miata_enjoyer

Hi there, first post:

My 94 1.8 engine is a bit tired, one cyl is making 90PSI, and after 160k I figured it's time to yank it out and have it rebuilt. But since the engine is coming out - does it make sense to do anything to the bottom end? Car will be a backroads driver, maybe a few HPDEs a year. Plan is for a reliable-ish 200whp, from an FM turbo setup (have to stay mostly CARB legal), on pump gas (93). I will still be NA for a while though, I want to sort out the rest of it first. My local machine shop offered me a total rebuild (OEM everything, new rods/pistons/rings/oil pump + gaskets) for $1600, with a warranty. If I bring my own parts the warranty no longer applies, which seems to be the norm.

So I guess my question is, what really makes sense to do for my power goals while the engine is out? Rods, BE pump, hardware, head studs? I don't want to spend any money that I don't have to, but I do want a reliable, no-fuss 200whp (if that even exists lol). If I can get away with the stock engine I'd love to, but I don't mind spending where it makes sense.

Thanks so much in advance, and please let me know if I missed anything (or if this has been answered before).

The Australian

Forged rods would be my recommendation. Maxpeeding can be had cheap. If you are replacing pistons and no re-ringing what you have, then consider forged pistons as well (have to select a compression ratio)

LeoNA

$1600 sounds low considering the relatively high cost of OEM parts. Aftermarket OE equivalent maybe, but still sounds low. OEM pistons and rings are $450-500. The OEM gasket set is $300. Doesn't leave much for cleaning, disassembling, inspection resizing the rods and boring/honing the block etc. The head work can be the most expensive part if it needs new valves and guides. This is still not a build for FI. The service life will be relatively low even at just 200whp.

I would include manley or eagle rods. Even though the factory rods are forged, they are relatively small and not worth the cost of resizing/new rod bolts. Also maybe a set of ST 8.8:1 forged pistons. A more legitimate quote would be $3k-5k depending on where you are located.

der_vierte

I'm sure they won't cover a boosted engine with the OEM rebuild. So your warranty is worth nothing in the end?

With that cheap of a rebuild from a professional, I would bring some China H beams and give a **** on the warranty. Should be nearly the same price in the end, but you don't have to worry about bending your rods, when you max out your turbo on 93 oct (~270tq/hp).

Hopefully they do a proper job for that price, that's even more important than rods

miata_enjoyer

Oh yeah, it's almost certainly aftermarket OEM, I'd be very surprised if they could do anything with Mazda OEM parts at that price. I agree it looks like rods make sense, but I'm reluctant to change the CR as I don't know how that's going to play with emissions. At what power level do people typically include forged pistons?

That's correct - my main concern for warranty is just that it doesn't spin a bearing or start burning a ton of oil in the first 50 miles lol. After the first few thousand miles I'd have a lot less anxiety.

I'm guessing the China rods are the typical Manley/Eagle/K1s?

It seems like the shop's price is way on the lower end but I've also heard good things about this place. It's City Motor Supply in Dallas, not sure if anyone has had experience with them. I'll call up some other shops and see what they can offer me. I know X-Factor racing is around here but he seems to mainly build high-end stuff.

So rods are definitely on the list - BE oil pump seems to be a good investment as well. Can everything else remain largely stock for my goals?

I really appreciate the info, this is helping a lot

technicalninja

Wow, from bottom of the barrel (CMS) to a true specialist (X-factor)
CMS will be throwing your money down a black hole and X-factor will be massively outside of your buget.
X-factor will probably be worth it...
I don't know him, have never spoken with him, but his website looks seriously Miata centric.
I'd get his take on your project if he will take the time to talk with you. I'd take donuts, kolaches by one morning and try to make friends.
I WOULD NOT pester him over the phone. He gets that **** every single day...
It gets OLD fast. I have an Automotive AC shop and talking to beginners can be a serious waste of time.
I'd guess a basic motor from him will be 5K plus.

Why oh why do you have to stay "carb legal" with a car that is over 25 years old in Texas?
Planning on moving back to Calif? If so, I'd advise keeping the entire 94 engine package together as a once every two years swap for inspection. Don't fix it at all.

Even in Dallas and Collin county you can register any car 25 years old and older as a "classic" and skip the inspection altogether.
The "normal" inspection for a 25 year old car in a non-attainment county is safety ONLY. You need to keep the appearance of stock emission controls, but they are not tested EVER!
Pretty much all of my buddies just go "classic" registration with 25 year old cars. It's about the same price as normal registration.
So staying "Carb legal" is not really an issue here in Texas unless you're less than 25 years old and in a non-attainment county.
"Carb" legal means California Air Resources Board. This is NOT a requirement for ANY inspection at all in Texas. We are what is referred to as "49 state" or "Federal" when it comes to emissions.

Changing the compression ratio will not have a measurable effect on base line emissions. Your car is low enough now (8.8-9.0) that it should work well blown.

IMO it is not possible to purchase high quality aftermarket parts or OE parts to rebuild that engine at $1600. Parts alone! No Machine work or labor included.

If I was in your shoes, I'd try to find a later engine (99 and up) and swap that in.

As long as the replacement engine is in useable shape surviving 200 WHP turbo system is a given...

Most of the cheapy engine rebuilders (CMS) replace the absolute minimum to make it run again.

There is no such thing as aftermarket OEM. It's either aftermarket or OEM.
2 decades ago, aftermarket was fine. The Chinese have priced the aftermarket suppliers into bankruptcy and aftermarket is trash now.
Now what we have is OEM, aftermarket junk, and then specialist parts. Specialist parts (BE pumps, Supertech, Wiseco, ARP, SuperMiata) are commonly more expensive than OEM Mazda but have attributes that make the additional price worth while.

Baseline bp4w (99-00) good to 220lbs/ft torque stock engine (approx 250 hp)
With rods, head studs, BE pump, balancer, proper assembly good to 275 lbs/ft (approx 300+ HP)

Build the stock 99-00 motor set up FIRST. Done right this could work for decades.
With $1600 I'm positive I could find a motor that would work.

More important than anything else is the tune. Don't cheap out here.
A good tune can keep a junkyard motor running for years.
A bad tune can trash even the most expensive build in seconds...

rjacobs

Good luck getting x-factor on the phone, email, text, etc... Ive been trying to get a price to do a rebuild on a BP6.....crickets... I think I have reached out like 6 or 7 times via various forms... that was probably 5 times to many honestly I dont care how good of work you do. At some point people stop calling. If you are that busy hire somebody who's job it is to respond to emails, answer the phone, text, etc... Maybe they arent a technical person that can provide detailed prices, but at least somebody to send a response. Instead...nothing. I have HEARD that he will respond to text messages in the middle of the night...maybe...

My buddy got his bottom end done like 2 years ago for 1500 bucks... I cant see that happening today for less than 3k, maybe more.

Im sure they do fantastic work, I dont doubt that, but im not driving to your shop to hunt you down and demand pricing and to get on your schedule... for the privilege of giving you thousands of dollars.

DNMakinson

iTrader: (3)

Reminds me of an older Appalachian man who said, years ago, "I'm not going to beg you and pay you, too."