More Power in Yamaha 115

[jdawwggin25]

I have a 1987 20' aquasport center console with the 1987 yamaha 115etlh powering it. I usually run at the highest 4500 rpm which I consider to WOT but not sure. At that range I can usually get the boat to about 30mph depending on the conditions. I am having trouble finding the specs on the engine and am not sure if I am at the correct operating range. I am afraid of going over 4500rpm and blowing the engine so I am not sure if anyone has any experience with this engine.

I am also looking to find a way to get more power out of the motor and be able to get the boat to top out at a higher speed. Without changing over to a yamaha 150 4 stoke which I would love but can not afford, are there any ways to pull more power from my current engine. I am building a custom top for it this winter and since we will be adding some weight I would also like to add more power. My uncle was telling me that switching to a stainless steel prop with a different pitch could make a difference. I am clueless when it comes to the props and what effects they will have on the engine and boat so I am unsure of how to go about that route. Any advice would be appreciated. Thanks.

Joey

 

[crb478]

Re: More Power in Yamaha 115

WOT should be around 5500 rpm on that motor, if it will only hit 4500 with your current prop you are lugging the motor. At 5500 I would also guess that you should be able to get 35 - 38 mph out of the boat maybe more. When you open the boat up full throttle what will the rpm's get to? Don't be afraid to push it to 6000 rpm for a couple of minutes. When you know your max rpm then get your prop pitch and we can adjust it to get the correct one for max WOT. When you get that set up you can cruise at whatever rpm you want.