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Skyactiv G 2.5L NA to Forced Induction Discussion

10K views 96 replies 14 participants last post by  Cdn17Sport6MT 
#1 ·
Has anyone ever done a Skyactiv G 2.5L Naturally Aspirated to Turbo Conversion? I've seen so many people make videos about the ridiculously expensive supercharger from VT Racing but haven't seen anyone use a turbo from something like the 2018 Turbo model and retrofit it to a different car. From what I've seen the engine head and everything is identical except for the turbo/intake/other turbo related parts and coolers. It's making me doubt myself if it's even possible. Am I just not good at reading and finding someone else who did it, and any experts here to assist if I was the first to try, especially with the ECU/Electonic part of things? This engine is built really well and I believe it definitely deserves a turbo to show what it can actually do.
 
#6 ·
Oh, that's really interesting, honestly, I wouldn't mind getting new pistons and rods but it's definitely worth adding to my cost estimate. That's why I came here to ask you guys. :)
As long as the price remains reasonable accounting for the additional fuel economy on highways, that I mainly use to travel to work, it would be worth it. I know the Turbo version has a lower mpg rating but I am confident with a tune I can get a few more mpgs. My main reason for this is the performance gain but the mpg benefit would help with the cost in the long run. Ex. If the project costs $5000, and I save $1000 in fuel over 5 years, then I consider that $4000.

Your search skills suck then, cause Corksport (no, i do NOT recommend them) released their package. But since they do NOT give any details on the tuning aspect of it, i will remain HIGHLY doubtful of it, period.
Can you link it, I couldn't find one, for sale at least?
The cylinder head is different on the turbo by Mazda. Quite a lot of engineering apparently went into that (Mazda) conversion, resulting in what appears to be a pretty-reasonably durable turbo engine which was tailored to a heavier car, and which focuses on bottom-end and midrange power. That also makes it a bit less suitable, by way of drive characteristic, for a manual transmission. The latter somewhat favour mid- to top end oriented engines/turbo's.
I might swap the head too if it requires it, but if it fits on the current head with minimal modification then I might keep the current one. I am guessing the modifications allowed for more performance/durability but I am aiming for economy/performance. I am not keeping the car more than 120k miles, its at 66k currently.

Also as a clear note for everyone, I'm not saying that I'll do it yet, I'm here to get help estimating the cost and work/parts to put in the car. If everything seems okay cost and work wise at the end then I likely will go ahead with the project. My original idea was to modify the intake to have an exhaust attached in series but unfortunately its plastic, which I cannot weld lol. If my current idea proves to be too hard/expensive then I might consider looking into making a steel/aluminum cast of the original intake and modify it with a turbo, that is if I can modify the ECU to go easy with it.
 
#4 ·
Your search skills suck then, cause Corksport (no, i do NOT recommend them) released their package. But since they do NOT give any details on the tuning aspect of it, i will remain HIGHLY doubtful of it, period.
 
#5 ·
The cylinder head is different on the turbo by Mazda. Quite a lot of engineering apparently went into that (Mazda) conversion, resulting in what appears to be a pretty-reasonably durable turbo engine which was tailored to a heavier car, and which focuses on bottom-end and midrange power. That also makes it a bit less suitable, by way of drive characteristic, for a manual transmission. The latter somewhat favour mid- to top end oriented engines/turbo's.
 
#13 ·
I don't know man, I can't find it on Corksports page but judging on what I've come across and what @TalonTsi90 has stated, i'd be very weary to go with them. The SC isn't all that bad but with all the modifications and work you are going to do might exceed the price of a bolt on SC. Just my change purse but if you do install it, make sure to post it.
 
#14 ·
I don't know man, I can't find it on Corksports page
Its literally on the New Products page lol. But still way more expensive than the S/C is.
 
#20 ·
The automatic, it has a dual clutch for "manual" mode.
Not to sound like a dick, but this right here tells me you know nothing about how a turbo engine works. The turbo goes on the EXHAUST side, not the INTAKE side.
No worries man I get where you are confused, the turbo uses exhaust power to spin up a turbine that connects to another turbine that forces air in the intake, so you can put it anywhere as long as there is the proper airflow from the exhaust and intake, intakes can usually be easily moved around compared to exhausts which is why turbos are placed on the exhaust side but in certain situations, it can be moved around, and looking at my engine bay it seemed that I'd have to modify both sides to find a place where the turbo can fit. But honestly, it seems like too much trouble compared to a DIY supercharger which is why it seems like I'll ditch the idea and instead have to worry just about finding a suitable supercharger + mounting it.
 
#21 ·
OP, the 6AT transmission is a conventional one with a lockup torque converter; no dual-clutch arrangement there. Regardless, that is not germane to the whole discussion. Incidentally, the torque converter is quite small, and the control methodology encourages early- (and often) clutch lockup.
 
