Forced induction bottom end build... AKA the unplanned child.
 

I was planning on building for boost, just not yet. Oh well.

So I lost a rod bearing in my '99 BP-4W. Now it's time to rebuild for boost. I already had a Moss MP62 on the car with intercooler and 70mm pulley. I was planning on Megasquirt and Injector dynamics for more boost, but now my dreams are on hold for 18 years. Well maybe months.

I have plenty of questions and will need some help so let me tell you how this engine will be used. I promise to reward with lots of iPhone photos.
This is a street car. Yes, I will track and autocross but primarily DD.
I have no immediate plans to spin past 7200 rpm. I would like the ability to do so later if I choose but I will not be touching the head (other than valve seals) for now.
Until I can save for MS and injectors, I will be keeping boost under 10psi. Once I get proper engine management and fueling, I plan on spinning the blower to ~16.5k or so (~17psi). I know people spin them faster but it's out of its efficiency range and I'd be better off with a turbo at that point.

I plan on ordering the following parts this week or next at the latest. I'm looking for a little feed back here.

Pistons: 949 Supertech pistons with Wiseco rings. I am planning on going to 84mm so that I can get 9:1 CR.
Who has run these? What piston to wall clearance do you run? What top ring gap? Second ring gap? Do they come with recommend tolerance in the box?
I know stock pistons can probably handle the sub 300whp I'm looking at in the near future but since I will not be reusing my stockers, I see no need to buy new set of Mazda pistons.

Rods: Manley H-beams. Not much to say here. I cannot afford Carillo's, so hear I am. Again, maybe these are over kill but since I have a damaged rod anyway, why not?

Bearings: ACL for mains, rods and thrust. Will probably be ordering most of my stuff from 949 so I just figured I'd put these on the list. Any benefit over OE?

Oil pump: I'm not sure what to go with yet. At minimum I will go with a new OE. But I've been looking at this: Miata Street/Strip Pump
Obviously more expensive. Do I really need it? I suppose I could upgrade later if I go more than 300hp.

Damper: not sure yet here either. A new stocker? Reuse my old stocker? SuperMiata from 949? ATI from FM?
Same as oil pump, seems like an easy upgrade for later horsepower upgrades. This and the oil pump could definitely save me some cash now but I don't want to be in the danger zone using OE parts either. So is a Mazda damper and oil pump good for sub 300whp on a mostly street driven car?

Flywheel and clutch: I wanted a FM happy meal but I'm out of monies now so I was thinking... Lighten the stocker to ~14 lbs. Should be okay for stockish redline right? It has an Exedy clutch in it now, and my labor is free so I'm going to reuse it. Hey, I'm out of cash and it wasn't slipping before. It looks good enough to get me back on the road at low boost.

Gaskets: Planning one using Mazda parts here. Is the stock head gasket alright for what I'm planning on?

The rotating assembly will be balanced by an engine builder friend of mine but I will be doing the assembly to save some cash. I will use a local machine shop the grind the crank and bore the block.

Any other recommendations?

Thanks for reading and in advance for replies.

I started a similar thread about my turbo build

what i have learned from all the responses and further research on miataturbo.com the billet oil pump and harmonic balancer (dampner)are a must i bought the supermiata

rod and piston combo are good i went 8.6:1 for just a little more safety and i would recommend revving to 7200rpm jut get yourself a better set of valve springs

that is all i can think of at the moment

Cool man, thanks for the advise. I just read your thread. Looks like you are shooting for a bit more that I will be.

Thinking I'll go with the billet pump now and slap on a damper when I get over 10psi.

I think with your goals you'll be fine with just the BE oil pump for now. You dont really need either right now but the pump requires pulling the engine and pulling the oil pan where as the pulley can be installed in car. Yes you probably should have the clutch, fw, and pulley all balanced together with the rotating assembly but not doing that isnt the complete end of the world.

And with future turbo plans you might want to think about the 8.6:1 pistons rather than the 9:1.

I was under the impression that this engine was internaly ballanced and therefor the flywheel was neutrally ballanced. So as long as crank, pistons, rods are ballanced together, all I have to do I make sure the flywheel and pressure plate are neutral. Am I off my rocker here?

Are most people running 8.6:1 for under 20 psi? I can get those pistons in a smaller overbore. Will the stock ecu handle that alright?

Pistons: 8.6:1 STs are fine, that's what I will soon be putting in.

Rods: they are all the same, go with the cheapest. I think I have 'scat' rods but they are identical to the manley.

Gaskets: I think Ebay for WP + gaskets is popular, search the forums though to confirm which one you want to get.

But with a kid on the way, you may be interested in the 'rods only' rebuild that 18psi is doing (and a bunch of other people here are interested in). Any reason you can't reuse your stock pistons?

The unplanned child is just a joke. The rebuild is the unplanned child. I was planning on it down the line but I will love it just as much now.

