Release the HONK! What exactly is twin-charging?
Turbos or superchargers? The debate rages on but, for a while in the 1980s, there was a school of thought that "both" was the only acceptable answer when it came to going Really, Really Fast.
Turbo-supercharging or twin-charging as it is more commonly known, is a theory dating back 35 years to the mid-1980s. A time of fluro, synth-pop, crazy hair and awesome cars. I mean, check out this crazy Volvo ad from the era!
Twin-charging involves a supercharger and a turbocharger plumbed to improve engine performance. Back in the early 1980s turbocharging, electronic fuel-injection and even supercharger technology were all still in their early years of being developed, so twin-charging seemed to offer a perfect solution to giving an engine a nice, linear power output.
Typically, turbo engines of the day needed low static compression ratios to prevent detonation due to the very simple fuel-injection systems that were controlling them and often low octane fuels available at the bowsers (for cheap!) Basically, the old school plain-and bush-bearing turbos of yesteryear were as slow to respond as Moog on a Sunday morning after a big night on the tofu kebabs.
But, when they did start working they hit you with all their power at once and early turbo cars were known for being nearly impossible to control such was the rush of power a turbo gave. On the other hand, superchargers worked great down low in the RPM range, but ran out of puff up top... kind-of like Marty running up a hill to get the last tofu kebab before Moog does. That honk we all know and love from Marty’s mad March Super-Turbo (check it out HERE) is the sound of a supercharger squishing atmosphere as best it can.
The theory behind twin-charging was that a supercharger would operate down low to give good low-and mid-range power, before a turbo came in up top once the supercharger was out of its efficiency range and you’d get a mad top-end full of tsu-tsu action.
The issue was the system is incredibly complex, especially when controlled by an old, out-dated 1980s ECU – Marty still has nightmares of vacuum hose-spaghetti. As turbocharger and EFI technology radically improved through the 1990s the complex twin-charged systems fell by the wayside as manufacturers were able to build more responsive, better-performing and more-reliable engine packages for their cars.
Nissan’s March Super-Turbo was the first real, commercially available twin-charged car and while some others played with the theory it stood for many years as the only successful twin-charged production car until the Volkswagen-Audi Group introduced the 1.4TSI in the Mark V-era Golf.
Producing between 103kW (138hp) and 136kW (182hp) in various VAG products, it used modern fuel-injection, supercharger and turbocharger technology to improve the driving experience and reliability.
Volvo even tried twin-charging on their 2L four-cylinder T6, Polestar and T8 models producing up to 300kW (402hp), and there is a little-known supercar start-up called Zenvo promising to build an 1163hp machine called the TS1 GT, which is apparently twin-charged.
The most awesome twin-charged car, in my opinion, is arguably the first. Italian marque Lancia tried the concept on their 1985 Delta S4 Group B rally car. A brutal 890kg off-road World Rally Championship race car its 1.8-litre four-cylinder produced anywhere up to 1000hp (746kW), though it mostly raced with approximately 375kW (500hp).
It was believed to be the most advanced machine in World Rally Championship history at that time, and was fast enough to lap Portugal’s Estoril circuit in a time that would have qualified the rally car inside the Top 10 for that year’s Formula One Grand Prix grid at the same track.
Lancia actually built 200 road versions of the S4, known as the Delta S4 Stradale, to homologate the car for Group B rallying. While the road versions weighed 1200kg and were only rated to 184kW (247hp) they are still highly prized collector cars today.
Here is some March Superturbo Revision for you!