hpmaniac

I'm going to improve the engine combination, it's not correct. Had rec port merlin heads and a dual plane rec intake. Changing to afr 290 oval ports and a dart single plane intake. Engine will gain 75 hp and 100 ft lbs torque for sure. Once you get over 500 cubic inches a dual plane is a huge choke point. Engine has cmi big tube headers already!

snapmorgan

I would stay away from oval ports. There is a reason they were never used on any factory engines over 330hp. While they sound good on paper and may work on a street car, they are not the best choice for a low rpm/high torque boat motor.

JaayTeee

Put a 25 mirage + on it, looking at the picture, it has the stock x dimension,
the drive is deep, it will be faster with the 3 blade over the bravo 4 blade.
The 4 blade will perform better out of the hole and cruise, but it’s not going to beat is on the top end

midwest272

Nice find on the 272 , I’ve had one for a long time ……(it just sits in the weeds now )

The main problem with going fast I found was getting the nose out of the water . When using a 4 blade bravo 28 it would feel like the faster it went the harder it picked up the rear and buried the front
The best prop I tried was a 29 mirage plus and it still would not even think about carrying the bow

Drive is low …. Can’t remember the number but it’s low . Ended up putting a nose cone on just to see if it helped even tho I was no where near the speed they help

Good boats , mine endured years of the loto washing machine and comfy for when your anchored

hpmaniac

My 272 is trimming up and lifting bow no problem, I got it ti chine walk a little at 70, tabbed down and it calmed right down. I love the way this prop cruises, I can back off from 70 and cruises at 62 at around 4100.

Brad Christy

HPManiac,

Just putting this out there....

We previously had a Rinker 236 SportCuddy with a mildly warmed over 468 (454, .040" over). It had a Bravo22 that had been reworked to 21P. The boat had some mechanical issues that I was not aware of or understanding of their implications when we bought it. We did not take a sea trial. I took a screwdriver with me and sounded the transom. It was dry so we bought it. after getting the issues worked out, we ran the boat for ten years, so it all worked out. That said, once we got the mechanical issues worked out, the boat would still just not run what we thought it should, including the opinion of those who'd helped us work out those issues. While running along side my dad in his boat, he remarked that we were running very "wet". We spoke with one of the guys that had worked on the boat, that just happened to have a wall of props. He suggested we try a 23P 3B or some unknown make. We went from 51GPS to 61 with just the prop swap.

Bravo props tend to provide lift at the transom, which may be stuffing your bow. Might be worth trying the suggested prop, just to see. I've been told I won't get our PQ280 on a plane with a Mirage, due to the step ventilating the prop too much, or I would have already tried a 29 Mirage myself. There's a thread on here somewhere where I had this very discussion.

Thanks. Brad.

hpmaniac

As always, Thank you sir.

hpmaniac

What was very nice was yesterday we were in the puget sound and got into some big water, 3-4 ft swells and white caps and this boat handled that stuff like nothing. Felt very confident in her. I just put a call in to bbblades for a prop. I think this boat is making enough power to move the boat in the 73-75 range. Just moving up from 4800 rpm to 53 or 5400 will be about 50hp at least. I do have a question, it has a Hardin marine billet water pump belt driven and a water gauge, what pressure should i see at say 4k rpm? it was only about 8 psi but engine never ran above 140 all day.

Brad Christy

[QUOTE=hpmaniac;I just put a call in to bbblades for a prop. [/QUOTE]

HPManiac,

Rots of ruck wit dat.

I understand he's a great guy.... He's very professional and knowledgeable. But my experience is that you'll never get an audience with him, if that's what you were hoping for. Try email. I've gotten responses from him that way.

Thanks. Brad.

hpmaniac

In my local area there is a place called the prop shop that is supposed to be good?