Trying to find if there is a difference in these 2 cranks??

[festivaWES]

The b6ZE(RS) 89-93 maxda miata 1.6 dohc 16 valve

The b6-E 86-89 mazda 323 1.6 sohc 8 valve

I know the bore and stroke are the same 78x83.6mm some I'm assuming i can use the pistons without a problem, want to try to hit 10.5:1 compression. But the big question is the crank....the miata crank is the lightest out there of that year with the flywheel to produce a 7200 RPM redline. I'm hoping they're are the same because I'm gonna start looking for one.

[DuritzCrows17]

hmm thats hard to answer without seeing both of them together, usually I would tell you to search rock auto and see if the parts have the same numbers but they don't carry cranks so I wouldn't know where to start besides getting them both or posting on a couple miata forums. Good luck, I am also interested to know now.

[elcamino1]

Why don't you have your crank and flywheel lightened.
Also have your head milled,and use a thinner head gasket.

[festivaWES]

Because I'd rather stick to parts that are made to fit with the specifications i need rather than to modify parts and pay double the costs in labor.

[Santos]

i thought the dohc cranks where forged to cope with the higher redlines and hence heavier

[festivaWES]

I think that's a myth because some of the sohc mazda motors have forged cranks

[Santos]

some sohc may have forged cranks but i be willing bet you the cars that they came out of had higher than 6000rpm on their tacho's not i can only go off the Oz delivered engines
(on a side note b3 cranks have the same stroke as b6, are they lighter?)

[DuritzCrows17]

some sohc may have forged cranks but i be willing bet you the cars that they came out of had higher than 6000rpm on their tacho's not i can only go off the Oz delivered engines
(on a side note b3 cranks have the same stroke as b6, are they lighter?)

hm, thats an interesting question, I am curious aswell.

[FB71]

not sure, but they have a smaller rod journal, so they're not as strong.

[festivaWES]

some sohc may have forged cranks but i be willing bet you the cars that they came out of had higher than 6000rpm on their tacho's not i can only go off the Oz delivered engines
(on a side note b3 cranks have the same stroke as b6, are they lighter?)

hm, thats an interesting question, I am curious aswell.

I guess we'll find out this weekend then!

[FestYboy]

ALL B3 cranks are forged, and as the B3 and B6 have the same crank, the B6 variants are also forged. the rod journals are the same between the B3 and B6, but the CRANK journal changed in the third? generation of the B6 cranks due to the snouts breaking. the years of the B3 and sohc B6s have interchangeable cranks. There IS a differance in weight due to the heavier pistons in the sohc B6 (larger bore), but it's for ballancing (NVH). you CAN'T use a Miata crank without having the block's crank journals line bored or having the crank's journals ground down. you'll also want the assembly professionally ballanced once you have the combo you want.

[FB71]

1.3L connecting rod jounal diameter = 40mm

1.6L connecting rod journal diameter = 45mm

[FestYboy]

ok, sorry there Jim. But the cranks for both ARE forged and the crank and rod journals CAN be turned down to fit the B3 forged rods.

[FB71]

agreed!