Exhaust Piping

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The Datsun 1200 used a 1-1/2 inch exhaust system. The cast iron exhaust manifold has a flat two-bolt flange. A donut-type asbestos seal was used to connects to the exhaust pipe, which extended past the rear axle. Finally a very, very quiet muffler with a short tail pipe was suspended by two rubber rings.

muffler with integrated pipe
Bottom (old) is the factory piece

A12 GX engine (twin carb) models used a quieter exhaust with a small resonator as well the regular muffler:

Notice is also used a cast header with dual outlets.

Sizing for Performance

A large diameter exhaust pipe is needed for maximum high-rpm horsepower. However, a small diameter pipe is needed for low-rpm horsepower. So you can see that a properly sized pipe -- not too big or too small -- is advantageous.

Single Exhaust

• Stock 68/69 horsepower A12: 1-1/2"
• lightly modded A-series engine: 1-3/4"
• 100 hp engine: 2"
• 150 hp engine: 2-1/4"
• 200 hp engine: 2-1/2"

Of course you can vary this. For example:

• The larger the engine relative to your car, you can get away with a larger pipe. Although the larger pipe cuts down on low-rpm horsepower you have a big engine so it's not so bad. This increases high-rpm (peak) horsepower
• For better street driveability, go a size smaller
• For drag racing where it is flat-out full throttle, a larger size may work fine