The Wait Is Over: The CorkSport Performance Intake Manifold Is Here

Can you believe we started this project back in 2012?

Yes, it’s been a long journey, and a few too many “two weeks”, only to find that more improvements were needed. We’ll be frank, this has been a challenging project to tackle, but we have prevailed. We have pushed past the challenges faced in manufacturing the complex design, and are proud to announce that we are ready to present you with the most complete solution for the Mazdaspeed 3 and Mazdaspeed 6 platform.

The CorkSport Intake Manifold is here for those of us wanting some more flow in our lives.

Our design focuses on performance without sacrificing OEM fitment or drivability. With equal flowing runners, higher flow than OE, and TMIC fitment, it truly is a complete solution to the OE intake manifold.

Fitment is huge when it comes down to large engine components like intake manifolds. While designing the CorkSport IM, we wanted to retain as many OE features and mounting locations as possible while maintaining neat and tidy packaging. By doing so, we were able to keep components such as the TMIC, OEM throttle body, MAP Sensor, and even the oil dipstick bracket in OE locations. This all means a relatively quick and easy part to install, but we made it even easier by clearing some space around hard-to-reach areas.

The CorkSport Intake Manifold may fit like OE, but that’s where the similarities end.

The CorkSport Mazdaspeed Intake Manifold is designed with performance and drive-ability in mind, with the larger plenum design and long cylinder runners. Since the intake plenum is about three times larger than OE, there is an increase in high RPM power capacity without sacrificing throttle response and drivability. By maintaining the length of the cylinder runners (vs the typical aftermarket intake manifold), we improved mid-range power while still having peak RPM capacity with the single runner design vs. an OE split runner design.

The increase in performance also comes with an increase in engine health.

By optimizing the design for equal flow between runners, the CorkSport IM eliminates the flow imbalance of the OE intake manifold. This significant imbalance causes cylinders to run excessively lean or rich, affecting engine durability and performance. Check out the graph below to see the difference. Not only does the CorkSport Intake Manifold outflow the OE design by 70CFM per runner on average, but also significantly reduces the flow imbalance to 2% or less vs the OE imbalance of 21%.

This means your engine can run stronger, longer, and have a higher potential to make power.

But enough talk about numbers and flow, let’s SEE some numbers. The dyno graph below shows the difference before and after the CS IM on a Mazdaspeed3 with a CorkSport TD05H-18G turbo equipped. Not only was there an increase in power and torque across the entire RPM range, the turbo spooled around 100RPM faster than with the OE intake manifold.

But wait there’s more! Along with the overall design improvement over OE; there are additional design features that you need to know about.

  • Firstly, we increased the size of the throttle body opening. This allows the OE throttle body to work great but also allows for a larger throttle body to be installed without modification.
  • Next there are added fueling ports for each runner. They are standard 1/8-27 NPT ports that can be used with methanol nozzles or other fueling options.
  • Finally there is an extra 1/8-27 NPT port that can be used for boost controllers, gauges, or the like.

Now you may be thinking, “But there aren’t any larger throttle bodies available.” To that we say, “Not just YET!”

Along with the great features of this new Performance Intake Manifold, we are also providing nearly all of the hardware you need for installation; that is, the brass fittings that come pre-installed on the intake manifold and the additional hardware and hoses needed for auxiliary components.

Now we would like to circle back to where we started with this conversation:

We here at CorkSport pride ourselves in doing everything in our power to provide you, our customers, with the best possible products out there. We also are committed to being real with you guy as well, because we too are Mazda-lovers who get a thrill out of overcoming the toughest challenges that stand between us and the ultimate car experience.

The most challenging aspect of this project has been getting the manufacturing to an acceptable quality, and consistent among each intake manifold. We have tested the intake manifold on multiple cars in-house and with various beta testers, the results speak for themselves: this is an exceptional performance product that your Mazdaspeed will love to have.

Believe us when we say that this design is tough to manufacture,  and that process results in no two parts being exactly the same visually; but it also means that each manifold has its own unique look and character, the same way our cars do.

