We are not just about amazing parts here at 27WON. We also do our best to continually share our knowledge of the 2016+ Honda Civic & Acura platform and our decades of experience modifying cars. So, in this latest installment of our tech blog series, we take a dive into turbocharger terminology so you can better understand the components that make up your CivicX and CivicXI turbo and participate in conversations without sounding like a newbie.

By definition, “ A turbocharger (turbo) is a turbine-driven forced induction device that increases an internal combustion engine’s efficiency and power output by forcing extra air into the combustion chamber.” If you didn’t quite get that, no worries. Let me break it down to basics.

The turbo is bolted to the exhaust side (the front when you open the hood) of your 1.5L or 2.0L Honda 4-cylinder engine. When the engine is running the exhaust gases flow through the turbo on one side to spin a wheel that is connected to a wheel on the other side via a shaft. This compresses the incoming air so that more air goes into each cylinder. More air means it needs more fuel. Ultimately, that means you get a more powerful bang and thus make more power which is what we are all after!

Taking a look at the turbocharger, we break it down into 4 key components here. 

1. Compressor Cover

2. Turbine Housing

3. Center Housing and Rotating Assembly (CHRA for short) 

4. Electronic Wastegate Actuator

COMPRESSOR COVER

The compressor cover is on the inlet side of your turbocharger. It “covers” the compressor wheel that does the compression of incoming air to make it denser. You will find the compressor cover at the end of your intake tract attached directly to your turbo inlet pipe. This piece is almost always made out of aluminum and has a flange on one end that the intake or inlet parts attach to. The size of the cover will vary depending on the size of the wheel that it is covering. In the most basic sense the bigger the wheel and cover are the more air that can be moved and the more power you can make.

TURBINE HOUSING

The turbine housing is on the outlet side of the turbo. It bolts directly to your Civic’s cylinder head and directs all the spent exhaust gas past a turbine wheel before continuing through the rest of your exhaust system and out the tailpipe. Just like the compressor side, the size of the housing is largely dictated by the size of the turbine wheel inside of it. Generally, the smaller the wheel the quicker the turbo will spool up (get to speed). This means more power sooner. However, once you get up high in the RPM range, the smaller wheels run out of steam faster and really drop off in performance. The opposite of that is true as well. If you have a really large wheel then the turbo will accelerate and spool up really slow which means you will have a car that “feels” really slow in the lower RPM range. Once you get the engine speed up and have the car moving the larger wheels can carry way more power on the top end.

CHRA 

The heart of the turbo is the CHRA.  It is made up of the compressor wheel, turbine wheel, bearing system, seals, and a shaft.  The center housing locates and lubricates these components. This area of the turbo sees a lot of action and is the most worked part of the turbo. The wheels can be stationary one second and spinning at 150,000 rpm the next. Water (coolant) and oil go through the bearing system to both cool and lubricate the bearings to make the system as efficient as possible.

The bearings have a super important job and that is to support and direct the weight of the wheels and the loads they see. As air is going in and out of the turbo at super-high pressures a bunch of forces act in several directions on the wheels and shaft. These components are machined to really high tolerances to ensure they can last. 

There are two main types of bearing systems. Journal and Ball bearing. We will go into greater details on the pros and cons of each in a future blog, but for now will leave you with this fun fact. The OEM manufacturer for the 2016-2021 1.5T Honda Civic was MHI (Mitsubishi Heavy Industries) however for the 2022+ Honda Civic 1.5T it is now a company called IHI. IHI is a large company that is involved in several industries including the automobile turbo sector. While the two turbos are similar in size and both have journal bearings, the internal design is quite different and noteworthy. We will take a deeper dive into the differences in a future blog when we introduce development for a 11th gen drop-in turbocharger.

ELECTRONIC WASTEGATE ACTUATOR 

Normally this piece on older cars would not get much attention because they were vacuum operated and fairly simple. On your 10th and 11th gen Civic however, they are electronic and have the super important job of controlling boost in your turbo with amazing precision. The E.W.G.A. (ELECTRONIC WASTEGATE ACTUATOR) is a one-piece unit that consists of a solenoid and arm. The solenoid gets input from the PCM (powertrain control module) and moves the arm in or out which acts on a flapper in the turbine housing to regulate boost on the turbo. The PCM looks at multiple variables to make sure the car is making the right boost at any given time whether you’re just cruising or driving at the limit. While not a part that is generally “upgraded”, it is super important your aftermarket turbo keeps this part because of just how important a job it does. 

And those are the four main components of a turbocharger. You will see us use these terms in our blogs very often so now you have a greater understanding as to what they are. If you want to see us dive into more detail on any of these areas of the turbo, be sure and drop a comment below.

Till next time

REDEFINE the Aftermarket
-Vincent