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

The CST6 has Arrived!


The long wait is finally over and you can now get your hands on the CorkSport CST6, which holds the record for the highest horsepower on the OEM turbine flange at 684WHP! In case this is the first time you’ve heard “CST6”, be sure to check out our blogs on the CS Turbo catalog, CST6 Design, and CST6 Testing. The CST6 is truly a big turbo, so if you’re ready for some serious power on your Mazdaspeed 3 or 6, read on!

CST6 with External Wastegate for Mazdaspeed

Let’s start by looking at the anatomy of the CST6. The backbone is a tried and true dual ceramic ball bearing Garrett CHRA. We opted for ball bearings to improve response and durability, especially when running at high boost levels the CST6 is capable of. As for wheels, the turbine is a 10blade GT35 while the compressor is an 11blade GTX76 that is rated for 64 lb/min. This combo provides fantastic spool characteristics for its large size, achieving 20psi by 3800-3900 with the appropriate supporting mods and headwork like on Barett’s GEN1.

Mazdaspeed Turbo

The quick spool is not due to the wheels and ball bearings alone though. A lot of research and development went into making the turbine and compressor housings the right fit for the CST6, and balance fast spool with top-end power. A 4” inlet with anti-surge ports provides plenty of air into that compressor wheel while a high swallowing capacity 0.82 A/R external wastegate turbine housing offers superior top-end power capabilities and optimum boost control. Even with all these changes, the CST6 fits in the OEM location; all you need is the external wastegate actuator and an intake that fits the 4” compressor cover.

CorkSport CST6

The CST6 is definitely not all bark and no bite though. We have thoroughly tested the CST6 up to its limits and beyond and have had nothing but success. Check out the graph below, that is the CorkSport CST6 in “calm” trim making mid-500s at 28psi. The difference in power on the graph was a back to back exhaust manifold change but more on that when we reveal more of the CorkSport Exhaust Manifold….

CST6 Dynograph

At the limit of the CST6 is a full bore 38psi, port-injected E85, and revving out to 8000RPM, resulting in 684.7WHP and 552WTQ. Check out the graph below. There may even be a little more to be had, with a larger 4” intake and 3.5” downpipe and exhaust.

CST6 Dynograph

Like every other CorkSport turbo, the CST6 comes with all new hardware, gaskets, and the needed oil and coolant lines to make your install as painless as possible. The CST6 is a little special though as it also comes with a v-band clamp and EWG elbow to help with the installation of your EWG actuator. While you will have to supply the EWG actuator itself, the elbow helps locate the Tial 44mm (or equivalent) wastegate in a usable location, whether you have an MS3 or MS6. In addition, we have a dump tube available for purchase to prevent any fabrication on your CST6 install.

So if you’re in the market for some serious horsepower on your speed, be sure to check out the CorkSport CST6. Let us know if you have any questions on the CST6, installation, or supporting mods, we’re happy to help!

P.S. If you buy a CST6 share your power graph with #CorkSport

Mazda 6 Turbo Lowering Springs Release!

2018+ Mazda 6 Lowering Springs

We at CorkSport are happy to introduce the Sport Lowering Springs for 2018+ Mazda 6 equipped with the 2.5L turbocharged engine. In our last post, we talked about the height, handling, and quality of our new springs. If you haven’t seen it, check it out HERE. Today we’ll cover how we tested the ride quality and go a step further to talk about damping and natural frequency. I’m going to warn you now; this gets a little bit complicated, but we’re happy to answer any questions you may have.

Spring Damping

Let’s start with a basic example–your car hits a bump which compresses the spring. It “springs” back to its normal length. In a perfect world with no friction or damping, the springs in your suspension would keep bouncing up and down forever, this is called oscillation. Add back in dampening and friction, and the spring will settle out to its normal length pretty quickly. How different strengths of damping affect the “oscillation” can be seen in the graph below.

Spring damping graph
Spring damping example.

The car has hit the bump at the bottom left of the graph. As time goes by, you can see the spring expand and compress and so on. The Greek letter is not important but what is important is the numbers. When it is 0 (black line) the spring compresses and expands over and over to the same height. As the number increases, you can see that the spring returns to its normal length faster until it gets too large and overpowers the spring (dark blue line). For a car, the 0.4 to 1 range is ideal as there is minimal “bouncing” without having too high of damping.

What does all this mean though? Let’s say from the factory the car is in the 0.7 range (orange line). If we went to a drastically stiffer spring, but kept the OEM dampers, we may end up in the 0.2 range (light blue line), which would be uncomfortable due to all the bouncing every time you hit a bump. The CorkSport front and rear spring rates chosen are small enough of a change to fit well with the OEM damping, ensuring no bouncing.

