I don't see why not but, unless you get a good deal on some one elses old stock units it is a better investment to buy aftermarket and bulletproof your bottom end more a simple piston and rod assembly from a good manufacturer will be more than enough for any amount of boost which is the only reason one would swap out internals from a mazdaspeed3 because the speeed3 has a turbo and installing those internals on a non turbo engine would make you lose power it all depends I have not seen many stock mazdaspeed3 engine parts floating around good luck
this is the response I got on the forum where im supposed to be buying the parts.
My sentence : dont know where you got your info from. But the 2.3 MZR motor and the 2.3 DISI MZR motor do in fact have the same exact bore and stroke.
The Response: the bore size where the rods meet the crank is not the same, nor is the bore size. not talking about the cylinder bore and rod stroke. i am talking about the line bore. think about it - if the cylinder bore and rod stroke is the same but the part numbers for the block and crank are not the same, there are other differences which prevent from being to swap cranks. another way to know the cranks will not simply interchange is looking at rods for either N/A or turbo car and comparing them. the bore size of where the rod mates to the crank is not the same between the two rods. the length of the rod is not the same between the two. the parts are not interchangeable.
The Next Response: The internals from the two motors are not compatible at all.
The mazdaspeed crank is much larger. You might be able to Line bore the regular block enough to bolt the mazdaspeed crank in, but that is assuming the main bearings are in the same place along with the balance shafts and all that crap. To me its worthless to find out since the chances you are going to break a steel crank and any power level these cars will make is 0.
Also mazda does not use cast iron cranks. Every crank they have is steel.
i don't know what those guys on that forum are talking about the MS3 has the same Bore and stroke as a regular N/A mazda3 it is the same basic internals just an added turbo and ignition and fuel but mechanically they are the same and if a ranger crank can fit in our cars then a ms3 crank and rods and such should be the same deal. and they don't know crap because the bore is the same all the way down the cylinder it doesn't change when it meets the crank just buy the parts and prove them wrong the people to trust on this stuff is the people on this forum because most of us know a lot about cars.
well they thought that they could throw a mz3 cosworth billet crankshaft in their cars so they called cosworth and was told that the focus crank would not work in their cars.
the only reason that i myself can think that would make that not work is the size of the bore on the rods themselves is larger therefore if you wanted to use a focus crank you would need focus internals and in my situation if i wanted to use a mazdaspeed 3 crank i would need to use mazdaspeed 3 internals.
[quote author=Verto link=topic=138680.msg2994335#msg2994335 date=1237061895]
LOL cosworth told them that? the cosworth crank will so fit... it's a standard duratec block... if the parts work in a focus they work in the mz3... they must be nub.
they = MS3 owners not MZ3
so cosworth said that the billet focus crank will not work in the MS3 block.
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