NA8 intake manifold on NB8A?????

jonosx · Postby **jonosx** » Wed Sep 22, 2010 8:37 pm

Ok..so continuiing the saga..

Mazda Australia have confirmed that it is not the original engine.

The engine number definitely starts with BP and is on the passenger side of the block, which makes me think its a 1.8.

On the back of the head, under the coil packs the head has "BP05-11-1"

According to this site http://www.solomiata.com/Mx5Engine.html it should have BP4W.

Any other ideas?

Could it be from an astina or similar???

JBT · Postby **JBT** » Wed Sep 22, 2010 9:20 pm

When Mazda say it is not the original engine, they probably mean it has been replaced but, in your case, with an engine from an NA. It begs the question - why such a dodgy fix?

jonosx · Postby **jonosx** » Wed Sep 22, 2010 10:05 pm

JBT wrote:When Mazda say it is not the original engine, they probably mean it has been replaced but, in your case, with an engine from an NA. It begs the question - why such a dodgy fix?

Who knows...

But how can it be an NA engine as there is no cas on the back of the head and it has the cas at the front as per NB???

but wait..i'm confused...

JBT · Postby **JBT** » Wed Sep 22, 2010 10:47 pm

Maybe the head was swapped too - all too confusing.

manga_blue · Postby **manga_blue** » Thu Sep 23, 2010 10:55 am

I think Matty picked it, remember he lived in Unzud. Here's a pic of an NB6 from a used car ad there.

NZ NB6 01.jpg

jonosx · Postby **jonosx** » Thu Sep 23, 2010 11:16 am

The NB6 engine number is B6###.

The general consensus from mx5 mania and mx5 plus is that its an na8 engine that has been fitted with the bits required to make it work in the nb from the original engine. (The original cam cover, cam position sensor, inlet cam sprocket, throttle body, crank angle sensor, exhaust manifold, knock sensor, coil pack)

Anyway..on the hunt for a new (proper) engine now, so if you know of one...

Locutus · Postby **Locutus** » Thu Sep 23, 2010 11:33 am

jonosx wrote:Anyway..on the hunt for a new (proper) engine now, so if you know of one...

why?

sure it's pretty weird but if it's road registered, the numbers match with your rego papers, and if it works...

jonosx · Postby **jonosx** » Thu Sep 23, 2010 12:01 pm

Locutus wrote:
jonosx wrote:Anyway..on the hunt for a new (proper) engine now, so if you know of one...

why?

sure it's pretty weird but if it's road registered, the numbers match with your rego papers, and if it works...

Well for one, i'm sick of the engine light coming on all the time as a result of there being plugs that arent plugged into correct sensors or nothing at all.

Plus i dont think the NA8 engine works partucuarly well with the engine management from the NB. It seems to be running overly rich and not as well as it should.

Plus its just not right....

93_Clubman · Postby **93_Clubman** » Sun Sep 26, 2010 5:52 pm

jonosx wrote:Ok..so continuiing the saga..

Mazda Australia have confirmed that it is not the original engine.

The engine number definitely starts with BP and is on the passenger side of the block, which makes me think its a 1.8.

On the back of the head, under the coil packs the head has "BP05-11-1"

According to this site http://www.solomiata.com/Mx5Engine.html it should have BP4W.

Any other ideas?

Could it be from an astina or similar???

BP05 on the back of the head means it's a BP 1.8 head, which were used in '93-'97 MX5, & 323/ Astina & Laser of roughly the same period. Whereas the NB8A head will have BP4W on the rear. The BP engine is also longer than the B6 engine of the the NA6 &, by the look of the NZ NB6, the NB6. Recall reading, in Keith Tanner's book I think, that there could be problems with forward compatibility, but would've thought if they had access to the old NB8A engine & accessories it could be made to work ok, although it won't have the same power as the NB8A engine.

Matty · Postby **Matty** » Mon Sep 27, 2010 11:42 pm

manga_blue wrote:I think Matty picked it, remember he lived in Unzud. Here's a pic of an NB6 from a used car ad there.
NZ NB6 01.jpg

I've got a similar pic in James Taylor's "Mazda MX-5 and Miata 1989-1999"
It doesn't exactly match the original photo - notice for example that the coil pack bracket is on the other side, and the shape of the manifold is slightly different.

At this point I'm guessing it's a NA8 motor with an NB cam cover, and probably NB cam pulleys (with the hall effect sensor), and the blank plug swapped in place of the NA8 cam angle sensor.

It was possible to put an NB head onto an NA8 block and swap the cam angle sensor, so there's no reason the reverse shouldn't be physically possible.