We guarantee that the CorkSport Intake Manifold will give you the best performance out there, but if for whatever reason you’re not satisfied with the unique look of your IM, please contact us and we’ll be more than happy to take care of you like we always do. – We’ve got your back!

That being said, if you’re looking to take your Mazdaspeed to the next level in both speed and reliability, the CorkSport Intake Manifold is the best comprehensive solution on the market.

These babies are only available while supplies last, so don’t wait, they’ll be gone before you know it!

Order 2007-2013 Mazdaspeed 3 & 6 Intake Manifold


Mazdaspeed by Another Name

In the past, Mazda has said the new motors will be used across all the models.

For the past few months, Mazda has been hinting at the homogeneous charge compression ignition (HCCI) motors, but the idea goes back to 2008 when Mazda started working on their Skyactiv technology and brand. The original plan was laid out to introduce the Skyactiv I technology, and then offer a Skyactiv II phase in the future, which was to be the next step up in efficiency and performance.

Recently, Mazda officially announced the Skyactiv X after Robert Davis gave a speech announcing there is more to be given from internal combustion engine (ICE). This has been Mazda’s plan all along and they are sticking to it.

So where does the Mazdaspeed by another name come into this conversation, you ask? Mazda needs to meet its corporate goals of improving fuel economy while also ensuring performance. Right now, Mazda has the 2.5 turbo motor used in the CX9 and the 2.2 turbo diesel motors as the go-to for horsepower.

In the past, Mazda has said the new motors will be used across all the models.

I found three references where the term “supercharged” has been discussed with the new Skyactiv X engines. The term has been used in the past for both belt-driven blowers and exhaust-driven blowers.  Give Mazda’s familiarity with the turbo motors on the Skyactiv technology, my money is already on the turbocharger for gas engines.

In the past, Mazda has said the new motors will be used across all the models.

In the past, Mazda has said the new motors will be used across all the models, which means that, yes, we should see a turbocharged Mazda 3 and Mazda 6 again in the future. I know the Mazdaspeed name and Mazdaspeed 3 and Mazdaspeed 6 models are dead, but we will once again be able to play with boost in our favorite manufacturer’s cars.


Derrick @ CS

New Product: Mazdaspeed Camshafts for DISI MZR Motor

Mazdaspeed camshaft

After multiple years of testing, design and research, CorkSport is proud to announce its release of camshafts specifically designed around the MZR DISI platform. This kit is engineered to reliably provide increased power and torque without lower rpm sacrifices.

The turbocharged MZR DISI engine was first introduced in the 2006-2007 Mazdaspeed6 and was later put in the 2007-2013 Mazdaspeed3. This engine has a High Pressure Fuel Pump (HPFP) that is driven off the intake camshaft. Other MZR engines use different camshafts and don’t have a HPFP lobe to run the fuel pump. This has been a limitation in the market since the engines introduction.

Camshaft Basics

In order to understand the basics you need to know some camshaft terminology. The most common terms are lobe, lift, duration and base circle.

Common Drawing of Camshaft Terminology
Common Drawing of Camshaft Terminology
  • Base Circle – The circle on the backside of the lobe. When the base circle faces the valve the valve is closed.
  • Lobe – The lobe is the portion of the camshaft surface that is not the base circle. This is when the valve is opening or closing.

Camshaft base circle and lobe

  • Lift – The distance between the base circle and the top of the lobe. This will be the amount the valve is allowed to open.
  • Duration – The distance, in degrees, that the camshaft is in the lift section. This controls the time that the valve will be open. This is shown in the diagram from A to B.

MZR Flow Testing

The first thing to do was flow test the head to figure out where restrictions might occur. To flow test, a constant vacuum was applied through the head and while slowly opening the valves. This is similar to what the engine is doing while running.

Intake lift

The factory intake ports do not flow much air above 0.350” of lift on the flow bench. The factory camshaft runs rough at 0.370” of lift. Shown in the graph below, minimal flow was increased between 0.350” and 0.400” on the factory head.

