'99 engine in a '97?
 

Been searching, but can't find quite what I need and figured someone here would know. Since the turbo project is taking so long, and all my funds, I need a quick/cheap fix for my beater daily. The daily is a '97. I have the chewed up head from my '99, but the bottom end of the daily is dying. Possibly the top. I've found a local '96 engine that has been sitting a year for $550. Also waiting on word about a '99 engine. Question is will the factory '97 ecu handle the '99 stuff?

Here is what I've figured on swapping the '99 motor in
-swap in the CAS
-I have spare square top so screw the VICS :giggle:
-fuel rail swap or mod. Not sure which I need to do. '99 is returnless
-compression difference, or extra flow going to be too much for factory ecu?

Or get the '96
-Keep the block and slap on the '99 head/square top
-see all previous issues except the compression difference

Current car mods
-Cone filter
-cheap exhaust
-cause daily beater and been dumping money at turbo car


No funds for a MS anything really. Lucky to swing the engine with wives laptop iffy, Jeep axel work, new MTBs, low income months lately, etc. Might sell the street bike soon, but not banking on that money. Not a fan of counting eggs before I burn bridges.

Yes it will run it, you will need to put the NA throttle body on the NB intake, no worries it bolts right on. You'll need the CAS. The NA8 intake kind of somewhat lines up with the NB manifold and stuff. I know my custom one worked on both but the stock one might not have enough slack. I cant say for certain on the fuel rail because everyone keeps arguing about how what fits and what not, I just used the M-tuned one.

Intake pipe I can work around. Probably have some Vatozone pipe laying around somewhere. Fuel rail may be the headache. I will attempt this over a weekend since it is my daily and may be the wives here soon (yay 30mpg). I can be down a vehicle since I have two. Just not for more than a few days. Stock ECU can compensate though?

Fuel Rail between NA/NB1 is incompatible. You'll need the NB fuel rail for the NB head. Don't worry about running returnless, the NB fuel line has a block off plate where the NA FPR can be bolted, but you'll need to bolt the FPR inverted in order to clear something; what exactly, I forget.

The intake manoifold is also car specific, NB head requires NB manifold. The bolt pattern is the same IIRC, but the gasket will not line up because the NB intake ports are angled much steeper than the NA ports.

Additionally, you may have a headache with EGR as the EGR system is different between NA/NB, most noticeably on the exhaust side. I don't know the differences on the intake side.

For the simplest swap, just put the 96 engine in. There is probably little use in putting the 99 head on the 96 block as the blocks are pretty much identical.

On my 99 swap I used a 99 fuel rail with the NA fpr. It ends up looking funky but works. This works fine with the oem intake manifold as well but I dont have a good pic of it.

https://www.miataturbo.net/attachmen...ine=1376424117

With whatever you do the factory ECU will be fine. I would not sweat that part at all. I would personally go with the 99 swap with flat top IM.

EGR is a very good point. I do not believe that the Square top manifold has any sort of EGR port on it. With sticking with OBDII compliance you will have to figure this out to not trip a CEL. If you do not have emissions and do not care about that CEL, you can just put a cap on the exhaust manifold to cap it.

That is a picture of the correct fuel rail. It is from a 99/00 that has the FPR flange up front. Hook up your stock FPR and run the line and it will work fine.

Square top has the EGR connections, the JDM manifold comes with blockoff plates installed the EDM has an EGR valve fitted.

Interesting, I thought I had seen pictures with nothing on the back there. If it is there then that is one less thing to worry about. Might have to get some adapters to make it fit, but doable.

To be honest I've been living in ignorant bliss and not doing a compression test. Well I figured I'd do one for fun.
Comp numbers
Cyl 1- 200psi
Cyl 2- 196psi
Cyl 3- 201psi
Cyl 4- 204psi
https://www.miataturbo.net/attachmen...ine=1376449846

I'm not brilliant at reading plugs
https://www.miataturbo.net/attachmen...ine=1376449846
https://www.miataturbo.net/attachmen...ine=1376449846

The engine smokes under load/open throttle above 5k rpm. Black and enough to see out the passenger side mirror. It eats oil if drive fun. Sips it if drive gingerly. Since it seems the bottom end is is okay maybe swap heads?

Things needed for 99+square top swap to 97 block
-ARP head studs (reusable if all goes to hell and sorta cheap)
-'99 fuel rail (actually don't have that)
-head gasket
-lap valves
-new valve seals
-make sure EGR connects up
-head gasket
-screw real machine work and slap them together and sacrifice a leprechaun for luck.

Stupid double post

The 97 throttle cable will be too long. You will need to relocate the throttle cable bracket further out or buy a 99/00 throttle cable.

I wouldn't bother taking heads off. IMO, taking a head and putting it back on without machine work is stupid when using a MLS gasket. Clean, flat surfaces are critical for MLS sealing.

^meh you're right. Probably a stupid question, but surface the head only maybe? One way or another I'll remove the head to fix the valve seals. Once again can't find the "check for valve seals leaking" info. I can do a leak down if I drive an hour to a compressor. Just not sure how that would check for valve stem seals. Or is there any way the rings could be toast with a 200psi comp test? Still confused how it smokes under heavy throttle/high RPM, idles ok, burns oil, misses a bit if giving it the beans and going uphill, etc with good compression. Plugs aren't black from oil, but they are nasty so might be the missing under load problem. Both the PCV (323 type) and vent are okay. Thought the vent was clogged, but pulled valve cover today and all is well.

Huh? News to me. Did they shorten throttle cables in 97? My '94 throttle cable bolted right into place.

OP, a good privately owned aluminum head shop will renew the head for you for only a couple hundo max. Excluding possibly the HLAs. I'd still just do the '99 swap though. Since your car still runs (although oily) you have time to replace seals/rings/etc. on a '99 long block. Then bolt it in and drive. If the price is a showstopper, then do the same thing with the '96 block - just make sure to offer him $300 or less for it.

My 94 TB was acceptable on the VICS manifold with the stock throttle body, but not tight enough to my liking. For a daily driver its fine, for someone who wants the cable just taught at idle for ultimate pedal control its unacceptable. Putting the skunk TB on spaced the TB out enough that the 94 cable can be taught.