Caliban Thunder, By ChipsWorx.
Some time ago, Marco and the folks over at Caliban Kit Cars
worked out a deal for the shop to purchase one of the last-remaining Mk6 Thunder kits. During a bit of a lull in the action around here at ChipsWorx, we finally decided to uncrate the thing, and what a sight it was…it was all in there, with the parts still wrapped in paper and coated in cosmoline. They could have buried the crate in a peat bog for a thousand years and it would have come out just as good as new!
After a thorough cleaning and inspection, we were all thinking what we’d like to do with the kit; it’s not every day that we get a chance to build a car from the ground up, so it presented us with an opportunity to do something really unique! Mind you, there were those who were of the thought that we should just build it as is, while others felt we should give the Thunder a full-on ChipsWorx re-imagination…it was a source of a lot of controversy for almost a month after the kit arrived. In the end, we decided, after some discussion with Caliban themselves, to re-imagine the Thunder, but not so drastically that the end product would be unrecognisable. This would be a build where the spirit of the car lives on intact, just with a few key enhancements.
Body and Interior
The Thunder is very 1980s, inside and out! We decided to keep the basic shape and profile of the car as much as possible, but with some unique ChipsWorx touches. The first thing you notice is that the car has a much more aggressive aero package that drew inspiration from early Group A rally cars, thanks to the larger, adjustable front splitter, roof spoiler and a large, period-correct wing fitted in place of the original Gurney flap on the rear hatch. Also, ChipsWorx’ distinctive “mouse ears” mirrors were fitted in place of the originals, adding to the period race car appearance, and a set of strakes on the C-pillar rounded out the aerodynamic changes to the car.
The front and rear fenders had a considerable amount of metalwork done to them to flare them, but still maintain the car’s pugnacious character. Inside, we kept the interior of the Thunder close to stock, reusing the seating, dash and controls, but with a more modern entertainment system fitted - this is 2018 after all!
After a trip to the paint booth for a handsome two-tone paint job in CMW’s Italenrot and Scagliati’s Nero Spazio, we had our team 3D scan the lower body of the Thunder, and custom-made an 80s-inspired full body kit, further enhancing the rally car vibe with its dark colour and fender flares. For the final touches, we were able to source a full set of retrofit lighting for the Thunder from our suppliers, and we applied a wild set of colour-matching stripes on the doors - very 80s chic!
We did very little to the supension and drivetrain of the Thunder; for what it was, the car was very advanced and really didn’t need much! We fitted more modern brakes to the Thunder, going to vented discs front and rear, which necessitated a change to 15-inch wheels over the stock 13-inch wheels, but that also had the knock-on effect of allowing us to use much more modern 195/50-15 tires as well, which proved to be a boon for performance. Other than that, we made some minor adjustments to the suspension tuning, giving the car a 5-millimetre drop in static ride height, bumping the camber a little and making a couple tweaks to the dampers. We tried more radical suspension tunes, but found they really took away from the character of the car, so we just kept it simple!
This is where we made most of the changes to the Thunder. While the little Screamer inline-4 was a decent engine in its own right, we found in our research that it was fairly common for Thunder owners to switch to CMW engines. In fact, we happened to have an old CMW 1.8-litre B13 inline-4 just sitting in our warehouse, unused after we finished a V8 install into a 1984 CMW CS130. We decided that we would take that engine and build it to be as close to the vaunted CS-RR touring car’s engine, the P13B25. While original P13 components can be made to fit the B13 engine, they are almost impossible to come by for those who aren’t fortunate enough to own a CS-RR, and our partners at CMW feverishly hoard their remaining stocks to keep existing cars on the road and on track; trust me, if we say you can’t find them, you really can’t!
With that obstacle, we decided to undertake the prospect of reproducing a P13 crankshaft ourselves, using our CNC machines to mill a faithful reproduction out of billet steel. Combined with a set of high-compression pistons, titanium connecting rods and a MoeTEC fuel injection and engine management system later and we were in business, with the now 2.1-litre engine producing 234 horsepower at 8300 RPM and 217 newton-metres of torque at 7000 RPM, and revving out to a ear-bleeding 9000 RPM redline. The new engine put out more than double the original engine’s 116 horsepower, and even more still than the Screamer’s 100 horsepower! Coupled to a close-ratio, 5-speed transmission and helical limited-slip differential, this allowed the ChipsWorx Thunder to zip up to 100 kilometres per hour in just 6.1 seconds, almost two seconds faster than the stock Thunder, and on to a tested top speed of 218 kilometres per hour, fully thirty more than the original car!
All of these changes, admittedly, added weight to the ChipsWorx Thunder, but not so much that it really affected the car in any serious way; weighing the Thunder beforehand, it came in at 822 kilograms, while the ChipsWorx car tipped the scales at 901 kilograms. Most of that comes from the engine and transmission swap, with the brakes, tires and aero package adding a few kilos here and there.