Completed Restorations

1980-83 Johnson 60

Johnson 60 shortshaft DP/SD racing motor with 1984 cowl. 53 mph @ 7000 RPM running a stock 12 1/2 x22 Booe SST60 prop on a 14' Allison. The DP record was nearly 54 mph.

We use the rig minus this powerhead to break in Hans' SST45 powerheads after they're rebuilt.

This is a mildly modified powerhead. Head was milled and sharp edges in intake passages were rounded for better flow.

The Stinger and 60 use exactly the same gearcase and propshaft. While the Stinger is geared 15:28, the 60 is geared much lower at 13:29. This accounts for the low 54 mph APBA kilo record vs. the 70.6 mph Stinger record. With the same gearing the DP record should have been about 64 mph. All this has been calculated from a scaling law.

The stock Johnson 50/55/60 tuner was 'closed end', providing a reflection that helped to clear exhaust from the combustion chamber. We cut out the flat plate so that the gearcase becomes part of the exhaust tuning, as on a Stinger.

On the 3 cyl. Stinger the gearcase provides an expansion chamber effect, a sound wave rams lost charge back through the exhaust ports just before they close. This works over a certain RPM band. No calculation was done so we have no idea if this effect occurs on the 2 cyl. 60.