There has been a lot of buzz about the new(ish) turbocharged SkyActiv-G 2.5L first found in the Mazda CX-9 and now in the Mazda 6. Along with all this buzz, there are a lot of unknowns as well. Here at CorkSport, we’ve taken the step to try and address some of these unknowns. What is Mazda’s “Dynamic Pressure Turbo” and how does it work? There have been diagrams bouncing around on the internet, but no close-up view of the turbocharger itself. That’s about to change.
The turbocharger found in the 2.5T equipped CX-9 and 6 is quite complex in design. There are many aspects to the OE turbocharger we could discuss, but today we are going to focus solely on the dynamic pressure system and turbine housing.
If you are reading this, then you’ve probably already seen various diagrams depicting how the dynamic pressure system works and showing Mazda’s clever 3-2-1 exhaust port design. If you haven’t, check it out below. Image credit to Car And Driver Magazine for the fantastic diagram.
Mazda’s 3-2-1 exhaust port design takes full advantage of the engine cylinder firing order. The advantage is improved exhaust gas scavenging for the adjacent cylinder (more or less the cylinder that just fired helps pull the exhaust gases out of the next cylinder that is about to fire). Ok moving on; this is great, but how does the dynamic pressure system come into the mix?
Shown here are the turbocharger assembly and the dynamic pressure valve assembled as one unit (the first two images also showed the fully assembled setup). The three ports are clearly visible along with the “vane” that passes through the three ports. This vane rotates depending on engine RPM to control the exhaust gas velocity entering the turbine housing. The vane itself is controlled by the larger blue colored actuator.
Now let’s take an even closer look. The vane does not open until approximately 1600rpm, but the engine could not run of no exhaust gas can flow out of the engine. To resolve this Mazda has designed the dynamic pressure system with two exhaust gas paths. Looking at the above image you can see a small opening just above the vane. This is the sub-1600rpm exhaust gas path.
By reducing the cross-sectional area of the exhaust gas path, the exhaust is forced to accelerate through the dynamic pressure system and into the turbine wheel. This effectively reduces turbo lag, improving the vehicle’s response at low engine RPM. Once the engine revs past 1600rpm the vane opens, allowing the larger path to be used.
Here we show the turbocharger assembly (right) and the dynamic pressure valve assembly (left) separated. Looking at the dynamic pressure valve assembly, you can now more clearly see the three small paths above the larger path with the vane inside. Then look at the turbocharger assembly and you will see the small upper path and the larger lower path.
The fact that these two assemblies are separate systems is great news for the enthusiast. The development of a performance turbocharger will be much more feasible and the dynamic pressure valve can be retained with the performance turbocharger. One more detail to point out.
Mazda put a lot of thought into the design of the wastegate port; let me show you why. First, looking at the inlet of the turbine housing you can see a small vertical wall in the large path. This wall creates a completely separate path to the wastegate port which is very unusual on an OE turbocharger. Combine this design with a very large wastegate port and you get a design that can “waste” or divert an excessive amount of exhaust gas.
This tells us the SkyActiv-G 2.5L engine is creating a lot of (currently) unused exhaust gas energy. Again this supports the feasibility of a performance turbocharger suiting Mazda’s new turbo engine quite well.
Great things are on the horizon for the 6, now if only Mazda would put this engine in the 3 paired with a 6-speed manual transmission. Oh, one can dream.
-Barett @ CS
Mazda’s Dynamic Pressure Turbo – A Closer Look September 11th, 2018CorkSport
The SkyActiv 2.5T has been around for a few years in the CX-9 however, things started to get interesting when the engine was dropped in the Mazda 6 for 2018. While lacking a manual and not a true Mazdaspeed, it’s a step in the right direction for the enthusiast. With one of the new Mazda 6s in the CorkSport garage, we’ve been getting curious about where all of that 310lb-ft comes from. Well we decided to call up Mazda and purchase a turbo to see how it all works.
There’s a lot to take in on the turbocharger and there are quite a few things that have changed from the K04 that made its home in the Speeds.
For starters, this turbocharger is pretty big. The wheels themselves are not large, with the compressor wheel very close in size to the old K04 & the turbine wheel only slightly larger than the K04. However, with the dual inlet turbine housing, 90° compressor outlet, and lots of attached electronics, the whole package takes up a lot of room in your engine bay.
The turbine housing is not far from the old K04. A large five-bolt inlet flange has two rectangular inlets to work with the dynamic pressure system (more on that later) and even a port where the EGR system sources its exhaust gases. The outlet is much simpler, using a five-bolt flange to mount to the downpipe, yet does house a surprisingly large wastegate port.
From a performance standpoint, the large wastegate should help eliminate boost creep but the turbine housing will likely need a larger scroll to get some more serious power out of the engine.
