XJ220 – a hidden story

The chances are you have already heard about the ‘Saturday Club’, a band of enthusiastic engineers who designed the stunning Jaguar XJ220 in their own time just because they had a burning desire to make their dream into a reality. But what happened after the concept was unveiled and why did the V12 get dropped in favour of the Metro 6R4 engine?

The original spec had the Jaguar V12 powering a 4WD system, the engine would be based on the race versions which were doing rather well in GT cars such as the 7 litre XJR9. The V12 engine also saw life as the 6 litre 450bhp motivation in the XJR15 road car. In fact Jaguar made 6 litres the standard displacement for the V12 in the last XJS and the XJ12, which soldiered on under increasingly stringent emissions regs until 1997 (X305).

The XJ220 concept had a 6.2 litre variant which had been producing a reliable 550bhp+ on test, it had been run at full power for extended periods of time and performed well under all manner of arduous test conditions. But the Friday before the 1988 NEC motorshow début the over worked engine unexpectedly seized, with no time to fix it the show car that thousands ogled at that year (including myself) had to be pushed onto the stand. Not a lot of people know that.

The car was simply stunning and orders poured in. So the next step was to put it into series production and the job was given to TWR who already had strong links with Jaguar. At this point things started changing and customers start cancelling orders, partly due to the recession and partly due to the spec change.

The original concept was declared too heavy, but at 1560kg it was still a good 200kg lighter than the lowest spec XJS and stacks up well against modern supercars. Curiously the Jaguar V12 was declared unfit for emissions, even though it was managing perfectly well in the XJR15 road car and the 546bhp Lister storm, as well as in lower state of tune in the XJ12. The 6R4 engine owned by TWR had proved a reliable and powerful lump, not only powering Metro 6R4s but also some of the Jaguar GT racer cars such as the XJR10, and was modified to get it through emissions regs and slipped in place. Extensive development of the engine was conducted on public roads in secret by grafting the whole XJ220 back end with the engine, gearbox and suspension, into a normal looking Ford Transit van (Now owned by Goodwood). I am sure this change from Jaguar V12 to TWR V6 was in no way motivated by any financial advantage to TWR for using their own engine. TWR still have the service contract for these cars, with costs totalling many thousands each time, providing a useful revenue stream to this day.

But with this engine the production car failed to meet its 220mph ambition, 217mph was achieved only by removing the wing mirrors and other tweaks.

Traditionally the problem with turbo engines is keeping the intake air cool at full load, as the turbos compress the air it gets hot and can easily exceed 100C. Hot air is less dense and reduces power. In a race a turbo engine can work well, as the intercoolers have a chance to cool down every time the car brakes for a corner, but when testing maximum speed the engine is flat out constantly and the heat just builds and builds. This is where a naturally aspirated engine has an advantage, the V12 had been run regularly in competition at power levels above 600bhp, in fact the XJR12 race car managed 750bhp from its 7.4 litres. So surely this would have been a more logical choice for a high speed super car?

Then there is the matter of the 4wd system, this was a version of the Ferguson Formula as seen on the Jensen FF. Ferguson research was another company offering engineering services to the car and motorsport industries, in a similar way to TWR. Ferguson would later be bought out by the mighty Ricardo organisation in 1994, and Ricardo would later take on a lot of Jaguar engineering work. Whether TWR saw the Ferguson involvement as a threat is unknown, but dropping the FF 4wd system meant that TWR had sole control over the whole project. In engineering terms the 4wd system has many advantages and the weight penalty is relatively small, as proved by later Lamborghinis.

What ever the real reasons for the changes, the car’s weight dropped by about 200kg which helped in cornering but did nothing for it’s main selling point – top speed. It also made it a lot cheaper to make, which must have been a consideration.

With many orders cancelled and built cars selling significantly under their list price the project lost a little of it’s shine. Many cars are still locked away with delivery mileage only, and in 2007 two unused shells were discovered in Jaguar’s Browns Lane factory when it was being cleared for demolition.

I am sure the decisions made at the time were based on sound judgement, but I cant help but wonder what would have happened if they had stayed with the original concept. Certainly a 750bhp V12 and 4wd would have giving it something in the order of 250mph capability and made it faster in a straight line than a McLaren F1. Maybe in some alternative universe they did just that, and the magnificent Jaguar matched the dreams of the Saturday Club and is the legend that it deserves to be.

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