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Discussion Starter · #1 ·
Does anyone know the technical specs of the Turbo in my new CX-30? Who makes it? What other models & makes use it? What's the boost?
 

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I'm not sure on the manufacturer of the turbo, but the whole system appears to have been done in house, custom, for the whole Mazda turbo lineup since 2018.

There's quite a few resources floating around that I've seen, here's an article on the system when it was first coming out.

There's a few other deep dives, but the general idea is that the intercooler, turbo, and the header all work together for a unique drive.

"A key enabling technology is its highly innovative, industry-first Dynamic Pressure Turbocharger.

Murotani says most variable turbochargers adjust the speed or direction of exhaust gas flowing into the turbine, but the Dynamic Pressure Turbo controls the degree of exhaust pulsation depending on engine speed.

By closing a valve located just before the turbocharger’s turbine and reducing the volume of the exhaust ports, the system reduces interference between exhaust pulses as they exit the cylinder ports. This maximizes the energy of each exhaust gas pulse, causing the turbine to spin faster at low rpms. Engineers liken the closing of the valve at low rpms to holding a thumb over the end of a water hose to increase the spray’s velocity and intensity."

“The increased pressure causes the turbo to spool up quickly even under light throttle, giving the smallish engine a boatload of low-end torque that makes the 4,000-lb.-plus (1,814-kg) vehicle responsive and as fun to drive as a mainstream CUV with three rows of seats can be,” writes WardsAuto Editor Drew Winter.
 

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Discussion Starter · #3 ·
I'm not sure on the manufacturer of the turbo, but the whole system appears to have been done in house, custom, for the whole Mazda turbo lineup since 2018.

There's quite a few resources floating around that I've seen, here's an article on the system when it was first coming out.

There's a few other deep dives, but the general idea is that the intercooler, turbo, and the header all work together for a unique drive.

"A key enabling technology is its highly innovative, industry-first Dynamic Pressure Turbocharger.

Murotani says most variable turbochargers adjust the speed or direction of exhaust gas flowing into the turbine, but the Dynamic Pressure Turbo controls the degree of exhaust pulsation depending on engine speed.

By closing a valve located just before the turbocharger’s turbine and reducing the volume of the exhaust ports, the system reduces interference between exhaust pulses as they exit the cylinder ports. This maximizes the energy of each exhaust gas pulse, causing the turbine to spin faster at low rpms. Engineers liken the closing of the valve at low rpms to holding a thumb over the end of a water hose to increase the spray’s velocity and intensity."

“The increased pressure causes the turbo to spool up quickly even under light throttle, giving the smallish engine a boatload of low-end torque that makes the 4,000-lb.-plus (1,814-kg) vehicle responsive and as fun to drive as a mainstream CUV with three rows of seats can be,” writes WardsAuto Editor Drew Winter.
This Dynamic Pressure concept is a good thing. I have noted that compared to my past turbo VWs & Audis, turbo lag is essentially missing with my CX-30.
 

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The actual manufacturing of the turbine is likely outsourced(?), but the design is in-house; it's a custom OEM product unique to the PY-VPTS engine and not found in any other make. Maximum boost pressure in factory configuration is said to be 17.4 psi.
 

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The actual manufacturing of the turbine is likely outsourced(?), but the design is in-house; it's a custom OEM product unique to the PY-VPTS engine and not found in any other make. Maximum boost pressure in factory configuration is said to be 17.4 psi.
When you say stock configuration at a max of 17.4 psi of boost, do you mean max physical capability of the engine and powertrain or max as dictated by the OEM ECU tuning?
 

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There is something that every owner of small displacement turbo-charged engines should be aware of, it's called LSPI in GM speak and is described in this Mobile1 page. (This is not an add for Mobile1 they just happened to show up high on a Google search, you can find this information via multiple sources) Low-speed pre-ignition engine protection | Mobil™ Another name for this is called Mega-Knock. Understanding this phenomenon is one of the reasons that I got my CX without the turbo especially because if my CX get's used like my last car it will see 400K miles during the next ten years. The power of the turbo's is nice and can be fun but long term they do add additional cost to service and repair on top of the potential risk of severe detonation.
 

