It is also in danger of spinning too quickly at higher engine speeds, when lots of exhaust is passing through the turbine. Most automotive turbochargers have a wastegate , which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds.
The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down.
Some turbochargers use ball bearings instead of fluid bearings to support the turbine shaft. But these are not your regular ball bearings -- they are super-precise bearings made of advanced materials to handle the speeds and temperatures of the turbocharger. They allow the turbine shaft to spin with less friction than the fluid bearings used in most turbochargers. They also allow a slightly smaller, lighter shaft to be used.
This helps the turbocharger accelerate more quickly, further reducing turbo lag. Ceramic turbine blades are lighter than the steel blades used in most turbochargers. Again, this allows the turbine to spin up to speed faster, which reduces turbo lag. Some engines use two turbochargers of different sizes.
The smaller one spins up to speed very quickly, reducing lag, while the bigger one takes over at higher engine speeds to provide more boost.
When air is compressed, it heats up; and when air heats up, it expands. So some of the pressure increase from a turbocharger is the result of heating the air before it goes into the engine. In order to increase the power of the engine, the goal is to get more air molecules into the cylinder, not necessarily more air pressure. An intercooler or charge air cooler is an additional component that looks something like a radiator , except air passes through the inside as well as the outside of the intercooler.
The intake air passes through sealed passageways inside the cooler, while cooler air from outside is blown across fins by the engine cooling fan. The intercooler further increases the power of the engine by cooling the pressurized air coming out of the compressor before it goes into the engine.
This means that if the turbocharger is operating at a boost of 7 psi, the intercooled system will put in 7 psi of cooler air, which is denser and contains more air molecules than warmer air. A turbocharger also helps at high altitudes , where the air is less dense. Normal engines will experience reduced power at high altitudes because for each stroke of the piston, the engine will get a smaller mass of air. A turbocharged engine may also have reduced power, but the reduction will be less dramatic because the thinner air is easier for the turbocharger to pump.
Older cars with carburetors automatically increase the fuel rate to match the increased airflow going into the cylinders. Modern cars with fuel injection will also do this to a point. The fuel-injection system relies on oxygen sensors in the exhaust to determine if the air-to-fuel ratio is correct, so these systems will automatically increase the fuel flow if a turbo is added.
If a turbocharger with too much boost is added to a fuel-injected car, the system may not provide enough fuel -- either the software programmed into the controller will not allow it, or the pump and injectors are not capable of supplying it.
In this case, other modifications will have to be made to get the maximum benefit from the turbocharger. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Under the Hood. Engine Performance. A turbocharger uses precisely the same principle. History will tell you that the downside of turbos are that there was usually a delay between when you floored the throttle and the exhaust gas started rushing by and spinning the turbocharger.
But modern engine management and smaller, lighter turbochargers have reduced that delay called lag and now turbo engines — especially those used in F1 — are hugely responsive. This article originally appeared on whichcar. Home Car News Tech How does a turbo work? Back to Tech. More like this: Does it work? Rear-wheel steering. The latest turbocharged engines use incredibly precise metering of the fuel and air to boost efficiency as well as power.
Exactly how it does this is a little complex, but easy enough to get your head round. An internal combustion engine works by drawing in fuel and air. That mixture is ignited to cause an explosion that generates power and the waste gases — exhaust — is forced out.
In turbocharged engines, the exhaust gases are reused. The turbo itself is a snail-shaped tube that funnels the exhaust gases towards a turbine and a compressor. The gases spin the turbine at incredibly high speed and the turbine spins the compressor. This sucks vastly more air into the engine than would be possible in a non-turbo — or naturally-aspirated — engine, which means a greater concentration of fuel can be used.
That creates a bigger explosion in the cylinder and the bigger the explosion, the more power Is generated. Early turbos were rather crude devices that delivered the extra power in a single, huge lump. Not only do turbos boost power, they increase efficiency. Smaller engines are always more efficient than bigger engines, increasing fuel economy and reducing emissions.
Car manufacturers have been exploiting that fact with diesel engines for more than 30 years. Diesel engines are particularly suited to turbocharging because they have simpler intake systems to mix the fuel and air and tougher engine blocks that can contain the immense air pressure turbos generate.
In the last 15 years or so, manufacturers have perfected metallurgy that allows a lightweight, alloy petrol engine block to contain ultra-high turbo pressures. Earlier petrol turbo engine blocks were usually made from heavy iron or steel. A lighter engine means the whole car weighs less and is more efficient. Naturally-aspirated diesel engines, by contrast, produce a lot of torque at low revs.
Adding a turbo amplifies the effect which is why turbo diesels feel so strong if you floor the throttle at, say, 50mph in top gear. Turbocharged cars also have quieter exhaust pipes.
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