Intake Ports of MZR DISI Head
Intake Ports of MZR DISI Head

Porting is the process of modifying the intake and exhaust ports of an internal combustion engine to improve the quality and quantity of the air flow. After porting the head, there were significant increases in flow, but around 0.400” of lift there was again minimal increase in flow, with more lift. Testing suggests a proper maximum lift of 0.390” for the intake camshaft. Factory heads or ones with a large port should show gains from this increase in lift.

Why Stop at 0.390”?

More lift above 0.390” would require very extensive head work to gain much more power. Another downside of going above 0.390” lift is the valves will require stronger valve springs to maintain proper valve operation at high boost or high rpm. Upgraded valve springs should not be required for a factory head with 0.390” of lift camshafts.

Exhaust lift

A similar process to that described during the intake lift process was used on the exhaust ports and an optimal lift of 0.355” was chosen. For comparison, the factory runs 0.321” lift on the camshaft.

Exhaust Ports of MZR DISI Head
Exhaust Ports of MZR DISI Head

Limitations of Existing Options

The factory camshafts were designed around a compromise of performance and emissions; from that design criteria, there is still more power and torque available. The reader can now understand why increased lift and duration can release this power. There are limited options to increase lift and duration on the MZR DISI engine.

Reground Factory Camshafts

In order to increase lift and duration on a reground camshaft, the factory camshaft must be welded and reground to the new profile, but commonly the base circle is reduced. This allows the lift to increase and also the duration to be adjusted.

There are limitations with this approach. When reducing the base circle, many other parts in the head will have to make up for the amount ground away. It is essentially limited to the amount ground away. It is also limited by the duration because the profile must fit within the factory profile design.

In order to regrind a camshaft it must be removed from the engine or a new camshaft must be bought. A used camshaft can have wear that cannot be fixed. Buying new camshafts to send out is expensive and adds to the total cost of installing the camshafts.

Aftermarket Camshafts

The only aftermarket camshafts currently available are not designed for the MZR DISI engine. This means the intake camshaft does not have the ability to run the HPFP.

The existing camshafts for the MZR engine were also designed around naturally aspirated (non-turbocharged) engines, so the duration, lift, and overlap between the intake and exhaust camshafts are not optimal for forced induction applications.

The best option to upgrade camshafts is to buy those designed and made for the MZR DISI engine specifically.

Camshaft Design

In order to start testing camshafts on the car, a blank camshaft is needed. This requires making a mold and casting a generic camshaft from a mold. Then the bearing services were machined to factory specs and after that a few dozen durations, ramp rates, and overlaps based on the engines natural pumping ability were chosen.

Blank Camshaft with Bearing Surfaces Ground
Blank Camshaft with Bearing Surfaces Ground

After carefully grinding all of the blanks, it was time to dyno the engine and determine the difference in power and torque.

An engine is basically a vacuum pump with the camshaft helping determine at what rpm the pump is efficient. Camshafts allow the power under the curve to be manipulated. If you have ever taken a calculus or thermodynamics class you might have flashbacks.

Power/Torque Factory Camshaft vs CorkSport Camshaft
Power/Torque Factory Camshaft vs CorkSport Camshaft

Potential variations in the engine tune, fuel, outside temperature, and other factors were monitored. The result is clear improvements in power and torque throughout the rpm range. The final design was chosen to limit lower rpm power decrease with a large band of power improvement over 4,500 rpm.

Exhaust Camshaft Comparison

Further examination of the exhaust lobe design is a good example of where the power comes from. When looking at the lift versus degrees as the cam spins, the changes to the lobe profile become apparent.

Exhaust Camshaft Design
Exhaust Camshaft Design

This change allows the camshaft to lift the valve more and longer. This allows more air to flow out of the engine.

Intake and Exhaust Relationship

The intake camshaft is electronically controlled. With additional tuning, turbo spool and power can be increased by controlling the overlap between the intake and exhaust camshafts. Overlap is the time when both intake and exhaust are open at the same time. Typically in a turbo car overlap is much smaller than in naturally aspirated cars. Below shows intake and exhaust camshafts placed over each other and the area that would be considered overlap.

