Prop debacle 250 repower w/ 07 350 MAG MPI

[Goldcoast 250]

I have repower from a '98 350 merc carb engine @ 220 hp to an '07 350 MAG MPI rated at 300hp. I have 98 250 dancer with 22 inch pitch props which seem to work ok butr I was thinking of going to 24 pitch since I need to replace (rock=1: me=0):smt021 and the 24 pitch props are more readily available. Any thoughts would be most welcome. Ed:thumbsup:

 

[Nehalennia]

I have repower from a '98 350 merc carb engine @ 220 hp to an '07 350 MAG MPI rated at 300hp. I have 98 250 dancer with 22 inch pitch props which seem to work ok butr I was thinking of going to 24 pitch since I need to replace (rock=1: me=0):smt021 and the 24 pitch props are more readily available. Any thoughts would be most welcome. Ed:thumbsup:

Not sure why it's a debacle other than you dinged your props.

I have the 24" and they have a nice cruise at 3500 RPMs at 25.7 NMPH. I'm not sure what gear ratio you have but what is the RPMs you're(were) getting when you were WOT with the 22's?

 

[Go Aweigh2452]

Go to your nearest prop shop and try a couple of props. Remember, you need to have a prop that turns w/i 200 rpm of your WOT or you will reduce the life of your engine. You may be able to go 24 and if that is still too high, have it cupped to keep it inside the 200 rpm range...

I'd also go stainless, less flex, better prop

 

[Dave S]

The first thing I would do is download Sea Ray's prop chart from this link http://www.searay.com/prop_charts.asp and do a little bit more research. Your hole shots and top end are governed by the engine, the prop pitch and the gear ratio for the outdrive you have. If Sea Ray offered a more powerfully engine in a 98 250 Sundancer was the outdrive ratio different than yours? And what pitch props came with that more powerfull engine? All of this is important to understand before making any changes.

Dave

 

[Nehalennia]

..
I'd also go stainless, less flex, better prop

That's the only wat BIII's come as far as I know.

The first thing I would do is download Sea Ray's prop chart from this link http://www.searay.com/prop_charts.asp and do a little bit more research. Your hole shots and top end are governed by the engine, the prop pitch and the gear ratio for the outdrive you have. If Sea Ray offered a more powerfully engine in a 98 250 Sundancer was the outdrive ratio different than yours? And what pitch props came with that more powerfull engine? All of this is important to understand before making any changes.

Dave

well it sounds like he has a new "'07 MAG 350 MPI, Bravo 3" as stated in the sig, so I'm assuming they came in a bundle. If that's the case, I'm wondering what his WOT is so we can see if 24's will benefit him.

 

[skolbe]

Wow, how bad are the props? They can be re-worked and a prop shop can work with you to help meet the specs you are trying to get. More or less RPM's at WOT.

 

[Goldcoast 250]

Here is the update. WOT is 5400-5500 rpm. Both prop have been reworked once already. The larger prop is the only one damaged (2 blades) and I have hamered it out to close to original since the damage was not too bad. Nevertheless. Searay shows a 24 setup with similar hp as my new engine. I will have to find out the gera ratio from the drive. My main concern beofre dropping coin was to see if anyone had a similar setup with the 24s for this boat. THanks again.

 

[Woody]

Your getting too high rpm. Should be 5000-5200. The 24p props should get you in that range. But.....what was your wot rpm before you damaged the props and took a hammer to them? Was it still 5400-5500?

 

[keokie]

Your props may still be very out of whack. Hammering them to what appears to be normal may not even be close.

The gear ratio is printed in the decal on the upper gear case.