Testing – CorkSport External Wastegate Housing for Mazdaspeed

Turbo EWG

Why EWG?  (it’s just about awesome turbo noises)

We hear this alot as the Mazdaspeed platform continues to grow and the 450-500whp build becomes the status quo. Following up the EWG Housing Design & Details Blog about the new CorkSport EWG Housing, we want to share some testing data and differences we saw between an IWG (internal wastegate) and EWG (external wastegate) setups.  

Details about design, flow, placement, data, and feedback from our CST4 EWG Beta Tester.  

IWG vs EWG comparison on the CST4
IWG vs. EWG on the CST4

Let’s jump right in!  First up is a spring pressure comparison between the IWG and EWG housing on a CST4 turbocharger.  Let’s first define what “spring” pressure is: this is the resulting boost pressure with 0 added wastegate duty cycle.  AKA we are not trying to add boost pressure.

Immediately you can see some very obvious differences.   The IWG setup has a taper up boost curve that could be considered boost creep.  Some boost creep is ok, but an excessive amount may reach the capacity of the fuel system or other systems in the vehicle.  In this setup that is not the case, but it does show that the IWG is at its limits for boost control.

With the EWG setup you see a much different curve.  The boost builds a few hundred RPM later (due to the larger 0.82 A/R) then climbs right to the spring pressure and then settles to a consistent plateau; very predictable and controllable.  

CAD EWG and IWG Designs
CorkSport EWG and IWG Designs

Now let’s look at the design to better understand why.  On the left is the EWG turbine housing with a 0.82 A/R and on the right is the IWG turbine housing also with a 0.82 A/R (we don’t want the A/R to be a factor in this review).   

The EWG housing has a very efficient flow path for the exhaust gas to reach the EWG control valve along with a much larger path to flow.  Both of these features provide excellent flow and thus control of boost pressure.

The IWG housing uses a side port in the turbine scroll to exhaust gas.  In this setup, the exhaust gas must make an abrupt turn and pass through a much smaller port.  Both of these issues reduce boost control.

EWG and IWG Explained

Here is a diagram showing placement of an EWG in the exhaust pre-turbine.  Granted we are comparing a EWG and IWG, but the concept of flow is the same.  

Exhaust gases will always take the path of least resistance and if the turbine wheel is the easier path than the wastegate then boost control will be more difficult.  

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

This graph was shown in the last blog, but we want to show it again so you can directly compare it to the data graph below.  

Below is the boost curves for the CST5 in both IWG and EWG setup.  Alone each graph actually looks really good, but when overlaid you can see some interesting differences.  

CST5 Dyno testing with IWG and EQG setup

IWG vs. EWG on the CST5

The purple IWG graph has a crisp spool and then flat-lines at approximately 30psi with a slight fall off at 6500rpm.  The CST5 IWG setup does control boost really well, but holding the turbo back at spool up and not over-boosting or spiking was a small challenge.  An abrupt boost curve like this can make the car somewhat difficult to drive because the torque “hits” very hard and you lose traction.

The EWG setup was a bit more controllable.  Not only did the CST5 turbo spool a bit sooner, but we were able to better control the spool up boost curve so we could create a torque curve that was more friendly to the FWD traction.  This makes the car more fun to drive. Looking at the higher RPM range we were also able to hold boost more consistently to 7500rpm.

CorkSport External Wastegate

We hope you guys and gals are as excited for the EWG options for the CST4, CST5 and CST6.  They really are an awesome setup for any driving style and power goal.  

Thanks for tuning in with CorkSport Performance.

-Barett @ CorkSport

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

SkyActiv 2.5T Cold Side Boost Tube Part 2: Testing

In case you missed it, we have been working on improving the flimsy rubber tube that comes stock on the cold side of your 2018+ Mazda 6 2.5T. Check out the first part on the cold side boost tube here and the full OEM piping & intercooler breakdown here. Since our last installment, we have been busy testing a prototype CorkSport Boost Tube and would like to share some results with you all.

Testing Results

SkyActiv 2.5T Boost Tube
CorkSport SkyActiv 2.5T Boost Tube

Starting off we tested and data logged both the OEM tube and CorkSport Performance Boost Tube on the dyno. We were not expecting to see too much of a difference to power with just the boost tube changing however, we did see tiny improvements here and there, most notably way up at the top of the RPM range.

Check out the graph below, (OEM: red, CS: green). We tested on the same day in identical conditions and the car had a CorkSport Intake and Cat Back Exhaust installed for both tests.

PLEASE NOTE: the variations below 2800RPM are due to inconsistencies associated with dyno testing an automatic car.

