Hi all, recently purchased a BP-Z3 to swap into my NA6 and I'm trying to plan out what parts I should use for a built turbo motor, (forged rods and pistons and other parts). I've come across the Maruha 85mm crankshaft and was wondering if it's worth the reduction in rotating mass as it's cast as opposed to the mazda forged crank.

I'm gonna be shooting for the ballpark of 350- 400 hp and it would be nice to have a lower rotating mass for a higher redline but is it worth losing the strength of a forged crank. I couldn't find anyone discussing their experience with them on the forum so I'm wondering if anybody has used these in a turbo application

 

For your goals, do you have money to just throw around? Then sure. If you want higher redline, you'll be better off spending your money on valves, and springs. From my understanding the crank won't help much if at all with a higher 'reasonable' boosted redline. If you're leaning on replacing the flawless forged crank, consider the 87mm over the 85. More bang for your buck.

Look up TheCarPassionChannel on YouTube. He's currently running the 87mm stroker.

 

Thank you for you reply, I believe that having a larger displacement will make it harder to pass emissions where I live (Australia) as I have to get the car engineered and mod plated once I complete the build. Perhaps it will just be a better idea to stick with the OE crank getting it worked over at a machine shop

 

No way I'd swap a forged crank for a cast crank on a turbo build high reving motor.

 

I agree with Pat.