mazdaspeed | CorkSport Mazda Performance Blog

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.

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.

Stay Up-to-date with CorkSport

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!

July 11, 2019August 8, 2019

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.

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

February 19, 2019August 17, 2023

CST6 | Behind The CorkSport Turbo Design

A few weeks ago we discussed some of the design intent behind the CST5 turbocharger for the Mazdaspeed platform. Today, we want to follow up with the CST6. The CST5 and the CST6 both were a result of CorkSport’s desire to develop a new stock flange turbocharger that goes beyond the power limits of our FANTASTIC CST4 Turbo.

During the development of a higher power stock flange performance turbo, we found that we were asking too much of the CST4 Design. The result of our efforts is the CST5 Turbo which you can see here and the CST6 Turbo which we are about to dig into.

In this blog, we’ll dig into the wheel sizing, the CHRA, and some of the challenges we faced in the development and testing stages for the CST6.

Stay Up-to-date with CorkSport

Compressor Wheel

The compressor wheel utilized on the CST6 is well-known and trusted, GEN1 GTX76. The GTX76 compressor is rated for 64 lb/min and is capable of boost pressures that will require a 4 bar MAP sensor upgrade. Like the CST5, the compressor housing is a 4-inch inlet with anti-surge porting.

Ball Bearing Design for the Mazdaspeed Turbo

Unlike the CST4 and CST5, the CST6 Mazdaspeed Turbo uses a completely different CHRA and bearing system, and for good reason. As the turbocharger wheel sizes increase so do the weight and potential boost pressure. This results in higher loads on the wheels, turbine shaft, and bearing system. To increase the durability and performance of the CST6, we opted to move from a conventional journal-bearing design to a more modern and robust ball-bearing design.

The ball bearing system improves durability and stability for high horsepower/high boost operation along with improved spool and transient response. Changing the CHRA did pose some new challenges, however. Ease of installation has always been a key feature with CorkSport products and that’s not lost with the CST6. The CHRA has been modified to support the use of the OE oil drain line and all necessary oil feed components and coolant components are included for seamless installation.

Turbo Compressor Wheel

Like the CST5 Turbo, we’ve put a focus on the wheel size ratio and have validated its performance. The CST6 Performance Turbo uses the Gen1 GTX76 compressor wheel paired with the Garrett GT35 turbine wheel…aka GTX3576r. This wheel combination provides us with a ratio of 1.12 which falls well within the rule of thumb discussed the in the past CST5 blog.

In testing, we found that increasing the size of the turbine wheel from a GT30 to a GT35 with the same GTX76 compressor wheel resulted in more top-end power and no penalty in spool time. This combo also provided a good power delta from the CST5 to better provide an optimal power option for the community. Since then the CST6 has proven power at 600+whp at ~34-35psi and testing will continue past 40psi.

External Wastegate

The initial testing of the CST6 Mazdaspeed turbo started with an internally wastegated turbine housing as that was the original goal with the CST5 and CST6. However, it quickly became obvious that a turbocharger of this size and power potential could not be safely controlled with an internal wastegate. The amount the wastegate port and “exhaust” or flow was not nearly adequate for proper boost control.

The boost would creep to nearly 26psi with no signs of tapering off. Nevertheless, we continue testing knowing that auxiliary fueling was necessary. Once the CST6 power and durability were validated we moved to design a turbine housing that could provide the necessary boost control and power potential.

Above is the removed CST6 internally waste-gated housing. In our testing, we pushed the turbo to nearly 600whp with 40gph of methanol auxiliary fueling. This amount of heat combined with a turbine housing that was literally being pushed to its limits resulted in a great learning experience. As you can see, the turbine housing was cracking! The GT35 turbine wheel and power was just too much.

From this discovery and analysis, we developed the EWG turbine housing with the CST6 in mind. The scroll size was increased, wall thickness increased in critical areas and the 44mm EWG port added.

With the use of the EWG turbine housing, boost control is now spot on and can easily control from spring pressure to an excess of 35+psi. Stick around as we continue to push the limits of the CST6 Mazdaspeed Turbo as we continue testing and validation of the CorkSport V2 Intake Manifold w/Port Injection.

Thanks for tuning in with CorkSport Mazda Performance.

