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Revision as of 08:23, 16 January 2013

The Mazda rotary engine is a good match for Datsun 1200 -- it is light and compact. It makes more power than a piston engine of the same size and weight. The engine weight is down low so it doesn't interfere with good handling.

1 Performance
2 Discussions
3 Engine
4 Engine Mounts
5 Oil Pan
6 Transmission
7 Differential
8 Exhaust
9 Photo Index

Performance

Typical engine power in stock form:

12A: 100-130 HP, 100-115 lb. ft. torque
13B EFI: 135 hp, 133 lb. ft. torque
13B-Turbo (1987-1991 "Turbo II"): 185-200 HP

Quarter Mile acceleration performance ranges from quick to insanely quick. With a totally stock rotary engine you won't be wanting for power.

19.8 secs at 65 mph: Stock Datsun 1200 piston engine (baseline)
16.1 at 90mph: bone stock 12A rotary engine tuned by ear
Ange's 13.7 second 12A bridgeport
JVML's 8.1 second 13B twin turbo

Rotor Power

Discussions

Engine

The Mazda rotary comes in two common sizes: 12A and 13B. In Australia, choose a 12A for street legal swaps. Everyone else, choose the 13B. There are less common versions, the old 10A and the ultra-rare and expensive 20B triple rotor.

12A

Mazda 13B carbureted

13B Fuel Injected

Mazda 13B Turbo rotary engine

Factory EFI 13B Turbo

13B Turbo with factory intercooler

20B triple rotor

Engine Mounts

Front Mount

Most use the front-mount case. If your rotary doesn't have it, you can retro-fit it using a 12A timing cover (which fits on 13B).

Side Mount

Cut out about 10mm out of the standard 1200 crossmember and brace it. Weld new custom-made brackets.

Mad Dat 13BT Fitting Kit allows the newer-type rotary engine side mount, their crossmeber curves down so the top of the cross member is lower.

Motor Plate

For racing a motor plate can be used. Not recommended for a street car as it transmit vibration directly to the body.

Oil Pan

Use the Moroso oil pan for Datsun 1200.

Transmission

Use the transmission that comes with the rotary engine (the Mazda transmission).

Driveshaft

A custom driveshaft to mate the Mazda transmission with your differential will have to be fabricated. Any driveshaft shop can make this for you.

Shifter

A new shifter mount hole may need to cut? Look into doing the shifter extension mod otherwise your shifter will be a little bit to far back for comfort (it will sit in between the front seats right in front of the handbrake).

Transmission Mount

Mount the gearbox the with a similar bracket to ca18 one.

or make a new gearbox crossmember:

Tunnel

Some fabricate a large tunnel. Is it necessary, or just used with beefy racing transmissions?

In any cause, you'll have to make the tunnel higher through the middle and make space for the clutch fork, or cut a hole for the clutch fork.

Alternatively you can fit an aftermarket hydraulic throwout bearing to replace the clutch fork.

Differential

The least 12A engine outputs 100 lb. ft. of torque. The stock Datsun 1200 H145 diff can handle that.

But many 12A put out 115 lb. ft. of torque, which calls for a stronger diff. The H150 from a B210 or B310 can handle this.

Stock 13B engine calls for an H165.

Any modified rotary (especially if the turbo boost is raised) will need a stronger differential, such as a Nissan H190. Drag racing versions need the ultra-strong Ford 9".

See: Rear Axle Swaps