#23 ·
@Lertu let me share my insights:
  • Auto Transmission: the torque converter contains a multi-plate clutch, so it is a hybrid between normal TC and DCT, where the normal TC style operation is only used for rev-matching during shifting (and at really low speeds)
  • Supercharger is really expensive?! Do some research, most complete boost kits are ~$5k, and most Eaton TVS supercharger kits are ~$6k, whereas the VT-Racing kit (using TVS compressor design) is less than $4k, so it's a really good deal for basically adding 2 cylinders (>50% more airflow).
  • Corksport turbo: with a starting price of $5500 + $1200 exhaust to get the power gains they are talking about, plus cannot DIY install, very difficult, initial customers are paying $2-3k for the install. So by the time you're done with the CS turbo I could have supercharged 2 Mazdas :devilish:
  • DIY custom turbo: this will certainly cost more than the supercharger kit, and given how advanced the ECUs in the Skyactivs are, you're going to have a very hard time getting it to work even if you did mechanically cobble together an engine that theoretically can take a turbo better, I don't know how you'd get it to run well and reliably without some serious ECU expertise.
  • Efficiency after boost: any of these options will cost you more in gas, not less. These will all end up burning more fuel to make more power. There is no chance of saving money on fuel. That being said, even with the supercharger I still get 35mpg, and because of the pumping efficiency of the compressor there are some mild throttle conditions where I get better mpg now than NA, but for the most part more power means more fuel.
*Note: the Corksport kit uses a purposefully over-sized turbo, because they were breaking transmissions... So the Corksport kit has no boost until above 3000rpm...
whereas the supercharger has gentle steadily building boost, and much less heat, with 2-3psi of boost even at 1200rpm, so even though the peak number is undoubtedly less than the turbo kit, the amount of power I have in the rest of the RPM range makes it wicked fast on track or daily driving.



and if you're worried about the supercharger performing... don't :)
 
#25 ·
Throwing in my 2 cents - I'd put the supercharger kit above a turbo kit. Money's the same, Dan's already proven it, plus turbo lag and surge-y behavior is no fun.
 
#28 ·
These gas prices have got the uneducated coming up with some really stupid ideas just to save some money. A guy on Reddit wanted to convert his 3 to flex fuel, i had to school him on how much it would cost just to switch it over. Not sure if i got through to him or not.
 
#32 ·
I certainly admire your willingness to try it. That’s an entirely bigger enchilada than I would care to bite into. Why add the turbo? More power? Or a status thing? Or…? You may get deeply into that project and realize that’s more there than you bargained for. Good luck. Whichever way you decide to go on this.
 
#60 ·
Honestly, I want to see how much more mpg I could get, or at least not lose any. In addition to beating my friend's CIVIC SI :ROFLMAO:.
@Lertu let me share my insights:
  • Auto Transmission: the torque converter contains a multi-plate clutch, so it is a hybrid between normal TC and DCT, where the normal TC style operation is only used for rev-matching during shifting (and at really low speeds)
  • Supercharger is really expensive?! Do some research, most complete boost kits are ~$5k, and most Eaton TVS supercharger kits are ~$6k, whereas the VT-Racing kit (using TVS compressor design) is less than $4k, so it's a really good deal for basically adding 2 cylinders (>50% more airflow).
  • Corksport turbo: with a starting price of $5500 + $1200 exhaust to get the power gains they are talking about, plus cannot DIY install, very difficult, initial customers are paying $2-3k for the install. So by the time you're done with the CS turbo I could have supercharged 2 Mazdas :devilish:
  • DIY custom turbo: this will certainly cost more than the supercharger kit, and given how advanced the ECUs in the Skyactivs are, you're going to have a very hard time getting it to work even if you did mechanically cobble together an engine that theoretically can take a turbo better, I don't know how you'd get it to run well and reliably without some serious ECU expertise.
  • Efficiency after boost: any of these options will cost you more in gas, not less. These will all end up burning more fuel to make more power. There is no chance of saving money on fuel. That being said, even with the supercharger I still get 35mpg, and because of the pumping efficiency of the compressor there are some mild throttle conditions where I get better mpg now than NA, but for the most part more power means more fuel.
*Note: the Corksport kit uses a purposefully over-sized turbo, because they were breaking transmissions... So the Corksport kit has no boost until above 3000rpm...
whereas the supercharger has gentle steadily building boost, and much less heat, with 2-3psi of boost even at 1200rpm, so even though the peak number is undoubtedly less than the turbo kit, the amount of power I have in the rest of the RPM range makes it wicked fast on track or daily driving.



and if you're worried about the supercharger performing... don't :)
Very great comments and I've certainly looked into it a lot, I've completely switched courses from planning a turbo to planning a supercharger, it would be a shame to not use those forged rods to their full potential, as for cost, I'm only worried about parts cost since I consider myself well experienced and equipped to install parts. For the cost of the VT Racing turbo I'd manage to LS Swap my car which in my opinion is too high of a cost for what I'm looking for.

