piston advice for motor build.
 

So im coming up on 85k miles, and im soon going to build the block. Suprisingly I have perfect compression. My goal is a respectable 450whp daily driven. Ive been doing alot of research and whar I see kinda scares me. I keep hearing that forged piston will result in short engine life, so im left struggling between manley pistons and oem. I originally planned to do manley h-beams and wiseco pistons on stock bore. Input from those with buipt engines is welcome and appreciated! I realize 100k+ miles is unrealistic, but i would hope to get close at least with the money it takes to build.

450whp go with OEM gen2 pistons

its alot better to get forged pistons because of all the ringland failures.
many people, myself included have been running forged pistons for years.
of coarse a good tune can make a big difference in longevity

If you go stock pistons, you'll have to shave them or the rods to make them fit, so I went with wiseco's and am very happy. Never had the forged piston slap folks talk about either.

For a simple build. I recommend a nice Wiesco set.
If anything your bearings will go before any type of rod and piston failure. But there are several factors to consider.
My 2 cents.

You'll be fine with Wiseco OTS pistons up to 600 whp.

I appreciate all the input guys. this has eased my concern with going with the wisecos like I originally planned. I believe they are pre coated as well which is a huge plus. I drive hard, but not like a dipshit. I.e. coldstart launching and red light grand prix. If I get a solid 75k out of her ill be okay with that.

If you go with wisecos, you have to bore out the cylinder .04mm. They expand more then the stock ones.

As far as I know the Wisecos are from 4032 alloy so they are probably the best for DD.
SP63 also has them in a custom form so that you will not have to worry about the oil squirters and possibly other issues because of the long skirts.
There aren't too many reasons why an engine rebuilt with forged pistons will not hold though.

As for your power goals, I guess as long as you keep the torque below like 370lbft and keep the cylinders and piston heads cool (read: WMI) you should be fine with the factory pistons at least for a while.

So what you're saying is that for the 87.5mm pistons you should bore to 87.54, and for the 88mm pistons you should bore to 88.04? It's the first time I read about this... and the 0.04mm in diameter is still not enough to make the rings to butt as far as I know.

You should look a little harder. Im also rebuilding my motor. I just got manley rods and i want to go with either the wiseco or sp63 pistons but i would need to bore the cylinders. There's more to a motor build than just slapping the best internals you could find in.

Introduction to piston design for forced induction engines | HorsepowerCalculators.net - Home of the Virtual Dyno & The comprehensive horsepower calculator

The link you posted has general things about the pistons and do not refer particularly to the Wiseco pistons and our 2.3DISI blocks. The the .04mm over is not determined from that article.
Plus this is the first time I read on this forum about the necessity of boring .04 over the piston specs.

So again, are you sure?

Let's just pretend that the post is not from 2010 when the rods where going before the pistons, but from yesterday. I still can't see where it's written about the 0.04mm bore past the piston specifications. After all, the reason a piston is spec'ed at 87.5mm is that because it needs a 88mm bore to fit in :) otherwise it would be a 87.54mm piston.

Also, why 0.04mm and not 0.05? As far as I know the honing machines have 0.05mm stepping. So you can bore to 87.5, 87.55, 87.6, 86.65, and so on. 87.54 is a bit unusual and it should be probably 87.55, the 0.01mm difference is probably even less than you get for the same engine when cold and when warm.

So I still don't know where you got that information from, but I'm pretty sure not from this forum. And this forum is the daddy of all mazdaspeed/MPS/2.3DISI-T forums, this is where people post about stock engines as well as 800+hp engines. So we would have known by now about this 0.04mm deviation from specs.

I found a lot of info on forged pistons and i cant find the specific post. Stock requires .025-.045mm clearance with little expantion. A forged is gonna be expanding indefinitely more so you want to compensate. Does this make any sense?

I went with the Wiseco's, stock bore, no boring... Running like a top. This is the first I've seen of having to overbore for any piston

My stock bore wisecos doing fine after 2 years. Thats bad info.

Jesus Christ. You don't have to bore for a stock sized aftermarket piston. You want a .0035-.004" pwc on the wiseco's (it's on the spec sheet) for a moderate-high hp build and .0045-.005" for very high hp build.

wiseco (and any other piston company) builds their Pistons with that in mind.

Is that cold or warm though?

I'd better be safe than sorry. I generally dont do anything until i get as much info about it as i can.

Yeah bro whoever wrote that is full of shit. Ive run stock bore wisecos in both my evo and my wife's 2g gsx without boring the cylinder. Put almost 65k miles on the evo at 497whp 512wtq, 62k miles on the gsx @ 556whp 417wtq.

