Offshoreonly.com - A question about rpm's with a Bravo 3 and Bravo 1 XR????????

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pax2you

09-15-2007 03:34 PM

A question about rpm's with a Bravo 3 and Bravo 1 XR????????

I have a 93 Formula 252 BR that I plan on making some drive changes to this winter. I am taking out the 454/330 dropping in a 580 hp BB, I am also going to change from a Bravo 3 (1.5 ratio) to a Bravo 1 XR (1.5 ratio).

The question I have is;
in its present state(with the 454/330), if I were to change out the Bravo 3 to Bravo 1(same ratio's), would my rpm be greater than, less than or the same as with the Bravo 3 at wot? My thoughts are that I would actually pull some more rpm’s simply because I will be displacing less water (i.e.: 1 prop working instead of 2) and thus the engine will gain more power and rpm. My buddy thinks it will be the same. Which is it? Whose right? Any thoughts or experience? Dinner is riding on this!!! Thanks, pax2you

Payton

09-16-2007 07:04 PM

A friend has that same boat and engine. he tried my spare bravo in placeof his Bravo 3. I picked up 2 mph but was a slower at 3600 rpm cruise speed. It depends a lot on which prop you try. He used a 23"Mirage Plus.

S4Hadi

09-18-2007 06:48 AM

I thought that I once read that the bravo1 with a 1.5 R was the
same/direct replacement for a Bravo3 with a 2.0 R ?

I think that you can just swap the lowers?

Knot 4 Me

09-18-2007 09:07 AM

What pitch propset are you running on your Bravo III? More than likely your current ratio is 2.20:1 or 2.0:1 depending on what pitch props are on the boat. Some manufactures may set the X-diminsion slightly different for Bravo I equipped boats vs. Bravo III equipped. If you go to the 1.5:1 Bravo I, I would run a Mirage Plus prop for the best speed. You should pick up some top end speed but might be slightly less efficient in the mid-range and at cruise. Holeshot won't be as good either but should still be acceptable. If you prop the Bravo I correctly, your max RPM should be the same. You will want to shoot for 4,600 with a light load. These motors make peak HP around 4,400 - 4,500 RPM.

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