I’ve been a car guy for quite some time but I’m a bit embarrassed that idrk how they exactly work. All that ik is that they give you boost and that somehow makes you faster 🤦♂️
In: Engineering
A car engine works by compressing an air-fuel mixture, lighting it on fire, then using the force generated by the expanding gasses into motion. In order to do this, the engine has to move that air-fuel mixture into and out of the cylinder for each ignition cycle.
For naturally aspirated engines, the air is drawn in as the piston moves downward in the cylinder. This creates a vacuum, and normal atmospheric pressure pushes air into the cylinder. This works pretty well. The measure of how effectively an engine moves air in and out of the cylinders is called volumetric efficiency (VE).
VE of 100% means that an engine moves 100% of its displacement through with every cycle. Amazingly, modern performance engines that are naturally aspirated can actually achieve VE slightly higher than 100%. The new Chevrolet LT6 engine found in the C8 Corvette Z06 has a VE >100% between 2000 and 5800 RPM.
But how could move even *more* air through an engine? What if we pressurized the air entering the cylinders?
That’s what a turbocharger and supercharger do. They’re called “forced induction”, because they force air into the intake.
In order to compress air, you need energy. A supercharger gets the energy to compress air through a mechanical drive; usually a belt. The belt is attached to the engine, and it drives an air compressor. You’ll see different types of superchargers, but the difference comes down to the type of compressor used.
A turbocharger gets is energy from the exhaust. Remember those hot, expanding gasses resulting from lighting the air-fuel mixture on fire? Well, those gasses have to escape somewhere so that new air can be drawn in. That exit is the exhaust.
As the gasses exit, they are forced out by the piston moving upwards, but interestingly, they are still expanding! The engine only harnesses part of the expansion when the piston is moving. The rest of the expansion occurs in the exhaust where it is normally wasted.
This is the genius of turbocharging. The turbocharger actually contains a turbine and a compressor that are linked on one shaft. So as the exhaust exits, it spins the turbine, which turns a shaft, which turns the compressor side. The result is compressed air that is forced into the engine.
This forced air means you can squeeze more air into the engine. Because air-fuel mixtures burn most efficiently at a specific ratio (14.7:1), more air means you can burn more fuel. This creates more heat, and that heat causes more expansion. More expansion means more force on the piston. More force on the piston means MOAR POWAH!
Imagine you’re eating a lot and farting. You put a tube in your butt and you take the pressure through a set of tubes that then push fresh food down your gullet and makes you fart even more. It’s like free energy.
Both are methods of forced induction. They compressed air and force it through the engine so you can burn more fuel and produce more horsepower. The problem is that the amount of oxygen in the air is reduced when you heat it by compressing it so you need to cool the air by using a heat exchanger to increase the air density and that is what really gives you the extra horsepower. Everything comes down to that, air density. More oxygen in the air means you can burn more fuel to maintain a good air fuel ratio and produce more power.
A combustion engine works on 3 basic things.
Air. You need oxygen to burn stuff
Fuel. You need stuff to burn
Heat. Gotta light it.
How would you get more horsepower into an engine? By adding more gas! but there’s an issue!!! if you add more gas…you only have so much oxygen.
So how do you get more oxygen into the cylinder when it’s already the same pressure as the air outside? Easy. Add more air.
So both super chargers and turbos basically take energy produced by the engine to run essentially an air compressor. This compressed air is put into the cylinder so you get more oxygen for the same volume. This allows you to add more fuel, and thereby increase HP
When you burn a fuel there is a perfect mix of fuel and air.
In simplest terms both super chargers and turbo charges stuff more air into an engine which allows you to burn more fuel which gives you more power.
The mechanics of how both do that are different.
A super chargers is directly driven by the engine and works like a big pump to jam more air in.
A turbo charger takes the mass flow and heat energy in the exhaust and spins a special fan to blow more air in.
It’s important to know when talking about boost in engines that what you want is more mass of air getting into your cylinder not the pressure.
That is why we install intercoolers since they cool the air making it more dense allowing more mass at the same pressure.
I do this for a living feel free to ask any other questions I’ll respond when I can.
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