I have a 1984 V20 with a 2003 Johnson (re-badged Suzuki) DF140. It's the cuddy cabin model, not the center console, and I added Bennett Hydraulic trim tabs which make a *world* of difference.
It's a fairly high-tech 4-stroke -- even though it's a 2003, and she has under 400 hrs on her.
I get a top speed of about 34 MPH at almost 5.8K RPM with a 17 pitch 3 blade suzuki stainless prop and a doel fin mounted on the cavitation plate. Without the doel fin, it sucked!
I need to check the setup, especially the engine height... I think it might be rigged to low.
I also think I can go up to a 19 pitch prop, but with the motor at the current height (which is how I got the boat) and without the Doel fin, she was over propped with the 19 pitch, and required at least 50% extension on the trim tabs to ride correctly... so I knew *that* setup wasn't working well!
A 17 pitch Solas 3-blade prop helped some, but not enough. Adding the doel fin made her seem like a new boat, and makes me want to go back to the 19 pitch prop.
With the 17 pitch and doel fine, she cruises nicely at about 22 MPH and gets around 4 MPG with 2 people and 60 gallons of fuel.
My bottom has a thick but chipped coating of anti-fouling paint.
Since I trailer and don't leave her in the water, I hope to scrape it, sand it, and seal it with some gelcoat or a 2 part epoxy paint.
I'm hoping to get closer to 40MPH on the top end once everything is said and done, including prop changes and engine height adjustments, but maybe that's too ambitious. Time will tell.
I think a bracket should help your performance, especially if it is a floatation bracket. I'm a big fan of the wide floatation brackets that are at least 5 or 6 feed wide, because they can (obviously) provide more buoyancy than a narrower bracket, and I believe that the buoyancy helps offset the comparatively heavy weight of 4 stroke motors and helps compensate for the extra lever arm that the bracket gives to the motor, and moving the center of gravity rearward by mounting the motor further a stern on a bracket.
I hope this helps! Keep us updated, pelase!