Stock 2018 Mazda 6 and CorkSport Modified Mazda 6
Stock height vs. CorkSport Springs

Natural Frequency Analysis

To go along with this, we did some natural frequency analysis. Natural frequency simplified is how quickly the suspension responds to a bump. Higher the natural frequency, the harsher the ride in a car is. Most “regular” production cars sit in a 1.0-1.6 Hertz (Hz) range for a comfortable ride. Sports cars are usually in the 1.6-2.3Hz range. Full race cars are usually 2.3-3.0 or even higher. An average person will start thinking a ride is stiff/harsh at around 2.0-2.2Hz. Using a special app that ties into the accelerometers of a cell phone we can approximately measure the frequency of a specific suspension setup. With stock suspension on the Mazda 6 2.5T, this yielded ~1.4Hz front and ~1.7Hz rear.

With a stiffer spring, these frequencies will increase, but we wanted to be sure to only increase them slightly, to not severely affect comfort. We went through a few different combinations to get our ideal result. Our final setup ended up at ~1.5Hz front and ~1.85Hz rear. This is enough to notice the suspension feels “sportier” without riding harsh.

2018+ Mazda 6 Roller Shot

There is one other big thing to highlight with frequency. Notice that both the OEM and CorkSport springs have a higher rear natural frequency than front. If your natural frequency front to back is close to equal, the car has a tendency to “pitch” front to back over bumps. Since your rear tires hit the bump slightly later than the fronts, to have a comfortable ride the rear suspension has to “catch up” to the fronts to prevent this pitching back and forth. If a frequency is too much higher in the rear, it can be too fast for the fronts and cause the same pitching issue.

Natural frequency was always on our minds when designing the CS springs and we tested a bunch of different combinations to determine the optimum balance of ride and handling.


That about does it for the Mazda 6 2.5T Sport Lowering Springs. Be sure to let us know if you have any questions-suspension is hard, even for us! Lastly, be sure to share your MZ6T with us by using #CorkSport.

-Daniel @ CorkSport

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CorkSport CST6

Testing & Validation of the CorkSport CST6

As we get closer and closer to announcing the launch of the new CorkSport Turbo Line-Up we want to share the testing and validation we put our turbos through.  You may not realize it, but we’ve already shared a lot about the CST6 without really saying so, check out Barett’s Built Gen1 Here.  

So we’ve talked a bit about the design intent behind the CST6; defining the wheel sizes, wheel size ratio, and the ball bearing CHRA.   If you’ve seen the teaser listing then you’ve already seen the 633 whp dyno graph, so we’ll look at the data to support it!

The First Look at the CST6 Performance

CorkSport CST6 dyno at 28psi
CST6 running at 28PSI

First let’s look at the CST6 at a more moderate boost pressure.  Above are the results of back-to-back testing comparing the XS-Power V3 Exhaust Manifold and the upcoming CorkSport Cast Exhaust Manifold.  All dyno runs were performed with the same 28 psi peak pressure tune.

So the exhaust manifold testing is exciting, but it’s not what we’re here to discuss.   What I want you to know is that the CST6 is fully capable of providing mid-500 whp power at 28 psi.   While we have and will continue to push the CST6 to its max ability, the 27-30 psi range has proven to be a sweet and efficient spot for the CST6.

Testing the Limits on the CST6

CorkSport CST6 Dyno Graph running 34psi
CST6 running at 34PSI

Searching for the limits with the current fuel system we can easily push past the 600 whp mark plus some.   The efficiency of the CST6 at this power level is still very strong and the turbo continues to pull through the RPM range.   What really makes the CST6 shine is the power under the curve. This is a BIG turbo and will respond like one, but the loss of early spool is easily compensated for with the abundant power curve and power that carries past 7500 rpm.  

It’s important to note that testing for the CST6 is not finished because we are currently limited by the fuel system on the vehicle.   The current fuel system is OE DI injectors paired with a boost based methanol system flowing 40 gph peak. In the near future, we will continue finding the limits of the CST6 with a true port injection system and Split-Second controller flowing E85.   This will give us headroom for 8000+ rpm and boost levels past 34 psi (let’s see what 40 psi give us!).

Looking at the CST6 Data Log

CorkSport CST6 Data Log
MAF Voltage and Actual AFR of the CST6

This is a datalog form the 633 whp dyno run and was recorded on the chassis dyno.   Because of that, it is not a perfect example of street driving… let me explain why. The dyno dynamics chassis CorkSport uses can control load and thus the rate at which the engine can rev through the RPM range.   In order for us to dyno a vehicle at this power level safely, we need to find the right ramp rate for low RPM and high RPM. The biggest factor this affects is the spool RPM of the turbo.

On the graph I marked ~200 rpm shifted to the left for the boost curve.   On the street, the CST6 spools about 200 rpm sooner due to the higher load on the street vs the dyno.   This puts the CST6 @ 20 psi around 3800-3900 rpm.

