[brinkleydog]

Give him a heads up on the very little tolerance for vibration so he can get ask BPS to balance his motor (cam, crank) and make sure his prop is setup right. These little blocks do not like much compression and if he is going to spin the prop at the magic "peak torque" be sure he knows its not going to last as long as it could.


Its going to be a nice boat when it done, and i'm ready to see how the BD5500 holds up with a fan on it!

 

[brinkleydog]

right at 50 hp with the single carb.....

Watch out pitching the prop too much. If the motor is under a load (boat sitting on bottom, hung on stump, or any large amount of resistance) and the driver hammers down on it for long period of time it possibly could cause more harm than good. This is due to the motor being at MAX torque at WFO. Motor are not designee to be at max torque at WFO/full speed because once you are moving you don’t need to torque you need RPM. The torque swing on the BD5500 is unknown to me so be sure to ask BPS what the swing is. If max torque is at 3200RPMS make sure the motor is not turning this RPM at WFO or you will have problems. If you are pitching the prop to reduce RPM you should think hard on that. If you want to give a max RPM get a rev limiter and drop the right chip for your liking. Pitching a prop to reduce prop is a known block buster with MudMotors, so I would recon it will have similar outcome with a fan.


It going to be fun, but be sure your client understand the risk so you don’t have to worry about finger pointing your direction from BPS if the block splits in 2. Also I know a guy who had a modded motor on a mini air boat and it didn’t last to long. His motor was NOT a BPS but mods are mods and need to be watched carefully.

 

[brinkleydog]

All i can say is do LOTS of research. Your thinking is not off, but you are comparing a lawnmower block to a high horsepower block. The Briggs design has the pistons/ etc..at a true 90 degree which is a deadly start for a block. Add a very think block wtih a void for the fuel pump takign up all the strength and you have BOOM.

Good luck!