Info About Vensura Props

[goneboatin]

I was a the Boat Show yesterday and was talking to the Mercruiser rep about factory recommened performance parts. He said the next step up is the Mercury Racing engines. I said I didn't want to go to that extreme and he pointed me to Rob Clarke of Quality Performance Marine in Carona. I told him I've got a Howard 22 open bow with the 350 Mag MPI with a Bravo I outdrive and want more grunt out of the hole. He ask me my prop size and I said it was a 19" Revolution 4. He said the prop was the wrong one on the boat. I told him I didn't want to sacrifice my top end with going to a smaller prop. He told me to go with the Mercruiser Vensura prop. According to the Mercury web site, that prop is for the Alpha outdrive and outboards with less than 175 hp. My engine is supposed to put out 300 hp. This seems like the wrong prop, Rob is the expert.
Has anyone out there in Hot Boat land had any first hand knowledge of these props?
Thanks in advance for any info.
GB
:idea:

[phebus]

I think that is the same prop they used to call the Offshore. The specs didn't seem to apply to my last application either, but the folks at Bronson Hill propellers told me that it worked far better then the Revolution 4 and to go with it. Great prop. Call Bronson Hill and ask them about it.

[CBLavey]

How does your Howard run with the Revolution 19"? Can you hit 5000 rpm with a light load? What gear ratio is your drive? There's no doubt that Rob Clarke and Bronson Hill both know there stuff,(Rob services my engine and Hill has always done my props) but I can't believe that you'll get much better hole-shot than a 19" 4-blade.
I've had good luck with Bravo 1 4-blades.... ;)

[goneboatin]

I just don't have the grunt out of the hole, once it gets going it's fine. I talked to them at Bronson-Hill and they say the Vensura prop is the wrong one for my boat. A 19" Vensura is smaller than the prop I have now and I'll probably hit the rev limiter. I've got 1.5 gears in my Bravo 1. I can max out at about 4900+ RPM. The speedo says 61. But talking to them at B/H that doesn't calc out - At 5000 with my 19" Revolution 4 should be moving me at 54 mph not 61 unless I only have an 8% slippage factor, but that's just too damn efficient. I need to make a hot lap with a hand-held GPS speedo to get an accurate reading.
I did talk to Rick at Pro Boats in San Dimas (another approved Mercruiser repair station), he said that he'll try my boat out at Puddingstone to see if maybe my prop can be tweeked for more grunt with out losing my top end (or maybe I live in a fantasy world). Another more expensive route to go would be to install a set of headers and reprop it to match the new torque curve. Or just drop in a 496 Mag HO, but I know the wife would never go for that.

[CBLavey]

I seem to remember a test of your exact set-up in Hot Boat a couples of years ago and I believe that the boat did hit 61 on G.P.S. with a Revolution 4.
The headers would definitely help. Rob at Qualiity Performance intalled a set of EMI's for me with custom pipes and I jumped from a 22" Bravo 1 to a 24" which I still had to have Hill rework and I can now pull 5200 RPM with 4 adults and full tanks. : :D