Maruha’s 4-throttle injection system in Mitsuoka 01

What do you think of when you hear the word extreme speed?

Yes, Caterham Super7!

The Lotus, so beloved by Maruha.
The Lotus 7 which Chapman thought of during his student years.
After that Lotus became a big company and Caterham obtained manufacturing rights.
The name was changed to Caterham Super 7 which became the outline of today’s Caterham Super 7.

Many years ago we got the chance to visit Caterham’s main office in Britain. We met the son of the company’s president and wanted to buy a Caterham Super 7.
However, we were advised to buy it from an official retailer in Japan.

In the end, we bought a few Caterhams and even these days there are Caterhams with Maruha’s 4-throttle injection systems running on Japanese roads.

Mitsuoka 01

All around the world, there are many cars similar to Super 7. For example, Birkin, Donkervoort etc.
Japan’s pride is Mitsuoka 01.
By using Miata/MX-5 components, it can become similar to Super 7.
Its bodyline is better than that of Caterham and even the inside is a finer design.

A light body with a B6, BP engine same as in the case of Miata/MX-5.

A few years ago we were asked to install a 4-throttle injection system to Mitsuoka 01 with BP engine. We accepted the request - The car’s one-off exhaust manifold with Maruha’s 4-throttle injection system.

Maruha’s menu was: 264°cam (IN, EX), head surface grinding, port grinding, 4-throttle injection system (40mm body)

In the case of the engine frame the funnel interferes that’s why we cut the manifold diagonally with a milling cuter and set it up 5°higher.

Now, to the power check:
Generally in the case of a BP engine with Maruha’s setup we can get around 170PS-180PS. However, with Mitsuoka we got a result of over 190PS.

Modified HP (PS) Modified torque (kgm)
Highest value 191.6 PS 19.0 kgm
Revolution 7,559 rpm 7,065 rpm

Even we were surprised by this power and couldn’t explain it with nothing else than the one-off exhaust manifold by Yoshimura.
Usually, 4-2-1 is being used for running on streets and 4-1 fits a model with high revolution. However, this can’t be always appropriate. Which means, that the best way is to try.


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