Zach’s Road to CorkSport

The Journey to CorkSport

Ever wonder what it was like to win the lottery. You ever let your mind wander and think what it would be like to actually “Live the dream.” I know I have, well, until I joined CorkSport! My name is Zach Sprague, and I wanted to share with you my experience of joining, what I believe to be, the best well known and respected company in the Mazda Community. Let’s take a look at my journey.

I’ve always been into cars and have had a pretty big obsession with FWD Hatchbacks. My passion for this platform started back in 2014. I sold cars for Toyota in Southwest Washington for about four years. During my tenure, I drove some pretty amazing vehicles, one of them being a 2013 VRM MS3 Tech pack. I knew what a Mazdaspeed was, a Turbo FWD Hatchback, and at that time that was more than enough to pique my interest in the platform. It was temporarily sitting on my lot, and I had to drive it back down to Portland to our sister store.

Before jumping into the seat, I didn’t know any horsepower or torque figures. I didn’t know what kind of emotion it was going to spark when I drove it. I had NO idea that it would become the screen saver on my computer. I slid in and pushed the button. (You know those Cold Starts) This car’s exhaust made my heart drop and gave me goosebumps. I honestly felt like an 8-year-old on Christmas Morning. 

Once on the ramp, I slowly shift into third at about three and a half grand on the tach and just sent it. Torque steer was prevalent as I was gently pushed back into my seat. I slammed 4th, and I hear this intoxicating PSSHHHHHH. I was done, I was hooked, addicted and didn’t know what to do with myself. I was so intrigued I stopped at every rest stop on the way down so that I could feel this car accelerate back onto the freeway. <insert uncontrolled giggling here>.

Flash forward a couple of years, and a guy I worked with, now one of my best friends, went out and bought a VRM Speed6. Everything on that car from top to bottom was stock down to the wheels. I slowly watched his build progress over the year and transform into one of the most inspiring builds I have ever seen. In that time he was kind enough to let me pick his brain about these cars and what they like, what they don’t like.

In 2018 this is when things got interesting! After a few months of looking and 100 YouTube videos later, I was finally ready to pull the trigger on one of my bucket list cars. I snagged a 2013 MazdaSpeed3 in liquid Silver. I drove almost 4 hours and paid an arm and a leg for sales tax, but it was worth it.

Miles of Smiles 

I was grinning ear to ear the entire way home; 4th gear dumps on the freeway, testing the grip of the tires out at a few stoplights, full-on shenanigans. I tell you what; I made it home a lot quicker than the drive up.  

I had the car for 3 weeks before I added my first mod. I already had a vision for the car, but first things first, I had to take care of those sloppy shifts. My shifter bushings and short shift plate showed up from CorkSport. At that time I knew they made great parts and were one of the very few places that even made parts for this car. What a difference that made! It felt robust and more responsive.

The Opportunity of a Lifetime

I always joked with my friends about working for a company like CorkSport. I just thought it was this elusive dream that I’d be sitting behind a desk helping other people build their dream cars. I never thought in my life that an opportunity like this would come into fruition. 

My buddy, who helped me get into Mazdaspeeds, sent me a message on FB, letting me know that CS was hiring. I thought to myself; this is no lie. “There is no way on god’s green earth I’d ever get that lucky.” However, I applied. What’s the worst thing that could happen, right? 

CorkSport isn’t a revolving door, and the team is made up of a close-knit group of professionals that also happen to be car nuts. They carefully consider who’s going to be a good fit with their existing team and identify candidates that are going to get the right shit done well. I knew this was a different company, and their standards were high because they didn’t just accept my resume; there was a pre-test.  

A funny little story. I got a message from CorkSport saying they wanted to set up a phone interview! I couldn’t believe it! That Friday, I called to set up a meeting for Monday. This is where the humor known as my life kicked in; I BROKE MY PHONE ON SUNDAY! *RED ALERT* My dream job was calling me on Monday, and I didn’t have a phone, so I went out and bought a little prepaid flip phone. 

Although I almost missed this opportunity, it went well enough for CorkSport to schedule a second interview over Skype. I must add, this occurred over two weeks. I was losing my mind; I couldn’t believe it was happening. All my buddies knew I had the job, they knew how obsessed I am with cars, especially my speed 3. I still was in shock couldn’t believe I had my second interview.

