CorkSport CST6

Testing & Validation of the CorkSport CST6

As we get closer and closer to announcing the launch of the new CorkSport Turbo Line-Up we want to share the testing and validation we put our turbos through.  You may not realize it, but we’ve already shared a lot about the CST6 without really saying so, check out Barett’s Built Gen1 Here.  

So we’ve talked a bit about the design intent behind the CST6; defining the wheel sizes, wheel size ratio, and the ball bearing CHRA.   If you’ve seen the teaser listing then you’ve already seen the 633 whp dyno graph, so we’ll look at the data to support it!

The First Look at the CST6 Performance

CorkSport CST6 dyno at 28psi
CST6 running at 28PSI

First let’s look at the CST6 at a more moderate boost pressure.  Above are the results of back-to-back testing comparing the XS-Power V3 Exhaust Manifold and the upcoming CorkSport Cast Exhaust Manifold.  All dyno runs were performed with the same 28 psi peak pressure tune.

So the exhaust manifold testing is exciting, but it’s not what we’re here to discuss.   What I want you to know is that the CST6 is fully capable of providing mid-500 whp power at 28 psi.   While we have and will continue to push the CST6 to its max ability, the 27-30 psi range has proven to be a sweet and efficient spot for the CST6.

Testing the Limits on the CST6

CorkSport CST6 Dyno Graph running 34psi
CST6 running at 34PSI

Searching for the limits with the current fuel system we can easily push past the 600 whp mark plus some.   The efficiency of the CST6 at this power level is still very strong and the turbo continues to pull through the RPM range.   What really makes the CST6 shine is the power under the curve. This is a BIG turbo and will respond like one, but the loss of early spool is easily compensated for with the abundant power curve and power that carries past 7500 rpm.  

It’s important to note that testing for the CST6 is not finished because we are currently limited by the fuel system on the vehicle.   The current fuel system is OE DI injectors paired with a boost based methanol system flowing 40 gph peak. In the near future, we will continue finding the limits of the CST6 with a true port injection system and Split-Second controller flowing E85.   This will give us headroom for 8000+ rpm and boost levels past 34 psi (let’s see what 40 psi give us!).

Looking at the CST6 Data Log

CorkSport CST6 Data Log
MAF Voltage and Actual AFR of the CST6

This is a datalog form the 633 whp dyno run and was recorded on the chassis dyno.   Because of that, it is not a perfect example of street driving… let me explain why. The dyno dynamics chassis CorkSport uses can control load and thus the rate at which the engine can rev through the RPM range.   In order for us to dyno a vehicle at this power level safely, we need to find the right ramp rate for low RPM and high RPM. The biggest factor this affects is the spool RPM of the turbo.

On the graph I marked ~200 rpm shifted to the left for the boost curve.   On the street, the CST6 spools about 200 rpm sooner due to the higher load on the street vs the dyno.   This puts the CST6 @ 20 psi around 3800-3900 rpm.

Also shown on the graph are MAF voltage and actual AFR.   Both of these are important because they provide real data about how the vehicle is being tuned.

Target AFR is set for 11.76 which is neither rich nor aggressive for this setup.  The slight up and down of the AFR curve from 3500-4000 rpm is due to the very high amount of auxiliary methanol starting to spray along with the DI injectors.

Looking at MAF voltage you can see us get well past 4.50v.  Actually, we are consistently seeing MAF Voltage around 4.65-4.70v using the CorkSport 3.5” Intake which has a true ID of 3.50”.  This is just further validation that the CST6 is flowing enough air to support 600+ whp.

There’s more to come from the new CorkSport turbo lineup so stay tuned for more info on the CST5, CST6, and EWG housings.

-Barett @ CorkSport

CorkSport External Wastegate Housings: Design and Product Details

During our development of the new CST6, it became clear that an external wastegate (EWG) would be the only option for optimum performance and boost control — Read about the CST6 design here. Since we were already developing a housing for this turbo, we just HAD to make similar options for both the tried and true CST4 and the upcoming CST5. In today’s blog we will cover what makes the new CorkSport EWG Housings tick and go through how the systems are different from a typical internal wastegate (IWG)setup.

CorkSport External Wastegate for Mazdaspeed
Mazdaspeed External Wastegate Housing.

How The CorkSport EWG Housing Works

Starting with the basics, the CorkSport EWG housings replace the turbine or “hot” side of your CST4 or CST5 turbocharger. The CS housings eliminate the small “flapper valve” of the internal wastegate with a path to a standalone wastegate actuator. While the housings will not come with the actuator itself, they will include everything you need to mount up a Tial 44mm (or equivalent) EWG, with the option to grab a screamer pipe to go with it.

CorkSport MazdaSpeed3 external wastegate
Mazdaspeed 3 external wastegate.

