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Very little is shared between the 2.5t and NA engines, cylinder head is a very different casting, valves and cams are different, different valve springs and exhaust rocker, some timing components are the same like the actuators and timing chain/guides. Cylinder block is a different casting, crankshaft is stronger, rods are quite a bit thicker and stronger, pistons are a different design to handle boost, lower compression and run a bigger wrist pin.
was hoping you would comment. thanks
Great, thanks. What do you think is the weakest link in these motors when making more power, aside from the turbo itself? Based on the issues Mazda has had, I'm inclined to say the heads or the head gaskets, but maybe you have a different take.
The cylinder head issue is a casting flaw vs an issue that will arise with more power. The bottom end is pretty stout and it has to be to be able to get the amount of torque we do at low rpm while lugging around something like a fully loaded CX-9 reliably. For a factory turbocharged engine the cams are pretty good and there is headroom there before that becomes an issue. Honestly the turbo and tuning software currently available are the biggest hinderance to making a fair amount more power. Mazdaedit is lacking some key tables that would make life much easier in that aspect. VFtuner keeps teasing Skyactiv support for the 2.5t and TCM control, both of those items will really help. Bigger turbos are in the works and that will help substantially as our turbo is just too small to keep moving enough air higher in the RPM range.
I would like to know as well. Maybe watch some teardown videos and see what can be gleaned.
Yep, all Skyactiv rods are forged, with the exception of some of the 1.5 versions the crankshafts are also forged, all of the pistons are cast for the gas engines but are a very high quality piece.
I feel better from a durability standpoint. The narrower the cylinder, the worse cylinder wash gets as there is less room for the fuel to spread out from the fuel injector (in direct-injected engines). This causes more fuel dilution of the oil and a more uneven distribution of cylinder heat and pressure, both of which increase the risk of low-speed preignition.
