Mazda’s Dynamic Pressure Turbo – An Introduction

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!

-Daniel

3 Turbos and a Supercharger for Mazda

A year ago we were all complaining at Mazda saying “where is the forced induction?” and it looks like Mazda was listening.

First up is the Mazda 6 turbo which Mazda has priced to sell as you can get into a GT Mazda 6 turbo pretty affordably.  Granted there is no manual gearbox but I can say first hand they are fun to drive and the torque from the boost is really addictive.  I find it hard to not want to screw with people in the 6 since it has no visible exterior queues that it has a turbo. I will say we have already been tweaking on the car and found that it does respond well to modifications.

Second up is the SkyactivX which Mazda says will be available later this year.  This engine is supercharged to allow it to be an HCCI engine, aka compression gas motor.  The forced induction setup is pretty tricky and the initial look I have done with it I get we can crank it up a bit more to improve the efficiency of the intercooler to give it more heat capacity to allow you to use the boost longer in the car for high performance driving.  Until it shows up we won’t know for sure but we are looking forward to trying it out.

Third is the Mazda 6 diesel which uses 2 turbos.  Mazda tried to release the 6 in the past but when they couldn’t match what VW was doing they declined to just “Send It” as the car didn’t perform as they needed it to and still hit the emissions targets without urea injection.  Later we all found out VW was a cheating bastard which kept us from having the Skyactiv diesel engine here to crank up the boost on. About every publication in the planet has posted up about the 2018 Mazda 6 diesel being seen in the EPA parking lot for testing along with a pile of other diesel models.  This is a good sign if Mazda says it will pass the US emissions and handed one over to the EPA we can expect it and soon.

I am going out on a limb here and saying that besides the announced Mazda 3 Skyactiv we are going to get something fun in the new Mazda 3 ~ a year after the initial release.  If you are reading this Mazda, please give us a Mazda 3 GT with a turbo motor.

-Derrick

Why no AWD?

Mazda has recently said they would like to have AWD in most models, but the current generation has some space/packaging constraints. I was scratching my head over this statement trying to figure out why the existing model Mazda 6 is offered in AWD in Europe with the Skyactiv diesel engine and Mazda is saying they cannot get it to fit.

I think I may have stumbled onto the answer after having a conversation with a friend recently. It is no secret Mazda is working on offering the diesel Cx5 to the US market, but it has been held up in government regulations with the EPA courtesy of VW and FIAT cheating on their engine mapping and emissions. Mazda has the setup which will pass and get the power they want to offer but here lies the problem.

Say you were going to offer a Mazda 6 diesel model that now meets the US emissions with the urea injection. Where are you going to put the tank to hold in the car? In the Cx5, which has more space to put something like a urea tank, it is not as much of a problem with packaging to find a spot. The Mazda 6 doesn’t sit off the ground as high and allow you a space to get everything to work out and be able to still fit the transfer case, drive shaft, and rear differential.

Why doesn’t Mazda offer both? This is a question I wish I could sort out. It wouldn’t be the first time Mazda would have models with different floor plans. Mazda has done this in the past with the 323s and Protégé, so I don’t think this is the reason why. This could be a possible play on the overall strategy with North America and only offer the AWD as a diesel model. This goes against what we have already with the Cx5 2.5 gas engine and the Cx9 gas 2.5 turbo motor, so I don’t think this is it which leaves this question for me to puzzle over a bit longer.

With the announcement of the Mazda/Toyota plant in Alabama and the statement by the chief of Mazda saying Mazda is going to build something different, this could be the queue that they will find a way to give us AWD turbo fun again. If anything the announcement of the new plant will finally get the EPA to give the green light to the Skyactiv diesel engine.

Overall Mazda desire to give us AWD still has me hopeful for the 2.5 Skyactiv gas turbo with all-wheel drive, but all the current signs say nope. Please Mazda, I don’t mind being wrong on this one.

-Derrick