MazdaSpeed 6 | CorkSport Mazda Performance Blog

February 20, 2020September 28, 2023

The CorkSport CST4 – The Best Turbo for the Mazdaspeed 3/6

How to get 400whp from your Mazdaspeed 3

Back in 2015, CorkSport announced the launch of the “CorkSport Turbo” or “CorkSport 18G” a high-performance drop-in turbo upgrade for the MazdaSpeed 3, Mazdaspeed 6, and CX-7. Fast forward to 2020, this potent turbo is now called the CST4 with the introduction of the CorkSport CST5 and CST6 Turbochargers.

The CST4 has found home in thousands of community members Mazdaspeeds since launch and continues to be a highly sought-after upgrade today…a testament to the CST4’s performance and durability. Starting from scratch, the CST4 is a 100% brand-new performance unit. No core, no revised K04 parts…this is a performance turbocharger from the ground up.

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Let’s recap what makes the CST4 the best turbo and a great fit for the MazdaSpeed. A proven MHI journal bearing center section, these offer great cooling capabilities and fantastic reliability, especially when combined with our high-performance journal bearings and 360° high-performance thrust bearing. The CST4 Mazdaspeed Turbo can seriously take a beating and does it in a package that fits perfectly in the OEM location.

Attached to this center section is a compressor and turbine wheel combo that is a little unconventional. Creating boost is a custom MHI 18Gbillet compressor wheel that is rated at 50lb/min while the turbine that drives the CST4 Mazdaspeed Turbo is a MHI TD05H 9 blade design. Compared to a traditional 12-blade turbine wheel, the CorkSport design is lighter weight for faster spool times and has fewer blades for higher maximum flow capacity.

Best Mazdaspeed3 turbocharger high flow exhaust wheel

The wheels are wrapped in new housings. On the compressor side, there is an OEM diameter inlet to simplify the installation with any intake system you had setup with your K04 Turbo. The turbine housing maintains the stock flange design for easy fitment with any exhaust manifold and downpipe that is bolted to the K04.

The best mazdaspeed 3 turbo upgrade internal or external wastegate, better than the BNR S3.

So what’s the hype now? Great question! The community has pushed this turbo to the limits and has asked for more…with the development of the 500whp CST5 and 600whp CST6, we found that an EWG turbine housing can be very beneficial to boost control. That development bleeds over to the CST4 in the form of an EWG turbine housing for increased boost control and an increase in A/R size.

Like the CST5, you can now choose your boost control. Internal wastegate for a stealth and simple install or go for the EWG turbine housing for extra noise and a little more top-end power potential. The choice is now yours.

Now what does all of this tech mean for you and your car? If you have a stock block you can easily max out power (~380WHP depending on fuel and bolt-ons) and keep some of the K04 Turbo spools you love. With professional tuning, you can keep a safe tune that hits hard and carries power.

The wheel and housing options deliver great response as well as great power. When pushed to its limits on a built block, 20psi was hit at 3300-3400RPM with a peak boost around 27-28psi carried to 7000rpm. Obviously, this isn’t stable for a stock block but is possible on fully built cars with full bolt-ons and a high-flowing head.

Mazdaspeed 3 Turbocharger installation hardware

Both the IWG and EWG options come with a full hardware kit that includes everything you need for installation. This means all coolant/oil lines, new gaskets, new crush washers, and even new studs and crimps nuts for both the turbine and downpipe flanges. The EWG setup includes a custom-designed elbow for excellent EWG actuator fitment on MS3 and MS6, and the correct clamp to attach it to the housing. More info to come later on an add-on screamer pipe option.

Best Bolt on Mazdaspeed 3 turbo EWG dump tube kit

Each Mazdaspeed CST4 Turbo comes with full CorkSport support, including full-color install instructions, a 1-year warranty, and assistance with any questions you may have. We are extremely excited for you all to get your hands on the CST4 and start taking your FBO Mazdaspeed to the next level. Check out the product listing for full details and to place to order.

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For A limited time get $125 off the CST4. Enjoy a more boost and increase your Mazda WHP up to 400!

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December 12, 2019September 21, 2023

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

We are proud to introduce the release of a new product: the CorkSport Mazdaspeed 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!

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 installed on Intake Manifold — Placement of the Mazdaspeed MAP on Intake Manifold

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.

