I've been wrenching on cars for over 15 years but have never built a motor and always wanted to. Now is the time.

I tore down my spare to nothing but bits this weekend. I asked all the local shops/ Miata people for a decent machine shop and Chix came up a couple times so I'm going to drop the block and head there tomorrow.

For $80 they will clean up the block. They asked if I wanted it bored .020 over and I said no. They said it was "crazy to do all that work and not bore it out". True? Added costs for larger pistons? Any reason not to bore .020 over?

The head is $275 and they clean it up and re-do the valve seats. My reading shows that on an FI car, ultimate flow is not a huge deal- we have enough pressure to overcome that to a certain extent. Fair price? Should I be doing more? Chix does not do any performance modifications.

The goal is a rock-solid motor running at 300rwhp. Was thinking just good hardware, pistons, rods, bearings, oil pump, water pump, belts/ seals etc. ALL other supporting mods have been done. Still thinking about the coolant re-route possibly with a modified head gasket. Still have some thinking to do here.

 

are you going with forged pistons? if so, then yes of course have it bored. if staying with stockers and they all look peachy, a light hone and you're set.

I pay $250 for similar head stuff, so I'd say that's fair (machine flat, hot tank, cut valves/seats, set lash). yes for your goals that should be all that's needed.

You don't need a modified hg. Just use 94-00 if you want to do re-route, and 01+ if you don't. Now is the time to choose, so choose wisely. (I'd suggest doing the early gasket and re-route since you track the car).

 

Yes, forged pistons and quality rods. Tempted by the Supertech due the cost. Might do Wiseco. Rods- Manley, Eagle or K1. ACL bearings, ARP studs. Boundary oil pump, and depending on $$ an ATI or Supermiata balancer.

I'm in no rush but want this build to be 100% right.


In the cooling thread it seems that using the early gasket on the VVT heads actually blocks off some cooling ports. Thought someone actually punched holes in one to make it work.

 

didn't both Sav and Emilio say that they use 94-00 gaskets on every single BP they build?

I know for sure Emilio said that at least a couple times.

 

Supertech from 949. Bore cylinders to true it up.

If you stud the main bearings you will need the block align bored.

Gently grind down the little slivers of metal between the intake valve reliefs and the edge of the piston like they do on the factory pistons.

 

Make sure to clean with solvent or carb cleaner and air blow all the oil galleys in all possible directions and beyond what you think you need and regardless what the machine shop says if they claim to have cleaned it before assembly!!
Ask me why i tell you this...

 

If you're getting forged pistons, then yes bore out for larger ones for a 1.9 build, why not.

As for the HG, as 18psi said, go for the '94-00 HG. But read below.

Pretty sure somewhere in that thread he said that the internet is saying '01+reroute is dangerous, but they've done a few enduros with that combo with no issue. I'm hopefully not wrong saying that.

This x10. I'd be worried if they say they don't do performance mods, yet they're suggesting you bore over .02"? Also clean the bores out with a new towel and degreaser until the towel comes away clean.

 

Thanks for the suggestions. I'm assuming that the .020 takes it to a 1.9.

The shop said they don't do any performance mods to the head.

I *think* what makes it potentially dangerous can be fixed by punching a few more holes in the head gasket. Whether or not this can be done while retaining the gasket's ability to keep oil and water separated... who knows.

 

You have to backwards, 01+ HG on a 94-00 head = death.

 

I'm in almost the exact same situation with doing the motor rebuild. I'm curious to see what path you go with. Good luck with everything.

 

Jasonscb or whatever his name is poked holes in a 94-00 gasket on an 01+ head to make use of all the coolant passages. I believe a picture of his work is in emilios cooling system thread.