The compressor side is packed full of features. As usual, the wastegate actuator bolts to the compressor housing, however, Mazda has switched to an electric actuator. Interestingly, the bypass valve is also electric and is even mounted to the face of the compressor housing.
Some fancy casting design leaves a pathway between the high and low-pressure sides of the compressor and lets the BPV decide when the passage is open or closed. These two electric actuators will mean easy and consistent boost control. The final plastic component on the housing we believe is a boost assisted vacuum source for the vehicle. Finally, the inlet is a typical clamp connection while the outlet uses a 90° turn and two-bolt flange for better accessibility around the wastegate actuator.
With the housings removed, the CHRA of the dynamic pressure turbo is very simple & standard. Oil feed in the top, two-bolt oil drain in the bottom, and standard crossflow engine coolant ports. The compressor wheel is a cast 6×6 unit and turbine wheel is a basic 11 blade unit.
We are looking forward to waking up the Sky-T in the coming months and making the 2018+ MZ6 into something a little closer to a Speed. Stayed tuned, there’s much more fun to be had from the 2.5T!
Mazda’s Dynamic Pressure Turbo – An Introduction September 6th, 2018CorkSport
You have probably heard us mention the new Turbocharger Mazda 6 in the recent weeks and months and have probably been wondering; “what’s going on?” Well, today we’d like to share a little bit about what’s been going on at CorkSport HQ with our very own 2018 Mazda 6.
Right off the bat, I can say we have a handful of exciting performance products in the works and will be sharing info on them as we make progress. Today we want to talk about the intercooler piping, specifically the cold side piping and the parts of the system. This is the piping that connects the outlet of the intercooler and the throttle body. It is commonly referenced as the “cold side piping” because the charge (boosted) air has passed through the intercooler and is therefore cooler.
The OE cold side piping consists of three main components. Starting on the right side of the image; we have the hard piping that connects to the intercooler and a soft rubber hose. Next is the soft rubber hose itself, which we will talk more about later. Lastly is the throttle body connection, which is the oddest part of this system. You can see why in the next image.
The above-mentioned intercooler hard pipe and the rubber hose are pretty common parts on modern turbocharged vehicles, but the throttle body connection is unusual from our experience. The throttle body connection appears to be designed for a quick connection (and not so quick disconnection) during the vehicle assembly process. Unfortunately, this leaves a very odd connection flange on the throttle body itself. Lastly are the fins inside the connection part; other than straightening the airflow entering the throttle body we don’t see many purposes these. We will be testing the effects and need for these in the near future.
Now let’s get to what we really wanted to talk about; BIG Silicone Performance Parts.
Mazda designed the Turbocharged 2.5L SkyActiv-G to function at a specified boost pressure and no more. However, we fully intend to change this set boost pressure for increased smiles per gallon. With increased boost pressure comes more force and strain on the OE rubber hose. Eventually, the OE rubber hose becomes too flimsy for the increased boost pressure and may expand or fail completely via a rupture.
So how do we develop a performance part to replace a rubber hose? Well, there is one obvious improvement and another not-so-obvious change that can be made. First, we use silicone as the prominent material for its excellent heat resistance and durability. Next, the silicone is reinforced with five layers of fabric braiding to withstand the increased boost pressures. Compare this to the OE single layer of reinforcement and you can see why this would make a big difference.
Now for the less obvious performance improvement; the CorkSport 3D Printed prototype is larger in diameter than the OE rubber hose. Leaning on our experience with past intercooler piping development, we have found that increasing the charge air volume directly in front of the throttle body increases throttle response and helps spool the turbo faster, reducing turbo lag.
Currently, we are still in the development phase but will be testing soon. Stay tuned for future updates on the CorkSport Performance Boost Tube and other exciting products for your 2018 Mazda 6.
-Barett @ CS
2018 Mazda 6 Performance Parts – Cold Side Boost Tube August 14th, 2018CorkSport
With our goals to make more power, we often forget about the opposite requirement so speed…stopping. The CorkSport Big Brake Caliper Kit is a great place to start, however, if you wish you could stop even faster say hello to the CorkSport 13inch Big Brake Kit. Designed for serious stopping power, it includes 13” directional rotors, powder-coated 4-piston calipers, upgraded pads, and everything you need to install it on your Mazdaspeed 6.
Read on for a breakdown of all the components:
Lots of thought has put into the design of the performance rotors found in the CorkSport 13inch BBK. The upgrade to 13inch diameter rotors provides greater braking torque for an equivalent braking force (like how a longer wrench makes it easier to loosen a tight bolt). The increased diameter combined with a thicker 28mm (vs 25mm for OE) rotor ring provides better cooling as there is a larger mass to reject heat into.
