Description
Since 2015, the Mazdaspeed 3 Drop-In Turbo has been one of the best performance upgrades for the platform.
Proven by thousands of community members, the CST4 Mazdaspeed K04 Upgrade is a perfect fit for the mildly modified Mazdaspeed 3 and Speed 6 using stock fueling up to budget-built engines with FBO and auxiliary fueling. Replace your KO4 Turbo with the easiest and most complete performance turbo for the Mazdaspeed and have room to grow to 450whp capabilities with the CST4.
The CST4 features a MHI Journal Bearing CHRA, OEM Fit Compressor Cover, and choice between 0.66 A/R Internal Wastegate or 0.82 External Wastegate Turbine Housings.
The CST4 external wastegate turbine housing is designed for 44mm EWGs (Tial is a great option) w/included EWG elbow pipe & V-band clamp.
Includes a FREE CorkSport 3.5 bar MAP sensor for accurate boost pressure up to 37psi.
Read The Blog The CorkSport CST4 – The Best Turbo for the Mazdaspeed
Drop In Performance:
Don’t let the size fool you; the CST4 packs a punch for such a compact and OE fitment package. From full bolt-ons to fully built with auxiliary fueling, the CST4 will support power from 250-450whp while maintaining quick spool and great transient response between shifts. The CST4 replaces your Mazdaspeed 3 K04 Turbo and fits like OEM. Follow our step-by-step instructions to easily install the turbo.
Stock Flange Fitment:
The CorkSport CST4 is the best upgrade for your K04 Mazdaspeed Turbo. Designed with simplicity and bang-for-the-buck power in mind and maintaining the OEM compressor inlet size means you can use any intake on the market designed for the stock K04 turbo. The same goes for the turbine side with OEM flanges for compatibility with your OE fit downpipe and exhaust manifold.
Billet Compressor:
Utilizing a custom MHI 18G billet compressor wheel, the CST4 can efficiently support 50 lbs/min flow rate and boost pressures to 30psi. Compared to cast counterparts, modern forge-milled wheels provide higher boost thresholds, improved response, and increased efficiency to get more power from a small package.
High Flow Turbine:
Paired with the compressor wheel is an MHI TD05H high-flow turbine wheel. This wheel uses a 9-blade design which reduces overall rotating mass and thus improves response and spool.
High Performance CHRA:
MHI Journal bearing CHRA housings are used for both the CST4 and CST5 turbochargers for their increased cooling capacity and proven reliability.
High-performance journal bearings and a 360-degree high-performance thrust bearing is used.
Comparing the compressor and turbine wheels, we have a wheel size ratio of 1:21.
Billet Wastegate Actuator:
One-off billet actuator is used for the CST4 so you can operate the turbocharger in bleed mode for the OE EBS or in interrupt mode with the CorkSport EBCS for increased boost control
All Hardware Included:
The CST4 Turbo Upgrade comes with all the necessary hardware for installation and saves you time and money on gaskets, studs, and the specialty parts.
Choose your Boost Control:
Do you want an easy-to-use Internal Wastegate setup or an External Wastegate setup and screamer pipe? You decide with the CST4 Mazdaspeed Turbo!
Internal Wastegate setup includes the 0.66 A/R IWG turbine housing and IWG Actuator.
External Wastegate setup includes the 0.82 A/R EWG turbine housing and V-Band Clamp & Elbow designed for 44mm EWGs. (EWG and Screamer Pipe Not Included).
Don’t worry, if you want to change your setup from IWG to EWG later you can.
- Vehicle Fitment: 2006-2013 DISI MZR found in the Mazdaspeed 3, Mazdaspeed 6,& Mazda CX-7.
- Designed in America: in Vancouver, Washington, in the Pacific Northwest.
- CorkSport Service & Support: 1 year limited warranty, full color installation instructions, all necessary components, and knowledgeable telephone support at (360) 260-2675.
- Upgraded HPFP Internals and COBB AP/Tune is required with this product.
- Auxiliary fueling required for peak power operation of this turbocharger.
- Some aftermarket and all OEM downpipes will NOT clear the EWG elbow that is included with the CorkSport EWG Turbine Housing. Check the "Fitment Notes" tab for details.
- EWG variant designed for Tial 44mm or equivalent external wastegates (not included but available).
- External wastegate is NOT included with turbo. Did we mention it is not included, because it is not.
