Ilmor One Drive

Ilmor's first production sterndrive offers silent shifting and solid performance.

Ilmor One Drive
Horsepower: 380, 430 | Displacement (liters/cid): 6.0/362; 6.2/380 | Gear Ratios: 1.78/1.97/2.18 | Propeller System: Counter-rotating twin propellers | Pitch Range: 22/24/26/28 inches | Clutch System: Hydraulic multi-friction plate | Shift Control System: Electromagnetic | Drive Weight (with fluids): 253 lb. | Engine Weight (lb.): 871/813Ilmor Marine

Ilmor Marine’s New One Drive pairs an Ilmor MV8 gasoline engine with a twin-prop sterndrive. We ran a pair of 430 hp One Drive powertrains in a Formula 350 FX CBR and came away impressed.

The One Drive is the first production sterndrive effort from Ilmor, which had success with its MV10 engines and Indy drive in offshore racing a decade ago. Since 2011, it has been the exclusive inboard-engine supplier to MasterCraft Boats. The One Drive will be offered with the 380 hp and 430 hp Ilmor MV8 OPS engines. Both are based on engines that Ilmor supplies to MasterCraft, with adaptations for the sterndrive application. The Ocean Performance Series package is designed for salt water.

Yanmar ZT 370 Sterndrive
Yanmar ZT 370Courtesy Yanmar

One Drive has been in development for about two years. The sterndrive, a Yanmar ZT370, is often paired with diesel engines producing 600 ft.-lb. of torque, so it’s robust, but it was not orginally designed to operate at higher gasoline engine speeds — 5,800 rpm compared to 3,800 rpm with diesel power. Ilmor claims it has tested the drive extensively to confirm durability. It has also achieved speeds of 69 mph with no prop blowout. Either Yanmar or Mercury Bravo Three propsets can be installed. The drive requires service every 150 hours, rather than the typical 100 hours. The drive housing boasts an anodized finish that can be applied in different colors or covered in a custom vinyl wrap.

The engines are based on the GM Marine LS “Gen IV” V-8, with an aluminum block (for the 6.2) and heads, port fuel injection, closed cooling, new down-tube exhaust manifolds, power steering, and a new intake manifold designed to deliver stronger midrange power. Already fitted with digital controls, Ilmor will offer twin-engine One Drive installations with a joystick based on the Yanmar system.

A key feature of the drive is its silent shifting, thanks to an electro-magnetically actuated hydraulic clutch, similar to the clutch used in an inboard transmission. It feels sophisticated and smooth, especially when paired with underwater exhaust. The 35-foot Formula 350 FX CBR weighs about 13,500 pounds, and the One Drive put us smartly on plane, running out to 56.7 mph at 5,780 rpm. Best cruise was a brisk 32 mph at 4,000 rpm, where we recorded 1.23 mpg. That top speed compares to the 55.95 mph of a Formula 350 CBR we tested in 2013, with twin 430 hp MerCruiser 8.2 HO/Bravo Three powertrains.

For now, the One Drive is available only to boatbuilders and not for repower. Service will be handled by the selling dealer, so the boatbuilder and dealer must work with Ilmor to have service in place. We think One Drive will appeal to premium builders with a custom mindset, building to order in close consultation with the customer and dealer — Formula being a prime example.