Once you go twincharging you never go…something
Well, we all know about turbocharging and supercharging, but a greater curiosity still is what is called twincharging. You may have never heard of it, but it’s already in showrooms.
You see, the auto industry has two competing interests at work. Customers want horsepower, but the various world governments want fewer emissions. One way these competing demands are being met is turbocharging. Turbochargers recycle a portion of waste gases while boosting the engine, giving performance with fewer emissions than natural aspiration.
However, as restrictions tighten, that may not be enough. How, then to get extra ponies?
Well, you can add a hybrid drive in tandem with the combustion-powered drivetrain, but that’s expensive to engineer, design and build. Another thing you can do? Slap a supercharger on an already turbocharged engine, boosting the horsepower even more. That’s twincharging. Boost, then boost some more.
The nitty gritty
Twincharging makes use of both methods of forced induction. A turbocharger is a two-stage fan and compressor, powered by the exhaust gases of the car. One fan, close to the exhaust, begins to spin, powering up a compressor (and another fan) that shoots air into the intake manifold. However, in for the boost to work, a turbocharger needs to reach a minimum threshold of internal RPMs to deliver the boost. The time spent spooling up before boost is called “turbo lag.” Typically, the bigger the turbo, the greater the lag time.
A supercharger uses a serpentine belt, which is driven by the engine’s crankshaft. That spins a fan that pumps air into the engine. The boost, then, is pegged to engine RPM, but does sap a few horsepower to operate.
A twincharged engine, uses a light capacity supercharger and a larger turbocharger. Boost from the turbo kicks in at higher RPM – due to the lag – but the supercharger works in the meantime so the lag is nearly undetectable. You also get boosts in horsepower from both the super and the turbocharger.
Why any of this matters
This twincharging crap matters because it’s probably going to start appearing in a lot more cars due to the competing incentives for horsepower and decreased emissions. You can make a big engine insanely powerful…or make a tiny one adequate for a passenger vehicle.
Here’s an idea of the potential: Lancia, according to Road and Track, during it’s Group B days, twincharged it’s Delta S4 Stradale rally racer. The stock engine was a 1.8-liter four-cylinder, which normally would be good for just a bit over 100 horsepower. With twincharging, it made 500 horsepower.
Nissan twincharged the Superturbo, getting 109 horsepower out of the 930cc engine. For reference, most Harley Davidson engines are about that big.
Volkswagen offered a twincharged engine, the 1.4 TSI, in various markets. While it garnered some criticism, it delivered the power of a larger motor with better economy. Audi and Lamborghini (part of the VW stable) are mulling twin-charged five-cylinders and Volvo, according to Motor Authority will offer twincharged 2.0-liter four-cylinders in the 2016 XC90 crossover. The XC90 – which is not a whole lot smaller than a Chevy Tahoe – will be good for 316 horsepower…with a 2.0-liter.