My name is William Dawson; for those who do not know me, I am owner/tuner at Purple Drank Tuning. In this Guest blog, I want to bring up some of the research & development I was able to contribute to with CorkSport (behind the scenes) to help bring some new performance parts to the Mazda community.
One day, many months ago, I was approached by Barett@CS to help with the tuning and development of some mystery parts CorkSport had in the works. Being who I am, I couldn’t turn down the chance to work on some new projects that could help continue to push the Mazda platform we love.
With the pleasantries out of the way, we got down to the plan and the data. Barett had a list of goals and how he wanted to move through the parts in testing. The amount of data that was communicated through the first live tuning session was great. On the CorkSport in-house dyno we took their shop car to an impressive 420whp (e48 + 6 port setup) with stock manifolds, stock throttle body, and stock camshafts.
This laid the groundwork and set the stage for their product release of the CS Camshafts which gained 22whp across the curve. Along with the power increase, the camshaft upgrade also netted surprising results with turbo response. The turbo spooled 100rpms quicker than the factory camshaft allowed. THESE ARE DROP IN RESULTS, ZERO ADJUSTMENTS!
Efficiency hit us with another surprise when we decided to put the CS Intake Manifold (set to re-release in early 2019) on the car and help the engine balance all of the air we have begun shoving into our test vehicle. Once again CorkSports engineering pays off with another 9whp increase and 100 rpm quicker spool up. The car lost 2-3 psi of boost which we were happy to put back in the car allowing for us to do an apples-to-apples comparison but the numbers elude me so I cannot speak to what we ended up with on that day.
At this point we did not know how much more we could get as the CorkSport Mazdaspeed Drop-In Turbo that was installed on the test car was producing an impressive 450whp, this did not stop us as we needed to test one more item. In comes the CS 72mm Throttle Body, this upgrade was constantly overlooked by the Mazdaspeed3 and Mazdaspeed6 community because of other attempts to get an upgraded throttle body created complications with drive by wire tables and throttle response.
Personally having a 75mm TB and not being able to enjoy the on/off throttle response and laggy part throttle was a very frustrating experience; one that even made me skeptical. Then getting to test CorkSports product was MIND BLOWING! The test car again spooled around 100rpms sooner and throttle response was phenomenal; all with just removing 4 bolts and swapping a Throttle Body this is insanity. This team did it again, my disbelief overshadowed by pure joy that they developed a working unit and it far surpassed the factory unit in throttle response and driveability.
I have known the CorkSport family for years and it does not matter what department I am working with they are always on point and pleasant to deal with regardless of the situation. Between PD and CorkSport I could not be happier to invest countless hours of hard work and R&D to allow this winning family to provide further developments and support to the Mazdaspeed 3 and Mazdaspeed 6 platforms.
– Will Dawson (PD Tuning)
Special thanks to Will for committing his time and expertise to help CorkSport continue to grow and support the Mazdaspeed community. – Barett @ CorkSport
Collaborating with CorkSport – R&D for the Community September 27th, 2018CorkSport
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.
In order to understand the basics you need to know some camshaft terminology. The most common terms are lobe, lift, duration and base circle.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.