Also shown on the graph are MAF voltage and actual AFR.   Both of these are important because they provide real data about how the vehicle is being tuned.

Target AFR is set for 11.76 which is neither rich nor aggressive for this setup.  The slight up and down of the AFR curve from 3500-4000 rpm is due to the very high amount of auxiliary methanol starting to spray along with the DI injectors.

Looking at MAF voltage you can see us get well past 4.50v.  Actually, we are consistently seeing MAF Voltage around 4.65-4.70v using the CorkSport 3.5” Intake which has a true ID of 3.50”.  This is just further validation that the CST6 is flowing enough air to support 600+ whp.

There’s more to come from the new CorkSport turbo lineup so stay tuned for more info on the CST5, CST6, and EWG housings.

-Barett @ CorkSport

Let’s Get Chilly: CorkSport Intercooler for SkyActiv 2.5T

It’s time to break down our design for the CorkSport Performance Intercooler Upgrade for the Mazda 6 2.5T. We have covered both the OEM intercooler and piping, and our design plan for the upcoming Sky-T intercooler piping upgrade in previous blogs, but today’s focus is the intercooler itself. Intercoolers are a delicate balancing act between size, cooling efficiency, and pressure drop so naturally things can get a little complicated. Buckle up and stay with us, and be sure to drop any questions you may have down below.

Taking a look at the stock intercooler mounted on the Mazda 6 (shown above) shows us quickly where our size constraints lie. With the large crash bar, we cannot go too much larger in height without trimming the crash bar, bumper, or both. However, there is a ton of room for added thickness and better end-tank design that can really help increase the width of the intercooler. The stock intercooler core is 24.5” wide, 5.5” tall, and 2.625” thick. Our plan is to fit a 27” wide, 6” tall, and 3.5” core without any trimming. This sizing combined with a low-pressure drop will be good for 400WHP with no issues! Because the Mazda 6 comes with just around 200WHP from the factory, this sized core provides plenty of room for upgrading down the road without causing excessive boost lag that can occur if an intercooler is simply too big. Check out a prototype CorkSport intercooler mounted on the car below.

Now that size is taken care of, let’s move on to cooling efficiency and pressure drop of the CorkSport intercooler for the SkyActiv 2.5T. These are tied closely together as getting extremely high cooling efficiency usually means high pressure drop and vice versa. Just so we’re on the same page, cooling efficiency is how well the intercooler cools off the pressurized air that passes through it. So a highly efficient intercooler will be able to bring the boost temperatures down similar to the ambient air temperature. Pressure drop is exactly what it sounds like, a loss in pressure from the inlet to the outlet of the intercooler which can be caused by a number of things: poor end-tank design, too many intercooler fins, or simply poor flow distribution in the intercooler. Too large of a pressure drop means lower boost pressures reaching your engine and/or your turbocharger working harder to achieve the same boost levels.

Pressure drop and cooling efficiency are influenced primarily by two things: fin density and end-tank design. Fin density is basically how many fins the boosted air must pass over when traversing the intercooler. More fins = better cooling efficiency, but also more pressure drop. To choose the best core for the SkyActiv 2.5T we plan to use multiple different fin densities and test each for power, cooling efficiency, and pressure drop. While we can get pretty close based on our work from the CS Mazdaspeed Intercoolers, it’s always best to test and identify the best one for each platform. With this extensive testing, we can reach our goal of improved cooling efficiency, lower pressure drop, more power, and no CELs.

End-tank design is critical as it determines how the air reaches the core of the intercooler. Sharp bends, poor air distribution, and small inlet/outlet size all adversely affect the performance of the intercooler. To fit the core size we want, we had to do away with the plastic inlet and outlet pipes of the stock intercooler. This was advantageous as it gave us more room to have a smooth flowing end-tank that distributes air well to all the runners and does away with the sharp corners present in the OEM end-tanks. In addition, we were able to increase the inlet and outlet size of the intercooler to 2.5”. This is a fairly standard size that has shown to work well for the Mazdaspeeds with stock power and without choking flow way up to Barett’s 600+ WHP.

Those of you with a keen eye have realized that the connection between the CorkSport front mount intercooler (FMIC) and the OEM Intercooler is not the same. As shown in the CAD rendering above, each intercooler kit will come with the silicone and custom adapters that are needed to work with the OEM piping. If you decide to upgrade to the CS intercooler piping kit, later on, the CorkSport Intercooler for SkyActiv 2.5T will not need to be removed, and you will only need to change some silicone parts.

We will have more info on this kit coming soon, with the next blog covering our testing of the different core designs using a few new toys from AEM Electronics. Be sure to check out the product listing for more info, and to be notified when the intercooler is available. Last but not least, CX-9 Turbo and CX-5 Turbo owners, we are 99% sure this kit will also work on your rides but we plan on validating fitment before release!

-Daniel @ CorkSport