When CorkSport called me to let me know, I had a final interview with the Company’s President, Corey – Hello nervousness, glad to see you again! I can’t put into words how excited I was; it was pure bliss and absolute disbelief. “IS THIS REALLY HAPPENING!” I screamed at the top of my lungs when I got off the phone. I showed up a half-hour early. It was cool; I got to meet someone I’ve stalked on Instagram for a while and who has been a significant influence on me since I got into the Mazda community – Brett White.

It’s so surreal when you get an interview for a job you’ve always wanted. Above all, I remember from the interview is telling Corey, “Even if I don’t get the job, knowing I made it this far and am sitting here with you having this interview is honestly a dream come true.” It’s unreal to think that one mistake, such as breaking my phone the day before my first interview, could have kept me from writing this blog for a company I’ve looked up to since I’ve been into Mazda’s.

I cannot believe I’ve been here a little over a year already! It’s a fun environment where everyone is looking out for one another. I’ve been able to FLY in the fastest thing I’ve ever been in (Barett’s monster Gen Juan), and had the chance to drive a car I’ve drooled over on social media (Brett’s Baby) for years. 

Barett’s monster Gen Juan

Looking back, it wasn’t even four days after joining the company before the guys a CS put lowering springs on my car. It took a little over a week for me to buy an AccessPort and a Dual VTA Bypass Valve, and that was just the start! You don’t want to be an employee driving a stock Speed with a CorkSport Sticker on it.

Stay tuned to see where CorkSport and I go with my car. I’ll catch you on the flipside and, thanks for reading my first blog!

Zäch Fröm CorkSport

Easy and Accurate Boost Readings: The CorkSport 4.5Bar MAP Sensor

Mazdaspeed 3 4.5 bar MAP sensor

We are proud to introduce the release of a new product: the CorkSport 4.5Bar MAP Sensor for Mazdaspeed 3, Mazdaspeed 6, and Mazda CX-7 Turbo. We’ve had the CS 3.5 Bar MAP Sensor for a while now as it’s a necessity when targeting over 21psi, however, while maxing out the CST6, we found the 35psi ceiling of the 3.5Bar sensor just wasn’t enough. Enter the CS 4.5Bar MAP Sensor!

Mazdaspeed 3 4.5 bar MAP sensor

Before I get into explaining what makes this sensor tick, lets quickly go over what exactly a MAP sensor does on your Mazdaspeed. Manifold absolute pressure (MAP) sensors in a nutshell just read the pressure present in the intake manifold of your car. During normal driving conditions, the sensor is typically reading vacuum (or negative pressure) as the engine sucks in air. While in boost, the sensor reads the positive pressure (boost pressure) produced by your turbocharger. In both situations, this pressure reading is being sent to the ECU so the ECU understands exactly what the engine is doing.

The OEM sensor is a 2.5Bar unit, meaning it can do 1Bar of vacuum (negative pressure) leaving you only 1.5Bar (~21psi) before the sensor runs out of accuracy. Both the CS MAP Sensors allow you to accurately read boost levels higher than the stock sensor, so your tuner can target a higher boost pressure for more power, provided you have the right supporting mods. The sensors themselves do not increase your boost pressure, they simply enable your tuner to safely do so.

Mazdaspeed 6 plug in 4.5 bar MAP sensor

Enough learning, let’s get into the 4.5Bar Sensor! The CorkSport 4.5Bar MAP Sensor can read a maximum boost pressure of ~48psi before it starts running out of accuracy. Having a huge potential boost pressure means nothing without a fast responding sensor, so we designed the CS 4.5Bar MAP Sensor to have near instantaneous response of only 2 milliseconds. This means if you have the build and turbocharger to do so, this sensor is ready for just about anything you want to throw at it.

A true plug in MAP sensor for your Mazdaspeed no adapter required

The CorkSport 4.5Bar MAP sensor uses a custom injection molded body that mimics the OEM sensor. This makes it a direct install into the OEM location and a direct plug into the OEM wiring harness. No wiring or adapter harness needed. This results in a clean install that takes as little as 15-30 minutes! 

