A recently notable new car release has been the VW Golf GT. Both supercharged and turbocharged, the boosted 165ps 1.4L does a pretty good job of moving the big Mk5 Golf body along. VW claims that it is the very first twincharged direct injection production car, and that is certainly true, but it isn’t the first production car to use twincharging.
Lancia tried it with a small number of Delta S4 homologation specials (so they don’t really count as proper production cars) but Nissan also had a twincharged production model, as long ago as 1989. And it came in the unlikely shape of the March subcompact.
Designed to dominate the under 1600cc class in Japanese rallying, the March Superturbo was powered by a 930cc four cylinder producing 110ps. Its bore was reduced by 2mm compared to the non-turbo March, so that for competition its equivalent-capacity was kept under 1.6L (the equivalency factor was 1.7). A pretty simple 2 valve SOHC engine, it was made remarkable through the addition of both a turbo and a supercharger.
The way it worked was that at low rpm the supercharger would offer instant boost response and torque, while at high rpm the turbo would take over for top end power.
To achieve this, the turbo basically blew through the supercharger (which was geared at 10psi). But when the turbo began to make boost, a bypass circuit would allow the turbo to blow directly into the intercooler, circumventing the supercharger. At that point the supercharger (which runs off an electromagnetic clutch) disengages to save friction losses. When driving gently the supercharger is also disengaged too. It’s a pretty clever setup although many elements of it, such as the clutched supercharger and the bypass valve were already done by Toyota when it released its MR2 Supercharger a couple of years earlier. It too, disengaged and bypassed its supercharger in gentle driving to save friction and economy. It was only when you hammered it that the supercharger kicked in.
In fact, the JDM aftermarket saw the potential of the MR2′s supercharger system too and for a time in the late 80s HKS marketed a twincharger conversion kit (pic just below) for the 1st gen MR2 which mated a T04 turbo to the Toyota supercharger and used the Toyota bypass mechanism in exactly the same way as the March did to switch between the supercharger and the turbo. So not only did Nissan beat VW to the punch with twincharging, HKS did as well.
To drive, the March does in fact feel like it has an engine much bigger than 930cc but the delivery is a little snatchy as the supercharger engages. But once it does, the power curve is seamless and the transition from supercharger to turbocharger at 4500rpm is imperceptible. But the powerplant was good enough to catapult the 770kg March from 0-100kmh in 7.5s and the qtr mile in 15.5s.
Where the March runs out of sophistication is in the chassis. Based on the econobox March’s layout, it’s a recipe of simple front struts and a rear beam axle. A viscous LSD is fitted, but handling is not the March’s strong suit, with vague, heavy steering and lots of power understeer. The limitations of the crude suspension and the flimsy bodyshell mean that the March Superturbo’s appeal is largely as a miniature dragster. But one packed with lots of interesting technology in the engine bay.