Suzuki DF70

Released five years ago, the DF60/70 is based on the 1.3lt Sierra 4WD engine but fitted with multipoint sequential EFI which automatically alters the air/fuel ratios according to barometric pressure, allowing the engine to run as well on alpine lakes as it does at sea level. And although the eight-valve DF60/70 is the most basic of the Suzuki four stroke range above 40hp, it complies with EU 2004 exhaust emission regulations - currently the DF60/70 and the DF90/115 are the only outboards to do so.

Features include a 25 amp under-flywheel alternator compared to 16A for the Honda BF75 and computer diagnostics to monitor operating problems. The deep ratio gearcase allows coarse-pitch, thrust-efficient props to be swung and increases manoeuvrability when pushing heavily-laden hulls.

I first tried the de-rated 60hp version on a Suzuki FE-210 longboat in 1998 and it pushed this magnificent hull to 59kmh with two adults aboard, outperforming the 70hp Evinrude version (now a Johnson). But until driving twin DF70s on a Kevlarcat 2100 Hardtop I hadn't tried this engine in a twin-rig application.

Ultralong (25in) DF70s were spinning 15in pitch alloy props. The engines were the minimum power you'd want on this size of cat but because of the significantly lesser weight than the DF90/115 they enabled the 2100 to plane easily and return excellent midrange fuel efficiency.

The engines started instantly hot or cold and never blew any oil smoke. They warmed quickly from cold, had very low vibration levels and using the one ahead/one astern technique were able to spin the 2100 in its own length. Providing the anti-ventilation plate was kept at least three-quarters immersed no cooling water starvation occurred and power astern was good. A level hull plane was achieved by trimming one motor in slightly.

Pushing a total of 2100kg including three adults, the Suzies trolled the 2100 at 5.1kmh on 700rpm consuming a total of 1.8lt/h. Increasing the revs to 1000 returned 7.0kmh while at 2000rpm the 2100 averaged 11.9kmh. A clean plane was achieved at only 20.6kmh and 3000rpm with the hull simply lifting onto the plane instead of having to overcome the normal planing hump.

Cruising quietly on 4000 revs with slight leg trim-out (the single button trim/tilt control of both engines was a brilliant feature) the 2100 averaged 31.7kmh using 18.0lt/h total. Allowing for a ten per cent reserve this gives a cruising range of 570km from the 2100's standard tankage. Through tight figure of eight turns at these revs no prop ventilation occurred despite the hull leaning out.

With the legs trimmed well out to just before the props blew out the Wide Open Throttle average was 53.3kmh on 5750rpm consuming a total of 40.5lt/h and even with the noise amplified by the hardtop we could hold a normal conversation at the helm.

One engine could not plane this hull. With one outboard up we averaged only 16.5kmh on 3800rpm. But with one engine switched off we were still able to manoeuvre in the confines of Runaway Bay Marina.

Powerhead access is excellent with components such as the oil dipstick and spin-on filter easily reached. Recommended servicing intervals are every 50 hours or six months after the first 20 hours with waterpump impeller replacement every 100 hours or once a year.

Well-engineered and straightforward to maintain, with regular maintenance the DF70 should return a long service life.

The warranty is two years for recreational applications.