 models in 1968. It had a similar short block to the old the 2.4 with addition of the later two rear water cooling holes for the straight port cylinder head, retaining the bore of {{convert|83|mm|in|1|abbr=on}} but lengthening the stroke by {{convert|9.5|mm|in|1|abbr=on}} to {{convert|86|mm|in|1|abbr=on}} to give a displacement of 2,792 cc / 170.4 cu-in. The power output of the 2.8 was listed as {{convert|142|PS|kW hp|0|abbr=on}} [[Horsepower#Deutsches Institut für Normung 70020 (DIN 70020)|DIN net]], which cannot be directly compared with the 133&nbsp;bhp [[Horsepower#SAE gross power|SAE gross]] of the last of the 2.4s in the 240 Mark 2.

The 2.8 gained a bad reputation early in its career due to a tendency for excessive carbon deposits to accumulate on the piston crowns during low-speed running, which would burn through the crowns when run at higher revs. This was later cured by a switch to stronger pistons but the engine was also a mediocre performer offering no real economy benefit and it was dropped in 1973, to be replaced by the ‘new’ 3.4.

All of the 2.8-litre XK engines used the straight port head unpainted, which some sources may describe as "silver", and had ribbed cam covers.

The 2.8-litre XK was used in the following cars:
* [[Jaguar XJ6|XJ6 2.8 Series 1]] - 1968-73, 2 × SU HD8 carburettors
* [[Daimler Sovereign|Daimler Sovereign 2.8 'XJ6' Series 1]] – 1969-72, 2 × SU HD8 carburettors
* [[Jaguar XJ6|XJ6 2.8 Series 2]] - 1973-74, 2 × SU HS8 carburettors

==="New" 3.4-litre===
Introduced in 1975 to replace the 2.8 in the entry level XJ6, the new 3.4 was not a simple revival of the original XK. Whilst it shared the old 3.4’s bore and stroke of {{convert|83|mm|in|1|abbr=on}} and {{convert|106|mm|in|1|abbr=on}} respectively, it carried over some features of the newer 4.2 litre engine - the main bearing spacings and bearing sizes, and stiffer bottom end but dispensing with the cylinder liners used by the 3.8 and 4.2. However the cylinder spacing remained as the original 1948 design. With 83mm bore, the cylinders needed to line up with the combustion chambers in the cylinder head (whose centres remained as the original 1948 design right up to the end of XK-engine production.
It used a straight port head and delivered {{convert|161|PS|kW hp|0|abbr=on}} [[Horsepower#Deutsches Institut für Normung 70020 (DIN 70020)|DIN net]] and far superior torque to the 2.8.

The "new 3.4" used the straight port head, had ribbed cam covers and the heads were unpainted.

The "New 3.4" litre XK was used in the following cars:
* [[Jaguar XJ6|XJ6 3.4 Series 2]] - 1975-79, ribbed cam covers, 2 × SU HS8 carburettors. From 1977, 2 × SU HIIF7 carburettors
*[[Daimler Sovereign|Daimler Sovereign 'XJ6' 3.4 Series 2]] – 1975-79, ribbed cam covers, 2 × SU HS8 carburettors. From 1977, 2 × SU HIIF7 carburettors
* [[Jaguar XJ6|XJ6 Series 3]] - 1979-86, ribbed cam covers, 2 × SU carburettors