Marginmn

What kind of speeds were you getting with the 496 - and what prop did you run? 1.50 ratio?

Spinletto

Mid to low 60's with a 1:50 Bravo 1 outdrive and 28 Bravo 1 prop and talk about slow to plane. I was going to put a 26 Bravo 1 on but I found this Ilmor and decided to go that route.

SDFever

Spin, how much work was this beyond installing any bbc in the boat?

Other words, was the Ilmor a real pain to adapt to or was it relatively painless?

I was thinking about steering, fuel, engine mounts, exhaust etc..

Spinletto

I dont' think it was to bad. The only real thing that I noticed was all the rigging was on the opposite sides of the engines. Meaning everything on the left of a Mercruiser is on the right of the ILMOR. The engine mount locations had to be redone, the holes in the transom for the exhaust had to be opened up a little bit, the bilge pumps had to be replaced with shorter ones, re rigging electrical and fuel lines in the engine compartment, and of course we added the power steering which I don't think there was any complications with that. All and all not so bad. We're still trying to figure out which prop and direction of rotation to use, and if we need to shorten up the outdrive any.

I'm taking my boat back to Supreme Marine tomorrow and I'll see if I can get a little more detail.

253

[QUOTE=Spinletto;3581628]Mid to low 60's with a 1:50 Bravo 1 outdrive and 28 Bravo 1 prop and talk about slow to plane. I was going to put a 26 Bravo 1 on.

A good friend of mine has the same boat & year as yours, but with a single 525 EFI, with a 28 pitch Bravo1 his takes forever to plane also, with 26 Bravo1 it's no problem.

A.O. Razor

Did you get the tach sorted out?

Spinletto

Yep.. I've got to get a new one.

Spinletto

Thanks Robert! It sounds 100% better now. I'm finally going to get a chance to prop test it this coming Wednesday.

http://s1215.photobucket.com/albums/...MIMufflers.mp4

Marginmn

Glad they worked out for you J.R. Good luck with the test.

Yamaha 225

This project is so cool. It just gives a good old Fountain boat a new life with new techology and a fuel efficient engine of a size that fits the boat! I remember one time I tested a 27 Fever with a std Merc 502 EFI 415 hp........ THAT BOAT WAS SLOW ON PLANE! I thought that it had nothing to do with a sport boat. With your set up, it looks like you will get a fun boat with a unique sound for a "small" Fountain.

Please post some more picture of the boat and your impression of the handling. I geuss the lighter engine make the boat stay higher in the water at standstill? What kind of trim level do you need to get it to air out? Speed and prop? It looks like your drive is a bit low, but th eboat also need bow lift to get it to perform well. Lower drive = more bow lift... You mention that your boat leans to the left due to the prop's rotation. I would assume that raising the prop axle would reduce this leaning to the left (port). I wonder if a torque tab like used on the outboards would benefit this rig? I use to make singel engine hi-perf V-bottoms alot better to run with a high "X-dimention".

If you fit a prop that is slow to rev up during the planing process, I know of someone who make a water-pressure activated valve that they put on the cavitation plate in order to let the prop ventilate to get more power and RPMs. Just like on the No6 drives with the vent pipes. When the boat planes, the water pressure close the valve in order to prevent cavitation at low planing speeds.

Please update when you have some more results!!

Thanks :-)