October 24, 2019October 23, 2019

The Solution to all those Boost & Vacuum Hoses – CorkSport Boost/Vacuum Block

Do you ever open the hood to you Mazda and cringe at all the boost and vacuum hoses – You know, the string of hoses and T-fittings winding in every direction? Here at CorkSport, we’ve had this same feeling and decided to do something about it.

Introducing the Boost/Vacuum Block and Fitting Kit…the simple and effective solution for your boost and vacuum accessories.

This simple part for your Mazda allows you to consolidate your various boost/vacuum hoses to one single source. You can finally rid your engine bay of the numerous T-fittings that plague that single hose that connects your intake manifold and BPV.

All the ports needed for your Speed 3 install

A central boost and vacuum source is plumbed to the block and then distributed to six standard ports with 1/8-27 NPT threads. If you have a plan and setup you are going for then opt for the Block and Plug Kit.

If you are unsure about what you need now or in the future, then the complete block and fitting kit is your best option.

Optional fittings for the easy installation

Either way you are sure to make a huge visual improvement to your engine bay. A little effort now will go a long way later with this billet aluminum and anodized boost/vacuum block.

Check it out here and get your today…your Mazda will thank you.

-CorkSport

September 26, 2019October 31, 2022

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.

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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!

February 28, 2019August 17, 2023

CST5 Mazdaspeed Turbo Spools!! Testing and Validation

We’re back on the new CorkSport turbocharger lineup again with today’s blog, this time focusing on the testing & validation of the “medium big” turbo, the CST5. Just in case you missed it, the CST4 (formerly known as the CorkSport 18G) is getting some company to go along with its new swanky name. Check out the full lineup here and the design behind the CST5 here. Now that you’ve read all that, let’s get into what you’re really here for, testing & dyno numbers.

Mazdaspeed turbo CST5 Replacement for K04 Turbo

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We started with the internal wastegate option, to validate the CST5 for drop-in fitment. Since we’ve had a great experience with the drop-in CST4, we knew how to design a turbo around the tight confines of the Mazdaspeed engine bay. The CST5 Mazdaspeed Turbo fits great in the OEM location with just a few minor revisions for proper fitment. It looks pretty good in there too if we do say so ourselves!

Mazdaspeed turbo installed with the CST5

Next the car got put on the dyno for tuning and to push the new CST5 to its limits. With a little help from our friend Will at PD Tuning, the CST5 was soon putting down some impressive numbers. We started off with a “calm” boost level of ~25psi. This netted us 450WHP and spool time which surprised us, achieving 20psi by 3500-3600RPM. Turning up the boost and pushing the turbo to its limits, we achieved 519WHP at ~30-31psi on Barett’s built GEN1 MS3. Check out the dyno graph below.

Taking the car out on the street surprised us further at just how early the car was building boost for this size of turbo. Road logs showed that we were making 20psi slightly sooner than on the dyno (3400-3500RPM) but even more surprisingly the CST5 was making 30psi by 3700-3800RPM! Obviously, this is an aggressive tune that would most likely kill a stock block, but, the CST5 Turbo can be tuned to be stock block friendly and still make good power.

Best Mazdaspeed turbo for K04 Replacement

Then came the testing on the EWG variant of the CST5. We had developed a fitment for the CST6 which meant the CST5 had no issues upon install on both Mazdaspeed 3 and Mazdaspeed 6. Next was a quick retune and some power runs. The larger swallowing capacity of the EWG housing meant some extra power at peak, yet spool was nearly unchanged. We made 525WHP at the same ~30-31psi.

Comparing the IWG and EWG turbine housings you can see a small variation in the graphs. This variation is mainly due to the change from internally waste-gated and externally waste-gated. The EWG setup provides more precise boost control through the RPM range. The EWG setup allows us to better tune the “torque spike” around 4200rpm vs the IWG setup. For peak power the IWG and EWG housings are within the margin of error which makes since because they are both 0.82 A/R housings.

Further supporting the IWG and EWG setups, both options allow you to tune the spring pressure so you can better setup your CST5 Turbo and Speed for the fuel and boost levels you want and of course the most noticeable difference is what you hear. What’s an EWG without a screamer pipe!

Wrapping up testing showed exactly what we were hoping for with the CST5: a great middle ground between the existing CST4 Turbo and the upcoming CST6 Turbo that can be used on both high-powered stock block and fully built cars. Our testing continues as this blog is written as the CST5 is being beta tested by a close friend of CS with a freshly built Dankai 2.

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

-Daniel @ CorkSport

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-Daniel @ CorkSport

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Stay up-to-date on the latest news and product updates from CorkSport.