I was seriously considering rods only. However after I pulled the pistons this weekend, I don't like the looks of the scuffing on the sides. Also I want to step down in compression due to California gasoline.

Oh yeah, absolutely :laugh:

Cool man thanks. I was worried about fuel trims over time causing MIL's. Nothing I want to be dealing with at smog time.

Where is this rods only build of yours mentioned above? I'd like to give it a read.

When you talk boost ms2 is your friend i went aem due to
That is my tuners preference

Just go turbo from the word go
Gt2871r
Artech manifold ( i wish i lived in the us)
3" dump
Big cooler

Smoke superchargers all day long

You are right except I live in California. It's nice to have a carb sticker sitting on top of my charger incase Johnny wants to look under the hood. Also, 250-300whp will be nice for a DD. Here is the big thing; I already have this expensive piece of equipment.
No doubt if I want all out power I will sell it and buy a turbo. For now I must concentrate on getting this bottom end together.

Thanks for the input fellas. I'm itching to pull the trigger on these parts. The consensus seems to be leading me to the 8.6:1 pistons so I'm leaning that direction.

What piston to wall clearance are you running on the supertechs? Do they come with manufacture suggested clearance in the box? I've read they can run slightly tighter than Wiseco do to the alloy (4032 expand less than 2618).
How about ring gaps?

Alright, I'm ordering parts Monday. I wanted to take the weekend to go over everything for the seventh time and make sure I get it right the first time.

I'm going with 84mm Supertech's with Wiseco rings from 949. Thanks Emilio for your help on this.

Found a good deal on Manley rods. Only a slight increase in price over ebay rods, makes me feel all warm and fuzzy inside.

I'm going with the BE street strip oil pump. What is the difference with this and the race pump anyway? Volume? Pressure? Both?

ACL bearings.

ARP head and main studs.

I found that Mazda sells a full engine gasket set. One stop shop for quality gaskets looks good to me.

Damper will have to wait for now. I will be stepping down in boost (for now) from my previous set up due to the pulley sizes I have for the new six rib belt setup that is going on.

I was looking at crank scrapers and found this. I know it probably won't give me any noticeable horsepower, but for $70 it just seems like icing on this little cake of mine. Can anyone give me a reason not to put it on? If it is a complete waste of money please let me know.
Ishihara-Johnson near-contact crankshaft scrapers - MiataRoadster - High-performance customer service...and parts for Roadsters

I've been doing plenty of reading in the last week and found a ton of information here. The entertainment value of hustler alone is worth the $40 a year. Thanks to those that have pointed me in the right direction in this thread and countless others I've read through.

Pistons skirts should scrap the sides of the cylinder walls. Is that the scraping you're talking about?

Also, the stock ECU comment was a joke, yes?

im currently building the bottom end of my motor for my 96 to go fi you guys have any tips?

You can search and keep this thread focused on the original poster please.

he is talking about a crank scraper it bolts it is a plate very close to the rotating assembly at the bottom of the engine minimizes oil splashing and sloshing around the engine

i looked into it i would not even bother

very few people even baffle there sumps they just over fill them a little

if you want to spend $70 buy adjustable cam gears so you can stuff with cam timing a little

Not joking on the ECU comment. I've never taken close to a full point of compression away from an engine and watched how a stock ecu handles it. I would think it could handle fueling it safely, but more importantly for me, will the fuel trims be off enough to turn on a check engine light? That is what I'm asking.

See what I'm thinking is: running a different octane fuel, with a colder plug, 1mm overbore and a full point lower in compression could affect the burn enough in non-boosted conditions that the stock ECU would see this (possibly as a rich condition?). If all of those factors only add up to a 10% change in fueling, I would expect the ECU to correct and not give and MIL. However they add up to something like 20% difference, I would still expect the ECU to correct for it but I would also suspect it would turn on the light indicating this lean or rich condition.

If you think it's a stupid question I'm okay with that. I'd rather look dumb and ask than be stuck with something I don't want.


I think you can find tips right here in this very thread. Also I will update my earlier posts with links to othe helpful threads.

Thanks.

Why buy Manleys when theyre just a rebranded Eagle with a price markup?

I think the question is, are you really expecting to run 300 rwhp with a stock ECU on a built engine or do you only care about the stock ECU for one weekend every two years when the power-adding bits aren't installed?

The former is nuts, the latter is probably not a big deal. My stock 99 ECU has had no issues with running my 9.0:1 supertechs without boost.

--Ian

1) I'm not paying retail (although still higher than ebay). 2) I know that the Manleys are finish machined by them to their tolerances. I cannot tell you who or where the eagles, ebay or anyother rods are machined. 3) If there happens to be a problem with them, I am dealing with a large company that stands behind their product.

No, lol. Stock ECU will never see over 200.

Good to know about your car, thank you.