Building a motor for future turbo? What do I need?
 

Ok, so heres the run down...

I just blew my head gasket. Motor has 145k miles on it. I figure its pretty tired. I am eventually going to have a full turbo setup, but for now, I just need to have a strong motor. I have resigned myself to just replacing the head right now. I was going to order a fully rebuilt one from one company or another. I figure 250 whp will be fine for me eventually.

Currently I am shopping for transmissions and differentials... I am looking at the RX7 unit. That should work right?

Anyways, should I upgrade anything on the head while I am at it? Stainless valves maybe? Not sure what to do to be honest.

I have a 1.8 liter block that I will be rebuilding in my spare time. At the moment, I am just trying to get the car running again.

So do tell. What should I do to the head while I have it off?

Fully rebuilt and only 250whp? Man ur aiming low, real low. When I rebuild my 1.8 next winter its 300whp atleast. Torsen/rx7 lsd rear end is a must aswell, search for more details on that one.

It depends on how much money you have really. You say you want to get it running again quick, well building stuff takes time and money, have both? If not just get it running again then boost it. 250whp is attainable on a boosted 1.8 (no build nessicary)

Ok, so 250 is doable on a stock motor. Well, I have already decided on doing the bottom end. Motor seems to be running right again, just low on oil? Adding oil made it stop burning oil. It was only half a quart down on the stick. Go figure.

So if I have the stock block, stock everything but pistons and rods, what else do I need to get me in the 400 hp territory as long as were dreaming.

Also, what options do I need on the head? Stanless steel valves or anything like that? Better springs? I plan on having it done at a shop, but anything that I can do myself I would prefer to do myself. Taking the dremel to the port for a couple hours is far cheaper than paying someone to do it, but I figure matching the new back cut valves to the head or whatever probably takes some skill.

And as far as ebay parts pieced together in a turbo kit, what kind of software do I need to control all this crap. I figure exhaust and turbo and intercooler and piping is all pretty easy to do, but making it run is a whole different story.

I'm gonna try to do what 93mimi did here https://www.miataturbo.net/forums/sh...?t=1026&page=3 to keep my boost and fuel in check. I know that it is a little crued but I'm hoping that by using either stock injectors or 305's (only aiming at about 6-8 psi) I will be able to get it idling easier than he did. Then again I wouldn't use this setup for 400hp.

I'm putting in forged Wiseco pistons, Crower H-beam rods, ARP head and main cap studs, SC50 turbo (I'll see how this handles and maybe upgrade to a SC61 later if this one will spool fast<-dreams), MS-I v3.0 (boost control, knock sense, launch control, meth injection), T-II Tranny, Diff, hubs, 3" SS exhaust, Egual Length Runner exhaust manifold, dual feed fuel rail, Custom intake (later), 255lph Walbro FP, 780ccm injectors, alcohol injection.

I hope this gets me to 380-420whp :)

2 parts suffer the most in a miata. The piston rings and the rod bearrings...
(rings 54dollar on ebay, bearrings 10 dollar...)
Hone the cylinderwall.

The head: check for play in the valve guides... Pull 1 valve out, check the play between the valve and the guides with the valve itself...

If there is no play the head is ok. other you need 2 replace the guides.(sometimes a new head is cheaper, buy it with cams)
The valve guide seals (rubber things on top) need to be replaced too.
(normally in an engine rebuild set.)

It's not a lot of money . only a lot off work.