In addition, slots were added to the friction surface to help sweep away any debris, brake dust, or gases that can otherwise affect your braking characteristics. Drilled rotors were not used as holes decrease your total friction area and increase the chance that the rotor will crack. Utilizing a two-piece design, we were able to decrease the overall weight of the rotor via center section produced from billet aluminum; while also helping dissipate heat from the rest of the rotor better. Semi-Floating mounting between the inner and outer sections allows for quieter rotor vs having a full-floating center section.
Lastly, the rotors feature directional internal vanes that promote more efficient airflow through the rotor which further increases the rotors ability to dissipate heat. By using curved vanes instead of the typical straight vanes, the rotor becomes directional and has to be used on a specific side of the vehicle; however, it also provides more efficient cooling. When the rotor turns, the curved vanes draw air through the center of the rotor and out through the edge, providing greater airflow than a straight vane and thus better cooling. There is another bonus to heat dissipation as the curved vanes have a larger surface area that will come in contact with air than an equivalent number of straight vanes.
Four-piston performance calipers manufactured from forged aluminum are included with the kit in a choice of powder-coated blue, red, or black.
Although each piston is individually smaller in diameter than the single OE caliper piston, the total surface area is increased so the braking force at a specific brake pressure is increased. Larger piston surface area means larger brake pads can be used as well. You also get more even braking force on each side of the rotor due to the opposed piston design. This encourages even pad wear, even rotor wear, and consistent braking characteristics. The piston diameter and material were chosen for optimum braking endurance and reliability. They are staggered in size, with the pistons on the leading edge being slightly smaller than the trailing edge pistons. This is another protection for even pad wear. Each piston is made completely out of stainless steel for its low conductive heat transfer. What this means is that the pistons themselves will transfer less heat to the brake fluid than an aluminum or steel piston, decreasing the chances of overheated brake fluid.
Street performance brake pads are included with the kit. The street sports pads bridge the gap between street and trackpads. They are a more aggressive compound than the pads included with the CorkSport Big Brake Caliper Kit but are not a fulltrack pad. They will produce less dust and noise than a track pad but still need to be warmed up for optimum performance. Should you need new pads or want to change to a different pad, you have a bunch of options from G-Lock, Carbotech, EBC, Hawk, and various other manufacturers.
Lines, Brackets, and Hardware
The remainder of the CorkSport 13inch BBK is composed of exactly what you need to properly and safely install the kit on your MS6. Coated stainless steel brake lines are included to remove any risk of a soft brake pedal and ensure the calipers are operating optimally. High strength billet steel brackets properly position the four-piston calipers on the new rotors using the OE bracket locations. All components are locked down using Grade 12.9 hardware with a corrosion resistant coating for lasting durability.
If you haven’t heard already, Mazda has finally kicked out a new Mazda 6 with a turbocharged engine!
CorkSport jumped on the waiting list early and we are proud to be one of the first owners of a 2018 Mazda 6 Grand Touring Reserve. Ours is Soul Red Crystal. In the short time we have had the car, it has already been on the lift, the dyno, and many backcountry roads. We are digging into the new platform and have already started work on a handful of new performance parts.
This license plate relocation kit is just the beginning of what we’ve got in store for this new car.
As with all CorkSport License Plate Kits, the 2018 Mazda 6 kit includes everything you need to move your plate from the middle of your bumper to the side and free up much-needed airflow (trust us, you’ll want that airflow for some other parts we are working on). All mounting brackets, hardware, and even bumper hole plugs are included to make for a quick and simple installation with no permanent modifications required.
All components have been proven to last and looking good while they do it. A zinc-coated steel adapter is used to connect to the OEM emergency tow hook hole. A laser cut, precision formed, and powder coated mounting bracket is used to support the ¼” thick Lexan plate mount. We even include stainless steel tamper proof mounting hardware to ensure your plate, and relocation kit doesn’t disappear in a parking lot.
While mainly a cosmetic modification, the CorkSport License Plate Relocation kit does provide a small increase in airflow entering your radiator and intercooler. Even though it’s a small improvement, we’ve already found the OEM intercooler needs all the help it can get (more on that in coming months).
For an added visual boost and to support the #1 brand in Mazda Performance, be sure to pick up a CorkSport License Plate Frame to go with your relocation kit!
This is the first of many performance parts we have in the works here at CS HQ. Let’s reveal a few of those already in the pipeline…
Upcoming products include an upgradable Short Ram Intake System, Performance Intercooler & Piping, Lowering Springs, and a Stainless Steel 80mm Cat-Back Exhaust System. We’ve already seen gains with the SRI System and will be testing the Exhaust and Intercooler parts in the coming months. Check back here for more updates!
CorkSport License Plate Relocation Kit for 2018 Mazda 6 June 28th, 2018CorkSport
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