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Old 11-29-2007, 07:49 PM   #1
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Question Time for a new motor.

Well, looks like my motor wasn't as healthy as I thought.
Compression:
1: 151
2: 136
3: 108
4: 92

Starting out at 135k beat-on miles and boosting 12-13psi w/bandaids for 15k miles might have done it. I was gonna run 14-15psi sooner or later, so I guess it's good I found out pulling out of the driveway

SO, where to go now?
The $$ factor is important here as I've gotta tell the wife I blew up the car. The actual work of SWAPPING the motor isn't a big deal (gonna do the clutch at the same time). I've got a hoist, tools, and lotsa space...

My goal w/MS has always been 220whp @12psi. I don't think I need anything that you would apply the word "built" to.

I honestly know very little about the costs comparison of stock parts vs. upgraded parts or what all I'll need to buy.

So, let's say for example that I need to keep the whole thing under $1000. The ACT XT is $344 from PSO, so that leaves me $660 for a new motor, or parts, a build, or whatever.
What exactly do I need?
Do I just need a shortblock? What all parts does that entail? Rods/Pistons/Rings???
How much is OEM stuff?
How much is (one step above OEM) aftermarket stuff?
Can I do an engne rebuild of the caliber we're discussing here in my garage with a GOOD set of tools?

Basically I need to know your suggestions on what you would do (on a budget) to get this car back on the road @12psi for at least 50k miles. Start at $660 and work it from there.

Let me hear it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Old 11-29-2007, 07:55 PM   #2
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I vote for just a 94-97 short block, or complete engine-swap and drive it.

Then take your original block and build that one up.

P.S. I don't remember what year your car, obviously a 94-97 short block would be a tough fit on a 90-93

We did have a professor at school that blew the motor in his K car. He took the block down to the machine shop, bored out the one bad cylinder and slapped back together (not sure where He got one oversized piston though) (this was back in the late 80's)

Or how about just finding a donor 1990 mustang? might as well put in a 'bigger' motor...
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Old 11-29-2007, 07:56 PM   #3
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well with a $660 budget you're looking at pretty much a stock rebuild or pick up a used motor.
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Old 11-29-2007, 07:57 PM   #4
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everyone says the rings are the weakest link, i wonder if you just got some really nice rings and left the rest stock, but still at 220whp you shouldn't have much of a problem
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Old 11-29-2007, 08:17 PM   #5
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If you haven't tried http://www.car-part.com it's a database of the inventory of a large number of junkyards, searchable by distance from your location. You might score a lead that way.
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Old 11-29-2007, 08:19 PM   #6
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From what I understand, the rings leaking is the problem, but the cause is the ring landings on the piston fail. Stock ring landings are not that beefy, and the stock pistons are not forged. If there is any detonation, or a cylinder is running hotter than normal, that ring landing is what's taking a beating.

If it were me on a budget, I would get a set of forged pistons and rebuild the bottom end. Look into new rodbolts as I've heard they are the first thing that fails on a stock rod. Make sure whoever does the machining is one sharp individual that really understands how to build motors and has a reputation for building excellent motors.
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Old 11-29-2007, 08:23 PM   #7
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Cheapest/easiest option is to pick up a complete junkyard motor with good compression. With a good tune and good starting compression a stock motor should hold up fine to 220hp/12psi without needing to upgrade anything. Recoup some costs if they leave any accessories attached that you already have (i.e. starter, alternator, CAS, coils, valve cover). Do all the routine maintence with the engine out of the car (seals, TB, WB, etc...). You can always separate the head/shortblock and clean things out a bit as well if you don't mind springing for a new HG and clean all the other stuff as well.

I got lucky and found a local engine with about 70-80k and good compression for $300. I sold off a bunch of parts I already had for almost the complete $300. Spent another $300 or so in all the maintenence stuff (including MS engine mounts, seals, pulleys, TB, water pump, gaskets, 323 PVC, etc..) Cleaned out the chambers and head before putting it together. So spent just over $300 for a "refreshened" engine. Most likely, you can find a low milage engine for ~$500 so it'd put you in the $600 total ballpark.
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Old 11-29-2007, 08:27 PM   #8
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Sam, I'm sorry man.

