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

CorkSport Mazda6 2.5T Boost Tube

We are proud to release the https://corksport.com/2018-mazda-6-2.5l-turbo-boost-tubes.htmlCorkSport Upgraded Boost Tube for 2018+ Mazda 6 2.5T and 2016+ CX-9 2.5T. The CorkSport boost tube is larger, stronger, more reliable, and of course better looking than the OEM rubber tube. Increase throttle response down low, hit boost targets easier and future proof your ride for mods down the road with a simple 1-hour install. Read on for full details and be sure to check out the R&D blogs here and here for the backstory.

In case you haven’t read the previous blog installments, the CorkSport Boost Tube improves on the OEM boost tube by first strengthening the tube. Instead of using rubber with one reinforcement layer, the CS boost tube use silicone with 5 layers of reinforcement. Aside from the extra layers of reinforcement, silicone stays strong at high engine bay temperatures that may cause rubber to flex excessively. In addition, silicone lasts longer and will better resist cracking as your Mazda 6 Turbo ages. The OEM boost tube is made from materials very similar to the OEM Mazdaspeed 3 boost tubes that showed signs from aging extremely quickly, especially when subjected to higher than OEM boost levels. Cracking or splitting of the OEM tubes results in boost leaks and a poorly running car, definitely not what you want from your brand new SkyActiv 2.5T.

The added strength prevents the CorkSport Upgraded Boost Tube from expanding excessively when subjected to pressure. When pressure tested at 20psi (the largest pressure we have seen at the intercooler outlet), the OEM tube was shown to expand 12% at the internal cross-sectional area. The CS tube tested under the same conditions expanded 3x LESS. This difference would get even larger when subjected to the same pressure at a higher temperature. What does this mean for performance though? When you get on the gas, the boosted air will have to expand the tube before it can enter your engine. The less the tube expands, the easier it is to hit boost targets, and the better throttle response you have, especially down low in the RPM range.

The CS Boost Tube also is a larger inside diameter than your OEM tube. It is 3” through the middle vs. the OEM ~2.44”. Since this area of the charge piping system is directly ahead of the throttle body, this large volume of air has the same effect as it does with our GEN2 Mazdaspeed3 FMIC kit, reducing boost lag and increasing throttle response. For full info on why this happens, check out the release blog for that kit here. As a basic overview, the large volume of air right before the throttle body fools the engine into thinking it has a larger intake manifold plenum than it really does. While not as severe of an effect with just changing this boost tube, try it for yourself and see what you think!

Installing the boost tube is a little tricky due to where it is located, but we include high quality installation instructions to make it easier. Even so, it can be installed in an hour or less in most cases. We also include polished stainless steel T-bolt clamps to ensure a complete seal and add a subtle visual boost.

Be sure to check out the product listing for more pictures, the install instructions, and a detailed product video. Let us know if you have any questions, we’ll be sure to help you any way we can!
Lastly, if any of you are looking for a more serious upgrade, stay patient, our FMIC upgrade & full piping upgrade kit are coming soon!

MZR DISI Injector Seals – The Correct Seal for YOUR Speed

Many years ago we helped bring a revolutionary design to the Mazdaspeed community.  Fast forward 4+ years and you’ll find that the CorkSport Tokay Injector Seals are still the best option for your Mazdaspeed.  

Recently, we had a customer ship their stock block engine core to us for a fresh Dankai 2 Built Block.  During the engine core tear-down and inspection, we found a set of CorkSport Injector Seals installed.  We realized this was a great opportunity to share what we found with the community.

When the CorkSport Injector Seals arrive at your door they look like this:

Brand new a fresh of the lathe with all of their beryllium copper brilliance.  After many thousands of miles of use and abuse they look like this:

Now to the untrained eye you may think they look bad, but the truth is they look fantastic!  The visible top of the seal has a small amount of carbon deposits present. This is to be expected because this surface is exposed to the combustion chamber.  Moving to the side of the seal you can see a distinct clean edge and no carbon deposits on the sides of the seal. This distinct clean edge is where the exterior of the seal is designed to seal in the cylinder head.  This is awesome!