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There is something that every owner of small displacement turbo-charged engines should be aware of, it's called LSPI in GM speak and is described in this Mobile1 page. (This is not an add for Mobile1 they just happened to show up high on a Google search, you can find this information via multiple sources) Low-speed pre-ignition engine protection | Mobil™ Another name for this is called Mega-Knock. Understanding this phenomenon is one of the reasons that I got my CX without the turbo especially because if my CX get's used like my last car it will see 400K miles during the next ten years. The power of the turbo's is nice and can be fun but long term they do add additional cost to service and repair on top of the potential risk of severe detonation.
I have heard this about turbos for a long time, but anecdotally, it seems that opinion is starting to change based on the newer technology built to solve the problems of turbos past. Below is an excerpt from a technical release article I linked earlier in the thread:

Knock Problem Solved With Creative Engineering

“We solved the problem of knocking through a combination of the Skyactiv-G high-efficiency combustion and high-pressure cooled EGR,” Murotani says.

Mazda managed to achieve a high 10.5:1 compression ratio while maintaining an optimum 14.7:1 stoichiometric air-fuel ratio (at which all the fuel burns and all the oxygen is used), even on regular gasoline, over a very wide rpm range.

In a first for Mazda – and perhaps for all mass-market turbocharged engines – engineers took a different look at cooled exhaust gas recirculation and used a 4-3-1 pulse-converter manifold design that positions the four exhaust runners closely together so cooler air from one cylinder gets vacuumed up by high-flow hot exhaust gas exiting a different combustion chamber like paint gets sucked up and streamed through the nozzle of an airbrush paint gun.

The four runners unite into three and then into one, where they converge at the turbocharger.

The benefit of this 4-3-1 layout is enough suction (or “scavenging”) to draw residual hot exhaust gases from each combustion chamber, in sequence, resulting in lower temperatures in each cylinder as it prepares for the next combustion cycle.

The lower cylinder temperatures allow the engine to run at the higher compression ratio without requiring lots of enrichment to prevent knocking.


Now of course, this doesn't mean that an NA engine and one with a turbo will age in the same way, or that the turbo will surely last as long (or longer) than the NA. But I don't think we are still in the days where we need to avoid vehicles purely due to their having a turbo.

Also, when you say small displacement turbocharged engines, you have to realize that Mazda's 2.5L sits near the top of that range, and that domestic (and import to a lesser degree) have been pumping out 3/4 cylinder 1.4-2.0 liter turbo engines with pretty much no custom design to alleviate the downsides of the turbo. I may be a Mazda stan, but there's no denying they put a lot more work into interfacing their turbo into their lineup than other manufacturers even a class above (not for long)
 

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When I was making my decision on the engine choice on the CX, reliability was at the top of the list. The turbo engines were out but not widely available to buy. The 2.5L NA ones have been around for some time and the 6-speed transmission was out for at least a decade. So while a turbo charged 250hp seemed fun I ended up going with the more mature setup for a long term reliability aspect of it. Like John, that was the main driver for the decision. I knew that the newer turbos are claimed to be more reliable but nonetheless, there are more parts to maintain.

That said, how long has the turbo setup has been available from Mazda? CX-30 is not the 1st vehicle that they put it in, correct? I think I saw someplace that this engine has been around since at least 2015. It that's the case, all the major and most of the minor bugs have been worked out by now. If Mazda will offer some more premium options like cooled seats on a 2022 turbo, I might consider an upgrade.

At the same time, I know that Mazda was trying to bring a diesel engine here - sold at other parts of the world - but eventually decided against it because of reliability concerns. The closest that they got is to offer CX-5 in Canada for a year or two. I think electric is the future but we aren't quite there yet.
 