Diagram of Overlap
Diagram of Overlap

Fuel Pump Lobe

Recall the intake camshaft drives the mechanical HPFP. In order to allow the end user to have the best camshaft possible and also have reliable fueling and limited wear the fuel pump lobe on the CorkSport intake camshaft is ground to match the factory camshaft lobe and then rechecked to ensure no clearance issues.

Mazdaspeed camshaft


The installation of camshafts in the Mazda MZR engine is not easy. Camshaft upgrades should be considered by an experienced enthusiast or professional installation is appropriate. To aid an experienced installer, detailed installation instructions are provided. Successful installation is supported in two different ways.

  • Color installation instructions
  • Excel Tappet guide available for download online

The CorkSport Camshafts for DISI MZR feature:

  • Created from brand new castings.
  • Break-In coating included on lobes to extend life of camshaft.
  • Designed exclusively for the MZR DISI engine.

Extensive testing to determine optimal camshaft design then manufactured to exact tolerance.

New Product: MazdaSpeed Dual VTA Bypass Valve

Many months ago here at CorkSport we decided it was time to bring a new high performance BPV to the market. The goal was to design a BPV that was compact, durable, and performed beyond just making noise; most importantly this BPV had to feature VTA functionality that was a right balance of daily driver friendly and performance. Ladies and Gentlemen, boys and girls, I give you the new CorkSport VTA BPV.

A beautiful picture of the outside looks nice, but does not even begin to show the many features designed into this BPV. Let’s take a look inside.

mazdaspeed bypass valve cutaway idle
Figure 1: Cutaway view in idle position

Looking at the first cutaway view shown in Figure 1, you’ll immediately notice the three O-rings. Two are located on the sides of the piston and one is located at the bottom of the piston. These are important for a couple reasons: the O-rings allow the piston to actuate/slide easily when combined with a proper lubricant and provide air tight seals in all piston positions. This allows the valve to hold 50psi of pressure without leaking.

I specifically identified the VTA port because it location is critical to the BPV design and the drivability of the vehicle. In the idle position the piston sits at approximately the same position as shown above due to the vacuum pressure sourced from the intake manifold. At idle the VTA ports are closed, keeping your fuel trims in check.

Next, let’s look at the BPV in positive pressure (building boost) situation.

mazdaspeed bypass valve cutaway pressure
Figure 2: Cutaway view in positive pressure position

Immediately after applying throttle, the intake manifold begins to increase in pressure due to the turbocharger building boost. At the same time the BPV piston is forced closed as shown in Figure 2. Like the idle position, the VTA ports are closed keeping fuel trims in check. The piston also creates an airtight seal against the base flange improving boost response.

Next you shift or get off the throttle which causes a sudden pressure change in the intake manifold and the charge pipe pre-throttle body. The excessive pressure build up in the charge pipe combined with the vacuum from the intake manifold cause the piston to open as shown in Figure 3 below.

mazdaspeed bypass valve cutaway high boost
Figure 3: Cutaway view in high boost lift off position

Unlike the idle position, the piston has moved up past the VTA ports. This is due to the excessive pressure differential between the piston vacuum chamber and the charge pipe pressure. The greater this pressure differential the faster the piston will respond and vent more air to the VTA ports. Testing has shown that the VTA ports begin activating at ~15psi or greater boost pressures on a K04 equipped vehicle.

So that’s how the CorkSport VTA BPV works, but what makes it so efficient in doing so? A combination of simple and effective features all wrapped up into one design.

