HP Question

[czuniga]

I will double check my height, just to be extra sure, if its off an inch or so, it would make a difference right? What would be the inconvinience if it sits a couple of inches under bottom of boat.

thanks

 

[czuniga]

im planning on removing taking exact measurments and removing the bracket and taking it out for a test run. WIll let you guys know how it goes,,

 

[Johny25]

It will cause a little more drag if it is down lower is all, not really that big of a deal. But I would make sure that it was too high and not just the prop before removing and putting more holes in the transom

 

[czuniga]

Some pics

 

[czuniga]

Pic

 

[czuniga]

This is the setup. If I remove the bracket it will sit 2.75 inches below
BOAT. That is my next option.

Wouldw this be too low

 

[Johny25]

I can't believe you are cavitating where the motor is currently. That pic looks plenty low not to be cavitating. I still think it is a trim or prop issue IMO. And no it won't be to low if you go down to where you are talking but it will give a little more drag is all. So have you tried trimming the motor up a notch to see if you get blowout?

 

[czuniga]

Yes I have tried raising it up a notch and sounds worst. The bracket only raises the outboard 2.75 inches. But from I have read online and on other threads. My setup should be just about right. My 10 prop stresses my engine. Perhaps I went too low in pitch with an 8

 

[Johny25]

Ok well it won't really stress your engine running the 10 pitch but it may not get to recommended RPM to produce peak HP. I am guessing you should be 5500 to 6000 RPM with your 9.9 Do you have a tach? This would answer a lot of your questions about what is really going on

 

[BrazosDon]

Where are you located? I have an 18hp on a 14X48 jon boat and no problems. The boat is rated for a 30hp I believe. I think maybe an 18 or 25 would work well for you. Good luck from Texas.

 

[czuniga]

Hello i am in brownsville the deepest part of texas. Once i remove the bracket its only 3 bolts i run it see how it does, ,should only be 2.75 inches under bottom of boat. And yes hopefully, a good deal will come along another outboard. ill just have to wait for that to come around

 

[czuniga]

hello,
i think i am definately underpropped. i removed the bracket engine sat about 2.75 inches below boat. Had the same weight on boat and still sounded like it slipped at full throttle. Glad i did not buy hydrofoil before running this test. I think i might need a 9 pitch prop. I had and 10 before and i dropped to 8 . Does anyone have a 9 that is willing to sell?

thanks

 

[bbstacker1]

I still think I would check the prop to make sure it hasn't spun in the hub.

 

[Johny25]

It sounds like it is definitely the prop, either spun or under propped. Why haven't you put that 10 pitch back on yet and run it? This will clarify the issue whether it is a spun prop if it does it with the 10 pitch also now.

 

[czuniga]

With the 10 prop the engine sounds like its gonna pop. Sounds like ovrtstressing. Like a standard truck when its asking for the second gear

 

[czuniga]

hello,

just wanted to update this thead hopefully it will help someone like new like me. I was definately underpropped. I removed the bracket and engine sat 2.75 inches below and still ran the same. I ordered a new prop (actually it was an even exchange with iboats) and i reinstalled my bracket and ran the engine as i had it before. Only now with a 9 pitch prop and ir ran really nice. Planed in no time and did not slip at all. Big difference from when i ran it with a 8 pitch prop. I think nine was definately a good choice. I have another thread of how to convert this 9.9 into a 15. These guys have been extremely helpfull. Dont know it would run into prop issues once i add a few more horses to it. But as for now its great. Thanks to everyone..

great site

 

[Johny25]

Just to warn you in advance, after doing the HP upgrade you will most likely be under propped again. You are going to be adding 33% more horsepower to the motor. You should invest in a tachometer for your engine so you can give us info and we can make sure you get the correct prop on there. My guess is you will need a 9.5X10 pitch and maybe even an 11 pitch? This is all good though, the higher pitch you can turn at your motor's recommended RPM the faster your boat will go : )

Thanks for the update also : ) I like when people come back and finish threads