extension boxes on flat bottom 42
 

I am considering a set of extension boxes on my 42 with bravo drives this winter for a little more speed / bow lift. From what I have been reading the -2 shorties don't seem to work on the old flat bottoms . Has anyone tried the boxes that raise the drive with any luck . The boat is only running 74 with the 525sc with chillers and 29 miriage props spinning 4950.

Re: extension boxes on flat bottom 42
 

The stelling boxes can raise your drives up but they use a solid coupler and are hard on the drives. I've heard a lot of people complain about drive failures after using the stelling boxes. The IMCO neutral boxes have a torsional drive shaft that helps prolong their life, but they will actually lower your X. What you could do is get the IMCO boxes with a set of shorties to bring your X back up. Or just leave it alone and save yourself a ton of money and work :)

Re: extension boxes on flat bottom 42
 

You know my opinion...money spent better else were.
But if you really need to do it, I have a set of the standard Bravo extention shafts for the IMCO's in the garage.
I had to switch to the XR ones when I went to the Bmax's.

Sorry, Phone pic has poor res.

Re: extension boxes on flat bottom 42
 

You mention that the flat bottom Fountains have not experienced gains with -2 shorties. I wonder who has tried the -2 shorties with a single step hull? I know Ran-Dom has used -2 shorties with success on his single step 35. Any one else used them with success?
I have heard that some don't like the shorties because you can't trim the shorties like most Fountains like to be trimmed.

Re: extension boxes on flat bottom 42
 

I like the extension boxes on 42's both stepped and flat bottoms.
That being said I agree with "Back for More" it is not where I would start in your case. I believe your motors are setup to turn 5250 rpm and as far as bow lift etc... I would start with a 4 blade prop and make sure they are turning in. Personally I like the Bravo I props; however, I have heard that the best prop for the Fountain is the Hydromotive.
The $5000-$7000 you would spend on the boxes etc... could do props and a good roller setup in the motors with a little more cam.
My engine builder just redid a pair of 525 sc's for a friend and went with a full roller setup if you need info.

Re: extension boxes on flat bottom 42
 

P Offshore, Has the engine builder you know been successful with a 575 SCi roller cam switchover. Any advice greatly appreciated.

Re: extension boxes on flat bottom 42
 

Since the 575 is efi it would require a cam very close to what you have now for the fuel map to stay the same. I think most reputable engine builders can measure your existing cam and order a full roller setup.

There are some kits available with intercooler I think they add 90hp.