Maruha Mahle Custom Piston Mazda MX-5 Miata

Maruha has been ordering pistons from some American piston makers and some domestic ones.

We still keep good relations with American top companies, but now we would like to introduce our latest pistons for 1800cc (BP) by Mahle.
These pistons are the result of the collaboration between Maruha and Mahle Motorsports.
Maruha is in charge of the basic design and tests, Mahle has the final profile and production.

By the engine dyno tests we develop the best engine performace with Mahle pistons.
This engine has 230HP over /7600rpm.
Garage Hundred One with Maruha engine got the best time on the Tsukuba Circuit on Dec 2006.

Mahle is one of the top piston maker companies in the world.
Through the cooperation with Mahle we got these special pistons for Miata BP engine.
We have a confidence in these pistons.

Maruha Power Piston for 1800cc (BP) / Features

1. Forged piston.

We use forged aluminum (4032), and we applied Phosphate Coating and Grafal Coating on the outside and the inside.
The end product is very strong and very smooth.

2. Calculated precision machining.

These pistons are produced in the same way using the same material and the same machining as the top racing engines for formula and GT series in the world.
Every part is designed for suitable size, has good endurance against thermal expansion.
And very smooth stroke by the suited skirt length to keep a good condition against oil consumption.

As for the intake side, no-trench to get more air.

3. Pin offset

Maruha power pistons are adapted to pin offset position.
Off set pin can reduce flap sound and make the engine become very silent.
Pin OD is 20mm, the same as stocks, using them with stock rods is possible.

4. the latest 3D profile

Maruha power pistons are designed by 3D profile.

Oval machine processing and barrel- type machine processing, these high-level precision skills are the source of our pistons.
As you know, pistons always move up and down with shaking piston top.
Maruha 3D profile can reduce these action and carry out smooth skirt meeting to the cylinder bore.  
Piston OD is 85.5mm(3.3661") and the total capacity rises up to 1951cc.

Maruha 3D profile can reduce these actions
and carry out smooth skirt meeting to the cylinder bore. 

5. An ideal top

To get power, Maruha power piston has an ideal top form.
C/R is 11.0:1 with Maruha metal head gasket(T-0.8mm)and without any head grind.
Crown top volume is 9.0cc.
This top form is from our repeated tests.

6. Rings

Maruha power pistons also have special rings by Mahle.
1ST and 2ND rings are 1.2mm thick. Usually American rings are 1.5mm for these size pistons.
As for oil rings, our ring is 2.8mm, American rings are basically 3.0mm.
Thick rings would be a cause of friction but we would like to avoid any friction to make the piston's work smooth and to get more power.

This total balance leads to the piston's long life, minimum oil consumption, silent engine and more power.

7.Oil jet recess


To avoid the interference with oil jet and piston, please bend the jet nozzle.
This work is very important and wrong bending would cause serious engine damage. 


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