user 8202

Hey all,

Im doing a forged engine build on my 97 Miata. 146k on stock motor. Currently running the full mkturbo kit with ms3pnp. Parts list include:
supertech 84mm 8.8:1 pistons with wiseco xx rings
manley rods
Acl bearings
be oil pump
Supermiata crossflow radiator with reroute
supermiata hybrid motor mounts

I have the engine out and torn down to the block. I need to find a machine shop now. What do yall think is needed at the machine shop? I know I need them to bore it, clean it, and deck the block. But should I have them check or polish or do anything to the crank? Do they check for what size bearings I need? Should I get them to file my rings? Do you recommend they do anything to the head? Or do I just slap it back on there?

user 8202

I almost feel bad taking the engine apart. It was super clean inside. I saw no marks or anything on the cylinder walls, bearings, crank, etc.

Turbomack

How do you know you need to bore it? I would suggest having a trusted machine shop make that determination. If you do, maybe 83.5 is all that it needs and leaves enough meat on the bone to do it another time or two after that. The questions you ask are pretty good ones but suggest to me that the shop should at least build the bottom end. If your build is 225 HP or less and there’s no indication that the head is a problem, I probably wouldn’t take it apart but new valve seals are a heck of a lot easier to do with the head sitting on a bench. Maybe a local MT’er with more experience will take a quick look at it for you. I certainly would if you were closer. Checking the lash is pretty easy to do at this point as well.

Cheers.

technicalninja

It's always better to start out with a "perfect" core. Don't feel bad about taking your "nice" engine apart.
List of stuff looks good.
I'd add ARP head studs.
I'd NEVER take a head off without at least hand lapping the valves, new stem seals, fresh valve springs, good valve adjustment, having the head milled, etc...
I'd be FAR more likely to just "refresh" the head and leave the short block alone...

I've been doing this stuff for 40 years and I DO NOT trust the machine shops I use. They ALL make mistakes (sometimes minor) and ALL work comes with a disclaimer that says YOU have to bring any mistakes to their attention before assembly...
When I send a head to the machine shop it is BARE, nothing but exactly what they need. They don't get to assemble ANYTHING AT ALL...
I will do a better job than they will, I will take more time and be much more exact than they will.
I'm a pinheaded bitch when it comes to assembly...

Turbomack is correct! Stay with the smallest overbore you can. Increasing bore size does NOT increase hp enough to matter but it can reduce cylinder wall thickness to the point that it does matter.
Pretty much all of the factory "turbo" applications decrease bore size when they add FI.
As it will have to be bored when adding forged pistons I would NOT try to use stock size. It's a bitch to bore one .002-.004 over. It's far easier to bore one .022-.024 over. (.020 over is a .5mm increase)
Don't ask for a bore at minimums.
Ask for a bore at .001-.002 OVER minimums. They're MINIMUMS not maximums...
I see this mistake on nearly every single beginner build.

user 8202

It's been a while since I updated the thread, but I did rbe first start today and got the car back on the road! So far its running really good. I followed the flyin miata engine break in procedure and currently have the turbo wastegate wired open so I can get a few hundred miles on it before applying boost.

Thank you to everyone on this forum who helped me and the forum itself! This was my first engine build and I couldn't have done it without all of these resources.

Newaza

Hey Jmatt, Savannah river dragway is supposed to open up again sometime in march for some test and tune if you want to try and get in some straight line work. Using the trap speed data (not the et) for tuning is a very good indicator of power and how well the car is able to use it.

user 8202

yeah that would be great. Thanks for the heads up!

user 8202