Re Power
 

I have an SF 18 with a 1998 Yamaha C115 that I'm thinking about re powering come spring. The motor has been very reliable and trouble free thus far and this past summer I had it compression tested and the mechanic said it read an even 120 across all cylinders but sooner or later its inevitable that it will have to be replaced.
The Yam. C115 weighs 330 lbs. and I'm trying to stay as close to those numbers as I can for obvious reasons.
According to factory specs here are the weights of the motors I am looking at.
Yamaha.....F115....weight.....377 lbs.
Yamaha.....F90....................366 lbs.
Merc.........115EFI................359 lbs
Etech....... V4.115................390 lbs.
Etech........E90DPX (inline)....335 lbs.
Etech....... E90HGL ..............390 lbs.
Would there be a big performance difference between the Merc. 115 HP and the Evinrude 90 HP since its a two stroke compared to the Merc.four stroke ?
My mechanical knowledge and experience is very limited so any insight on the subject would be greatly appreciated.

Light is right, but I believe Merc's new 115 Command thrust is much more motor than the etec 90. I think you'll find it closer to the etec 115 in performance. It's a 2.1L with gearing that allows more considerably more prop. I'm pretty certain the etec 90 would perform similarly to your Yammie. A hair slower WOT perhaps, but excellent cruising torque curve and economy, incredible economy through manatee zones.

"bitsamonkey" had incredible numbers from the Suzuki 90 on his 18,also...
http://www.classicseacraft.com/commu...ki+performance

Thanks for bitsamonkey's link, the numbers look really good but the question brought up about staying up on plane at lower speed was not addressed and I would also like to know about that. The command thrust is slightly heaver at 363lbs. but that's still doable, if I relocate my starting battery from the transom compartment to the console it should float at an identical level its at now and she's sitting just right.

Anxious to hear more about the subject, please keep it coming.

Very happy with my merc 115ct on my 20

I can plane at about 12 knots/14 mph with a carburetted Yamaha F100- a glorified 1.6 liter F90 on a 20 foot master angler and a 4 blade prop and aquashield. Before I added the T-Top, it would come off plane at just over 10 knots. I have a 12-3/4 x 15 4 blade prop- the $100 Solas Amita 4.

http://www.classicseacraft.com/commu...07&postcount=6

It isn't the 18, but I thought the data point might be relevant.

Edit: I want the inline Etec 90 for my next outboard, if it is really 10-15 hp more power than nameplate..

Anyway of finding out and confirming the Etec 90 inline is actually 10-15hp more than its rated ? At 335lbs its the lightest in that power range.

Why not a Suzkuki do 90? 341 lbs. Super fuel efficient.

The NAEBM requires that advertised HP be within + 10% of actual HP, and BRP seems to be sandbagging on most of the E-TECs by up to the full 10%. The I-3 90 is basically 1/2 of the 2.6L V-6, which is made in 4 different HP ratings, i.e., 135, 150, 175, and 200 HP. The HP/Torque curve for the "150", which was published in a brochure a few years ago, shows it actually producing 165 hp at the prop. I suspect that the "90" is actually 95-100 HP at the prop. What's more important is the mid-range torque that you need to get on plane quickly; all 2-strokes are typically much stronger in the mid-range than comparable 4-strokes, even if they're about the same at max rpm.

I have a 19' "sawzalled" bow rider with a 2007 I-3 90 E-Tec w/ 500 hours run time. Makes 18-19 Knots at 3500 RPMs with Power-Tec 13-3/4 X 14" - 3B wheel. Tops out about 31-32 Knots. I usually run with a big load (3-4 Divers, 8 tanks, fish box gear, food cooler etc.) We ran 68 miles New Years weekend - lightest load was 5 adults - topped back off with 8 gallons.
The 90 E-Tec has a very flat torque curve and pulls like a John Deere. The 115's are a little more pipe in the mid-range - I also have two of those. I believe 3 three cylinder motors are harmonically balance and are super durable with few Hot Spots. the new G-2 Etec's are actually two three cylinder motors grafted together with a common crank - Starboard Injectors, Port Exhaust on both banks. that should tell you something.
That being said - EVERYBODY MAKES VERY GOOD MOTORS THESE DAYS. Find you best local mechanic and pick a color. It all good, Bro'!

I will consider any or all of them but there has been some comments made about the Suzuki 90's torque at mid range. On a previous post specifically on the Suzuki 90. the question of mid range torque and keeping the boat up on plane at slower speed was not addressed which leaves me suspect.
From what I have read in this thread so far, it seems the Etec. inline 90 would be a better choice over the Suzuki 90 at a comparable weight. It offers better mid range torque, and may also be under rated as to actual HP, which leaves only one question. How would the two compare in fuel efficiency ?
As I stated in my original post, my knowledge of outboards is very limited and this is going to be a substantial purchase so I just want to make sure I make the right decision and not have any regrets afterwards.