Everything needed for installation is included with the CS 4.5Bar MAP sensor. A new mounting bolt is supplied to ensure everything stays put, while a fresh O-ring is attached to the sensor to provide a good seal in your intake manifold. To top it off, calibrating for the sensor is easy as the calibration for use with Cobb Accessport is laser etched right on the body of the sensor.

Speed3 3 bar MAP sensor

Mazdaspeed EWGs Made Easy!

We’ve talked a lot about external wastegates with our recent CST6 development but today we are happy to announce the standalone CorkSport External Wastegate Housings for the CST4 and CST5. Available right now as an update for your existing IWG CST4 or CST5, the CS EWG housings make it easy to get the best in boost control for your Mazdaspeed 3, Mazdaspeed 6, or Mazda CX-7 Turbo.

Bolton upgrade to go external wastegate with your Mazdaspeed

While the CST6 will only come with an EWG housing, the external wastegate (EWG for short) is a new concept for the CST4 and CST5. Both of these turbos originally hit the market with an internal wastegate (IWG) only option that has a small flapper valve on the inside of the turbine housing to let off excess exhaust gases. Instead, the CorkSport EWG housings use an offshoot from the turbine scroll that has a v-band flange on the end. This flange allows for the fitment of an external wastegate for improved boost control. To run an EWG on an original CST4 or CST5 previously, you needed an EWG capable exhaust manifold and some sort of block off for the IWG port.


Mazdaspeed 3 turbo internal and external wastegate housings

The new CS EWG housings make running an EWG on your Mazdaspeed3 easier than ever. Each housing comes with the elbow and clamp needed for great fitment. We even offer a dump tube/screamer pipe that works for both MS3 and MS6 as an add-on option. If you pick up the screamer pipe to go with your housing, all you need to supply is the EWG itself. 

Mazdaspeed external wastegate installation kit includes everything but the Tial wastegate

We strongly recommend a Tial MV-R 44mm wastegate as all design work and testing used this specific wastegate. Other wastegates may require modification for use. The 44mm size is a great fit for the Mazdaspeed engines, whether you are running an upgraded turbo on the stock block or fully built one that you intend to push to the limits.


Tial wastegates are a proven turbo commodity for the Mazdaspeed 3

So why would you want an EWG? For starters, EWGs truly offer the best boost control setup for any turbocharged car. Because the wastegate is separate from the turbocharger itself, it is easier to place for optimum boost control, plus, the design of the actuator itself can be optimized. As a result you get a wastegate that hits boost targets more accurately and responds quicker to changes in boost. This means no more boost spikes right when the boost hits (a common problem with poor quality IWG setups), and a near-flat boost curve. The isolated actuator also makes for faster and easier spring changes should you need to service or change your wastegate preload. For more info on the design behind the CS EWG housing, check out the full blog HERE.

A direct flow path for the exhaust gas on the Mazdaspeed 3

One of the best parts of EWG over IWG is the sounds that come with a screamer pipe! While only intended for off-road use, a screamer pipe dumps the exhaust from the EWG directly to the air. This allows for a fantastic noise during a WOT pull, that sounds truly unique. It’s not all just noise though, by venting the EWG to the atmosphere instead of venting the IWG in your downpipe, you are decreasing exhaust turbulence right after the turbine wheel, reducing backpressure. On very high horsepower setups, this often generates some extra power as the turbine housing can be used more efficiently. Check out the product video below for some great EWG sounds from Barett’s MS3.

There’s one final benefit of the CS EWG housings: housing design itself. Without having the IWG in the way to worry about, we were able to do some optimizing on the scroll and A/R. For CST4 owners, this means an increase in A/R from 0.66 to 0.82. Typically an A/R change like this will cause a slight decrease in spool time but an increase in max power potential. CST5 owners have this 0.82 A/R even with the IWG setup but there’s another benefit: greater swallowing capacity. This refers to the amount of volume in the turbine scroll. By increasing the swallowing capacity the turbine can ingest air more efficiently at the peak, which is especially important if you have an upgraded exhaust manifold or high flowing head. After all, an engine is an air pump – what good is shoving more air in if you can’t get it out?