SkyActiv 2.5T Boost Tube Performance Dyno

After noticing these changes, we went to the data logs to see how the boost changed between the OEM tube and the CS Boost Tube. The graph below shows the engine RPM versus the manifold pressure in psi. Both lines have the same smoothing done to the raw data. As you can see, the CorkSport tube (green) holds about 0.5psi through the midrange (3500-5000RPM) and is almost 1psi more when above 5500RPM. This correlates well with what we saw while dyno testing.

SkyActiv 2.5T Boost Tube Manifold Pressure Test

Testing the Changes

The small increase in boost pressure is likely due to the CorkSport tube not expanding as much when under pressure. To confirm this, we capped off both ends and pressurized the each tube to 20psi. Note: do not try this at home as the caps can easily fly off and injure you.

Boost Tube being tested

After measuring multiple locations both before and during pressurization, we found that the OEM tube expands about 12% in internal cross-sectional area while the CorkSport Boost Tube expands 3x less at 4%. Keep in mind that this would be an even larger difference if the same test was performed with the tubes installed on the car due to the heat of the engine bay. Since silicone is more stable than rubber at high temperatures, the heat of the engine bay will not soften it nearly as much as the rubber OEM boost tube. A softer rubber tube would mean even more expansion when pressurized and even more inconsistent boost pressures.

CorkSport and OEM Boost Tube Comparison
CorkSport Boost Tube (left) & OEM Boost Tube (right)

This data may not show drastic changes but it does not tell the whole story. The larger diameter and thus larger volume of boosted air of the CS tube provides a little bit better response when low in the RPM range. While this may just be a placebo effect on our end, there’s not too much of a wait before you can try it yourself! Stay tuned for more information. If you want a more serious upgrade though, keep your eyes out for information on the upcoming CorkSport FMIC kit and Piping Upgrade kit!

P.S. 2016+ Mazda CX-9 owners and future Mazda CX-5 2.5T owners, don’t worry we will be checking this for fitment along with other CS goodies!

-Daniel @ CorkSport

Collaborating with CorkSport – R&D for the Community

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! 

Mazdaspeed camshaft

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. 

 

Mazdaspeed 3 intake manifold

 

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. 

 

Mazdaspeed3 72mm throttle body

 

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

Creating CorkSport Parts with 3D Scanning

While creating a new CorkSport part, we sometimes run into issues where calipers, bore gauges, and angle finders are simply not enough to get the measurements we need.  We’ve discussed how we use 3D printing in a previous blog, but today I thought I’d go over the opposite: 3D scanning.

Where 3D printing takes a CAD design from computer to physical part, 3D scanning takes a physical part and converts it into a computerized model. This is especially useful for things like intercooler piping, intake design, and even creating exterior body parts. What these components all have in common is that they are a complex, difficult to measure, shape where fitment is critical. Check out the 3D scan below from the development of our GEN2 Mazdaspeed 3 front lip. While not a perfect replica, this 3D scan information was vital for designing the CS front lip to ensure great fitment and stylish look.

At CorkSport, we do have a small 3D measuring arm that can take measurements of 3D objects and input them directly into a CAD program. The arm does this by first having a “home” position established that the arm can measure from. Then as the arm is moved around, it knows how far the tip of the arm is from the home position in x, y, and z coordinates. This is a very basic form of 3D measurement as the arm must actually touch the surfaces of the part. Mostly simple information like mounting surface locations, angles, and hole sizes can result from this arm. While not a full 3D scan, it is especially useful for things like the GEN3 Transmission Motor Mount that have mounting planes at different angles.

For intercooler piping with completely round surfaces and bends, CorkSport’s 3D measuring arm has its limitations. We typically get a full 3D scan performed on the OEM piping to give us solid locations and a great visual reference to design from. The 3D scanning arm bounces a laser off the part to determine its shape and size. Then, software that accompanies the 3D scanner stitches all the information together into a full 3D CAD model. The scans achieve great accuracy; check out the embossed writing and even texture on this OEM intercooler piping for the SkyActiv 2.5T.

From this point, we design the new CorkSport parts. In terms of intercooler piping, we analyze where the larger piping will fit to get the performance gains we want. In some cases, we can also simplify the pipe routing to get smoother airflow than the OEM piping. Having a full OEM piping scan makes this much easier as we can easily double check our measurements with the OEM parts on the car. As a result, our first 3D print can often be the final version before having metal parts made. An early design for an upgraded Mazda 6 SkyActiv 2.5T hot pipe is shown below (blue) with the OEM part scan (gray). The routing was carefully chosen to achieve our desired piping size within the constraints of the OEM engine bay.

 

3D scanning has a huge range of uses and we are just beginning to explore the full capabilities. Be sure to share your ideas on how we should use this technology and what new CS parts we should make with 3D scanning’s help!

-Daniel