Well, if you want to be safe than sorry, as you've said, do some reading first. But proper reading not back street legend reading. You can start with the threads you've mentioned and then continue with the drop-in build threads. Listening to people who've gone through this and have strong healthy engines is also something you should do.
Throwing unverified and incorrect information on the forum is not something anyone enjoys in any way. Mistaking the thermal expansion differences for machining specs is a really big mistake, and after all this is why the pistons have rings and they do not seal the cylinder chamber themselves alone, just because the thermal expansion.

forged pistons in 2 cars for over 60k mile sin both and you are worried about the speed? or did I read that wrong? Youll be fine with wiseco's and manleys. a good tune and maintainence will help them go a long way.

Keep in mind there is a big difference, both of the previous cars had 4g63 engines, meaning cast iron blocks. Cast iron is alot different from aluminum. You guys have definately eased my mind. Hows your build going btw? @hatchedspeed3

gotcha. forgot about that part. my bad bro. my engine is done, 2nd crank is good. I pick it up next week. I should have it all buttoned up by the end of May, as I still have a few things to pick up first.

Im so excited for your build to be done! Its gonna be a total beast. =D

as am i. wouldve been able to order the last of the parts, but I had a cracked rim so....new shoes lol. if only I could deicde what snail to put on the block....decisions decisions lol

What turbos are you stuck between?

What internals did you end up going with? Im trying to just build something i can drive for 100k or more. Sofar ive got manley connecting rods. Im gonna keep the stock pistons. Im gonna try to get a compressor that will put out around 15 psi. Nothing to crazy

well, part of me wants to wait for the s4 to come out. Rumor has it that it'll flow 475-500 ish. Im also looking at the 5858 and gtx3067r. Im not trying to break 500whp, but I want fast spool. I originally looked at the s3 (for spool), but its not going to get me where I want hp wise.

keep in mind, you will have to modify the rod to get it ot fit on stock pistons. there is nothing wrong with wiseco pistons. A lot of guys have been running them successfully for many miles. Its all in how you take care of the car, and how meticulous about maintainence you are.

A GTX3071 may get you where you want and also have decent spool. Or wait for the S4 or the GTX2971.

you dont think ill run out of room on a 3071? gt, definately, but a gtx? and what is this 2971 you speak of?
@cam1391; sorry for the thread jack bro

for that matter what is the S3 and S4 you speak of? BNR turbos?

correct good sir.

I am in that same situation right now. The problem is, the car I am rebuilding was a flood car with 5k miles on it. From the tear down, it looks like it sucked some water up(bent a rod and rust on the intake valves).

So I am sitting here with a 5k mile K04 that may be good, may not be good. I want to just install this once, so I was looking at the BNR S3 or the GT/GTX2871. I am not looking for CRAZY power, it will be a daily driver(300-350 is a-ok, I have a track Miata). The new motor is getting a forged bottom end.

@brandontrek; you shoul dbe just fine with a s3

We've seen a few GTX3071s pushing well past 500whp on this forum. You will need a lot of meth and an E mix but since you also mentioned a BNR S3 which needs quite a lot of meth and a higher concentration of ethanol to push to 400 I simply saw the GTX3071 as a better option which will get you past 400 while being more relaxed and running cooler.

The S3 clearly spools faster than the 3071 but this is not necessarily a good thing when you go WOT on a FWD, because the torque ramps too fast and on a MS3 this is far from ideal. On a MS6 you can go with whatever you like, but on the MS3 it's a bit more tricky.
I'm not sure where the S4 will be in therms of spool and flow compared to a 3071, we'll see. The 2971 (not yet released yet, I only heard rumors about it) should spool like 200rpms faster than the 3071 and provide about the same top-end flow.

Ive been hearing a lot of good things about the 3067. I will be running meth and a 5 gal mix of e, as I know I'll need that to get over 400 regardless. @kbz0129; has a gtx3076, so when we get his finished up, running, and I can drive it, I'll have a really good idea of what direction to go in.

I truly believe anything less than a gtx3076r will leave you dissappointed. Its just a feeling, but take it how you will

i know the 3076r is more than capable of putting me at the power levels I want, its just a fact of spool. I feel like it'll be a little too laggy for me (and I'll risk a few hp up top for better spool). I wont know for sure until I can really experience @kbz0129;s car. If I knew I could hit 450 on a s3 without straining the fuck out of the turbo and making it constantly work hard, then thats what I would run

Have you considered the HTA3076? Middle ground of GTX3076-3071. Flows about like a 3076 but spools like a 3071.

PS order early if you decide this route. I ordered my HTA 3 weeks ago and It still hasn't shipped. At this rate CPE may beat them to my door step with delivering my manifold.

i havent looked at the HTAs yet. I looked into the EFRs and after speaking with @Enki; decided not to go that route. I'd have to look at how the 3071 spools and go from there. Based on videos, it looks like the 3067 is going to give me the spool I want, but more research needs to be done. Finding that middle ground is the tricky part. do the HTAs have a stock location flange, or is that something I will have to consider when ordering a manifold?