Easy bolt up external wastegate upgrade for your Mazdaspeed 3

If you’re in the market for a change on your Mazdaspeed, check out the CorkSport EWG housings for the CST4 and CST5 turbochargers. Better boost control, a more efficient housing, and best of all, a great new sound. Be sure to check out the listing for even more images and don’t be shy to ask questions we’ll be happy to help!

Mazdaspeed 3 Exhaust Manifold Break Down

Today we want to break down the OEM exhaust manifold for the Mazdaspeed platform so that you can better understand how and why the CorkSport Manifold makes power.  

If you haven’t heard, CorkSport has been developing a performance cast exhaust manifold for the Mazdaspeed platform.  We’ve tested and validated samples on Mazdaspeeds ranging from 350whp to 684whp. We’ve done dyno testing on the OEM exhaust manifold vs the CS manifold, as well as on the XS Power V3 manifold vs the CS manifold with the man, Will Dawson of Purple Drank Tuning, setting the calibrations. Both tests showed good gains from just the CorkSport Exhaust Manifold alone.   However, we can get into those details later.  

Mazda Exhaust Manifold Design

Mazdaspeed Exhaust Manifold Flange
OEM Exhaust Manifold Flange

This is the OEM (original equipment manufacturer) exhaust manifold found on the 2007-2013 Mazdaspeed 3 and 2006-2007 Mazdaspeed 6.  Manufactured from cast iron and very compact in design, the OEM design leaves A LOT on the table in the performance department.   

In the image, we’ve labeled each cylinder since that will be important for later discussion.  

OEM Manifold Exhaust Flow

So now let’s talk flow.  Fluids (or exhaust gases in this situation), will always take the path of least resistance.  When the flow path is not clearly defined for the exhaust gas, such as a merge between different cylinders, turbulence is created which reduces the efficiency of the exhaust manifold. 

A prime example of turbulence is shown in the image above with the orange arrows at the merge for cylinder 1 and cylinder 2.  Cylinder 2 comes to a “T” and therefore could flow left or right.  This creates turbulence which causes a loss in potential power.  

Next is the yellow arrow.  This is identifying the inner diameter of the runners in the OEM exhaust manifold.  To our surprise, the inner diameter of the OEM exhaust manifold is actually pretty decent at ~1.48 inches.  This diameter partially defines the power a manifold can support efficiently. Bigger is better in this situation, but small changes here will make big differences in the final performance. 

Surprisingly, there are “performance” exhaust manifolds on the market for the Mazdaspeed platform that have smaller inner diameter runners… 

Mazdaspeed Exhaust Manifold Gasket
OEM Exhaust Manifold Gasket

We also wanted to point out an unusual but important aspect of the Mazdaspeed exhaust manifold and gasket.  Have you ever noticed the seemingly useless extend flange off of cylinder 4? This extended flange acts as part of the passage for the exhaust gas recirculation port.  

You can more clearly see this port path in the gasket.  

OEM Exhaust Manifold
OEM Exhaust Manifold

Designing For Efficiency

In this image, we want to direct your attention to a very unique and troubling design feature of the OEM exhaust manifold.  There is a right way and wrong way to pair cylinders on an exhaust manifold for a 4 cylinder engine… and this is the wrong way. 

Referencing our cylinder callouts in the first image above; you can see that the OEM design pair cylinder 1 & 2 together and cylinder 3 & 4 together.  This design physically works, but it is not ideal from a performance standpoint. In a divided manifold you should pair cylinders 1 & 4 together and cylinders 2 & 3 together for optimal cylinder exhaust gas scavenging. To learn more about exhaust scavenging you can check out a blog on that here, or watch the video below!

Exhaust Gas Scavenging. See the difference between the CS and OEM Manifolds.

Before we wrap here we do have one good thing to say about the OEM exhaust manifold.  It does sound really good and gives the Mazdaspeed platform a unique exhaust note, but don’t worry you don’t lose your unique rumble with the CorkSport design.   

Thanks for checking in with CorkSport Mazda Performance.  Stay tuned for more info about the CorkSport Performance Exhaust Manifold.  

