90 etec prop questions!

[sublauxation]

First, sorry for the long question, and I appreciate any advice. Buying new props is expensive, and the wife wont give me to many chances at it.
I have a 2006 90 etec on an 18 foot mid 1980's Sylvan deep v.
My dealer recommended a 13.25X17 OMC aluminum prop.
At WOT GPS speed is 31.5 mph, and the tach reads 4300rpm
I didn't expect much more for speed, but It sounds and feels like the motor has more to offer. I was told the tach is probably not calibrated properly and is reading low, but it was calibrated when I had it rigged. I'm going to have the dealer re-check that out when I get the chance, but assuming the tach is correct, any prop recommendations. The boat planes almost instantly and has a wicked hole shot. It seems dropping to a 15P aluminum still wont get me close to the recommended 5200 RPM. Does stainless make that much difference vs aluminum? Reading these forums it sounds like I should raise the motor a bit. Does it make sense to find the optimal prop first, then make height adjustments, or is it not that easy
Thanks for any help

 

[steelespike]

Re: 90 etec prop questions!

I wouldn't be surprised to see you at 15" but::But check the tach seems low
also on a new setup be sure the throttle is opening all the way wouldn't be the first one to be off a little.
I would fine tune the height.Starting with the anti vent plate even with the bottom.If your not haveing any venting issues then the motor is probably too low.Most tollerate a little venting to get that fine height adjustment.Raise it a hole at a time to a point just before venting becomes a problem.Be sure it pumps water.Fine tune the trim at each hole.A stainless can do wonders but at what cost.The hustler turning point is said to deliver stainless like performance at aluminum cost. Once at that ideal height the right prop selection could give you a little more height.Depending on the present setup you could gain a couple of mph and some rpm.And a prop change could add 400 or more rpm.

 

[sublauxation]

Re: 90 etec prop questions!

Thanks for the info. Sounds like first thing I have to do is a lot of set up change. I talked with another guy who has a similar boat and same motor. He has almost the same speed and rpm as mine. He switched to a 15 pitch and raised the motor. Better RPM but he lost 4 mph vs the 17 pitch. How important is it really to fall near that 5200 RPM mark?

 

[steelespike]

Re: 90 etec prop questions!

The 90s performance reports list the rpm range as 4,500 to 5,500.Near as I can tell the lowest test rpm was 5,000 I estimate the average rpm was 5,300
with about 5,600 as a max.I would raise the motor to the ideal point then select a prop.I wouldn't change height and prop at the same time. I believe your boat is about 1200 lbs.While the boats were somewhat smaller and lighter than yours speeds were about 38 including a 1273lb Starcraft and 1100lb Mirrocraft. a couple were over 40.Of course if yours is truly a deep V then it could be slower.Generally aluminum will be slower tha stainless. The performance reports were stainless.Again the huster turning point delivers close o stainless performance.

 

[Silvertip]

Re: 90 etec prop questions!

Having the engine run within or at the top of its recommended rpm band is extremely important because if it can't reach that rpm the setup is wrong throughout the entire range. If you are familiar with a stick shift car or truck, you know that you can't climb a steep hill in high gear without lugging the engine. Well a boat is in high gear all the time -- get the picture?? You are seriously lugging this engine.

 

[sublauxation]

Re: 90 etec prop questions!

I appreciate all your help. Things make more sense when you guys explain it. I talked to the dealer and he said it's easy to lower the motor by yourself, so I plan to have them set it as high as it will go, and test from there. (First I'll have the linkage and tach checked). I bought a 15 pitch Hustler, which I'll try after height adjustments. Unfortunately boating time is running out for the season, hopefully I can get to it before ice so I don't have to think about it all winter. Thanks again for all your help and advice.

 

[steelespike]

Re: 90 etec prop questions!

Go to it; let us know how things go.Good luck.

 

[Silvertip]

Re: 90 etec prop questions!

Setup is a logical progression of changing things, but changing them one at a time. Raising the engine, changing the prop, and doing other things all at once means you will never know what the real issue was. Do one thing and then test. Raising the engine and changing the prop at the same time may make the situation worse and you won't know why.

 

[patiomae]

Re: 90 etec prop questions!

Hi...I had a similar problem with my prop. I'm from Kansas City and we have a great local shop here that someone else referred me to. They have some FAQ stuff on their website, but I just gave them a call directly to see what I could do about changing pitch to help me with getting out of the whole vs top speed.

http://www.midwestpropeller.com/index.html

Good luck and happy boating. Hope they can help.

 

[Senderofan]

Re: 90 etec prop questions!

Good Day:

I'm looking to repower with an e-tec this winter. I had a lot of questions regarding propping and rpm's and such. I found an e-tec site....they have this guideline that BRP puts out for dealers regarding WOT rpm:

2008 RPM Range Quick-Reference


Model Operating Range Optimum Range
40 HP 5000 - 6000 5400-5600
50 HP 5500 - 6000 5600-5750
60 HP 5500 - 6000 5600-5750

75 HP 4500 - 5500 5000-5200
90 HP 4500 - 5500 5000-5200

115 HP (60?) 5500 - 6000 5500-5600

150 HP (60?) 4850 - 5850 5500-5600
175 HP (60?) 4850 - 5850 5500-5600
200 HP (60?) 4850 - 5850 5600-5850

200 H.O.(3.3 90?)4500 - 5800 5500-5600
225 HP(3.3 90?)4500 - 5800 5500-5600
225 H.O.(3.3 90?)4500 - 5800 5500-5600
250 HP(3.3 90?)4500 - 5800 5500-5600

250 H.O.(3.4 90?)4500 - 6000 5500-5600
300 HP(3.4 90?)5000 - 6000 5500-5600

2008 Evinrude? E-TEC? Models


What I've been told....you want to be in the "Optimal Rnage" when running with your "Normal Load." In my case....if I'm in the boat with a light load....I'll be near the max WOT rpm listed by BRP. But my normal load is four to five adults....fishing gear etc. So, with the extra weight, I'm going to drop in the max rpm's....should be in the optimal range.

Hopes this helps some.

Wayne

P.S.

The guidelines didn't transfer like they should have. The optimal wot rpm for your motor is listed as 5000 to 5200.

 

[sublauxation]

Re: 90 etec prop questions!

I know this is an old post but thought I'd add to it. Raised the motor one hole and started to cavitate on turns, so I lowered it back down. Learning to use tilt and trim properly made a big difference.