Magnum 25 Sport Drive Setup
 

Running 540/ 600hp with Bravo 1 - 24 pitch 4 blade clever. Rpm tops at 4900/ 55mph. Bravo limited 15.5 diameter. Getting prop trimmed down for reduced stern lift and rpm increase.
What are best bravo drive alternatives for increased performance?
Imco shorty?
Bravo 3?
XR?

A 540 600 hp motor on a 25 ft boat only turning a 24 p to 4900 and 55mph????? Were you dragging the anchor or anchors?

Chris

No anchor drag but it had quarter inch thick bottom paint and nose cone. Removed 90% of paint and cone and gained 6mph. Drive is 25 upper 125 lower for standard 150 ratio. The former owner had 21 pitch clever but was turning over 6k rpm. Have not tried 3 blade yet. Wonder if setup does better with more cup on prop?. Dyno sheet has peak 601hp at 5500.
I know it's a heavy boat but figured 60-65mph was reasonable expectation...
Looking for ideas on best tweak to find the sweet spot...

Oh...had ZERO bow lift with trim before removing nose...nada! Now it has some carry but still rides pretty flat. Told reducing the prop diameter will reduce the stern lift (increase rpm).

With that power I still can not see how you are only turning a 24p only 4900.I wonder if the label is incorrect re some one changed the gears in your drive. Well at least you have a dyno sheet. I would try a 3 blade and shoot for 5500. Maybe start with a 23 Mirage plus. The plus has more cup and will give you more bow lift. Just for a stab at a cheap fix, I would replace your cap and rotor and put a timing light on it to check timing. Do you know what dist and what brand spark controller it has?

Chris

What year is this boat? Was it originally rigged for a bravo?

1974 not sure on original outdrive but it has Volvo transom hole with bravo conversion plate.
Just retested - 5400 rpm with trim but no additional now lift after the 1st 2 bumps.
55/56mph but only 1-2mlh gain from 48/4900 rpm.
Tested 23 pitch bravo prop yesterday and lost 5-6 mph and rpms went to 6200.
I removed most of the bottom paint but bottom is not 100% smooth. Didn't see any hooks on bottom.
Definitely not getting much bow carry with 4 blade...runs very flat.
It's not motor - all fresh with new cap and rotor.
X dimension eyeballed at 6, cavitation plate looks right 1-2 inches above v bottom.
May just need sport utility prop with now lift.

Bravo props are usually 4 blade and come in even # You need a 3 blade mirage+ which will be odd # like 23 25 ect