Now let’s look at the inside of the used seals:

Again we see carbon deposits, but they are in and only in the expected locations.  Moving up the side of the seal you can see a “shelf” or “step” that is clean. This is the edge that the fuel injector seals against. Beyond that the inside of the seal is clean.

From this inspection we can see that the injector seal was functioning as designed and doing its job effectively.  

So you might be asking…”What is so special about this design?” Well, we wrote a two-part design blog answering that exactly.  We highly suggest spending the 10 minutes to read these.

Injector Seals Design Part 1

Injector Seals Design Part 2

This is exactly why every single CorkSport Dankai Built Long Block includes a set of CS Injector Seals, but if you’re not looking for a built block but still want the assurance of the CS Seals you can check them out right here.  The install of the seal can be a bit tricky sometimes, especially getting dirty injectors out of the cylinder head.  Because of that we’ve developed an injector puller tool that makes the job MUCH easier.  

We hope you enjoyed this quick tech inspection of the injector seals!  Thanks for tuning in with CorkSport Mazda Performance.

-Barett @ CS

Performance Exhaust for the 2018+ Mazda6 2.5T

Mazda did a great job bringing a turbocharged engine back to the Mazda 6 (Mazda 3 next please?), but may have done too good of a job of keeping it quiet. Say hello to the CorkSport 80mm Cat Back Exhaust for 2018+ Mazda6 equipped with the turbocharged 2.5L engine. If you’re interested in waking up your SkyActiv-T in both excitement and power, read on as we breakdown the newest CS exhaust.

As with all CorkSport exhausts, the goal of the MZ6 2.5T exhaust is to improve power and sound by improving the flow of the OEM exhaust. We started by increasing the size of the piping from 60mm to 80mm. That is an increase of over three-quarters of an inch to really help your turbocharger breathe better. In addition, the CS exhaust system eliminates the crushed areas present in the OEM exhaust and replaces the restrictive muffler sections with pass-through resonators. These resonators control volume and drone without affecting power output.

All that extra flow does mean a power increase. In our in-house dyno testing, we saw an increase in 5-6WHP just by bolting on the CorkSport  Cat Back Exhaust. Check out the dyno sheet down below to see. This increase came with no tuning changes, no check engine lights, and the only other mod being the CorkSport Short Ram Intake, which was installed for both tests. With the 80mm piping size, this exhaust is ready to support future modifications and would likely show more power gains with proper tuning.

The CorkSport MZ6T exhaust is more than just function. We went through multiple iterations and designs to ensure the best sounding exhaust for your 6. The finished product ups the volume without being annoying to daily drive yet still sounds great when in hard acceleration. We strongly recommend you watch the video below to hear what to expect from this exhaust.

To give a great looking, long-lasting finish to each exhaust, they are manufactured from fully polished 304 stainless steel. To ensure a high quality fitment, all components are precision TIG welded together on jigs made from OEM exhaust components. Lastly as a finishing touch, we use 100mm dual wall exhaust tips. They fill out the bumper cutouts and are extended slightly to give a classy look and enhance the new Mazda 6’s styling.

The CS Mazda 6 Turbo Exhaust comes with all the hardware and gaskets you need for installation, high quality instructions, and CorkSport support for any questions you may have. Pick up a CorkSport MZ6 2.5T Exhaust today and liven up that daily commute.

2018+ Mazda 6 2.5T OEM Intercooler & Piping Analysis

We’ve already mentioned briefly that we have an upgraded intercooler kit in the works for the SkyActiv 2.5T, but now it’s officially time to dive in and get into how and why an upgraded intercooler kit is a good fit for your 6. To understand how to make a performance part, we first have to understand what makes the stock parts tick and where we can improve them, which is what we will be covering today!

For those of you that are new to the boosted lifestyle, I feel that I should go over a few terms that will be thrown around frequently later in this blog.

