Re Power

[sidelock]

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.

[McGillicuddy]

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

[sidelock]

Originally Posted by McGillicuddy

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.

[FishStretcher]

Originally Posted by sidelock

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.

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..

[72potter20]

Very happy with my merc 115ct on my 20

[sidelock]

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.

[Bushwacker]

Originally Posted by sidelock

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.

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.

[Terry England]

Originally Posted by sidelock

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.

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'!

[sidelock]

Originally Posted by Terry England

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'!

Wow, four divers, 8 tanks & equipment etc. and a heavy boat, that's very impressive for the I-3 90 Terry ! I personally would have thought you would have a hard time getting up on plane but like I said, I have very limited knowledge on the subject, hence my post asking for opinions and advice. I've only had three people once in my 18SF with fuel and fishing equipment and I noticed getting up on plane was not very swift, turning a 13.5"x 17P Power Tip Ballistic on the 98 Yam. 115.
Can you pleas elaborate on what you mean by few "Hot Spots" ?

[Bushwacker]

[QUOTE=sidelock;241201] . . . Can you please elaborate on what you mean by a few "Hot Spots"[QUOTE]

Before the advent of the G2 E-TEC, the exhaust ports on all V-4 & V-6 2 strokes dumped into the V between cylinder banks, creating what could be considered a "hot spot" that required extra cooling, which I suspect is what Terry was referring to. The inline engines and the G2 E-TEC do not have this problem.

Regarding fuel consumption differences between the 90 hp Zuke and E-TEC, I suspect that the Zuke will be 10-15% better at cruise, and the E-TEC will be 25-30% better at low speed (below ~1800 rpm) when it's in the stratified charge mode, so the overall average mpg will be very similar on both. For example, my 150 E-TEC burns 0.5 gph @ 1000 rpm & 5mph (=10 mpg) and gets ~3.8-4.0 mpg at cruise; my overall average when carrying a heavy cruising load (2 big coolers, groceries and gear, extra H20 and gas) is typically about 4.4 mpg. A few years ago I circumnavigated S. Florida via the Okeechobee waterway, Florida Bay and the ICW, running almost 700 miles and burning 158.5 gal of fuel and about 1.5 gal of oil for an average of 4.4 mpg. I've also made the 90 mile run up to Sebastian for CSC gatherings 3 times and I typically burn about 20 gallons each way. Another good resource if you have any questions on the E-TEC is the Owners Forum, which is supported by some very knowledgeable techs.

The other items to consider are maintenance costs and proximity to a good dealer. As Terry says, nobody makes a bad motor these days!