Rinker 192 3-4 blade prop

Rinkerfor4

I currently have a 4.3 Mercruiser with an aluminum 3 blade 14x21 and it will rev out to 5100 rpm !!!  I am looking at a 4 blade SS Michigan 14x20. Would this prop give me a WOT rpm drop ? 

mvn

I believe a stock prop was a 3 blade aluminum 19" pitch.  I'd be surprized if it was over revving with a 21".  Verify your engine speed with an accurate tach.  The Faria tachs aren't very accurate.

When I had a 192, I believe I settled with a 4 blade stainless which had a 20" pitch.

Mark 

Rich_

Pretty sure factory WOT range for the 4.3 is 4400-4800 so if you like your engine do not run it that high. While adding another blade will probably drop your rpm down a bit, I doubt it would be enough to get in the range of a 300 rpm drop. Normally all things being equal, a change of one degree of pitch is about 200 rpm. First verify your rpm with a good tach and if accurate you probably need two degrees of pitch if same brand/style of prop or a degree and another blade. If buying this prop new, consider propgods.com for their advice and exchange program

mvn

Here's an example of the analysis I did a long time ago on the 192 I used to have.  All of the engine details are listed.  Note that the WOT range for that particular engine was 4200 to 4600.  Yours may be different.  I chose to prop at the high end of WOT due to my requirements.

Mark

Rinkerfor4

So I got the Michigan wheel prop installed.  4 blade 14x20 stainless.  She plans out instantly even with 5 adults in the boat.  Revs to 4800-4900 RPM  

mvn

Perfect!