  • Hot Side Piping: Also known as just “hot side” or “hot pipes” this piping section carries the pressurized air (boost!) from the turbocharger to the intercooler. As it is before the intercooler, the air has not been cooled and the “hot” name is quite accurate (think 200-250°F. or even more on a turbo that’s too small). Shown above on the right side.

  • Intercooler: A basic heat exchanger. Air flows through the inside and is cooled by air flowing through the outside while you drive down the road. The same way a radiator works except with air inside instead of coolant. It is made up of three parts the “end tanks” and the “core”. The end tanks are what transfer the air from the piping to the core while the core is the actual heat exchanging portion. Shown front and center in the above image.

  • Cold Side Piping: Also known as just “cold side” or “cold pipes” this piping section carries the pressurized air from the intercooler to the engine. As it is after the intercooler, the air has been cooled to make more power. Shown above on the left side.

 

Now into the details…

The hot side piping must make its way all the way from the rear of the engine to the front of the car. The OEM piping takes a pretty direct route, and is a decent diameter for stock piping, starting & finishing at just under 2” inner diameter. This, however, is where the good things end.

To start, the two rubber sections of the hot side are single ply. These allow for good flexibility on install and to allow for engine movement but will start to expand on higher than stock boost levels, increasing boost lag and decreasing throttle response. In the image above, the main rubber section squishes under the small weight of the upper plastic section of the hot pipe. This isn’t even the main issue with the hot side piping!

The upper plastic section of the hot side has quite a few small radius bends, and a few areas where the pipe reduces in diameter severely, affecting the maximum flow and restricting the power of your 2.5T. Check out the worst area below, it’s tiny!

And what might be causing this reduction in diameter you may ask?

That’s right, its clearance for a hose clamp. Mazda, I’ve got to call you out on this one, couldn’t you have just rotated the clamp, and kept the diameter in the pipe? Anyways, on to the intercooler itself.

The intercooler itself isn’t too bad, a decent sized core with lots of fins to help cool as good as it can. That being said, there’s still plenty of room for improvements. First: make it bigger. The intercooler mounting could’ve been simplified to get more width, and there’s a bunch of room to go thicker. While thick is not the best for heat transfer efficiency, it will still help cool off the air better. Height is already more or less maxed out without cutting up the crash beam, but we should be able to make enough extra volume elsewhere to make a big difference.

Intercoolers are a delicate balancing act between cooling efficiency and pressure drop. Cores that cool extremely well usually have a larger pressure drop (loss of pressure from inlet to outlet) and vice versa. With the high fin density of the OEM intercooler, we can expect a relatively high-pressure drop (2-4psi would be my rough guess) but pretty good cooling. From early dyno testing on the CorkSport Short Ram Intake, the intercooler does a good job cooling but loses power on back to back dyno runs. I expect that this is the intercooler “heat soaking”. Heatsoak is what happens when an intercooler is undersized or is not getting enough airflow, it heats up and is no longer able to cool the boost off, robbing you of power.

The two images above show the real Achilles heel of the OEM intercooler and what is likely causing the heatsoak issues: the end tank design. Since the charge air enters and exits the core at an upward angle, it’s being directed away from the lower runners of the core. There is a sharp angle that would be hard for the air to turn, meaning the bottom three internal runners (shown with the red box) are likely not actually doing much. So you’ve got intercooler taking up space that is likely not doing much… We aim to fix this.

The cold side of the system is actually pretty good-inner diameter of just under 2.25” on the ends (even larger in the middle) and a short path into the throttle body. We’ve already covered the basics of it when discussing the upcoming CorkSport boost tube HERE. Like with the hot side, the rubber connector is prone to expansion under increased boost levels. While the CorkSport silicone boost tube will still be coming on its own, we plan to offer something even stiffer that is optimized for our upgraded FMIC kit.

Much more information to come in following blogs as we’ve been busy working away on this project. Stay tuned for full details on the upcoming CorkSport FMIC kit, and if you’ve got any questions, leave them down below.

-Daniel @ CorkSport