« Reply #1 on: Feb 18, 2012, 7:51 pm »
 
What engine choices are there?



Unfortunately there is no such thing as a purpose designed hovercraft engine. The engines in use today are derived from many sectors such as the industrial, automotive, aviation and motorcycle areas.

The most important thing is weight. This cannot be over-emphasised, no amount of power will make up for the extra weight of some enormous automotive V6.
 
2 strokes

2 strokes have favourable weight – they are incredibly light. But, for cruisers today, the disadvantages of poor reliability, high fuel consumption and high noise levels outweigh the weight advantage.

Two strokes are best avoided for cruising use.

4 stokes

4 strokes are heavier than the 2 stroke alternative, but are quieter and more efficient, and generally more reliable.

A few lightweight car engines and some motorcycle (not high revving) engines are suitable. Look for all-aluminium engines.

The Subaru flat fours continue to be popular, whilst the BMW 'R' series motorbike engines are used a lot.

Recent developments in 4 stroke microlight engines are very suitable for hovercraft, but may be a little expensive.

Diesels

Whilst many agree that diesel reliability would be an advantage, they remain heavy just at present so there are few small diesel powered craft around. There are a number of developments in lightweight diesel engines, so this may change in the future

Small craft

The Briggs and Stratton, Kohler or similar industrial/garden tractor engines in 25-40hp are suitable for small craft, say between 12 and 16 feet. Car engines are likely to be too heavy for this size of craft.

Larger craft

Craft of 15 feet and upwards may be suited to the lightweight car engines, such as the Subaru flat  fours, or Suzuki 3 cylinder engines.

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Ian Brooks
Gloucester, UK