EWG Housing Placement

The placement of an external wastegate is very important for proper boost control. We chose the location of it carefully as the offshoot from the scroll of the turbine provides an optimum path into the wastegate. As shown in the diagram below, a shallow angle into the wastegate offers the best exhaust flow path which results in optimum boost control.

Wastegate Placement Diagram
Mazdaspeed wastegate placement diagram.
Click to Expand

A Properly Sized Wastegate

Sizing is also important for boost control. Too large of a wastegate is hard to fit on the car and can be difficult to control boost as it does not need to open much to flow a lot of volume. Too small of a wastegate can cause over boosting from a lack of flow. For most Mazdaspeed applications, 38mm and 44mm sized wastegates are most commonly used. We chose the 44mm option for its better usability on the street. Since a street car is not using the turbocharger at peak efficiency 24/7 and is usually at a relatively low boost level, the larger 44mm wastegate will more effectively vent the excess exhaust gases.

EWG Tial for Mazdaspeed 6
External Wastegate Tial for Mazdaspeed 6.

Choosing An Internal or An External Waste Gate

Now on to a big question: why an external setup over and internal setup? While they both have their pros and cons, the biggest answer is better boost control. In general, an external wastegate setup will control boost more accurately and respond quicker to changes in boost than an internal one. While the CST4 and CST5 have been optimized to work with IWG, an EWG setup will almost always have better boost control. It should be noted that, generally speaking, an EWG will have higher peak power capabilities. First, back pressure in the exhaust system is reduced due to the removal of the exhaust gas that would usually cause turbulence as it exited the IWG right near the turbine exit. Second, an IWG setup can reach a limit in flow where literally no more gas can flow through the turbine & IWG port. Most EWG setups do not have this problem as the EWG port can be larger & the wastegate gases do not have to exit in the same location as the turbine gases.

Check out the diagram below, as it illustrates a common problem with internal wastegate setups. A boost spike as desired pressure is achieved then inconsistent boost as RPM increases. External setups (right diagram) typically do not have either of these issues and can achieve a near flat boost curve.

Internal and External Wastegate performance chart
(Left) Internal Wastegate Setup | Common Issues
(Right) External Wastegate Setup | Optimized Setup
Click to Expand

The CorkSport External Wastegate Design

Moving to an EWG design allowed us to tweak the design of the housing itself. The CorkSport external wastegate housings all use a ~0.82 A/R. This number is a ratio that is determined by the geometry of the scroll. I won’t go too much into it, but for more info be sure to check out Barett’s turbocharger white paper here. This is larger than the CorkSport internal wastegate setups. Essentially, the increase means you may sacrifice a little bit of spool time but gain peak power capabilities at high RPM.

In addition, the volume of the scroll itself was increased. This is referred to as “swallowing capacity”. By increasing this volume, the turbine housing will be able to air more efficiently at peak, again increasing your max power potential. This is especially important when you have a high flowing ported head or an upgraded exhaust manifold. Check out the CAD models below, you can really see the difference in the scroll size.

CorkSport Turbine Housing
CorkSport Turbine Housing for Mazdaspeed 3.

I almost forgot the best part! An external wastegate setup gives you the option to run a screamer pipe which sounds amazing while under boost. While screamer pipes are sold for race use only, they add far more excitement to a wide open throttle pull! Stay tuned for more, next time we will be sharing testing information & some more teaser shots.

-Daniel @ CorkSport

New & Improved: The CorkSport Aluminum Skid Plates for Mazdaspeed 3

CorkSport Aluminum Skid Plate
CorkSport Aluminum Skid Plate

Aluminum Skid Plates for 2008-2013 Mazdaspeed 3 and 2004-2013 Mazda 3.

While not a new product, there is still plenty to be excited about. Say hello to the new and improved CorkSport Aluminum Skid Plates for 2008-2013 Mazdaspeed 3 and 2004-2013 Mazda 3. We took all of the great features present in the original one-piece design, and then went back to the drawing board to improve the fitment, make installation easier, and make shipping cheaper for everyone. Read on as we go through the full details of this redesign.

CorkSport MazdaSpeed 3 Skid Tray
GEN 1 Skid Plate for 204-2009 Mazda 3.

Designing the GEN 3 Skid Plate

While designing the GEN 3 Skid Plate for 2014-2016 Mazda 3, we realized that utilizing a two-piece design is a fantastic way to save you some money on shipping. The overall design is smaller which allows us to use a smaller box to eliminate any oversized package charges from shipping companies. This is the same reason why our GEN2 Speed3 Front Lip is made of multiple parts. By designing the skid plate into two-pieces, installation on your vehicle becomes more flexible when aligning the front and rear sections. The multi-piece lineup creates wiggle room to help get everything all lined up properly on your car. Since each and every car is just a bit different, the extra wiggle room helps to achieve the best alignment possible, even on cars that have had their subframe, radiator support, and/or bumper removed and not reinstalled perfectly.

