Miata engine donors?

My son is tentatively buying a 97 Miata with a "blown engine"

If the engine is indeed trash, what other vehicles use a compatible power plant?

Ferrari 308?

Looking for stock replacements?  stock-ish replacements?  LSx replacements?

Let's go with Stock/Stock-ish.    Nothing that requires massive modification for a 17yo that seeks dads guidance.

Will the FWD protege / escort  long blocks work?

LSx?

Easiest answer: 1994-97 Miata.  1996-97 is identical, 1994-95 will require a bit of futzing around with a crank sensor.

Next easiest: 1999-00 Miata. Pretty darn close to a bolt-in, but it's going to cost more.

Next, 2001-05 but it'll work best if you get a VVT control box.

The Escort GT and Kia Sephis GS use the same engine, but you'll have to swap the oil pan, the thermostat neck and the intake manifold at least. I don't know if they have the crank sensor mount that you need.

I'd be tempted to start with diagnostics. It's pretty hard to kill a Miata motor honestly. Maybe it had a cracked rad that led to overheating and a blown headgasket, in which case checking the head for flatness and replacing the gasket may be the best choice.

Keith,

Are the heads aluminum or iron?   Can they safely be milled if slightly warped?

In reply to Grtechguy :

Aluminum head, iron block.  I have a 97 that I bought after it overheated and filled the cylinders with coolant.  I sent the head over to the local machine shop and they cleaned up the head, put new valve seals in, and milled it a tiny amount.  I checked the block with a steel ruler, a plate of glass, and a feeler gauge.  Everything looked good, so a popped on a head gasket (make sure the locating dowels are in place) and put it back together.

Yup, a machine shop should not have any difficulty milling the head. I think I had one of mine milled by 0.030" for extra compression years ago.

If it is not salvageable, any 1994-97 Miata head is a direct swap.

When you put the head gasket on, make sure it's the right way up. Upside down is expensive because you block an oil feed to the head.

I went through a similar thing recently. Wobbly crank on a 97. It's really hard to find an engine to just pull, and slap in. They are all old/high mile.

Had it to do over again, here are my top approaches in order.

1. Buy a running parts car. Swap and go. New belts/seals/clutch/etc. After the fact, I found a $250 parts car that would have saved me thousands,

2. buy a NB engine, have the 97 head resurfaced, throw it on the later long block, and enjoy the compression bump. Note, potential minor starter issue: one bold doesn't line up. Either leave it out or swap starters.

3. full rebuild, like I did. Budget at least 3 grand, and know you took the nuclear option. Maybe you can just do the head?

Any way you slice it, finding out what you've got is the first step. Good Luck!

wheelsmithy (Joe-with-an-L) (Forum Supporter) said:

I went through a similar thing recently. Wobbly crank on a 97. It's really hard to find an engine to just pull, and slap in. They are all old/high mile.

Had it to do over again, here are my top approaches in order.

1. Buy a running parts car. Swap and go. New belts/seals/clutch/etc. After the fact, I found a $250 parts car that would have saved me thousands,

2. buy a NB engine, have the 97 head resurfaced, throw it on the later long block, and enjoy the compression bump. Note, potential minor starter issue: one bold doesn't line up. Either leave it out or swap starters.

3. full rebuild, like I did. Budget at least 3 grand, and know you took the nuclear option. Maybe you can just do the head?

Any way you slice it, finding out what you've got is the first step. Good Luck!

You missed 0. Do a Loctite fix on the wobbly crank :)

They stopped making 1997 Miata engines 14 years ago, so it's not surprising that any ones found in junkyards are old and high mileage. The pristine cars are worth enough to fix now.

If you can't find a used engine, you can also do okay just fixing the problem and not doing a full rebuild.  At Eclectic, we've seen that the issues are usually head-related or crank-related, but rarely both.  If they're head-related (usually a burned or damaged valve), pulling the head and sending it to the machine shop is $100-500 around here, depending on the scope of repairs.  On the bottom end, it's usually a rod knock and we get the crank turned, the rods reconditioned and the block cleaned/honed.  We can usually re-use the pistons and just do the rings.  The machine work is in the $300-700 range.  If you have the machine shop reassemble the bottom end of engine, maybe $500 more.  Miata engines are not tricky to assemble and it may be a good project for your son.  My son did one when he was 17 and I really didn't help him because he trusts Youtube more than me.

