Turbo Ready Engine

[Flash13783]

I'm doin the rebuild on my motor and i want to turbo it!
Is there any special gaskets i should order or will the oem pistons and rods work here's the kit im suppose to be getting. i talked to them and they said that they should be fine as long as i wasn't going higher than 15 boost. What do ya'll with a little more experience with turbos suggest??


http://www.performance-auto-parts.com/engine-rebuild-kits/engine-rebuild-kits-mazda.php

[ben91]

I don't understand why you'd spend the time and money to rebuild an engine to stock type. It's not difficult to get a used, good condition motor, and it should cost less than a basic rebuild.

If you are indeed going to build a motor, think minimum $1,500 but realistically $2,000+ to do it right.

[RotorNutFD3S]

If you want to rebuild, do it right the first time. Or find a used replacement as Ben suggested. That's why I suggested to you before you tore it down to do a compression and leakdown tests. Honestly, your engine was probably a good candidate for a 10-12psi turbo setup as it sat.
The main failure points on our engines are the rods and piston rings, and usually because of detonation (it's all in the tune). But because of keeping those failure points in mind, in my current rebuild I'm using a set of CAT forged rods and I took the OEM pistons and had them tri-coated (ceramic coating on the dome, dry-film lubricant on the skirts, and an oil shedding coating on the underside). This is because I don't like the behavior of forged pistons, i.e. odd rates of thermal expansion and piston slap.
In any case, Ben's estimate is right on. I'm just under $600 in brand new seals, gaskets, hoses, bearings, bolts, etc. alone. But I can assure you that's almost every piece needed to make an engine new. Plus $300 for the rods (which sell for $350 regularly). $140 for the piston coatings. Plus I still have to have the block machined and the rods and pistons installed, which because that will include the cost of the piston rings and pins, rod bearings, and crank and thrust bearings, it will add to my cost list. Then there's the head work that will be done to install the Supertech valves, some deshrouding, and smoothing out the intake and exhaust ports.
Rebuilding an engine properly for boost is not for the light hearted. Expect to invest a lot of time and money to the project.

[Flash13783]

well....i should have listened from the start now that im into it i should have left the block alone and had the head worked. and put it back together...but I dont have that kind of money right now so do you think i should just get that kit and make the block stock and then have the head worked and put it back together with basically a new stock engine and just boost that later down the road??? Will that be safe for 10-12psi??? since the stock motor could handle that??

and maybe get those cat forged rods to keep me right at $1000??

[RotorNutFD3S]

How far apart have you taken your engine first of all?

And when you say you want the head worked, what are you looking to do?

[Flash13783]

Block is completly disassymbled and everything is getting cleaned tomorrow. and im dropping the head off to dover tomorrow also. The only thing i'm upgrading is the rods. Everything else will be OEM

[Roadster]

Don't be afraid of forged pistons. They just have to run a little more clearance: .004 to .006 since they expand a little more than cast pistons. Build it right and they're no problem.

[RotorNutFD3S]

I don't think that forged pistons are a problem, it's just the wear and tear that they will cause that should make someone weigh the pros and cons of running them. They're great for cars which primary use is a track or non-daily driven. For a daily driven car, it's not worth it IMO.

No matter how it's built, the way they slowly expand will cause faster wear on the piston walls (piston slap). Daily drive the car, and you're constantly beating up on the cylinder walls until the pistons have acheived their fully-expanded size. Because of this, you can expect to have to tear down an engine sooner rather than later. However, if you daily drive a car with forged pistons and have the time and money to do so, go for it.

[Doppelgänger]

So how much HP can the stock pistons hold? So you're saying that a goal of like 350rwhp can be achieved safely on stock pistons with forged rods? Hmmm.. that brings the price down a good bit on making big power.

[Roadster]

I dunno, I guess it's six of one, half dozen of the other.

Cast pistons have a high infusion of silicon. The more heat cycles they go through (especially extreme ones, i.e., under boost), the more brittle they become.

We run forged pistons in all of the engines that come through the shop. Even the street/resto-rod engines. A lot of them get driven regularly. No abnormal wall wear. It seems like it would be even less severe on an inline engine instead of a V configuration. I mean honestly, when is an aluminum piston going to be banging up against a steel sleeve and the aluminum wins? Not gonna happen. Steel trumps aluminum. :P

I'm not sure what the threshhold is on stock Miata pistons for how long they can survive under different amounts boost, but when I pop my first motor after the supercharger, it'll be getting all forged internals. Go for 350hp on cast pistons and see what happens, maybe I'm wrong. :)

[RotorNutFD3S]

Mike, do some dedicated reading on this subject on MT.net. The conclusion I came to is that the pistons are not the problem at all when it comes to making big power. I read of someone stating that they made almost 400whp on completely stock internals, and the internals weren't the limiting factor (I want to say it's one of the dudes in Canada). Failure comes from the lack of detonation control (good tune) which causes rings/ring landings and rods to fail. Or hydrolock if you're me. :lol:

I had the piston domes ceramic coated to give myself some protection against detonation and heat, not because I will doubt the tune, but just for precaution's sake. The coating does a good job of reflecting the heat away from the piston where it belongs.

After having torn down 3 different daily-driven engines with forged internals, all of which were built by reputible shops, the wear I saw does not make me comfortable with having forged pistons on a daily driver. It looked like a perfect recipe for blow-by and reduced compression in certain parts of the stroke.