Evinrude e-tec 90 hp prop selection

bucks or bass ?

Recruit
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Jan 3, 2008
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2
Hi Everyone

Great Site

I have read posts from this site and many others in regard to finding a stainless prop for a 2007 90 hp e-tec. The details for my boat are as follows a 1997 Aluminum Grumman 16 foot SP Single console, weight dry 680 lbs. I have calculated total boat weight to be 1580 lbs, this is for 2 guys, the motor (90 e-tec) and all the gear batteries trolling motor, fuel etc. I have narrowed my selction down to a viper 13.88 x 19 or a Turbo 13 1/4 x 19. I had a 1997, 70 hp Johnson on the boat previously with 13.78 x 17 aluminum prop. The WOT with one passenger was 37 mph at around 5500-5700 depending on the water conditions. Also just when I would trim the motor high the motor would cavitate and lose RPM's (just when the boat would be lifting nice and riding well). The boat had a tendencey to porpose before it was riding nice. I adjusted weight to accomadte for this over the years. All the weight is in the back of the boat, two batteries, fuel tank and the seats are rear situated. I have one shot at selecting a prop as my funds have gone into the e-tec. Any suggestions or insight on prop selection between the two I have identified or any others is appreciated.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
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28,771
Re: Evinrude e-tec 90 hp prop selection

Your expectations of getting this right the first time are rather slim. Without a base-line to work with, you can only hope for "close" or "lucky". The proper prop is one that allows the engine to run at the high end of the manufacturers wide open throttle RPM with what you consider an average load. Since we have no RPM data to work and not being familiar with that boat (other than it is very light), all I can suggest is that the E-tec should have no problem twisting a 21P prop. To cut your expenses, you might consider buying an 21P aluminum prop. Get the base line numbers and then go for the stainless adjusting the pitch up or down as required. You should have a spare prop anyway so what better way to do it. Ventililation on your previous setup may have been due to the engine being mounted too high. Your dealer should have a good idea what would be a good starting point as well. The best scenario would be if someone on this forum happens to have the same or similar boat with the same engine and has done this research for you. I run a 19P aluminum prop on a heavier boat than yours and its twisted by a 75 HP Merc triple. With more ponies and a lighter boat, a 21P should be close and provide great hole shot on your setup.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Evinrude e-tec 90 hp prop selection

Hi Everyone

Great Site

I have read posts from this site and many others in regard to finding a stainless prop for a 2007 90 hp e-tec. The details for my boat are as follows a 1997 Aluminum Grumman 16 foot SP Single console, weight dry 680 lbs. I have calculated total boat weight to be 1580 lbs, this is for 2 guys, the motor (90 e-tec) and all the gear batteries trolling motor, fuel etc. I have narrowed my selction down to a viper 13.88 x 19 or a Turbo 13 1/4 x 19. I had a 1997, 70 hp Johnson on the boat previously with 13.78 x 17 aluminum prop. The WOT with one passenger was 37 mph at around 5500-5700 depending on the water conditions. Also just when I would trim the motor high the motor would cavitate and lose RPM's (just when the boat would be lifting nice and riding well). The boat had a tendencey to porpose before it was riding nice. I adjusted weight to accomadte for this over the years. All the weight is in the back of the boat, two batteries, fuel tank and the seats are rear situated. I have one shot at selecting a prop as my funds have gone into the e-tec. Any suggestions or insight on prop selection between the two I have identified or any others is appreciated.

If you go to the BRP site there are many performance reports.Boats in your size/weight are tested with 40 and 50 hp although a couple are heavier with 75 hp.I think most of the boats tested weigh around 1300lbs total.
Props range from 15" to 19" (19 may be a miss print)speeds from about 29 mph to 34.Most of the 90 hp boats are about twice your weight. Some prop dealers will let you test run props if you buy from them And even though they may charge more it may be well worth the investment.At almost double the 50 hp test I would wonder if 19 inches is enough.But it is a starting point.If your going to guess your better off under propped if you keep the revs down.I do think that Silvertips 21" suggestion would be closer to what you need.I would think your dealer would have some idea of a correct prop.
 

bucks or bass ?

Recruit
Joined
Jan 3, 2008
Messages
2
Re: Evinrude e-tec 90 hp prop selection

The reason I thought a 19 on the Viper or Turbo is because from other threads I read these props typically run like a 21? Is this your thoughts or should I run a 21 and go from here? Thanks for the input.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Evinrude e-tec 90 hp prop selection

I stand by my original suggestion. Buy an aluminum 21P, work with engine height to get the best setup and then go to the high buck stainless from there. My personal feeling is that you will be under-propped with a 19P.
 
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