They aren't particularly rare motors.  Just keep an eye out and buy a direct replacement.

don't do what I'm doing and stuff a 2005 VVT motor into a 93 chassis.   By the time being nickle and dimed to death I may as well have done an LS swap.

If you check around on some of the other forums you can find <100k VVT motors with good compression shipped from overseas to your house for less than $800.

The problem is that the VVT motor brings other challenges when installing in an NA. Those may not be desired.

wheelsmithy (Joe-with-an-L) (Forum Supporter) said:

I went through a similar thing recently. Wobbly crank on a 97. It's really hard to find an engine to just pull, and slap in. They are all old/high mile.

Had it to do over again, here are my top approaches in order.

1. Buy a running parts car. Swap and go. New belts/seals/clutch/etc. After the fact, I found a $250 parts car that would have saved me thousands,

2. buy a NB engine, have the 97 head resurfaced, throw it on the later long block, and enjoy the compression bump. Note, potential minor starter issue: one bold doesn't line up. Either leave it out or swap starters.

3. full rebuild, like I did. Budget at least 3 grand, and know you took the nuclear option. Maybe you can just do the head?

Any way you slice it, finding out what you've got is the first step. Good Luck!

Why would you put the worse flowing head of an NA on an NB engine? 

I'm not following the logic here. NBs already have higher compression than the NA.

In reply to Grtechguy :

Up here in the arctic  tundra ( Minnesota ) also known as the rust belt.  Miata's that age are filled with rust holes and yet typically don't have high mileage.   They're just not fun  in the cold snowy weather . If your body is decent I'd shop for a cheap rusty relic with an under used engine up here . And combine it with yours probably be cheapest way to a good car. 

Be prepared to spend a minimum of $1200. These were my choices: 

A) rebuild old engine in the cheap and hope it doesn't blow up.

B) buy a low mile used engine and hope it doesn't blow up. 
 

C) spend $1200 down on a used NC and not have to lift a finger. 

Just a data point... car-part.com says that the closest they have record of is actually these guys in Toledo, OH, a '97 w/124k tested miles for $995.  Shipping available (or pick up.)  

z31maniac said

Why would you put the worse flowing head of an NA on an NB engine? 

I'm not following the logic here. NBs already have higher compression than the NA.

That's my preferred way around dealing with variable intake tract or variable valve timing.

In Short: it lets you use the unmolested factory computer.

Also, the variable intake tract engines are two year only, and in the highest demand of all Miata engines. Alternately, use this long block with the skunk manifold designed to fit all non variable valve timing 1.8s.

Note, I am giving an opinion, not claiming this is the best way forward. 

Variable intake tract (it's actually opening up a resonance chamber, which is pretty interesting) can be left alone with only a minor cost to the power curve or it can be controlled with a simple RPM switch. I'd have to think about the throttle body - IIRC the TPS signal lacks an idle switch on the NB but it has one on the NA and IIRC you can't swap the TBs around. I don't recall specifically, I think all of the NB into NA swaps I've done have also involved programmable engine management.

The 1999-00 engines had the highest mortality rate, the shortest production run and are the easiest performance upgrade to swap into other cars. So yeah, they're highest price. If you do buy one, pull a cam cap or two and look for damage. They are known for having thrust bearing problems (usually happens before 30k) which will basically destroy the engine starting with the cam journals.

John Welsh said:

Just a data point... car-part.com says that the closest they have record of is actually these guys in Toledo, OH, a '97 w/124k tested miles for $995.  Shipping available (or pick up.)  

This is clearly the best way forward

Well,  Supposed to go look at the car today.   The asking price is 1200.    How low should we lowball him?   

No idea why the seller is claiming "Blown Engine"

$1200 is a good price. Just a few months to spring and you could double your money, even still not running (assuming things like low rust and decent soft top and interior.) 

Judge the car on its overall condition and then be prepared to drop $2k more into making it great. 

In reply to Grtechguy :  Did you get the $1200 Miata? I know it's hard to stop a son from buying their first car, no matter how bad the car is.