gtr to miata head conversion ?

[bpt-4w]

k guys i have come for advice from the horses mouth so to speak so hear goes, , is the late model 323 (before going to 2ltrs) the same motor as the mx5/miata motor , if it is the only diffrence would be that the head has hydralic lifters in the 323 and solids in the miata , if this is the case i'm swapping my ported and polished gtr head for a mx5 head , with a 323 manifold.

[BigMal]

Cant swap the manifolds over to the BP-4W head the ports dont match on either side. All I know
about this I got from the solomiata site I told you on fordlaser. I think a call to Justjap or
someone like that and pretend you have a early 1.8 mx-5 and want to upgrade to the 99 head
and see what they say. Do advise the results :)

Mal

[bpt-4w]

yeah for the old bp motor to the new motor , but what about the new 323 bp was it the same head as the miata.

[bpt-4w]

yeah for the old bp motor to the new motor , but what about the new 323 bp was it the same head as the miata.

[Cosmo Dude]

The BP05 N/A Astina and BP26 GTR should be a straight over swap, you will remove a restriction cast into the BP26 inlet chamber and a few more kw as a result.
If the goal is solid lifters then I'd look at building a BP05 head, have the ports and valve seats machined, install the Mx-5 lifters and begin messing around with valve lash settings. It may cost a little more but but the job will be done properly.

[bpt-4w]

k i'm taking the gtr head off and putting on the mx5 head, i just want to know if the mazda protege 323 came with the same head as the mx5, if so it might be a easier option than trying to find a mx5 motor or head (bit rare). so anyone know if they are the same (protege = mx5???) :?

[BigMal]

No thats why the MX5 99 BP-4W head not to be confused with the BP-05 head
but the BP-4W head helped the MX5 make the 110kw over 92kw for the Astina.
Astina's after the BA 94-98 run a different engine all together not BP at all.

Mal

[Cosmo Dude]

I believe that the BP-4W head would be made specificly for the RWD configuration.
The FWD engine picks up the radiator and heater points from the back of the head where the Mx-5 has the firewall, also intake and exhaust are pointing the wrong way. Hence the difference.

[BigMal]

Aren't all the water pickups etc on the block not the head ???

[bpt-4w]

sorry for the long time i have been camping out bush for a month, anyway the deal with the protege head went through, mainly due to the fact that the guy sold it with every thing attached to it , well at least the head is one stage up , but not two stages up from the older gtr head, now all i have to do is get the toda solid lifter kit and the cams done , and the head ported to a inch of its life with bigger valves and a few other goodies, anyway thanks for the info it was a help in the purchase , hopefully i will be able to post a full work up on the car and engine when finished cheers :)

[BigMal]

So you bought a head off what then ??? I know it says protege but from what model to be an step up from a GTR head or are you saying that
because the N/A head doesn't have the hump.

[bpt-4w]

k the head with the full metal tappit cover, not the one with the plastic cam gear cover (current one i have ) , the ports are wider and the design is a little better over the older head , mainly due to computer cad designing and better casting tech now used , but if i can find a 99 onward miata head for reasonable price i would snatch it up since that one is a lot better, if you want more info go to google and search for the "mazda engine interchangability guide" and it has cut outs ect , plus i went to JHH head works and looked at the diffrent flows from the heads he has done and found the protege/astina head is up there with the 99 in flow it just doesn't do as well in the real world with the 99 making more torque and better down low power due to better port design.

[bpt-4w]

ah yeah forgot , i looked at the head last night and with all the casting marks, dags, bad lining up of manifolds its amazing the engines make the pwr they do :(