CorkSport Skid Plate for MazdaSpeed 3
Skid Plate for 2010-2013 Mazda 3 and Mazdaspeed 3

The Perfect Fitment

Going to a new design gave us the freedom to improve fitment even further. We have revised the mounting locations to ensure the easiest installation possible and reshaped a few areas to best fit on your car. Like the original though, no permanent modification to your Mazda is needed as we use all OEM mounting locations. Plus, the CorkSport Aluminum Skid Plates for Mazdaspeed 3 ship with all of the tools that you will need to install it.

CorkSport Underbody Skid Plate
CorkSport Underbody Skid Plate for MazdaSpeed 3

Ultimate Protection Without the Weight

Both GEN1 and GEN2 CorkSport skid plates are made from laser cut and precision formed 0.090” aluminum sheet. This thickness offers great protection from road debris and the occasional tall speed bump without adding a ton of weight to the front of your Mazda3. Where an OEM plastic splash shield would crack and fail, the CorkSport skidplate can take a beating, offering you peace of mind whether you’re riding at stock height or have lowered your MazdaSpeed 3. Speaking of riding low, the CS under tray sits up slightly higher than the OEM shield, giving you that little bit of extra clearance when you need it.

CorkSport Aluminum Skid Plate Installed
CorkSport Aluminum Skid Plate on MazdaSpeed 3

If this is just your next mod in a long list of mods do not worry. The CorkSport Aluminum Skid Plates fit with both GEN 1 and GEN 2 Front Mount Intercooler Kits as well as the CorkSport Lower Tie Bar. The CS GEN2 Front Lip will fit as well but may require some modification to the skid plate and/or front lip. For all of you Mazda 3 owners, just a heads up that these skid plates were designed for the Mazdaspeed models so you may require some minor trimming for best fitment, all of which can be done with a simple hand saw or razor knife.

CorkSport Aluminum Skid Plate

There you have it folks, the new and improved CorkSport Aluminum Skid Plates for GEN1 and GEN2 Mazdaspeed 3 & Mazda 3. Let us know if you have any questions down below and we will be sure to help you out!

Let’s Get Chilly: CorkSport Intercooler for SkyActiv 2.5T

It’s time to break down our design for the CorkSport Performance Intercooler Upgrade for the Mazda 6 2.5T. We have covered both the OEM intercooler and piping, and our design plan for the upcoming Sky-T intercooler piping upgrade in previous blogs, but today’s focus is the intercooler itself. Intercoolers are a delicate balancing act between size, cooling efficiency, and pressure drop so naturally things can get a little complicated. Buckle up and stay with us, and be sure to drop any questions you may have down below.

Taking a look at the stock intercooler mounted on the Mazda 6 (shown above) shows us quickly where our size constraints lie. With the large crash bar, we cannot go too much larger in height without trimming the crash bar, bumper, or both. However, there is a ton of room for added thickness and better end-tank design that can really help increase the width of the intercooler. The stock intercooler core is 24.5” wide, 5.5” tall, and 2.625” thick. Our plan is to fit a 27” wide, 6” tall, and 3.5” core without any trimming. This sizing combined with a low-pressure drop will be good for 400WHP with no issues! Because the Mazda 6 comes with just around 200WHP from the factory, this sized core provides plenty of room for upgrading down the road without causing excessive boost lag that can occur if an intercooler is simply too big. Check out a prototype CorkSport intercooler mounted on the car below.

Now that size is taken care of, let’s move on to cooling efficiency and pressure drop of the CorkSport intercooler for the SkyActiv 2.5T. These are tied closely together as getting extremely high cooling efficiency usually means high pressure drop and vice versa. Just so we’re on the same page, cooling efficiency is how well the intercooler cools off the pressurized air that passes through it. So a highly efficient intercooler will be able to bring the boost temperatures down similar to the ambient air temperature. Pressure drop is exactly what it sounds like, a loss in pressure from the inlet to the outlet of the intercooler which can be caused by a number of things: poor end-tank design, too many intercooler fins, or simply poor flow distribution in the intercooler. Too large of a pressure drop means lower boost pressures reaching your engine and/or your turbocharger working harder to achieve the same boost levels.

Pressure drop and cooling efficiency are influenced primarily by two things: fin density and end-tank design. Fin density is basically how many fins the boosted air must pass over when traversing the intercooler. More fins = better cooling efficiency, but also more pressure drop. To choose the best core for the SkyActiv 2.5T we plan to use multiple different fin densities and test each for power, cooling efficiency, and pressure drop. While we can get pretty close based on our work from the CS Mazdaspeed Intercoolers, it’s always best to test and identify the best one for each platform. With this extensive testing, we can reach our goal of improved cooling efficiency, lower pressure drop, more power, and no CELs.

