Suzuki DF175 Review,Specifications,And Price Details

Suzuki DF175

words - Andrew Norton

Suzuki's DF175 is real competition to DFI two-strokes, reports Andrew Norton

Suzi's big four

Released on the Aussie market four years ago, the DF175 is the largest displacement and most powerful four-cylinder outboard in Suzuki's four-stroke lineup and is uprated from its DF150 counterpart.
The DF175 has all the features of the 150 including Suzuki's offset driveshaft, watercooled voltage regulators for twin-battery charging, chain driven camshafts and twin counter rotating balance shafts, but differs in that a continuously variable intake valve timing system is fitted. This system is also fitted to the Suzuki DF250 and DF300 and differs from Honda's VTEC in that it actuates from 1500rpm upwards instead of 4500rpm for the BF150 and BF225.
The engine breathes better across most of its rpm range and unlike the Hondas, there's no surge in the upper rpm-range, resulting in overall performance approaching that of a similar-output DFI two-stroke.
THE COMPARISONS
Up until I tested a DF175, every Seafarer Victory 6.0 I had previously tried was powered by a DFI two-stroke, whether it be a Ficht, E-TEC or OptiMax, so the demo rig supplied by The Haines Group made for a very interesting comparison.

Spinning a 21in pitch stainless steel Suzuki prop and pushing a total of 1.7 tonnes, including two adults and a full fuel tank, the DF175 was perfectly matched to this hull, which is rated to 225hp and 279kg on the transom. Trolling at an almost vibration-free 2.9kmh and 650rpm it used 2.1lt/h, compared to 4.7kmh and 1.1lt/h for an OptiMax 150 spinning a 17in prop and pushing 1.8 tonnes with four adults aboard a demo Victory.
Increasing the rpm to 2000 returned 12.4kmh and 8.0lt/h compared to 13.0kmh and 8.3lt/h for the OptiMax. A clean plane was achieved at 30.6kmh and 3200rpm whereas the OptiMax planed us at 29.7kmh but the same rpm. Spinning a 21in prop and pushing a total of 1.7 tonnes an E-TEC 225 on a Victory planed us at 32.2kmh and 2600rpm.
Cruising effortlessly at 4000rpm the DF175-powered hull averaged 44.5kmh and used 25.6lt/h compared to 48.1kmh and 25.7lt/h for the OptiMax and 61.2kmh and 37.1lt/h for the E-TEC. The lower speed at these rpm was to be expected as the DF175 develops maximum power around 1000rpm higher than the DFI two-strokes.
Through full lock figure of eight turns at 4000rpm the DF175's prop refused to ventilate. Surprisingly for a continuously variable valve timing system, there was a rapid increase in rpm when the throttle lever was floored from 4000rpm with acceleration out to Wide Open Throttle as good as the OptiMax.

At my maximum recommended cruise rpm of 5000 the DF175 averaged 61.2kmh while at WOT the averages were 79.8kmh and 65.6lt/h at 6300rpm, just 200 below where the rpm limiter cuts in.
At WOT and 5050rpm the OptiMax-powered Victory averaged 65.8kmh and 57.9lt/h, while at WOT and 5500rpm the E-TEC-powered hull averaged 96.6kmh and 75.7lt/h. The Suzy at WOT was much quieter than the OptiMax and E-TEC and despite having four cylinders compared to six, the vibration levels were comparable.
NO OIL SMELLS
The DF175 started instantly hot or cold and didn't blow any oil smoke, but unlike the OptiMax and E-TEC there was no oil smell when backing upwind. Providing the antiventilation plate was kept at least three-quarters immersed power astern was good. The Suzuki remote control box had a positive shifting action into ahead or astern gear.
Powerhead access is very good with the oil sump dipstick and filler cap easily reached.

The large capacity oil sump effectively handles oil sludging from piston ring blowby during extended trolling periods. Recommended servicing intervals after the 20-hour initial check-up are every 100 hours or yearly when the waterpump impeller should also be changed.
The combined Hydrocarbon (HC), Oxides of Nitrogen (NOX) and Carbon Monoxide (CO) emissions are 171.9 gm/kW/h, slightly lower than the OptiMax 150 but higher than the OptiMax 175 and E-TEC 225. However, as the DF175 has lower HC + NOX emissions than the OptiMax 150 and 175 it gains an OEDA 3 Star rating whereas the latter pair are rated 2 Star. The warranty is five years for recreational usage, and long, extra long and extra long counter rotation models are available.

SPECIFICATIONS

SUZUKI DF175

Engine type: Crossflow DOHC four-stroke

Cylinders/valves: Four inline/16

Prop HP at rpm: 172.9 at 5800

WOT rpm range: 5500 to 6100

Piston displacement (cc): 2867

Bore x stroke (mm): 97 x 97

Ignition system: CD w/ electronic timing advance

Charging circuit (amps): 44 w/voltage regulation

Break-in period (hrs): 10

Fuel delivery: Multipoint EFI

Fuel type: ULP 91 or 95 RON

Fuel capacity: Portable tank not supplied

Oil type: Suzuki SAE 10W40

Oil capacity: 8.0lt

Gear ratio: 2.50:1 overall

Transom heights (in): 20/25

Weights (kg): 215/220

Rec. retail prices: $23,830/$24,131

Spare S/S prop: $1000

Servicing costs*

Year One: $484

Year two, etc: $308