Inside look: CorkSport Turbo Design

The development and evolution of the CorkSport Performance CST5 and CST6 turbochargers are uniquely intertwined.   We’ll be honest, we started with the goal of a single larger turbo than the CST4 in mind, but as development progressed we were not getting the exact results we wanted. We wanted fast spool & transient response, huge power, and to retain the internally wastegated system.  Something had to give…we realized that we were asking too much from a single turbocharger, thus we redefined what we wanted and realized that two separate and focused turbochargers for the Mazdaspeed platform were the ideal choice.

CST5 Billet Compressor
CST5 Billet Compressor

Today we will focus on the design around the glorious CST5, specifically the theory and design around the wheel selection for the CST5 and why it works.  

CST5 Wheel Design

CST5 Turbine
CST5 Turbine

The compressor wheel utilized on the CST5 is the well-known and trusted GEN1 GTX71.  Compact and efficient, this compressor is rated for 56 lbs/min flow rate with a relatively high-pressure ratio threshold.  Paired with a 4-inch anti-surge compressor housing and we have a very versatile and responsive compressor setup.

Now here is where the design begins to deviate from the standard path.  The turbine wheel is an MHI TF06 design that is designed for high-performance applications.  The TF06 turbine wheel is the key to the performance of the CST5. Let’s see how and why below.

If you are unsure of the turbine wheel size don’t worry, that will get covered shortly.  For comparison, the MHI TF06 is very similar in size to the well-known GT30, but there are a few very specific differences that affect performance.  

Turbine Blades

Turbine Blades
Turbine Blades

The first and most obvious difference is the number of turbine blades; this difference has a couple of benefits. First, less weight; even a small difference in weight can make a significant difference in the spool and transient response characteristics of the turbocharger.  Second, reduce flow restriction; with one less blade, the “open” area through the turbine wheel exducer is increased which increases the peak flow potential for top-end power.

Inducer & Exducer

Inducer & Exducer Comparison
Inducer & Exducer Comparison

Next, are the less obvious differences.  The GT30 has a 60mm inducer and 55mm exducer which equates to an 84trim turbine wheel vs the TF06 with a 61.5mm inducer and 54mm exducer which equates to a 77trim turbine wheel.   

There are two key values to pull from this:  First, the turbine wheel inducer directly relates to the peak flow of the wheel and the overall wheel size balance which we will cover next.  Second, the turbine wheel trim affects the spool and response characteristics of the turbocharger. The smaller the wheels trim the faster the spool and response.  

Sizing

CST5 Sizing
CST5 Sizing

Alright here is the most important and commonly overlooked aspect of a turbocharger.  There is a rule of thumb when sizing the compressor and turbine wheels for a turbocharger.  

If the turbine is too large then the turbocharger will be very “lazy” and have trouble building boost.  

If the turbine is too small then the compressor may be overpowering the turbine wheel causing excessive exhaust gas buildup that can rob power even though you may be running a very high boost pressure.  

So what is the right balance?  From our experience in turbocharger design, development and validation along with industry professionals we have consulted there is a rule of thumb we have found when sizing the compressor and turbine wheels.  The exducer of the compressor wheel should be 10-15% larger than the inducer of the turbine wheel as shown in the image above.

CST5

So why does this work?  Well, let’s look back a bit first.  Many think you can just install a larger and/or higher flowing compressor wheel onto the turbocharger to make more power.  Now that is true to a point, but quickly the approach becomes very inefficient for the engine. Forcing more air into the engine without improving the flow out of the engine can only go so far.  

Everything that goes into the engine must come out, right?  Increased A/R sizing and turbine wheel sizing is the key to exhausting all the gases from the engine efficiently, and efficiency is key to making power.

With both the CST5 and CST6 development we focused on the overall performance of the engine, not just the development of a high-performance turbocharger.  

