Talk:Jaguar XK engine

The original XK 3.4 was a fine engine but limited by its long stroke and closely spaced cylinders; Lyons was advised at the time that there was little potential for growth and that the design would not be very free revving.

To overcome this the 3.8 used a new block with wet cylinder liners to allow the larger bore and although freer running than the 3.4 it still used the same cylinder head (Lyons was notorious for his tight control of expenditure). The 3.8 was the best XK. (Only if you don't mind burning oil hand over fist!--Steepwiki (talk) 03:04, 29 March 2009 (UTC))


 * All early XK engines burned great quantities of oil & petrol, as did most English engines of the time. The 2.4 was supposed to be "economical" but burned almost as much fuel as the 3.4 DesmondW (talk) —Preceding undated comment added 12:28, 27 April 2009 (UTC).

American markets demanded automatics and still more torque was needed. The rather compromised answer was to move pairs of cylinders together to allow further increased bore. Yet again, the original cylinder head was used so now the combustion chambers partially overlapped the cylinders! Problems with balance meant that the engine was limited to lower RPM, it produced more torque than the 3.8 but was no more powerful.

The 2.4 was a short block short stroke version of the 3.4 and, amazingly, still used the same original cylinder head! Its breathing was severely hampered by twin Solex carburettors and the output was barely 100hp, hardly enough to drag the heavy Mk1 & Mk2 to 100mph. Finally, for the last gasp 240 a revised head was produced with different carburettors and the output so much increased that it was almost as fast as the 340.

Right up until the end of production (1994) the engines were made using much of the original pre-war tooling.

Engine outputs quoted by post war English manufacturers were exaggerated by testing with all ancillaries removed (fan, water pump, & generator) and Jaguar further exaggerated by testing carefully prepared "blue printed" engines.

Comparison with the Daimler engines is interesting. The Daimler Mk2 with 2.5L V8 was just as fast as Jaguar's 3.4L version.(NOT TRUE. The 2.5 was faster than a 2.4 but was left for dead by a 3.4) Jaguar also experimented with the Majestic 4.5L V8 engine in a Mk10 which proved much faster than the 4.2L XK.(Again untrue. The exact story is shady some say the XK was quicker some say it was the same and some say it was quicker.I personally belive the XK to be quicker.) Apparently, however, the Daimler engines were more difficult to manufacture.--DesmondW 18:21, 20 February 2007 (UTC) I believe that Daimler had tooled up for relatively small production levels for their V8s and it would have been necessary to renew much of the tooling to produce significantly larger numbers of them RGCorris (talk)


 * True - Jaguar 2.4 0-60 17.3s (manual) 3.4 0-60 11.9s (manual) Daimler 2.5 0-60 13.8s (automatic, manual not then available)
 * Also true - en.wikipedia.org/wiki/Daimler_Majestic_Major DesmondW (talk)

It is perhaps unfortunate that this page is titled Jaguar XK6 Engine, using XK6 rather than XK. The engine is occasionally referred to as the XK6, but to Jaguar enthusiasts it is known simply as the XK. This means that the articles on the XK120 and XK140 etc which refer to the engine do not find this page. .--Brymor 17:15, 28 February 2007 (UTC)

OK, I've edited the pages for XK120 and XK140 so that the XK engine links to the XK6 page, solving the problem.--Brymor 17:40, 28 February 2007 (UTC)

Was the 3.4 litre engine in the XJ6 any different from the earlier 3.4? If so, it would be good to mention the differences in the section on the 3.4.--Steepwiki (talk) 03:04, 29 March 2009 (UTC)


 * Yes I think it was different, like the 2.8 this later 3.4 was based on the 4.2 block and not the original block although bore & stroke were identical so the main difference was the offset cylinder bores of the 4.2. Different carburettors were used and output was 160 bhp DesmondW (talk)  —Preceding undated comment added 09:01, 27 April 2009 (UTC).

Detail of the "new 3.4" has since been added to the article Steepwiki (talk) 03:10, 10 March 2012 (UTC)

The Four
I've a vague recollection of the four ending up in one of Goldie Gardner's record cars - am I imagining it? Mr Larrington (talk) 13:43, 30 October 2009 (UTC)

Head Colours
A potential minefield this but I have stuck closely to the data in the 'Jaguar Catalog' appended to Heiner Stertkamp's "Jaguar: The Complete Story". Note that the 'Jaguar Catalog' section contradicts some of the head colour detail in a list of engine number prefixes in the 'Jaguar Engineering' appendix that precedes it, e.g. the Engineering appendix asserts that the 2.4-litre Mark II's B-type head was painted light blue-green but the Catalog does not. I once owned a mint and original 2.4-litre Mark II with the B-type head and I know that its head was unpainted. I have never seen a pukka 2.4-litre with a painted head. Has anyone else? Also, the Engineering appendix asserts that the 3.4-litre S-Type shared a dark blue metallic head with its 3.8-litre S-Type companion, whereas the Catalog, I believe correctly, states that the 3.4-litre S-Type's head was light blue-green. I don't wish to criticise Herr Stertkamp's meticulous work, which provides Jaguar enthusiasts with an excellent resource ... we just need to beware that it cannot be 100% correct due to these (and therefore possibly other) anomalies. Steepwiki (talk) 08:22, 9 August 2010 (UTC)

Jag D Type Heads
The table carries wrong data. D Type heads were of at least 2 types, none were 'straight-port': 1. Production type was heavily modified C type. 2. Race version of 1 even more modified 3. Wide-angle is race-only type works cars etc, completely different casting to 1 and 2 4. Later version of 3 used with injection on D Type 5. Altered variant of 4 used on Lightweight E Type Bill Jones   sparetire100@yahoo.co.uk92.21.40.12 (talk) 03:58, 17 June 2011 (UTC)

Thanks Bill, I have amended the table in accordance with what Heiner Stertkamp's book "Jaguar - The Complete Story" says about the use of the 'wide angle' head. This clears up some of the other issues you raise but one can only add the other detail you have provided if you can quote a published reference. Wikipedia's rules not mine but you can see where they're coming from. Steepwiki (talk) 03:08, 10 March 2012 (UTC)

XKSS
The XKSS is absent from the list of road cars using the XK engine - which version did it have ? RGCorris (talk) 09:47, 4 March 2013 (UTC)

3.8 but I have no docs to back that up. 116.231.74.1 (talk) 12:52, 23 January 2017 (UTC)

XK 120's with Webers ?
"In 1953, the XK 120 C switched to a triple Weber 40 DCOE carburettor setup. "

Where did this come from ? I have never ever heard this, and I had an XK120 in 1967, was a devout Jaguar fanboy. There were kits for $600 in the back of some of the magazines and the factory race cars had Webers but I have never ever heard of any street cars coming with Webers. I could almost imagine the possibility of a special order E Type but not not not the 120 ... Unless this can be documented I think it should be removed. 116.231.74.1 (talk) 12:51, 23 January 2017 (UTC)
 * as it says here this was something that was not supplied by the factory. let me know if you find any more information. until then i have amended it. Acetoe (talk) 19:56, 12 December 2021 (UTC)

valve angles on the cylinder heads
at one point in the article, it claims that both the b-type cylinder heads and the straight port heads had valve angles at an equal 35 degrees, at another point it says that number is instead 45 degrees. please clarify. Acetoe (talk) 04:19, 11 December 2021 (UTC)