To celebrate twenty-five years in the car conversions business, Janspeed of Salisbury held a recent open day at its works.
Aside from watching over 70 employees at work on the traditional go-faster manifolding, cylinder heads and carburettor kits, we were also allowed to drive two intriguing examples of future Rotomaster turbocharger installations: a twin-turbo XJ6 Jaguar of the new 3.6-litre/24-valve breed, and a single turbo implanted upon Rover’s 2-litre 800.
The Jaguar’s two turbochargers nestle adjacent to the offside of the dohc inline six-cylinder block. Rumour has it that Jaguar is currently examining turbocharging as part of the AJ6 powerplant’s future— along with Sprintex supercharging and many other options a manufacturer needs to examine to stay in touch today — and there are obvious problems.
Once the necessary intercooling and associated plumbing has been incorporated, some engine ancillaries have to be juxtaposed opposite their original site, and the engine bay itself becomes not just crowed, but a reaso table setting for volcanic under-bonnet temperatures. Janspeed has become involved within the last year in the tuning pattern of the future, reprogramming the electronic microprocessor management systems which rule the lives of injection and ignition systems, but that step is presently only complete for the Rover V8s. Thus the Jaguar could not be considered more than a prototype at present, running 6-7 psi boost in association with a compression “too close for comfort” to the Standard 9.6:1, in founder Jan Odor’s frank words
In fact, there are lower compressions available for the AJ6, notably the catalytic convertor models at 8.5: I , which provide 184 bhp instead of the standard 224 bhp. Janspeed’s turbo twins provide approximately 50 bhp extra. On the road this means, even in the automatic transmission trim provided, the kind of acceleration rate between 30 and 90 mph that the owner of a 286 bhp BMW M-car will understand. The difference is that the power has been carefully tailored to provide stump-pulling capabilities in the 1500-4000 rpm band, rather than the sweet and comparatively high-revving BMW power quality.
Janspeed’s staff and boss were quick to point out the shortcomings in this first attempt at AJ6 turbo power, but I thought the positive qualities over-ruled many of their reservations. Noise levels are increased, but because Jaguar does such a stunning job with the standard car, it is unlikely that anyone enthusiastic enough to enjoy this Jaguar’s memorable performance would object. I was constantly surprised at the sheer speed registered in the comfortable cabin, which was unmodified save for the presence of a quality leather rim steering wheel by Italvolanti-Janspeed.
The Rover also delivered 6-7 psi to a largely unmodified engine which inhaled via four valves per cylinder, but this installation looked far more practical. For the single R60 Rotomaster sits in the cool airstream in front of Rover Group’s four, and there is plenty of underbonnet space on this front-drive Anglo-Japanese co-operative to dissipate heat and strategically place additional components.
As was the case for the Jaguar, unmodified suspension accompanied the turbo conversion, which was also aimed at building mid-range motoring muscle. It had been successful in this aim, but the Rover displayed more front-end floppiness over the same Salisbury Plain terrain than the Jaguar, and exhaust resonances were more pronounced.
The effect on front-drive steering reaction was not as adverse as one would expect from recent experience in the now modified MG Montego Turbo. However, from the manufacturer’s viewpoint, one wonders whether Rover will be content to leave aside turbocharging on the 800 line as out of character and unnecessary? After all, there is greater V6 power offered in the 825 choices, and a torque-plus-power bonus to come when the Honda Legend Coupe’s 2.7 is available to supplant the present 2.5 V6.
Thus Janspeed, and others in the aftermarket power business, may find the Rover 800 four cylinders do provide a commercial opportunity — not the widespread appeal of the previous rear-drive model for further modification, but a chance to fill one of the increasingly rare holes in a mass manufacturing range. JW
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