Light It Up

Steyr’s new small-block diesel

Lightweight, high-performance diesel engines have become ubiquitous in the last five years, often replacing gasoline engines in small- and medium-size fishing boats and cruisers. What do these traditionally gas-powered boats gain by burning diesel instead? Increased range, enhanced safety, and a higher retail price are the primary benefits.

This market segment is dominated by Cummins MerCruiser, Volvo Penta, and Yanmar. Into the fray comes Steyr Motors, an Austrian company with 80 years of marine diesel experience in Europe. How does Steyr compare to the established big three? Based on a comparison of specs for the popular 240-bhp diesel stern drive range, we predict it will give the others a run for their money-especially in the important horsepower-to-weight ratio and alternator output categories.

In equal boats, a higher hp/wt. ratio provides better performance. Steyr achieves its lightest-in-class rating by using what it calls a Monoblock alloy engine block, chromed molybdenum crankshaft, and silicon aluminum cylinders. Alternator output is important for keeping your batteries charged as well as for running all the sophisticated navigation and engine electronics crammed into today’s boats.


Other features include electronic control for better diagnostics, more precise combustion, and the ability to display functions such as fuel burn at the helm. An engine’s configuration indicates its relative physical dimensions as well as how hard each cylinder has to work. For instance, an in-line-4 configuration will fit in a smaller space and provide better serviceability than an in-line-6, but its parts work harder to make the same power. Also, if the cylinders are wet sleeved, the engine is often less expensive and easier to rebuild. Dry-sleeve-parent bore or bore-in-block-engines are known as throwaways in repair circles, because rebuilding them isn’t usually feasible. Steyr claims that its Monoblock, though dry-sleeved, is more robust than others. (Bear in mind that the mean time to rebuild for high-speed, modern diesels averages 3,000 hours.)

For reference, I’ve compiled a chart comparing the 239-bhp Steyr MO246 with its closest competitors in this market segment. All four engines are available with stern drive, V-drive, jet drive, or conventional straight-shaft drive trains. All are suitable for repowering a gas boat.

Steyr motors are sold and serviced nationwide through their distributor, Stewart and Stevenson, in Florida. Contact 888/567-5490,

Volvo Penta KAD44P Yanmar 4LHA-STZP Cummins 4B-250 Steyr MO246
BHP 248 240 240 239
Weight 968 855 1,001 708
Alt Output 60 amp 55 amp 60 amp 90 amp
Elect. Control Yes No No Yes
Configuration in-line-6/wet in-line-4/dry in-line-4/dry in-line-6/dry