22p to 24p swap and losing rpm???
 

i have a 28ft commander deck boat and i bought it with a 22p on it and i was only pulling 57mph @ 4600rpm on a good day. Just put on a 24p this weekend and now im at 50mph @ 4100rpm. What could be the issue ?

Ahhh when you go up in pitch you lose rpms :)

John jr

we talked to a few different people and they all said to run a 24 and we should do at least 60+...any ideas?

What engine? how many hours?

They were wrong. A 200rpm loss per inch of pitch increase is normal.

You were barely pulling enough rpms with the 22" prop.

What engine???

It takes a lot of hp to turn a larger prop. It seems that you are propped pretty close.

you need to go down in pitch to increase rpm and put the prop at its most efficient rpm.... we need to know what engine you have to know what is its peak operating rpm range. the 22bravo1 is more like a 21. so a 21 3 blade would most likely act about the same. you may want to try a 19p mirage plus and mabye have it re-worked with a little more cup or pitch to about the 20 range to get you at that 48-5000 rpm range.

If it's a standard 454 not a Magnum, 4600rpm is the correct rpm.

4600 is a little shy. i thought mercruiser likes to run around 4800 for most of their applications.

PatriYacht is correct. Standard 454 with cast internals has an operating range of 4200-4600 and the 454 Mag is 4600-5000. So if he has the non-mag engine he is on the money with 4600 rpm.