-Barett @ CS

Connect with us:

You may also like

February 5, 2019September 11, 2023

Inside look: CorkSport Mazdaspeed Turbo Design

The development and evolution of the CorkSport Performance CST5 and CST6 turbochargers are uniquely intertwined. We’ll be honest, we started with the goal of a single larger turbo than the CST4 in mind, but as development progressed we were not getting the exact results we wanted. We wanted fast spool & transient response, huge power, and to retain the internal wastegate system. Something had to give…we realized that we were asking too much from a single turbocharger, thus we redefined what we wanted and realized that two separate and focused turbochargers for the Mazdaspeed platform were the ideal choice.

CST5 Mazdaspeed Turbo Billet Compressor — CST5 Billet Compressor

Today we will focus on the design around the glorious CST5 Mazdaspeed Turbo, specifically the theory and design around the wheel selection for the CST5 and why it works.

CST5 Wheel Design

CST5 Turbine for the Mazdaspeed turbo — *CST5 Turbine*

The compressor wheel utilized on the CST5 is the well-known and trusted GEN1 GTX71. Compact and efficient, this compressor is rated for 56 lbs/min flow rate with a relatively high-pressure ratio threshold. Paired with a 4-inch anti-surge compressor housing and we have a very versatile and responsive compressor setup.

Now here is where the design begins to deviate from the standard path. The turbine wheel is an MHI TF06 design that is designed for high-performance applications. The TF06 turbine wheel is the key to the performance of the CST5 Mazdaspeed Turbo. Let’s see how and why below.

If you are unsure of the turbine wheel size don’t worry, that will get covered shortly. For comparison, the MHI TF06 is very similar in size to the well-known GT30, but there are a few very specific differences that affect performance.

Turbine Blades

The first and most obvious difference is the number of turbine blades; this difference has a couple of benefits. First, less weight; even a small difference in weight can make a significant difference in the spool and transient response characteristics of the turbocharger. Second, reduce flow restriction; with one less blade, the “open” area through the turbine wheel exducer is increased which increases the peak flow potential for top-end power.

Mazdaspeed Turbo Inducer & Exducer

Inducer & Exducer Comparison for the Mazdaspeed turbo and K04 — Inducer & Exducer Comparison

Next, are the less obvious differences. The GT30 has a 60mm inducer and 55mm exducer which equates to an 84trim turbine wheel vs the TF06 with a 61.5mm inducer and 54mm exducer which equates to a 77trim turbine wheel.

There are two key values to pull from this: First, the turbine wheel inducer directly relates to the peak flow of the wheel and the overall wheel size balance which we will cover next. Second, the turbine wheel trim affects the spool and response characteristics of the turbocharger. The smaller the wheels trim the faster the spool and response.

Size Matters in the Mazdaspeed Turbo

Mazdaspeed CST5 turbo Sizing — CST5 Sizing

Alright here is the most important and commonly overlooked aspect of a turbocharger. There is a rule of thumb when sizing the compressor and turbine wheels for a turbocharger.

If the turbine is too large then the turbocharger will be very “lazy” and have trouble building boost.

If the turbine is too small then the compressor may be overpowering the turbine wheel causing excessive exhaust gas buildup that can rob power even though you may be running a very high boost pressure.

So what is the right balance? From our experience in turbocharger design, development and validation along with industry professionals we have consulted there is a rule of thumb we have found when sizing the compressor and turbine wheels. The exducer of the compressor wheel should be 10-15% larger than the inducer of the turbine wheel as shown in the image above.

So why does this work? Well, let’s look back a bit first. Many think you can just install a larger and/or higher flowing compressor wheel onto the turbocharger to make more power. Now that is true to a point, but quickly the approach becomes very inefficient for the engine. Forcing more air into the engine without improving the flow out of the engine can only go so far.

Everything that goes into the engine must come out, right? Increased A/R sizing and turbine wheel sizing is the key to exhausting all the gases from the engine efficiently, and efficiency is key to making power.

With both the CST5 and CST6 Turbo development we focused on the overall performance of the engine, not just the development of a high-performance turbocharger.

Thanks for tuning in with CorkSport Mazda Performance, more to come…

-Barett @ CS

Connect with us

You may also like

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

Stay Up-to-date with CorkSport

Mazda Exhaust Manifold Design

OEM Manifold Exhaust Flow

Designing For Efficiency

Stay Up-to-date with CorkSport

Compressor Wheel

Ball Bearing Design for the Mazdaspeed Turbo

Turbo Compressor Wheel

External Wastegate

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

CST5 Wheel Design

Turbine Blades

Mazdaspeed Turbo Inducer & Exducer

Size Matters in the Mazdaspeed Turbo

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