- EWG dumptube/screamer pipe is NOT included with turbo but can be added as an option.
How To Install Your Mazdaspeed 3 and Mazdaspeed 6 Upgraded Turbocharger
It will take you 5 hours to install the CorkSport Mazdaspeed CST4 with our easy-to-use instructions.
5 Hour Install Time
4/5 Difficulty
1-Year Warranty
No CEL
Reviews
Sebastien Lopes
Best mod for your stock block, stock fuel mazdaspeed! Wakes up your entire power band! And it comes with the option for EWG no other turbos in this class offers that! highly recommend!
Yaz H
Very happy with this turbo! Has been in my Gen2 Speed3 for about 1.5 years. My setup FBO on 93oct tuned by PD @ 20psi, factory internals. Turbo pulls hard all the way through redline with plenty left for more. My Speed is the perfect sleeper now. Catches many people by surprise. I have a great set of tires and still spin the wheels at full throttle. Under 60 degrees I have to ease into it or wheel spin all day. With this turbo the car is an absolute weapon. No regrets with this turbo. In the future I plan on building the motor and turning up the boost with more aggressive timing. This turbo is more than capable for a mild/wild street setup.
Mario Orsini
Awesome turbo a must to upgrade to. The power this turbo makes is night and day difference from the K04. The K04 runs out of breath in the higher rpms were the CST4 keep on going though the whole power band. On pump gas here crappy 91 octane. My car made 336 hp and 366 torque @ 25 psi on a mustang dyno.
Kiel Massengale
Great turbo, installed on car for 4 months without a tune. Still ran amazing. With corksport cat less down pipe. Spools up to 23psi with a box tune at 3200 rpm. Would recommend to any other speed that wants to go big turbo.
Anthony
Very impressed with turbo it made 430whp/424tq on e30 @24psi stock block.
Cory Hill
Phenomenal turbo. Boost holds all the way to redline, spools quick, and sounds amazing. Just looking at it compared to the k04 you can tell it's much better quality and slightly bigger. Don't even need to know all the numbers to notice that. All around am very happy with it. Can't wait to see what it can do on e85.
Dustin A.
This turbo is awesome. installation is not for the faint hearted but with that being said, the rewards are ten fold. Boost can be felt from 3k up until nearly redline(6500-7k) one thing id like to add is going with a FMIC with this turbo(especially MS6 owners). the boost hits hard but with all that heat in the engine bay, a FMIC would be your best bet for cooler BATS. Corksport really knew what they were doing and looking for when R&D for this turbo was done. If at any time you doubt your K04, don't hesitate to upgrade to this turbo. it is LITERALLY A DROP IN TURBO and comes with the necessities( MAP sensor, hardware and COLOR instructions. Pair this with the EBCS and a good tuner, your GOLDEN.
Angel Diaz
I just bought this a few days ago. I was not expecting what this is. I have seen many speeds get 400whp safely and reliably without any meth, ethanol or port injection so I bought this one over the other options. But oh boy I just got done installing this. I made a slow pull of only 11psi and this thing sounds amazing. Ive never heard a turbo make such a noise. With the reliability, power and awesome sounds it makes it gets 5 stars. plus discount and free map sensor. Why would I not give it 5 stars?
Jonathan Barnhill
Amazing medium turbo for the stock block. At first I was skeptical due to the long process of tuning it has taken due to it being race season. I was coming from an E33 tune on the K04. But now on my second revision on a E25 mix, I am loving the way it pulls. It will still roast the tires if you want it to, but it is a lot easier to manage when you don’t. This is comparing it to the monster torque early rpm K04. Yes it spools slightly later then the stocker, but it pulls up until redline. Unlike that massive, uncontrollable surge you used to get. You may have hit 320-330 hp and whatever torque, but was it useful that low in the rpm range? No. No it wasn’t, was it? Bottom line is; if you’re on the stock block this is the turbo for you. If you decide to go built in the future, then you can have fun with this now, and get CTS5-6 when you are.
Demetrius Smith
I've had this turbo for close to a year (or whenever they introduced the version one's) and decided to come back and write a review. I love this freaking turbo so much. It spools so good and man that whistle puts a smile on my face every time. I was finally able to break my 400hp (hit 420) benchmark goal on 100% meth at 24 psi with the help of Will Dawson at Purple Drank. That's nuts to me. But this turbo, you won't be disappointed.
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