Am I in the zone?

[booger man]

Ok ,i have a 1978 merc 1150 on a 17 ft pro select deep v boat running a 19 pitch vortex aluminum prop gps reads 42mph and the tach is at 5000rpm at max trim.Am i good with this ? also have a 17 pitch spare but i haven't tried it yet....Also would a 19 pitch stainless steal prop raise my rpms any ,and would i notice any performance gains worth the money difference.

 

[walleyehed]

Re: Am I in the zone?

First, you're about 800RPM low of where you need to be. Without raising the engine, I don't think you'll get where you need to be with an SS in 19.<br />I'd run the 17 and test for RPM with it first, and I think an engine raise will be in order for that prop to reach the R's you need too...

 

[booger man]

Re: Am I in the zone?

the anti-ventilation plate is 1.5 inches above the v of the keel is that ok

 

[walleyehed]

Re: Am I in the zone?

That's fine.....you should have no water pressure issues going 1 hole higher.

 

[booger man]

Re: Am I in the zone?

what do you mean by one hole higher? iv'e heard this before but not sure what it meant...

 

[walleyehed]

Re: Am I in the zone?

Lifting the engine on the transom...there are 4-5 holes forthe top bolts, and slots for the bottom bolts. loosen the bottom 2, and with some help, remove the top 2. Before you do this let the trailor jack down all the way and place boards under the skeg until they are realclose to touching...with the help of a friend to steady the engine, jack the trailor up (lifting the engine by lowering the transom) until the top bolts will go thru the next set of holes.<br />Tighten the top 2, remove and re-seal the bottom 2. That would be raising the engine 1 hole.

 

[booger man]

Re: Am I in the zone?

my seloc repair manual says my WOT should be betweem 5000 and 5500 rpm so how am i 800rpm below where i should be? I'm going to hold up on raising the outboard till i can afford a jack plate (don't want to drill more holes into the transom) also will a stainless steel 19pitch prop raise my rpms compared to the aluminum any ?

 

[walleyehed]

Re: Am I in the zone?

5000 to 5500 in 1978 yes...when we had good, quality fuel...not the case today. We've found by experience that most all of the 5500 Max rated engines will last much longer and have much better efficiency (fuel milage) if we prop them for atleast 5800RPM. Anything under 5500 is considered lugging by todays standards and combustion temps are higher than intended and so is the fuel consumption.<br />In most cases, unless it's a new boat with a newly designed hull, your results with a 19SS will drop your RPM by somewhere around 100. It would be in your best interest to maximize with a 17P and get the R's up where they should be....<br />Many people have been through this on this forum, and those that followed the recommended set-up, found out they were very happy with the results.<br />Adding pitch does not mean you will go any faster...infact, at the RPM you are at now, your speed will likely drop.