Talk:Jaguar XK6 engine
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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.
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. Jaguar also experimented with the Majestic 4.5L V8 engine in a Mk10 which proved much faster than the 4.2L XK. Apparently, however, the Daimler engines were more difficult to manufacture.--DesmondW 18:21, 20 February 2007 (UTC)
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)
