yes the GX was a "performance model" only sold in Asian markets (and in South Africa). It had a factory twin-carburetor 1200 motor.

The GX block was normal, but most were fitted with flat-top pistons instead of dished pistons for increased compression.

The other changes for GX were all in the induction system: twin carbs, large-port cylinder head, slightly higher-RPM camshaft, and freer-flowing exhaust manifold.

Don't know if you can use any of that in your class. Maybe the flat-top pistons, which you can find in any old Datsun 1000 Coupe engine. You know that alone should be good for 1-2% increase in power.


Comparing the A12 engine to other 1200cc engines you're allowed to use (Toyota 3K). It was not a particulary high performing engine. However, the Nissan A12 was lightweight for the time (aluminm cylnder head), super reliable and super simple to work on, a "pushrod" engine. Original engines are still going strong 35 years later. Mine is an original, never rebuilt engine, daily driver. But it seems the 3K is the same, also a pushrod engine, with exactly the same rating of 68 HP as the Datsun A12 engine.

If you are allowed to use a non-stock carburetor, fit a single Weber 36/36, that should increase performance notably.