Over three years ago, Suzuki broke new ground in outboards when it introduced its DF350A, which featured contra-rotating propellers seen previously in sterndrive applications. The dual-prop setup creates more bite in turns, better handling around docks, and a quicker hole shot when climbing onto plane. It also negates the need for left-or-right spinning arrangements in multiengine installations. This fall, Suzuki released its latest powerplant to feature twin props, the DF300B.
“We have had a lot of requests to offer the Suzuki Dual Prop System in 300 hp,” says Dean Corbisier of Suzuki Marine. “Many of the boats that customers are repowering are rated at a 300, 600, 900 or 1,200 hp max rating. So, with that, the Suzuki engineers redesigned the DF350A powerhead to create a max of 300 hp. This was accomplished by lowering the compression ratio and programming the ECM (engine control module).”
Like the DF350A, the DF300B is a V-6 with 267.9 cubic inches (4.4L) and an operating range from 5,000 to 6,200 rpm. And like the 350, the DF300B is meant to push heavy boats in either single or multiple-engine rigs. The DF300B has a 10.5-to-1 compression ratio, as compared to a 12-to-1 ratio for the DF350A. It features two fuel injectors per cylinder, which helps keep the fuel cool and allows for more precision in the delivery, as well as a more efficient burn. The direct-air-intake system also helps to keep the engine cool and prevent knocking. The engine is designed to run on regular 87-octane gasoline.
Suzuki’s lower unit features a two-stage gear reduction from the powerplant to the props, first between the drive shaft and the crankshaft, and then within the gear case in order to achieve the 2.29-to-1 gear ratio at the props. This, along with the contra-rotating propellers, helps the DF300B achieve quick acceleration and higher fuel efficiency at cruising speeds, as well as at the top of the rpm range. The two-gear reduction also allows for a more compact, streamlined gear case that reduces drag.
Read Next: Suzuki DF350A
We’ll test a DF300B soon. For now, Suzuki provided test numbers from a Premier 310 Accolade with twin DF300s. At 3,000 rpm, the Premier hit 22 mph at 2.2 mpg. At 6,200 rpm, it reached a top-end of 48.5 mph at 0.9 mpg.
As with the DF350A, the DF300B will be available with 25- and 30-inch shaft lengths, weighing 727 or 747 pounds, depending on the model. As of press time, the retail price was still not available.
