Ok hello gents.

My first post here and not sure if this is the spot to post this but I need help with a idea of doing a experimental engine use.

I have a copperhead surface drive on my duckhunting boat and want to replace it with a Hirth f-33.

The motor is powered by a vanguard 23 right now but it's heavy and want to use the f-33 to lower the weight if the motor on my boat.

The vanguard produces more torque and produce'sit at a low rpm rate and dosnt make as high rpm rate as the f-33.

What I need to know is how can I go about increasing the am out of torque the f-33 makes and how can I go about getting it to make the torque at a lower rpm rate.

The reason for increasing the low end torque is so the engine will make enough power to the prop to push the boat out of the hole shot and plane it out.

The Vanguard makes 38#' s of torque and tops out around 4000 rpm's.

I know I can change out the belt pulley size and tooth count to help deal with this but I only have so much room in the drive systems case for changing to diffrent size belts and pulleys, so I want to rework the engine to make up the most of the diffrence and then change out belt pulley size and tooth count to make up the rest if need be.

I have contacted a few performance shops and didn't get anywhere's with them because none of the shop's i contacted knew anything about aircraft engine's.

So what all can be done to rework this engine to fit my needs?