Re: will a 25 pitch stainless steel quicksilver prop work with my v8 5.0 alpha 1 engi
pls. help. I am replacing my prop for my 1989 celebrity mercruiser boat. i cannot find my prop size on the old damaged prop even after removing. what size and pitch prop do i need?
Well...since none of the usual folks have chimed in just yet, I will.
Personally, I strongly recommend searching the other old posts for further advice on this subject. Volumes have been written about how you pick the proper prop size.
That said, here is my advice, summarized from others more experienced than me. If you are running the original gear ratio outdrive that came with your boat, I would not expect a 25p prop to work well at all. However, if you already have a 25p prop, give it a try. Note your maximum rpm with that prop. I assume it is going to be well below your max recommended rpm. You want your boat motor to reach max rpm when you are at full throttle with a typical load, so...
Here is the typical advice given. Decreasing your prop pitch will raise your rpm, approx. 200 rpm/pitch decrease. Adjust your pitch (by trying different props) until your motor can reach close to its max recommended rpm (without going over) at wide open throttle. This will typically give you your max speed, which is what most folks equate to max performance.
If however, you have a heavy load, or are pulling heavy or mulitiple tubes and/or skiers, consider running an even lower pitch prop. It will be necessary to pay close attention to your rpm gauge to make sure you do not over rev your engine, but this type of prop will give you a stronger hole shot...with the trade off of a lower top speed (rpm self limited I hope).
The problem I believe you will reach with a 19p prop is exceeding the recommend max rpm of your engine. You could over rev and see how far past it will go, and use this info to figure what prop you need, but of course you risk blowing your engine. Please don't do that.
Start over propped, then adjust accordingly...that is my personal advice. Do not, I repeat, do not continue to run your engine over propped thinking it will get you good fuel mileage. It will not. What it will do is slowly destroy your motor. Work with the prop pitch until you hit max rpm at WOT without going over.
Just my two cents, consider what you paid for it.
Mike
