Welcome to another edition of RPMGO Answers, our bi-weekly feature (hey, we even got a logo now!) in which we try to explain some of the most common auto-related debates in the industry. We’ve talked a bit about the various types of traction systems up until now, pitching front and rear wheel drive against each other, or four-wheel drive against all-wheel drive.
Now though, we’re taking a route into a more performance-oriented segment of the industry, and will talk about forced induction methods, more specifically about turbochargers and superchargers, in order to find out which is better.
So say goodbye to naturally-aspirated engines and hit the jump so we can reveal a few things about these relatively easy ways of getting more power from regular engines.
If you want to extract more power from any engine, you can either enhance its displacement, allowing for more fuel and air to enter the cylinders and provide a bigger bang, or you can force more air, and obtain the same result, but sparing you an increase in weight, fuel average and emissions output.
The latter solution is called forced induction, and these days it is done by two very different, but in the end very similar systems: a turbocharger or a supercharger.
First, let’s talk about the most popular and most used type of forced induction: the turbocharger. As I’ve said above, the turbocharger’s main role is to force more air into an engine in order to get a bigger bang and thus more power. How does it do that you ask? It uses a turbine that pushes air into the cylinders, which is powered by the exhaust gases that are being eliminated by that same engine. This is one of the most common types of forced induction, due to the low cost of the assembly, the small space it occupies and the reliability of the components.
Sadly though, as I’m sure most auto fans will know, turbochargers do suffer from one drawback, the so-called turbo lag, which actually isn’t lag per se. In order to properly push air to the engine, the turbocharger needs to build up pressure in its assembly, thanks to a wastegate, that is closed until that boost threshold is achieved. Until that point is reached, the turbocharger is largely useless. This phenomenon is a big problem on older cars, which have a high boost threshold, and you’ll observe such a thing by the sudden increase in acceleration, like someone just bolted on another engine.
Luckily, on newer cars, the boost threshold has been extremely lowered, even reaching the engine idle point, meaning that the turbine is already feeding air into the engine when you are pulling away from a standstill for example. Another solution is the use of a small electric engine in order to spin up the turbine by itself until the pressure inside is enough to keep it spinning, a technique called e-boosting.
Turbochargers are commonly used in diesel engines, but are also popular in gasoline ones. For units which have their cylinders in a V-shape, you will most likely see two turbochargers (twin-turbo) setups, and for supercars like the Bugatti Veyron, which has a W16 engine, you’ll see four of them (quad-turbo).
But for those carmakers which don’t want to stress their heads with the prevention of turbo lag, the supercharger is the simpler solution. Basically the same setup from a turbo is used, but instead of relying on the exhaust gases to spin the turbine inside, it is connected directly to the engine via a belt, pulley or chain.
This means that as soon as the engine is started, the turbine is spinning and pushes air into the cylinders, resulting in an increase in power. But even though that sounds pretty good, the fact that it uses the engine’s power does mean that it takes a toll on its stock output before increasing it through its performance.
Such a fact, coupled with the increased size of a supercharger assembly (a setup like this sometimes requires a hole to be chopped in the hood), makes the supercharger a rarer sight these days, but it doesn’t negate its proof-of-concept.
Don’t think that these two technologies cancel out each other, as some engines were made to support both of them at the same time, a setup which is called twincharging. Well, at the same time is a stretch, as the supercharger is used before the boost threshold is reached in the turbo, after which it is turned off and the turbo starts doing its thing. Sadly though, such a setup is expensive, not to mention a bit on the fuel hungry side, so you won’t be seeing it often.
In the end, both setups have their advantages and disadvantages. If you want to modify your engine, it only depends on what type of performance you want from it. Do you have your own preferred type of forced induction or is naturally-aspirated how you, I mean your engine, rolls?
Pic Sources: Wikipedia, Sprintex
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