Thanks for tuning in with CorkSport Mazda Performance, more to come…

-Barett @ CS

Safely Upgrade Your Mazdaspeed Turbo

It doesn’t take long for those building power to use up the stock K04. They are prone to fail, especially when you start shoving that extra air through it. A common question is, “My Mazdaspeed is smoking, is my turbo bad?”

First things first. There is a BIG difference between replacing a bad turbo and upgrading to a more efficient one for more power. If you want to replace it, go with OEM and just plug and play, you’re good to go, wash your hands and get on with your life. This will have your car up and running pretty quickly. However, your maximum power output will be limited and you will eventually have the same problem – the KO4 will fail.

If you are saying to yourself, “It’s time to upgrade…I NEED more power in my life!” Then this blog is for you. Below, we lay out the basics needed to successfully install a CorkSport Mazdaspeed Turbo, highlighting the required supporting modifications to keep your Mazdaspeed safe. And as an added bonus, we keep our installation instructions on each of our product pages, so you can preview how easy the install will be for your experience level.

Here it is, the list is comprised of the BARE essentials to run the 18G CorkSport turbo.

 

HPFP INTERNALS

Giving you 50% more efficiency with your fueling system, as well as, a strong base to build power for your Mazdaspeed. The CorkSport Max Flow Fuel Pump Internals are built to directly replace your stock fuel pump internals and perform with immediate improvements.

CorkSport fuel pump vs. competitors

ACCESSPORT (or VERSATUNE if you have a CX-7)

The Cobb Accessport will give you the basis for tuning, and since this is required with the CorkSport turbo – you’ll want to make sure you have this in hand and ready for when you install your turbo.

These are the basic foundation to our Mazdaspeeds, without these two items you cannot operate your Mazda after installing an upgraded turbo.  You will need your Mazdaspeed tuned, and your tuner is going to say the same thing.

That’s it, that’s all you need to run the CorkSport Mazdaspeed turbo safely. With this proper foundation, you can put yourself in a position for efficiency, or more power.

Now the question is do you want to make it go fast and harness the power that this turbo is built for? Keep reading and we’ll provide some other awesome upgrades that are the next step once you have your turbo installed and running.  Oh, and if you are looking for a proven path to make 400WHP, check out our Chasing 400 WHP Blog here!

CorkSport Upgraded 3.5” Intake

The CorkSport turbo is rated for up to 450WHP with the right set up. Unless you are going for the MOON and shooting for over 700WHP a 3.5” intake will be more than sufficient for this turbo. Giving you some extra airflow to increase your power range, and harness what your Mazdaspeed3 is capable of. Note: Will require additional tuning!

 

CorkSport Mazdaspeed Downpipe

Doesn’t matter if you go with a high flow catalyst or opt-in for one without, the choice is yours. However, if you want to utilize its flow you are going to have to upgrade to a bigger diameter. Our 80mm one does really well, plus it sounds GREAT.  Note: Will require additional tuning!

The CorkSport Cat Back Exhaust System gives your new 2016 Miata the power it needs without the annoying drone.

CorkSport Cat-Back Exhaust

It’s no secret that car engines are just big air pumps, the faster you can shove air into the engine and how fast you can expel it efficiently is what it takes to make more power. No need to run the stock 63.5mm exhaust when you can run our 80mm (like to wake up the neighbors every morning, go with our non-resonated, you can’t beat the cold start)

CorkSport Top Mount Intercooler

If your power goal is 450whp or less you can get away with just upgrading your TMIC and be on your way and they look great in your engine bay.  Note: Will require additional tuning!

If you have the 2nd gen you can really utilize that hood scoop from the factory.  Not only that but you can even see a noticeable performance gain with our larger hood scoop and a TMIC set up.

 

When it comes to your Mazdaspeed we know you want to create safe power and harness the true potential of your ride. Be sure to build upon the proper foundation and head in the right direction for your build. Our techs are available for any questions you have and are ready to assist with planning your Mazdaspeed build path! Any questions – give us a call directly – (360)260-2675, email to sales@corksport.com or leave a comment and we’ll get back to you!