MX-5 Maruha Crankshaft 87mm Stroke NA8 , NB8

A good engine consists of several components such as camshafts, pistons, valves and other parts.
The most important component, the core of the whole, so to speak, is the crankshaft. Without a stable crankshaft, a good engine tuning is not possible. The length of the crankshaft support is usually not enough.
The oil pump, timing gear and pulley hub are attached to this mount and secured by the center bolt. The problem is the remaining space after the timing belt gear is installed.
This remaining space is used to secure the pulley boss, but is only 6 mm on a normal crankshaft. The heavy front pulley is attached to the pulley boss, which is relatively insecurely attached to the only 6 mm of space. The belts for the alternator, air conditioning and power steering are tensioned from the right and left sides and attached to the front pulley. The vehicle must be operated with this load for thousands of kilometers. All this load must be held by the only 6mm space.  The Maruha original crankshaft has been machined so that 14mm is now available to hold the pulley hub stably and securely. As a result, an extended service life can be expected. The special revised Maruha original crankshaft is over 1000grams lighter than the original crankshaft. An improvement in responsiveness can be expected.
The stroke of the original crankshaft is 85mm.The length from the center of the crankshaft to the crankpin is 42.5mm.Therefore, the stroke distance per stroke between top and bottom becomes 85mm. The stroke length of 87mm (43.5mm x 2) Maruha original crankshaft is also available. If you want to increase the exhaust volume, then 87mm stroke Maruha original crankshaft is recommended. The wobble radius is 1mm longer with an 87mm Maruha original crankshaft than with the original crankshaft. When using an 87mm Maruha original crankshaft with the original pistons and connecting rods, the top position of the piston (top dead center) is 1mm larger than the original. The use of +1mm thicker gasket is easily adjusted to this 1mm protrusion of the top position of the piston. Not only any size of pistons from MAHLE, but also the products of other manufacturers can be used. In addition to the method of absorbing the +1mm at the cylinder head gasket caused by the 87mm crankshaft, MAHLE's new 85.5mm design piston (for the exclusive BP) has been introduced.
The profile is the same as the conventional type, but the pin height is shortened by 1mm for adjustment. With the matching Maruha Mahle piston set MAR21020610 a displacement of approx. 1997ccm can be achieved.

The cylinder head gasket is available as usual in 0.8 mm or 1.0 mm thickness.
Please note:
Suitable for all Mazda MX-5 NA , NB , NBFL with 1.8 Ltr engines ( NA8 & NB8 ).
Maruha recommends the use of the items used under accessories