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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Best Mazdaspeed 3 Turbo bolt on 400whp

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.

Upgrade Your Turbo with the CST4
Mazdaspeed 3 Mitsubishi 18G CHRA

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. 

Mazdaspeed 3 turbo upgrade dyno sheet

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. 

Best Mazdaspeed 3 EWG bolt on turbo kit

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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CorkSport Balance Shaft Delete Kit for 2006-2013 DISI MZR

Looking to add some Extra Excitement to your Mazdaspeed?

What if we told you could add extra engine protection at the same time? Introducing the new CorkSport Balance Shaft Delete Kit for 2007-2013 Mazdaspeed 3, 2006-2007 Mazdaspeed 6, and 2007-2012 Mazda CX-7. It contains all the parts you need to safely remove the OE balance shaft from your MZR DISI engine and give it the extra rev-happiness that it needs.

The OE balance shaft is an 18-pound lump that lives in your oil pan to help balance out the natural vibration and harshness that are inherently present with an inline four-cylinder engine. It does this by connecting to a large gear on your crankshaft and using rotating mass to help cancel out the vibrations from the engine. By removing the balance shaft, your engine has less weight to turn and thus, can change RPM more rapidly. If this sounds familiar, it’s because lightweight flywheels do the same thing; remove some of the rotating mass of the engine to gain a faster revving engine and even a few bonus horsepower.

The OE balance shaft needs an oil supply to ensure that it stays well lubricated and does not lock up. The CorkSport BSD Kit uses a stainless steel plug and O-ring to seal this oil passage. The O-ring is not enough to seal and keep the plug in place, however, it is locked down by a securing plate which gets attached using one of the OE balance shaft mounting holes. We chose stainless for its strength over aluminum. By doing so allowed us to create a lower profile plug with a thicker O-ring for better sealing. We were also very careful to choose an O-ring that is safe for all types of oil and safe up to 400°F.

But you may be asking where does the engine protection come from?

Since the OE balance shaft lives in the oil pan, it takes up some volume that could otherwise be used for oil capacity. This means roughly a quart of extra oil can be used once the BSD kit is installed. Also, the CorkSport Balance Shaft Delete Kit comes with an oil pan baffle to help control your oil’s movement during aggressive driving.

While rapidly changing direction or during a long sweeper at high speed, the oil in your oil pan can move around a surprising amount. If the wrong set of circumstances happen, your engine can be starved of oil, which can easily damage vital engine components. The CorkSport Oil Baffle controls your oil’s movement, ensuring that your engine will have a good supply of oil no matter the driving situation.

We again choose stainless over aluminum for the oil baffle, so that it is rigid enough to control your oil and prevent any vibrations or rattles while your engine is running. The oil baffle is made from two laser cut pieces that are then attached using stainless steel rivets to eliminate any risk of corrosion or improper hole alignment.

Note: the CS BSD Kit comes fully assembled and ready for installation.

Since the CorkSport BSD Kit removes a stock component designed to make the car more comfortable, it will naturally have an increase in noise and vibration coming from the engine compartment. As such, we cannot in good conscience recommend this mod to everyone. That does not mean it is unbearable though, Barett at CorkSport still daily drives his fully mounted Mazdaspeed3 with a CS BSD Kit installed.

If you are looking for the next mod to get some more excitement from your Mazdaspeed, look no further than the CorkSport Balance Shaft Delete Kit. After all, how many mods come with some extra engine health as well?