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. 

CNC Vacuum Manifold

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

Mazdaspeed 3 Vacuum Block

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.

Easy Mazdaspeed 6 installation

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

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!

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

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

CorkSport CST4 vs. OEM K04

For the last four years, we’ve been asked countless times if the CST4 is a direct replacement for the OEM K04. With the number of cars experiencing their 2nd, 3rd or even 4th owner, this question is being asked more frequently.  While CorkSport’s intent is to freely share information across the Mazda community, we cannot be everywhere all at once, and we will most likely miss the exact moment the debate explodes on your favorite Facebook page. For that reason…

Today, we’re setting the record straight: The CST4 is a drop-in UPGRADE from the ground up, and by no means is it an apples to apples comparison with the asthmatic K04.

How Does It Work?

Before we dive into the dirty details, you might be craving more details on how a turbo works? You are in luck! Check out our white paper on the CST4 and what makes up the anatomy of a turbocharger, bone up on the importance of a “bolt-on” vs a “drop-in” turbocharger, learn the difference between an internal vs external wastegate and finally why the turbine wheel design/materials make a difference. Now let’s get back to what this means for the CST4 and K04.

CST4

Is The CST4 Reliable?

The CST4 continues to prove itself as one of the best bolt-on options coupled with the needed reliability to withstand the additional demands of chasing 400 WHP  – something the KO4 cannot accomplish. This is due to an upgraded center housing rotating assembly (CHRA) which has a larger center shaft and larger bearings than the OEM turbo. The CorkSport turbo also sports a performance journal bearing with a full 360° thrust collar, which is what allows the turbine shaft and compressor to spin freely. The OEM K04 turbo comes standard with a limited 270° thrust collar.

Does The CST4 Have Increased Airflow Over The K04?

CST4 specs vs. k04 specs

Next comes wheels, which is where the CST4 really shines. Shown in the image above, we have the CST4 on the left and the OEM K04 on the right. The CST4 is 12% larger on the compressor inducer, and 21% larger on the exducer than the OEM K04. Combined with the use of a taller wheel (green line), every revolution of the CST4 not only brings in a greater quantity of air into the compressor, but has a higher airflow capacity, thus moving a greater volume of air. For those of you that need a few more key specific numbers; The OEM K04 uses a 45mm inducer; 56.25mm exducer cast compressor wheel, while the CST4 uses a 50.5mm inducer and 68.1mm exducer forged billet compressor wheel.

On the turbine side, the OEM K04 uses a 50.1mm inducer and a 44.5mm exducer 12-blade cast wheel. The CST4 uses a 56.2mm inducer and 49mm exducer high-flow 9-blade design. Again, the CST4 outshines the K04 with the turbine inducer being 12% larger and the exducer 10% larger. The 9-blade design has two key benefits: more peak exhaust flow as there is less material in the way of flow, and 21% lighter for a faster spool time.

CST4 Side View

The final component is the compressor and turbine housings. The K04 uses restrictive housings that cannot keep up at higher RPMs, and especially at higher boost levels. You can feel this as your stock turbo “runs out of steam” up above ~5200RPM. The CST4 housings may fit exactly in the OEM locations and use the OEM hook up points but that is where the similarities end.

Both the compressor and turbine housings were increased in size, increased in A/R, and optimized for the stock inlet and outlet sizes to provide better top end capabilities. The compressor ended up at a 0.53 A/R while the turbine ended up at a 0.66 A/R. This combo of housing and wheels keeps power all the way to redline, and in initial testing showed a 50WHP gain at the same boost pressure.

How Much Power Does The CST4 Make?

So what does all of this mean in terms of power? We’ve seen the OEM K04 pushed way out of its comfort zone and make in the 350-360WHP range with the right supporting mods. This is far out of the efficiency range of the little K04, and it’s a ticking time bomb when running at this power level. The CST4, on the other hand, is perfectly happy running in the 400WHP range all day, again, with the right supporting mods. We’ve even seen it pushed to its limit in the 450-460 range.

For those of you more interested in boost pressures, the K04 can hit a max of ~24-25psi in the midrange before it’s out of its efficiency range and starts producing just heat.  At redline, the K04 is typically at a max of about 17-18psi. What you feel as your car seems to stop accelerating after ~5200RPM on the stock turbo. The CST4 does a lot better, hitting a max of ~29-30psi in the midrange but carries the high pressure into higher RPMs, with peak boost pressure at redline of ~26-27psi. This keeps you pushed into your seat with a smile on your face!

CST4 Mounting Point

How Quickly Does The CST4 Spool?

We get a lot of questions on how fast this turbo spools, so let’s take a moment to discuss both. The OEM K04 spools very quickly since its housings and wheels are so small. If tuned incorrectly it can spool almost instantly and kill blocks with an extremely low-RPM torque spike. The CST4 also spools quick, making full boost by approximately 3300RPM on most cars. The big difference is that the CST4 carries power out to redline instead of falling off as the K04 does. To be clear, you still have to be careful with the CST4 as it too can kill a stock block with too aggressive of a tune.

Is The CST4 A Drop-In?

So bringing things full circle, the “drop-in” aspect of the CST4 means you can run it with almost no other supporting parts, only a HPFP upgrade, access port, and a tune are required. It also means that it hooks up directly to the OEM inlet and outlet flanges so that there is no excessive modification required to make the turbo fit. We even include new studs, lock nuts, gaskets, a custom upper coolant line, new coolant and oil crush washers, and the correct oil feed banjo bolt so there is no hassle of finding replacement hardware, gaskets, or lines to make your turbo function. We do strongly recommend picking up a CorkSport EBCS to best control boost on your CST4. We have also found that the stock intake size will be maxed out at around 18-19psi on the CST4. To get more power from there, a 3 inch or 3.5-inch intake will be needed.

By no means is the CST4 a K04 though as it’s larger and has much higher horsepower capabilities. For those of you more familiar with Garett turbos, the CST4 is just a smidge bigger than a GTX2867.

If you want even more info on what makes the CST4 tick be sure to check out the white paper on the subject HERE. As a final afterthought, remember that the CST4 is getting an EWG housing option in the coming months, for added features (and noise!) that just don’t come with the K04. Stay tuned for that, and be sure to ask any questions you may have.