17 replies to this topic

[ChrisS]

Guys I am new here and I have searched the archives with no satisfaction. I just picked up a nice 94 spec Miata. I got the GCR and went over it and over it. I new I needed a 1.8 motor. I did not realize the major issues inthe two 1.8's. I got a good 1.8 and trans. I installed it today and now I see the harness has extra or missing sensor plugs. The owner said it came out of a 2000 model. I want to be able to run in SM class. I thought about FP but I think that will be out of budget. Do I need to get a new motor to get running and legal?

[38bfast]

Yes, You need a 1.8 from 94-97 model years.

[ChrisS]

well crud.That is waht I thought. Looks like I will be taking it out tomorrow and on the search for a 94-97 complete. Man over looking or not understanding completely is frustrating. I have learned alot today.

[Ron Alan]

NA and NB 1.8's are very different motors...though not visually. When looking for the NA motor try and find a 94 or early 95...only because mid 95-97 are OBDII motors which could have a few slightly different plugs(I think?) if you use more than just the block and head(with all the bolt-ons from your original motor)

Good news is you wont have any problem selling the NB motor!

The only thing your car came with originally that you can't use(In SCCA)is the diff. If it hasn't been done already you'll have to change from 4.1 to 4.3 gear ratio. Several ways to do this...you can search and find several threads on the subject. Good luck!

[Keith Novak]

Be forewarned, since you do have a NA 1.8, sometime in the middle of `95, some stuff changed so 94-97 parts are not 100% compatible with one another like coils.

[ChrisS]

Thanks guys. I am pulling it out today and will be on the search for a motor. I will list the motor I have here for sale soon. Thanks again for the help.

[ChrisS]

Guys let me know if i need to continue my question in another post or area. I am still lost a bit. from what I can tell the 1.8L from 94-97 are the same motor but others have said I need to get the 94-early 95 motor. If I can not find a complete drop from a 94-95 what should I expect if I get a 96 or 97 motor? I want to try to run SM in 2012 or sooner.

[Keith Novak]

The complete motor from any 94-97 will drop right in. The longblock is the same. If you unbolt the stuff from your current engine, it will all bolt right on and you'll be legal. The early cars do have some electrical differences so if you use say one from a 96 and it has other parts still on it, you can't plug the later coil into your wiring harness. Most of the parts are good for all those years though.

[Ron Alan]

What Keith said and I mentioned above...not very clearly

As long as you have your original motor and all the bolt-ons...buy any 94-97 1.8 and you'll be fine.

[davew]

99+ engines have lots of different things, intake, exhaust, injectors, electronics. Unfortunately your 2000 engine is not usefull for your car. But it still has plenty of value to the right person.

The electronics actually have 3 versions; OBD1, OBD2 and OBD1.5. most 94-95 cars have OBD1, but a few late 95's had a hybrid system. ECUs will not interchange. All 96-97 cars have OBD2

On the mechanical side, the only difference is the lack of a timing wheel on 94-95s and the bolt hole for the crank pickup (used for OBD2) is not threaded on an OBD1 engine. The hole is there, just not threaded.

For your purpose, any 94-97 engine will work, just transfer your manifolds and accessories to the new long block

Dave

[FTodaro]

NA and NB 1.8's are very different motors...though not visually. When looking for the NA motor try and find a 94 or early 95...only because mid 95-97 are OBDII motors which could have a few slightly different plugs(I think?) if you use more than just the block and head(with all the bolt-ons from your original motor)

Good news is you wont have any problem selling the NB motor!

The only thing your car came with originally that you can't use(In SCCA)is the diff. If it hasn't been done already you'll have to change from 4.1 to 4.3 gear ratio. Several ways to do this...you can search and find several threads on the subject. Good luck!

I don't have a 95-97 but is this true that in all cases the stock diff has to be swapped our or are you saying you are allowed to upgrade??

[Keith Novak]

I don't have a 95-97 but is this true that in all cases the stock diff has to be swapped our or are you saying you are allowed to upgrade??

Frank,
The'94-97 came with a 4.1 diff. All the other years came with a 4.3. A rule change last (?) year required all years to run a 4.3 so the 4.1 equipt cars only have to swap gears.

[Ron Alan]

Last year you could change the 1.8 cars to the 4.3 rear end...or keep it 4.1. This year all cars have/had to run 4.3

Changing ring and pinion(gears)is one option...easiest and cheaper usually just to find a NB open diff and stick your torsen in it!

[Blake Thompson]

Frank,
The'94-97 came with a 4.1 diff. All the other years came with a 4.3. A rule change last (?) year required all years to run a 4.3 so the 4.1 equipt cars only have to swap gears.

This is correct, and after putting a 4.3 in my fiance's car she dropped 1.5s/lap at small and big tracks. SOooooo it's in your best interest as far as I can tell

[Keith Novak]

This is correct, and after putting a 4.3 in my fiance's car she dropped 1.5s/lap at small and big tracks. SOooooo it's in your best interest as far as I can tell

That sort of depends IMO. On one track here, the lower rev limiter on my car compared to the 1.6 means they either shift half as much or stay on the gas longer before braking and don't run out of gear as early in 2nd gear corners.

[Blake Thompson]

That sort of depends IMO. On one track here, the lower rev limiter on my car compared to the 1.6 means they either shift half as much or stay on the gas longer before braking and don't run out of gear as early in 2nd gear corners.

I also thought it would be one way on some tracks and another on others, but Blackhawk and Road America are about as diverse as they get and she's hotter at both, now.

[ChrisS]

Thanks guys for the info. I have the motor sold and my car was bought with no motor so I can not swap manifolds and other things. I am now searching for another complete car to use for parts or just a complete motor. I have the car getting painted while I search. I guess I better tear open the diff. The last time mine was on a track was 2004. Run by Robert Lloyd. I will search forums to figure out if I have a 4.3.

[Ron Alan]

Thanks guys for the info. I have the motor sold and my car was bought with no motor so I can not swap manifolds and other things. I am now searching for another complete car to use for parts or just a complete motor. I have the car getting painted while I search. I guess I better tear open the diff. The last time mine was on a track was 2004. Run by Robert Lloyd. I will search forums to figure out if I have a 4.3.

No need to tear open the diff. Spin the drive shaft until a tire makes one full revolution. As you do so count the number of times the drive shaft rotated 360 degrees. If it is right at 4+ the diff is a 4.1. 4 and about 1/3 more turn and it's a 4.3. If you do break the diff apart count the teeth on the ring gear...it's going to be either 41 or 43. The pinion gear will have 10 teeth. If by chance the pinion gear has 11 teeth and the ring gear 43, this is a 3.9...this is unlikely though possible. Call Eaststreet for motor and diff...guarantee he has what you need.