Silver Wraith 8.1L 430+ bhp

V8 Small Block Chevy 496cid

This engine is literally the pride and joy of our technical director Dave Martin. Developed in constant consultation between himself and David Vizard to specifically meet the needs of Greg Copp, Technical Writer for Motorboat & Yachting magazine. It is a superb choice for the discerning owner of a larger boat, 35ft+. Greg has a 43ft Sunseeker Thunderhawk which weighs in at 7.5 tons, and was very thirsty. Swaymar have always maintained that, especially for larger heaver boats the 496 cid is actually a better engine than the 502 cid commonly offered.

Despite being slightly smaller in capacity (all be it only 98cc) the 496 achieves its 8.1 litre by using a smaller bore but longer stroke than the commonly offered 502, and while the big bore short stroke of the 502 may be ideal in the cars and trucks they were designed for, they develop their power further up the RPM range, not a problem in a vehicle with gears. We recognise that boats, especially heavier ones, benefit from as much power and torque as low down the RPM range as you can get it. Figures commonly quoted for 502's are 420 BHP @ 5200 RPM. Because of its longer stroke, our Silver Phantom 496 makes 431 BHP and an awesome 521 ft. lbs of torque almost a thousand RPM lower @ 4350 RPM. in fact it topped the magic 500 ft.lbs of torque at just below 3000 RPM. This is a petrol engine that dwarf's many turbo diesels, yet because of the hugely increased efficiency, at cruising speeds can actually save fuel over the standard 330 BHP units. These carefully considered engineering improvements result in a considerably faster boat but without the usual fuel penalties associated with more power.

Compatibility

• Mercruiser
• Volvo Penta
• Indmar
• any boat running Chevy V8s

Whilst fine on Volvo Penta Duo-prop legs, in Mercruiser applications it is recommended not to use legs of less than Bravo 2X or Bravo 3X specifications.

Recommendations

We strongly recommend to all of our customers to consider trying a 1 piece stainless exhaust system and do away with the fear of leaky cast iron ones ruining your engine. You can find more detailed information on stainless steel marine exhausts as well as independent articles written by marine surveyors on the pit falls of cast iron manifolds at stainlessmarineexhausts.co.uk.

Propeller Pitch

Depending on boat, in order to prevent over-revving, and feel the full effect of its extra torque, this engine may need to carry a larger diameter or coarser pitch propeller.

Specification