Mazda CX‌-30 Forum banner
21 - 26 of 26 Posts

·
Registered
2020 CX-30 GT Polymetal Gray
Joined
·
73 Posts
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.
Well I thought it odd they told me it was stroked but not bored. But still could be the same block casting, especially if it was designed that way. Manufacturers do this all the time. Obviously heads would need to be different as well as the crank for the longer stroke, but it would be interesting to know if other parts are interchangeable.
 

·
Registered
2020 Mazda 3 Premium Hatch polymetal gray over red/blk
Joined
·
245 Posts
Well I thought it odd they told me it was stroked but not bored. But still could be the same block casting, especially if it was designed that way. Manufacturers do this all the time. Obviously heads would need to be different as well as the crank for the longer stroke, but it would be interesting to know if other parts are interchangeable.
Yes, but in this case, in the interest of making the block casting for the 2 liter as light as possible Mazda gave it it's own casting. By merely taking the 2.5 and destroking, deboring no weight savings of any significance would be realized. This is not like the old chevy small block that came in any number of displacements but all weighted about the same when cast in iron. Sky g, like most modern engines , come with wet liners made as thin as possible to be as light as possible, not suitable for anything but a delicate overbore. Happily, due to advancements in metallurgy and lubrication they are not so likely to need one.

Sorry to repeat myself but the 2 liter is roughly 100 lbs lighter and this could not be achieved using the same block.

Wish I could give you a source on all this, but It was something I read in a technical discussion in Car and Driver back many years when the sky g was first introduced.
 

·
Registered
2020 CX-30 GT Polymetal Gray
Joined
·
73 Posts
Ok I believe you:)

For the sake of argument, since there are cast iron sleeves the weight saving in the 2 l would be marginal by boring out for the 2.5 l. Stroking typically means a modified crank as it’s a cheap way to get more displacement (within limits of course).

I know that the pre- Skyactiv-G 2 l was bored and stroked for the 2.2 and the 2.5 and maybe the dealer thought that it was the same.
 

·
Registered
2020 Mazda 3 Premium Hatch polymetal gray over red/blk
Joined
·
245 Posts
Ok I believe you:)

For the sake of argument, since there are cast iron sleeves the weight saving in the 2 l would be marginal by boring out for the 2.5 l. Stroking typically means a modified crank as it’s a cheap way to get more displacement (within limits of course).

I know that the pre- Skyactiv-G 2 l was bored and stroked for the 2.2 and the 2.5 and maybe the dealer thought that it was the same.
I could be wrong on the this last point, but with the 2.5 being a scaled up 2.0, I think they do not have common bore centers which negates a lot of possibilities for parts interchangeability, the crank being the most obvious but also heads, induction, and exhaust pieces.
 

·
Registered
'21 Turbo Premium Plus (On Order)
Joined
·
93 Posts
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.
Would something like a 50-50 BPV/BOV help mitigate the tendency to run lean, i.e. venting some of the air (that the MAF "thinks" is there) to atmosphere, resulting in a richer mixture?
 

·
Registered
Joined
·
1 Posts
At 17 psi turbo boost your engine should last a really long time..

17 boost is in the mid range for boost
Keep up with your oil changes and use premium gas and you will have a great car for many years... the cx-30 turbo is the perfect sleeper car and I look forward to driving it every daybof my life.
 
21 - 26 of 26 Posts
Top