-Barett @ CS

CST6 | Behind The CorkSport Turbo Design

A few weeks ago we discussed some of the design intent behind the CST5 turbocharger for the Mazdaspeed platform.  Today, we want to follow up with the CST6. The CST5 and the CST6 both were a result of CorkSport’s desire to develop a new stock flange turbocharger that goes beyond the power limits of our FANTASTIC  CST4 Turbo.  

During the development of a higher power stock flange performance turbo, we found that we were asking too much of the CST4 Design.  The result of our efforts is the CST5 Turbo which you can see here and the CST6 Turbo which we are about to dig into.  

In this blog, we’ll dig into the wheel sizing, the CHRA, and some of the challenges we faced in the development and testing stages for the CST6.  

Compressor Wheel

CST6 Mazdaspeed Turbo

The compressor wheel utilized on the CST6 is well-known and trusted, GEN1 GTX76.  The GTX76 compressor is rated for 64 lb/min and is capable of boost pressures that will require a 4 bar MAP sensor upgrade.  Like the CST5, the compressor housing is a 4-inch inlet with anti-surge porting.

Ball Bearing Design

CST6 Turbo Backside

Unlike the CST4 and CST5, the CST6 uses a completely different CHRA and bearing system, and for good reason.  As the turbocharger wheel sizes increase so do the weight and potential boost pressure. This results in higher loads on the wheels, turbine shaft, and bearing system. To increase the durability and performance of the CST6, we opted to move from a conventional journal bearing design for a more modern and robust ball bearing design.  

The ball bearing system improves durability and stability for high horsepower/high boost operation along with improved spool and transient response.  Changing the CHRA did pose some new challenges, however. Ease of installation has always been a key feature with CorkSport products and that’s not lost with the CST6.  The CHRA has been modified to support the use of the OE oil drain line and all necessary oil feed components and coolant components are included for seamless installation.

Compressor Wheel

CST6 Compressor Wheel

Like the CST5 Turbo, we’ve put a focus on the wheel size ratio and have validated its performance. The CST6 Performance Turbo uses the Gen1 GTX76 compressor wheel paired with the Garrett GT35 turbine wheel…aka GTX3576r.  This wheel combination provides us with a ratio of 1.12 which falls well within the rule of thumb discussed the in the past CST5 blog.

In testing, we found that increasing the size of the turbine wheel from a GT30 to a GT35 with the same GTX76 compressor wheel resulted in more top-end power and no penalty in spool time.  This combo also provided a good power delta from the CST5 to better provide an optimal power option for the community. Since then the CST6 has proven power at 600+whp at ~34-35psi and testing will continue past 40psi.  

External Wastegate

CST6 Turbine Wheel

The initial testing of the CST6 started with an internally wastegated turbine housing as that was the original goal with the CST5 and CST6.  However, it quickly became obvious that a turbocharger of this size and power potential could not be safely controlled with an internal wastegate.  The amount the wastegate port and “exhaust” or flow was not nearly adequate for proper boost control.

The boost would creep to nearly 26psi with no signs of tapering off.  Nevertheless, we continue testing knowing that auxiliary fueling was necessary.  Once the CST6 power and durability were validated we moved to design a turbine housing that could provide the necessary boost control and power potential.

Turbo Internal Wastegate Housing

Above is the removed CST6 internally waste-gated housing.  In our testing, we pushed the turbo to nearly 600whp with 40gph of methanol auxiliary fueling.  This amount of heat combined with a turbine housing that was literally being pushed to its limits resulted in a great learning experience.  As you can see, the turbine housing was cracking! The GT35 turbine wheel and power was just too much.

From this discovery and analysis, we developed the EWG turbine housing with the CST6 in mind.  The scroll size was increased, wall thickness increased in critical areas and the 44mm EWG port added.  

CST6 IWG vs EWG

With the use of the EWG turbine housing, boost control is now spot on and can easily control from spring pressure to an excess of 35+psi.  Stick around as we continue to push the limits of the CST6 as we continue testing and validation of the CorkSport V2 Intake Manifold w/Port Injection.  

Thanks for tuning in with CorkSport Mazda Performance.

-Barett @ CS