I've also read up a lot more about the engine and tranny, so I'm glad to report I don't think it's a dual clutch anymore XD

Now the latest thing I've been trying to figure out is how I could install something like a Paxton VR-70-86A or a similar supercharger, space is my biggest headache right now due to the engine mount and AC piping interfering around the belt. A supercharger is definitely the way to go but I'm trying to figure out how I could do it with minimal cost and modification. So far if I don't figure out a way to fit in with the stock intake, I might consider replacing the manifold with a custom one I fab that could incorporate the supercharger better. As a side thought, I am also considering running a rod as a pulley extension connected to the belt above the intake which can transmit the rotation to the left and place the supercharger in place of the airbox, but it does seem like a very unstable and stupid idea, who knows.

Heres an example I found on google
Vehicle Car Hood Motor vehicle Automotive design
 
#34 ·
This is the wrong group to try and say that to, i mean, cause, youre already proven wrong.
 
#38 ·
CorkSport, with their turbo's apparently kept losing 6MT's with their turbo development...
Again, cause they dont know what the hell they are doing :)
 
#59 ·
The shocking thing is that many of these advancements are not unique to SA-D. Toyota's Direct Shift-8AT and -10AT both have multiplate lockup clutches, and I recently read that there is a company that specializes in converting several GM, Ford, and Chrysler transmissions from single plate to multiplate. Interesting times.
 
#67 ·
Wow, nothing like waiting 5 years to make your first post. How are you tuning it? Full ME?
 
#79 ·
Thanks, that’s partly why I went larger turbo as well. Keep the torque low down in the rpm, and power up top. It won’t spool until around 3k anyway lol. I may make a separate thread later on. Thanks for the suggestion! The intercooler was rated for 500, the turbo a bit over 600. I won’t run more than 300-350 whp for a while. 8 psi on the gate, if I ever choose to go up, I have already a manual boost controller on the car. More info to come soon!
 
#80 ·
Thanks, that’s partly why I went larger turbo as well. Keep the torque low down in the rpm, and power up top. It won’t spool until around 3k anyway lol. I may make a separate thread later on. Thanks for the suggestion! The intercooler was rated for 500, the turbo a bit over 600. I won’t run more than 300-350 whp for a while. 8 psi on the gate, if I ever choose to go up, I have already a manual boost controller on the car. More info to come soon!
I'm not sure I understand what you mean here. A larger turbo will not spool until later, meaning you get neither torque nor power at low rpm. Unless I'm not correctly reading what you're saying.
 
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#81 ·
I'm not sure I understand either... Seems to me it is torque which can break things in a transmission, not so much HP... HP, I suppose, could generate heat that maybe has to be dealt with (in the lubricant of the manual transaxle and maybe more so the automatic)... but I think we're talking about the (relatively weak) manual.

So, keeping the turbo from generating much torque at lower revs, I'm not sure how that eases the forces on the transaxle, if it then makes torque at higher revs?
 
#82 ·
I'm sure there's probably some physics to it, but the biggest impact, in the way I understand it atleast, is that you rarely go above 3000rpm in normal day to day driving, unless you're intentionally trying to go fast, therefore only getting the high torque when you want it and reducing unnecessary load. Which is why there isn't any gains in mpg usually, unless you're racing lol.
 
#83 ·
Your understanding of the physics is equating to "delaying the inevitable". Nothing wrong with that, but consider this: When the boost suddenly appears it will suddenly bring all that torque through the clutch and then into the transmission. The same torque that will damage it at less than 3000 will damage it at 3000 and beyond. What I have heard said over the years is that when you have a delicate manual transmission you don't install a steel or multiplate clutch. Instead, you install a clutch with just a slight bit more bite than stock. In this way it can transfer a bit more torque than OEM, but should things go bad, the clutch acts as a fuse and will burn out before transferring too much torque to the box. Replacing a clutch is far cheaper than replacing a transmission. Plus, the driveability of a smaller turbo is often times far more advantageous than a snappy, laggy big turbo. Remember, power corrupts, and absolute power corrupts absolutely. Just my $0.02 there, though.
 
#90 ·
This is the article I grabbed my information from. If it’s correct, we have a forged steel crank, forged aluminum rods, and non-forged aluminum piston heads with molybdenum steel cylinder walls.
 
#92 ·
Here’s one site that sells forged aluminum rods. BME Forged Aluminum Rods

I also did reread that paragraph from the article and you are correct in stating that the article did not specify the material for the connecting rods. That information is up in the air, regardless, however, steel is stronger than aluminum, and if they were to be forged steel, rather than forged aluminum, we would have less worries regarding the engine itself then.
 
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