Suzuki DF60

Torque of the town

De-rated from its DF70 counterpart, the DF60 uses the same relatively simple Suzuki Sierra powerhead that has two valves per cylinder and a single belt-driven overhead camshaft.

Fortunately, it is a non-interference engine so if the camshaft belt breaks the valves won’t contact the piston crowns.

As with its more powerful counterpart, the DF60 has sequential multipoint EFI that automatically alters the air/fuel ratios according to barometric pressure, enabling the engine to run as efficiently on high altitude lakes as it does at sea level. The EFI also provides true turn key starting hot or cold and the engine warms quickly from cold, settling down to the normal 700rpm in or out of gear in a couple of minutes from cold.

Because it is a de-rated engine, the DF60 is substantially heavier than its Yamaha F60C competition and is best mounted on forward control runabouts where helm and passenger weight forward counter the transom weight, rather than cuddy cabins and centre consoles where passenger weight is biased aft of amidships. And, in my opinion, it should be used only on hulls that have full-width transom pods designed to take the weight of four strokes compared to direct transom-mount hulls which are better suited to lighter carbie and DFI two-stroke outboards.

In July, I tested a DF60 on a Blue Fin 475 Weekender runabout that had plate alloy topsides – the same hull I had tested a carbie two-stroke Tohatsu M70C on a month earlier. Despite the additional 50kg on the transom, the DF60 performed almost as well and was very fuel efficient. The demo DF60 started instantly hot or cold and didn’t blow any oil smoke and, providing the anti-ventilation plate was kept at least three quarters immersed, power astern was good. The four-cylinder powerhead was smoother across the entire rev range than the three-cylinder M70C. At wide open throttle, the Suzy was also quieter, allowing us to have a normal conversation at the helm.

Spinning a 15-inch pitch Suzuki alloy prop and pushing 810kg, the significantly under-propped demo DF60 averaged an almost silent 4km/h and 700rpm when trolling using 0.8lt/h. It achieved a clean plane at 24.4km/h and 3200rpm, whereas pushing 780kg and spinning a 15-inch Tohatsu alloy prop the M70C-powered hull planed at 26.2km/h at the same revs. Cruising quietly at 4000rpm, the DF60 averaged 34.1km/h and 7.8lt/h, compared to 36.1km/h and 11.5lt/h. Through full-lock figure of eight turns at these revs no prop ventilation occurred. We averaged 44.5km/h at maximum recommended cruising revs of 5000. The WOT averages were 54.7km/h and 19.1lt/h at 6000rpm, compared to 55.6km/h and 27.6lt/h at 5800rpm for the Tohatsu.

Having such a greater piston displacement than the Yamaha F60C, the DF60 produces a lot more torque. Spinning a 13-inch Yamaha alloy prop and mounted on a Horizon 4750 Seabreeze bowrider and pushing 800kg, the demo F60C trolled at 4km/h at 700rpm, using 0.8lt/h. It planed us at 20.8km/h and 3500rpm. Cruising at 4000rpm, it averaged 31.4km/h and 7.7lt/h, while at 5000rpm we averaged 43.3km/h. At WOT, the averages were 50.1km/h and 19.2lt/h at 5650rpm, so the F60C performance does not match the DF60 on comparable hulls.

Powerhead access is good and the engine oil dipstick is easily reached. Recommended servicing intervals are every 50 hours or six months after the first service at 20 hours. The waterpump impeller should be replaced every 100 hours or yearly.

The DF60 meets CARB 2008 exhaust emission requirements and for recreational usage the warranty is five years.