How Much Do You Really Know About Turbos?

HISTORY

One of the biggest growing power adders in racing today is the turbocharger system. While there are many different types of turbocharger setups from single, to twin turbo, to even tail pipe setups. How many of you actually know how they work or where they came from? Well that is what we are going to go over in this episode. A little about the history of turbochargers and some of its many different designs and applications as well as how it physically works. So let dive right into the history of the Turbocharger.

To start at the very beginning we have to go over forced induction, the idea that forcing more air into an internal combustion engine would in the end make the engine much more efficient and produce much more horsepower. This came way by a German man named Gottlieb Daimler Patenting his discovery 1885 using a gear driven pump to force air into an internal combustion engine.

The Turbocharger itself was invented by a Swiss engineer by the name of Alfred Büchi , the head of diesel engine research at what is now Sulzer engine manufacturing. Alfred received a patent in 1905 for using a compressor driven by exhaust gases to force air into an internal combustion engine to increase power output but it was another 20 or s before the idea actually came to fruition.

In the 1920s turbochargers were used on production aircraft engines although they were much less common than an centrifugal supercharger. Turbos also started showing up on diesel engines in ships and locomotives around the same time.

Parts of the turbo.

  

A trubocharger has three main parts. The turbine ( hot side), the compressor ( cold side) and the center housing. The turbine is spun by the exhaust gases from the witch spins the shaft running through the center housing. The center housing houses the bearings witch ever type your particular turbo might have. The shaft then spins the compressor wheel and begins to build boost.

DIFFERENCES BETWEEN TURBOCHARGERS AND SUPERCHARGERS

There is a divided field when it comes to witch is better superchargers or turbochargers. Im not really going to get into that today. Maybe I will cover it in a later episode but not today. That being said you do have to know the differences in the two. While not going in to the crazy technical differences the main difference is that turbochargers produce boost by way of an exhaust-driven turbine wheel used to spin a shaft that in turn spins the compressor wheel. A supercharger is driven via a shaft that it actually rotated by the rotational assembly of the engine either by a pulley and belt or on most full race applications it is directly ran off of the crankshaft.

While both use the same main principle of how forced induction is helpful by forcing air into the cylinder. One of the largest differences is the ability of the turbo to be able compress air with better  adiabatic efficiency. Witch is the ability of a compressor wheel to compress the air without adding excess heat. This is one main disadvantages of a supercharger the fact that they will add more heat to the air that the supercharger is forcing into the engine. Turbochargers often produce 15 to 30% more power based solely on the differences in adiabatic efficiency.

Also one of the main advantages of the turbocharger is that it does not tax the engine of power to create boost. Unlike superchargers that create additional rotational force needed to create boost. The increased rotational force causes the engine to use some of the available power the spin the supercharger.

This gets us into the one draw back of a turbocharger setup. TURBO-LAG this the time it takes for the turbo to “spool up” or make it to its boost threshold, or the rpm that the exhaust pressure is great enough to spin the turbo turbine at a speed that will create boost from the compressor wheel. The supercharger being ran directly from the engine rotating assembly means that boost is almost instantaneous.

Turbo Lag

Turbo-lag is one of the things that for some people is a deal beaker on a turbo system. The big issue with this is that with sufficient research and a turbo system that is properly set up you can minimize the affects of turbo lag. A few things that you can do to help reduce turbo-lag is first to use ceramic or lighter material inside the turbo to lower the rotational inertia of the turbo. Its pretty simple lighter parts means less resistance witch means less easier to spin and builds boost faster. Changing the turbines aspect ratio, witch is the size of a cross section of the turbo at any point on the turbo divided by the distance from the center of the turbine wheel. Using twin-scroll turbos witch we will go over in a few minutes. Decreasing the volume of upper deck piping. Anti-lag systems, or spool valve and running multiple turbo setups. Also upgrading the rotating assembly of the turbo from traditional ball bearings to less friction causing foil bearings.

One of the newest ways to drastically decrease turbo lag is “E boosting”. “E boosting” is using an electric motor to pre-spool the turbo. And also hybrid turbo setups that use a full electric turbo/ supercharger one the compressor side and the turbine side is used as generator to power the electric motor powering the compressor.

Different Turbo Systems

As you guys know there are a few different types of turbo systems. Twin turbo, Twin-charging, Tailpipe kits as well as single stage. So lets just start with the simplest. Single stage turbo systems, as the name implies there is one turbo. While you can use any size best suited to your application this setup is usually used with larger size then would be used for a multiple turbo setup.    

Twin Turbo systems use two turbos as the name implies but there are more than one arrangement that can be used. With a parallel twin turbo setup the exhaust gases of the engine are divided in half and split between each turbo. In this arrangement typically smaller turbos would be used as on a single turbo setup. With this system and smaller turbos though turbo lag and be decreased due to the small turbos spool time. The second twin turbo option is called sequential turbos. Where as the turbos are ran in sequence to deduce turbo lag even more. Two stage twin turbo systems use a smaller turbo that spools quicker for lower rpm power with both turbos engaging during mid range and with the second larger turbo making boost at higher rpms. This system is used commonly on diesel applications.

One the coolest and most interesting systems is twin-charging where the engine is both supercharged and turbocharged. This system not only looks the coolest but it also almost eliminates turbo lag with the supercharger supplying the engine with boost in the lower rpm ranges and the turbo system picking up in the higher rpm ranges

In closing what I am hopping is that after all of this you have a better understanding of turbochargers and there systems. What do you think are you more a fan of turbochargers or superchargers? Either way one thing I think we can all agree on it that boost is awesome!

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