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That said, how long has the turbo setup has been available from Mazda? CX-30 is not the 1st vehicle that they put it in, correct? I think I saw someplace that this engine has been around since at least 2015. It that's the case, all the major and most of the minor bugs have been worked out by now. If Mazda will offer some more premium options like cooled seats on a 2022 turbo, I might consider an upgrade.
The SkyActiv G 2.5T has been around since it was first introduced with the 2016 CX-9! So it has been around longer than most realize.
 

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Mazda managed to achieve a high 10.5:1 compression ratio while maintaining an optimum 14.7:1 stoichiometric air-fuel ratio (at which all the fuel burns and all the oxygen is used), even on regular gasoline, over a very wide rpm range.
Any training and information is better than none, that being said we often find that some of things that we have learned in the past and treasure as knowledge gained turn out to not be 100% correct and in some cases myths.

The 14.7:1 A/F ratio being presented as Stoich. is one such piece of information that we have had to move past if we are truly to understand todays technology. 14.65 :1 is the number used in a laboratory for pure gasoline, but we don't run pure gasoline in our cars. In most cases it's "close to" 10% ethanol plus other additives. I won't drag this out too far but even the oxygen content in the atmosphere isn't a fixed percentage so "Stoich." isn't a fixed number, and even if it was it's closer to 13.9~14.1:1 in most cases today.
Also, when you say small displacement turbocharged engines, you have to realize that Mazda's 2.5L sits near the top of that range, and that domestic (and import to a lesser degree) have been pumping out 3/4 cylinder 1.4-2.0 liter turbo engines with pretty much no custom design to alleviate the downsides of the turbo.
The technology has advanced and I am well aware of engines that have had more problems, but the 2.5 is still in the same family of small engines. We have seen 3.0L engines suffer similar failures especially when non O.E. software is employed which as I read one of the responses was hinted at. In order to try to control LSPI O.E. software first tries to avoid the conditions during which it is most likely to occur. This is done by keeping the engine in a lower gear ratio (higher engine rpm) and also being very aggressive at closing the throttle (taking the air away) if the vehicle enters operating conditions where LSPI could be more likely to occur. Other strategies like knock protection mode which use multiple injection events, with the main fuel delivered very late in the compression stroke are used by multiple manufacturers with GDI engines. (Gasoline Direct Injection)

I'll leave the cylinder scavenging and EGR topics for another day. They are way too complicated (dynamic) for this discussion.

One of the most interesting theories about LSPI is the role that the engine oil has to play. Microscopic droplets of engine oil that can be scraped from the cylinder walls and distributed into the combustion chamber are a primary factor in an LSPI event. In order to address the oil's tendency to spontaneously combust, even before the gasoline does is to address both the additive package as well as the base stock of the oil. Additive packages that use calcium (detergent) need to be avoided and the base stock needs to be a true synthetic (Group IV POE or a Group V Ester) which goes hand in hand for why I used the Mobile1 reference. The real challenge for anyone, professional technician or a DIY'er is figuring out just what is in a bottle of oil sitting on a store shelf and if it truly meets the engines requirements or not.
 

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So while a turbo charged 250hp seemed fun I ended up going with the more mature setup for a long term reliability aspect of it. Like John, that was the main driver for the decision. I knew that the newer turbos are claimed to be more reliable but nonetheless, there are more parts to maintain
Totally agree here. The turbo would probably make a difference in about 1% of my normal commute, and it might not even be that much. But the additional wear and tear and maintenance concerns for that ~1% of fun just didn't add up for me.
 

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It was the opposite for me - it wouldn't have been worth upgrading from a 2016 CX-3 to just gain 40hp. The extra space and ground clearance are nice-to-haves, but the compelling "killer app" that made it worth it to upgrade now was the turbo engine. Winning freeway-onramp stoplight drags in a sleeper mini-crossover brings a smile to my face every time. The fun-to-drive factor on my CX-3 was already high; putting all that torque under my right foot just seals the deal for Mazda. Will there be additional maintenance costs? Sure (the spark plug replacement interval is almost halved, for example) but given that this motor has been around for five years in a lot of vehicles and hasn't shown any serious design flaws or failure patterns, it doesn't seem like it's a ticking time bomb under the hood.
 

