Bubba & Crew, (Crew being all you other smart people!) The Nissan 4 HP four stroke motor comes with a 7.8 X 7 pitch prop. The Nissan 5 HP and the 6 HP motors come with a 7.8 X 8 pitch prop. See Prop Chart below I have a 4 HP Nissan motor that I have boosted to 6 HP by installing the Nissan 6 HP carburetor on my motor. Motor starts and runs so much better now! Do you think that it would be worthwhile to spend $70 to buy a 8 pitch prop? I'm hoping to increase my boat's speed a little bit. One of the local propeller repair shops said that they doubted if I would notice any increase in boat speed with a 1 degree increase in pitch. I'm a little worried that the larger carburetor will allow me to over rev the motor with the smaller 7 pitch prop. What do you think?