Project Starcraft Chief with new power

[Watermann]

I bought a donor 1988 CC Cavalier 19' with a very well taken care of MC Alpha one 205 HP 4.3L. The drive train is going in my 18' Chief but I have my concerns about using the existing prop 13.75 x 21 MI Wheel. The Chief will be at least 1000 Lbs lighter than the water logged CC and I don't know if it's even the stock prop size. I plan on using the old prop only as a spare since it shows some signs of being burned by ventilation.

I don't really plan on much if any water sports or towing, mainly just cruising. Also I would like to go with a 4 blade AL. Any input on prop size would be greatly appreciated.

 

[Texasmark]

Re: Project Starcraft Chief with new power

They sell props on the site. Fill in the blanks and you get a selection. On the perfect match all is a wild guess until you run it; may be an educated wild guess, but still a guess. 1000# is a lot of weight difference and the hull and load make a big difference too. I think the Starcraft Chief is alum with a semi V hull which has an easily planing hull. You need to know where you are running in WOT rpms now and where the engine is rated. You can expect several inches of pitch increase for my SWAG.

Or, go to a prop shop that charges more but gives you the option to try before you buy....as long as you run out, test it, and run back with it with no dings......so they can sell it as a new prop to someone else.

Good luck,
Mark

 

[Bondo]

Re: Project Starcraft Chief with new power

I bought a donor 1988 CC Cavalier 19' with a very well taken care of MC Alpha one 205 HP 4.3L. The drive train is going in my 18' Chief but I have my concerns about using the existing prop 13.75 x 21 MI Wheel. The Chief will be at least 1000 Lbs lighter than the water logged CC and I don't know if it's even the stock prop size. I plan on using the old prop only as a spare since it shows some signs of being burned by ventilation.

I don't really plan on much if any water sports or towing, mainly just cruising. Also I would like to go with a 4 blade AL. Any input on prop size would be greatly appreciated.

Ayuh,.... Put it together, 'n run it with the prop ya got, Just to get some numbers to work with,...

ya need rpms at wot, 'n yer speed,...

 

[Mi duckdown]

Re: Project Starcraft Chief with new power

What Bondo said. TRUE rpms and GPS speed.

 

[Watermann]

Re: Project Starcraft Chief with new power

Thanks for the replies, sounds like some good suggestions. Don't want to drop the cash on something that is going to be waste.

 

[Watermann]

I'm back with the Chief all together and running great with the 205 HP 4.3 A1. As expected the old prop size worked but due to the damage I talked about above I don't really want to keep it around as a spare. I decided to go with the similar prop for starters and picked up a MI wheel vortex 14.25 x 21 AL 3 blade figuring I would get another prop housing and not need a new hub. I built the boat as a cruiser and I'm not really into any water sports, just relaxing out on the lake or river while cruising.

Hole shot is amazing with the smart tabs, on a plane prior to 20 MPH in under 3 seconds just easing the throttle forward. Mashing the throttle down will really set you back in the seat, even when cruising at 30 MPH if I stab it the acceleration is incredible. Cruising speed that felt good for the set up was 30 MPH but I was running 3200 RPMS to do it. The set up is new to me and that RPM seems high so I'm looking to reduce RPMS at cruising speed and maybe pick up some fuel economy when running under when the 4 BBL starts howling. 4500 RPMS is all I ran it up too but it seemed after 4000 RPMS I didn't gain much speed, 43 MPH and way more noise. I don't want to put any undue stress on the outdrive for the sake of a gallon of premium or a few extra miles an hour so I'm wondering how much of a pitch increase could I go looking to lower RPMS at cruising speed and as a side effect most people are looking for here, to increase speed.

 

[Watermann]

I tried to resurrect this thread rather than starting a new one to get some input. At 4500 RPMS with 43 MPH GPS, I have quite a bit more throttle left that I'm sure would over rev the 4.3 beyond 4800 and no I didn't want to see what it would rev up to at WOT and abuse the motor. After more reading, I've decided I'm going to try and up the prop pitch to a 14 x 23 Merc blk diamond that has the interchangeable hub system with the MI wheel vortex I already have. With the incredible acceleration of the 21" pitch on the 4.3 LX in this light boat I believe the 23" pitch should be enough of an increase to reach a compromise of lower RPM cruising and the ability to go WOT without over revving.

 

[steelespike]

It does appear that a 23" should settle down around 4800 with 11% slip speed should be about 50.
A more typical wot speed with a setup like yours.Should also get more speed at a given rpm.
If you have tabs try it with the tabs released.

 

[Watermann]

Thanks for the reply, the 12 x 23p Black Diamond did what I hoped for with the cruise speed and RPMS. Now at 3200 RPMS I get 35 MPH with the 1.81 ratio for a 9% slip. Cruising at 35 and if I put the hammer down the acceleration is excellent and hasn't seemed to have changed from the 21p but the top end doesn't seem to have corresponded to the pitch increase, it's like there's a wall. At 4500 RPMS I got 44 MPH and I wonder if it's the tabs? I guess that's where it stays for now. Not sure about going to a 25p, I know the motor has the power to turn it but...