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Discussion Starter · #14 ·
Potential turbo issues influencing your buy decision? I know this is anecdotal but I drove three turbo autos hard for 22 years (1 VW & 2 Audis) before buying my CX-30 Turbo and I never had any reliability problems in the past. I always used top tier synthetic motor oil changed @ 5K miles. Two of my prior turbos were "Chipped" (ECU reprogrammed). I frequented VW & Audi enthusiast forums for years and only very rarely heard a report of turbo failure - Usually when someone had an ECU re-program that was pushed to maximum boost. My aftermarket ECU re-programming was somewhat mild compared to some offered. From my prior experience, I'm not afraid and also I've come to understand that Mazda's auto engine engineering is way ahead of the rest of the auto industry. Although it may be available, I don't intend to re-program my ECU because the HP & torque output on my Mazda is really great.
 

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Potential turbo issues influencing your buy decision?
It did mine for sure. I had turbo cars prior, granted they were from the late 80s early 90s. Those were finicky on a best day. Modern turbo cars are leaps and bound in comparison. But extra complexity does have its cost. Hence the price difference between na and turbo. Mathematically, there are just more parts to maintain or possibly fail and it wasn't worth it. But that's just me.
I do like that Mazda added the option. Good on them to bring more hp/tq to the CX brand.
 

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Discussion Starter · #16 ·
It did mine for sure. I had turbo cars prior, granted they were from the late 80s early 90s. Those were finicky on a best day. Modern turbo cars are leaps and bound in comparison. But extra complexity does have its cost. Hence the price difference between na and turbo. Mathematically, there are just more parts to maintain or possibly fail and it wasn't worth it. But that's just me.
I do like that Mazda added the option. Good on them to bring more hp/tq to the CX brand.

Yes, finicky on a best day.
My brother had an early Volvo turbo wagon that had it's issues!
 

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Wow I had no idea how amazing the engineering is behind the turbo. I was always curious to why the CX-30 turbo had so much torque at the low end.

Another interesting tidbit I learned from the dealer was that the 2.5 l is a stroked 2.0 liter, basically they are the same engine.

Also for those worried about detonation, I wouldn’t worry. The engine management will never let it happen, as it continually adjusts spark timing and air/fuel mix. Mazda’s do run lean however and are typically on the edge of knock.
 

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Also for those worried about detonation, I wouldn’t worry. The engine management will never let it happen, as it continually adjusts spark timing and air/fuel mix. Mazda’s do run lean however and are typically on the edge of knock.
Here are a few of the finer points on A/F ratios and detonation. ( pinging) During moderate acceleration a GDI can stay close to Stoichiometry, but under a heavy acceleration they will still command a rich mixture, something close to 12:1 or .75 Lambda. "Leaning out" on acceleration where piston damage could occur does not mean lean as in a Lambda >1. It actually means Lambda should be .75 but rises to .85~.95 which is still a rich mixture compared to Stoich but leaner than the engine requires to make good power.

As a fuel mixture leans out above a Lambda of 1, the incomplete combustion that is occurs causes a reduction in an cylinder temperatures so piston damage is less likely to occur.
 

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Another interesting tidbit I learned from the dealer was that the 2.5 l is a stroked 2.0 liter, basically they are the same engine.
Never ever take what a dealer tells you at face value.
Sky g 2 liter bore and stroke 83.5 x 91.2 mm
Sky g 2.5 liter 89 x 100.
The architecture of the 2 motors are nearly identical but everything is scaled up for the 2.5. Block, heads, crank and many primary components are not interchangeable. That is why the 2.5 is about 100 lbs heavier.
 

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Discussion Starter · #20 ·
This thread is getting WAY too technical for me - I just came here to ask what's the best air freshener to hang on my rear view mirror! 🤪
 
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