Response is key to a great performing BPV, plain and simple. The piston inside the BPV must respond and accelerate extremely fast in order to reduce the pressure in the charge pipe and protect the turbocharger. Attaining that response comes down to simple physics in the form of Force = Mass * Acceleration. We can directly affect the mass of the piston via design and materials, which we were able to get down to a mere 38 grams w/O-rings. We can semi-directly affect the force required to accelerate the piston which various spring rates. Therefore by reducing the weight of the piston and optimizing the force applied to the piston we were able obtain a remarkable response time.

vta bpv response
Figure 4: CorkSport VTA BPV response time during high boost throttle close situation

Looking at Figure 4, you can see two separate graphs shown. The blue graph shows the intake manifold pressure in a 0-5volt range. Boost pressure was leveling at ~23.5psi on a CorkSport turbo equipped vehicle. The red graph shows the charge pipe pressure just ahead of the throttle body approximately where the BPV is located.

During the test the car is held steady at ~6000rpm so that boost can level off for ~5sec, then the throttle is abruptly closed; this is shown in the blue graph with the sudden decay. This causes sudden vacuum in the intake manifold and increased pressure in the charge pipe pre-throttle body. The pressure delta causes the BPV piston to react and vent which is shown with the slight increase and then decay of the red graph. The response time of the BPV is time delta from the intake manifold going into vacuum and the BPV beginning to open and vent. The resulting time delta is a remarkable 50 milli-sec or 0.050sec in general terms.

The piston isn’t the only optimized part of the BPV. The piston design and the BPV cap were designed to work together. Looking at Figure 3 you can see that the hose barb fitting is integrated into the cap design and more importantly is “inside” the piston as much as possible. By reducing the volume of the vacuum/boost signal chamber in the BPV, we have reduced the total volume that must be removed from the chamber before full vacuum occurs and can begin moving the piston. You could compare this to “shot-gunning” a can of beer. The tall boy is going to take longer than your standard 12oz right? Same idea with the BPV, but we are trying to shave milli-seconds.

bpv flange adjustability
Figure 5: CorkSport BPV flange adjustability

Another awesome feature on the CorkSport VTA BPV comes in the form of installation flexibility. Not only is the BPV compact at just 2.50 inches tall, but the flange can be adjusted to a total of five positions. The center BPV in Figure 5 shows the typical position for a Mazdaspeed BPV. From there the flange can be adjusted 15 or 30 degrees clockwise or counter-clockwise to aid in installation.

cad flow simulation
Figure 6: CAD flow simulation at ~220CFM with piston BPV fully open

Lastly, and arguably most important, the CorkSport VTA BPV flows great. Figure 6 shows a CAD flow simulation of the BPV fully open with inlet condition 23psia @ 110F and outlet condition 7 inches of H2O vacuum. Mach flow or commonly called “choke flow” is the situation when the air velocity reaches Mach 1. At this point no more airflow can be pulled through the BPV without increasing the pressure at the BPV inlet (charge pipe). In the CorkSport VTA BPV, Mach flows begins to occur at the nozzle throat shown in Figure 6. This is to be expected with the compact design and was a compromise made in the design process; however you will notice that the CAD simulation does not take into account the potential flow of the five VTA ports. These will only increase the maximum potential flow of the BPV.

To top it all off, the CorkSport VTA BPV makes an array of noises ranging from subtle whistles to loud whooshes. I invite you to check out the video found in the product listing as words just cannot give it justice.

We set out to design a high performing VTA BPV for the Mazdaspeed community that delivered with performance, style, and entertainment. We believe we delivered with a leak-proof, fast responding and glorious sound BPV. We hope you enjoy your new CorkSport VTA BPV as much as we enjoyed designing it.


Barett Strecker-01

CorkSport Mazdaspeed 6 Short Shift Plate

It is back from the dead! CorkSport is happy to announce the return of the Mazdaspeed 6/MPS 6 shift plate. We took our original design and adjusted it based on feedback from customers who owned the original to bring you a new and improved product.


CorkSport’s Mazdaspeed 6 Short Shift Plate has been designed to provide a 33% reduction in shift throw. The unique design of our shift plate provides maximum benefit to Mazdaspeed 6 drivers by changing the geometry at the shifter end to remove the feeling of synchros where it is most noticeable – in gears one and two. The shift plate bolts directly to the car, eliminating the need to bolt on to the factory or an aftermarket counterweight.

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