NB8C (later model) Oil baffle kit for Mazda Miata NA8C/NB8C (early model)

The 1.8L BP engine is different in the case of NA8C/NB8C (early models) and in the case of NB8C (later models).
In the case of NB8C (later model) the piston’s compression is higher, it is set up with variable valve timing and the engine’s output is better too.
The crankshaft’s baffle plate and the oil pan have changed too.
In other words, the oil baffle is different from that in NA and NB (later model).

Plate for NB8 (later model): high rigidity

Attention is especially on the oil baffle plate on the crankshaft side.
Unlike the NA models, in which 1 plate has been pressed in the case of NB8 (later model) the crank cap part is three-dimensional.
The plate’s thickness is different and its rigidity is quite high.

Left: we put the crankshaft and piston together
Right: then we set up the NB8 (later model) plate and connect it to each crank cap

The number of the crank caps that fix the crankshaft is 5.

In the case of other makers these crank caps are being called "ladder beam" and are being united or connected in the form of a beam aiming for rigidity.
The crankshaft’s rotation is the engine’s pillar. It secures smoothness, better rigidity and better oscillation-suppression.
To get this result, we must fix the crankshaft properly.

However, in the case of NA8C and NB8C (later models) there is no such a setup.
Using the crank baffle and oil pan of NB8C (later model) we achieved a better block rigidity. Furthermore, Maruha created an oil pan – baffle kit and stabilized the oil control.

The number of the crank caps is in total 5. We use 4 of them with special bolts and connect them to the baffle plate.
The tip of the baffle plate is being fixed in between the block and the oil pan. Like this the whole block becomes stronger.

Left: the setup of the clutch cap at the plate’s inner
Middle: from the surface we can see the special bolt
Right: the special bolts for fixing – altogether 8 pieces are needed

Important points

 A premise is the female screw used for fixing on the crank cap’s side. However, note that there are cases, when these screws might not be obtained from the parts catalogues.

 NB8C (early model) ・・・serial number N8C – 100 000
NB8C (later model) ・・・serial number N8C – 200 000~
 In the case of using a later model oil pan, the oil pan seal too is a later model.
Note, that in the case of NA or NB8 (later model) the seal’s shape is different.
 For the oil pan conversion no further processing is needed, it just has to be connected.


Maruha Motors Co., Ltd.
Ushizuma 2095-6, Aoi-Ward
421- 2106 Shizuoka city, Shizuoka prefecture
TEL: 0081-54-294-0076
FAX: 0081-54-294-1312
E-mail: info@maruhamotors.co.jp