To keep costs down, stick with the 1.6--otherwise you gotta get all the conversion hardware and tweak your charge pipes, plus at minimum a new exhaust mani, if not also a new downpipe. I'd also just get a new clutch disk instead of dropping nearly $400 on a whole clutch assembly. That should free up some funds to get into the motor a bit. I know you said you don't "need" to build it, but you could get into a very minor build: forged rods (our friend Jim Belfab has them on ebay for $300 right now), and if your pistons aren't broken get them ceramic coated (if they are, you can pick up used pistons for nearly nothing), get new rings and have them moly coated, new bearings, head gasket, and oil pump, and the basic machine work. You'll come in at budget, and have a stronger than stock motor that's probably safe for 7500 rpm and 300 hp. Overkill for 220, I know, but my thinking is that odds are you won't be able to break it (really bad tuning aside, of course), and then you'll have the ability to get into more power if you ever want to. And eventually you probably will.

Of course, it's a slippery slope while you have the block apart...
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Old 11-29-2007, 08:43 PM   #9
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Quote:
Originally Posted by Ben View Post
Of course, it's a slippery slope while you have the block apart...
QFMFT
Quoted for mother ******* TRUTH!!!!!!1111oneoneeleven
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Old 11-29-2007, 08:53 PM   #10
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that's insane, i dont see how a few quick pulls hitting the boost cut would kill it......

do what i did and swap the short block if you can. I only spent about $300 getting mine back togther. $250 block/head, $30 HG/timing belt, $40 milling.
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Old 11-29-2007, 08:56 PM   #11
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I've actually got a spare hg I could mail you if you wanted to do that.

PS. scott didn't buy a new hg, I sent him my other spare with his head.
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Old 11-29-2007, 09:00 PM   #12
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Quote:
Originally Posted by Braineack View Post
$30 HG/timing belt
Where'd you get a decent HG/TB for $30? I think my last timing belt alone was ~$45.

edit:
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Originally Posted by neogenesis2004 View Post
PS. scott didn't buy a new hg, I sent him my other spare with his head.
Oh, I see how it is
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Old 11-29-2007, 09:09 PM   #13
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ahem http://www.rpmmachine.com/engine-reb...ts-mazda.shtml 326 $ For the major engine kit and it comes with everything or, you can get some belfab stuff etc, for a little more. In either case it sucks to hear that you are having problems GL man.
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Old 11-29-2007, 09:31 PM   #14
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I totally love the idea of just getting a used low-mileage engine. I can part out as much of my current engine as possible to recover some costs. But when I hear "low-mileage", I'm thinking like 30-40k miles... not 80k. Sure, 80k in a '90 is low mileage, but not to me when the intention is boost. It looks like I'm on the hunt (you guys let me know if something pops up in your travels).

I also really like the idea of a mild "build" with some upgraded rods and coated pistons/rings like Ben suggested.

Can I, in my garage, disassemble and re-assemble an engine with new parts? I'm pretty savvy mechanically, and I do have all the tools. I understand that I'll need the piston walls worked on... but can I do the rest? I've never done any major engine work, but I'd never installed a turbo or changed a clutch before this car either.
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Old 11-29-2007, 09:38 PM   #15
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Sam, the miata block is pretty simple. You should be able to do everything except the machine work. After reading your other write-ups, I bet you'd absolutely love the ability to scrub and refinish/repaint everything. The only tool you probably don't have is the piston ring compressor you'll need if you install new rings.
Does your base of a hobby shop for you guys?
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Old 11-29-2007, 09:43 PM   #16
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Put it together in the kitchen like me, its much cleaner there. I also have a ring compressor you can borrow if you decide this path.
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Old 11-29-2007, 09:47 PM   #17
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Of course this is a little premature. Aside from low compression, what other symptoms are presenting? Did you try a leak down?
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Old 11-29-2007, 09:52 PM   #18
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It would be a hoot if this was just a HG like scot had go bad.
I think you are very qualified to do the work so long as you just pay attention.
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Old 11-29-2007, 10:12 PM   #19
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Old 11-29-2007, 10:23 PM   #20
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HAHA, not even I linked that ****. I figured it was beyond the scope of what he wanted. I'd love to see him convince his wife.
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