What to use on 90 E-Tec?

[imported_walleyeman]

I currently have a 2007 90hp E-Tec (20" transom) mounted to a 2005 Lund 1600 Prosport. It came with a 13.25 x 17 BRP Alum prop. With two adults and two small kids the boat performance at WOT is 5000-5100 RPM's while doing 41 mph. I know that I could raise the motor up a hole but would rather leave it where it is since it does not cavitate nor ventilate even when fully trimmed out. the ventilation plate is at the level of the drain plug.

Is there a reason to try and raise the WOT RPM by using a different prop or is the current RPM satisfactory? I would like to eventually get a second prop and if I am spending the $ I might as well get one that will increase the performance in particular raise the RPM's without sacrificing the current top speed. ( I should also mention that with the current set-up the boat planes out in 3 seconds, turns with no problems and is overall really great.

The prop that I would like to go to is an SST. What would happen if I went to a larger diameter but the same pitch? Or would it be wise to go to the same diameter and pitch since the rpm range is smack dab in the middle of the recommended range?

Thanks

P.S. When testing setups are you supposed to go WOT with the motor fully trimmed? This is what I have done...hope it was correct?

 

[Dhadley]

Re: What to use on 90 E-Tec?

By going to a prop with less pitch you'll probably lose efficiency even though the r's come up. Raising the motor will reduce drag thereby increasing efficiency from holeshot to top end. And spend a lot less bucks.

Being able to use 100% of the trim range without venting the prop is a classic sign the motor is too low for that design prop.

 

[imported_walleyeman]

Re: What to use on 90 E-Tec?

I am just a novice at this technical talk, so please bear with me. I would like to know then how do I know when I have reached 100% of my trim range? Do I just go by the guage? Also how does one describe venting, what actually happens?

Thanks.

 

[steelespike]

Re: What to use on 90 E-Tec?

Ventilation: To keep it simple the motor will rev but the boat may actually slow.When severe you may have to actually slow down and start over.
You want the motor as high as possible without venting problems and keeping sure it is pumping water.Once you have the ideal set up the experts here can reccomend a prop that may give you even more performance.
Another prop may allow you to raise the motor even more.
Depending on the present height one hole could give you 1 or 2 mph.

 

[longshot]

Re: What to use on 90 E-Tec?

I am running a 90Etec and a 13 7/8 X 15 SST on a 1860 lowe roughneck. I am getting 5350-5530 RPM WOT at 38MPH depending on where my fishing buddy sits.

I am going to move the motor mount up one hole at a time since I can use 100% of my trim without bouncing in the front with a bit of chop on the water.

thanks
longshot

 

[imported_walleyeman]

Re: What to use on 90 E-Tec?

Where is your ventilation plate in comparison to the bottom of the boat?