What can i do to make a 8 hp engine faster?

Question

its a n old boat engine ive had for awhile and i want to make it a tad faster

Answer 1

There are two things that influence the speed of a motor more then anything else- the pitch in the prop, and the design of the boat- some boats are much faster then others due to design .since the 8 horse can't run a prop with too high a pitch due to a lack of power, and your choice of boat has probably already been decided, out side of a tune up and make certain the prop has not been knocked out of balance and is in good shape your only choice ( it would be costly ) is to over bore the cylinder and install over size pistons and rings. You will then need to bore out the jets to a larger size to get more gas and make fuller use of the over bore kit- do this in very small increases in size of the jet to make sure it's not drilled too big - I've used the very small drill stems that are use to clean out acetylene and oxygen torch tips for this. You will get an increase of horsepower from this that will let you increase the pitch of the prop and give you  more top end.

Answer 2

Lots of good ideas from others.  Also try raising the motor on the transom by shimming with wood.  The optimum height is when the cavitation plate (flat metal just above the prop) is just barely below the bottom of the boat.  If you raise it too much, the prop will cavitate (suck air and make noise and slow down) on turns.  If you want to raise it more than a half inch or so, be sure you make a solid shim the thickness of the transom and glue and s***w it down so you don't lose your motor.

Answer 3

As you might already know some boats have their own design, which in is good for certain reasons. For this reason your boat may be better to cut through choppy water than for speed, you can always give a tune up, use low ash oil, a little hotter plug, advance the timing(not recommended), or simply test props.

Answer 4

in addition, to the above, balance your load evenly, and jettison as much weight as possible.

Answer 5

two things can be done

1st dont take anything that ads  weight  dont take it   aslo change the prop  the prop can make a big differance

Answer 6

Make sure it's tuned, and if it's a gas engine, replace the spark plugs and make sure the timing is correct. Inspect your prop to make sure there are no dings or inconsistencies in it. If it's an outboard, you might want to put wings on it, which will help your boat get up and plane.