Prop Question.

[Gary H NC]

I'm running a 3 blade old stainless thats nicked up and has rough edges.<br />I can't read the serial number but it is a 20 pitch x14.5<br />I'm getting 4200 rpms at WOT and about 41 mph.<br />I'm wondering if going with a new 19x14.25.<br />Will i loose alot of top end.I was wanting to get the rpms up a little.Hole shot is not bad with the 20 pitch.<br />19ft 4.3

 

[LubeDude]

Re: Prop Question.

I think you might want to go to a 17P X 14.5.

 

[Gary H NC]

Re: Prop Question.

Thanks LubeDude.How much top end should i figure giving up?

 

[Silvertip]

Re: Prop Question.

I assume we are talking outboard here and not I/O? Before spending a bunch of coin on props, play with engine height first. If the AV plate is even or below the bottom of the boat, raise the engine mounting. Re-test. Raise again, re-test. The theory is less engine in the water, less resistance, higher RPM. Just don't go so high that you lose water pressure. A water pressure gauge is a valuable and inexpensive addition to the console as it also indicates relative condition of the water pump impeller. When you reach optimum setup, then determine the prop you need.

 

[Silvertip]

Re: Prop Question.

I assume we are talking outboard here and not I/O? Before spending a bunch of coin on props, play with engine height first. If the AV plate is even or below the bottom of the boat, raise the engine mounting. Re-test. Raise again, re-test. The theory is less engine in the water, less resistance, higher RPM. Just don't go so high that you lose water pressure. A water pressure gauge is a valuable and inexpensive addition to the console as it also indicates relative condition of the water pump impeller. When you reach optimum setup, then determine the prop you need.

 

[Gary H NC]

Re: Prop Question.

Its an I/O..4.3 Cobra..<br />I'm not wanting to loose speed but get the rpms up a bit..gaining speed would be nice.<br />Hole shot is fair now.<br />I just think its time to replace...prop looking kind of rough.<br />See if i can find some more numbers or markings on the old prop.

 

[Ron G]

Re: Prop Question.

I dont know what the recomended rpms for that motor is but it seems a 19 would work,it should put you around 4400.but my a loose a few mphs,if the prop you have now puts you close to your rpm range you could get it reworked.