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

2018 Mazda 6 Performance Parts – Cold Side Boost Tube

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