End-tank design is critical as it determines how the air reaches the core of the intercooler. Sharp bends, poor air distribution, and small inlet/outlet size all adversely affect the performance of the intercooler. To fit the core size we want, we had to do away with the plastic inlet and outlet pipes of the stock intercooler. This was advantageous as it gave us more room to have a smooth flowing end-tank that distributes air well to all the runners and does away with the sharp corners present in the OEM end-tanks. In addition, we were able to increase the inlet and outlet size of the intercooler to 2.5”. This is a fairly standard size that has shown to work well for the Mazdaspeeds with stock power and without choking flow way up to Barett’s 600+ WHP.

Those of you with a keen eye have realized that the connection between the CorkSport front mount intercooler (FMIC) and the OEM Intercooler is not the same. As shown in the CAD rendering above, each intercooler kit will come with the silicone and custom adapters that are needed to work with the OEM piping. If you decide to upgrade to the CS intercooler piping kit, later on, the CorkSport Intercooler for SkyActiv 2.5T will not need to be removed, and you will only need to change some silicone parts.

We will have more info on this kit coming soon, with the next blog covering our testing of the different core designs using a few new toys from AEM Electronics. Be sure to check out the product listing for more info, and to be notified when the intercooler is available. Last but not least, CX-9 Turbo and CX-5 Turbo owners, we are 99% sure this kit will also work on your rides but we plan on validating fitment before release!

-Daniel @ CorkSport

CST5 Spools!! Testing and Validation

We’re back on the new CorkSport turbocharger lineup again with today’s blog, this time focusing on the testing & validation of the “medium big” turbo, the CST5. Just in case you missed it, the CST4 (formerly known as the CorkSport 18G) is getting some company to go along with its new swanky name. Check out the full lineup here and the design behind the CST5 here. Now that you’ve read all that, let’s get into what you’re really here for, testing & dyno numbers.

We started with the internal wastegate option, to validate the CST5 for drop-in fitment. Since we’ve had great experience with the drop-in CST4, we knew how to design a turbo around the tight confines of the Mazdaspeed engine bay. The CST5 fit great in the OEM location with just a few minor revisions for proper fitment. It looks pretty good in there too if we do say so ourselves!

Next the car got put on the dyno for tuning and to push the new CST5 to its limits. With a little help from our friend Will at PD Tuning, the CST5 was soon putting down some impressive numbers. We started off with a “calm” boost level of ~25psi. This netted us 450WHP and spool time that surprised us, achieving 20psi by 3500-3600RPM. Turning up the boost and pushing the turbo to its limits, we achieved 519WHP at ~30-31psi on Barett’s built GEN1 MS3. Check out the dyno graph below.

Taking the car out on the street surprised us further at just how early the car was building boost for this size of turbo. Road logs showed that we were making 20psi slightly sooner than on the dyno (3400-3500RPM) but even more surprisingly the CST5 was making 30psi by 3700-3800RPM! Obviously this is an aggressive tune that would most likely kill a stock block, but, the CST5 can be tuned to be stock block friendly and still make good power.

Then came the testing on the EWG variant of the CST5. We had developed fitment for the CST6 which meant the CST5 had no issues upon install on both MS3 and MS6. Next was a quick retune and some power runs. The larger swallowing capacity of the EWG housing meant some extra power at peak, yet spool was nearly unchanged. We made 525WHP at the same ~30-31psi.

Comparing the IWG and EWG turbine housings you can see a small variation in the graphs.  This variation is mainly due to the change from internally waste-gated and externally waste-gated.  The EWG setup provides more precise boost control through the RPM range. The EWG setup allows us to better tune the “torque spike” around 4200rpm vs the IWG setup.  For peak power the IWG and EWG housings are within the margin of error which makes since because they are both 0.82 A/R housings.

Further supporting the IWG and EWG setups, both options allow you to tune the spring pressure so you can better setup your CST5 and Speed for the fuel and boost levels you want and of course the most noticeable difference is what you hear. What’s an EWG without a screamer pipe!  

Wrapping up testing showed exactly what we were hoping for with the CST5: a great middle ground between the existing CST4 and the upcoming CST6 that can be used on both high powered stock block and fully built cars. Our testing continues as this blog is written as the CST5 is being beta tested by a close friend of CS with a freshly built Dankai 2.

There’s more to come from the new CorkSport turbo lineup so stay tuned for more info on the CST5, CST6, and EWG housings.

-Daniel @ CorkSport