2017 Outboards - MIDDLE WEIGHT Comparisons / bye-bye 2-strokes.

**RSWORDS** · 06-10-2017, 07:54 AM

Originally Posted by David

Remember the 4 stroke weights are 'dry' so add some lbs for oil and water. I doubt the 4 strokes have the low and mid range of the 2 strokes. If I had to replace my 115 HO tomorrow I would get another.

The newer ones do. Mercury's 3 liter 150 is an absolute monster. The 2.1 liter 115 is no slouch either. I run one on our work skiff. 19' Carolina skiff, running a 21 enertia I've seen a best of 51 on the GPS on the limiter. I have a 115 proXS sitting in the show room that I'm kicking around tossing on.

**powerabout** · 06-10-2017, 08:02 AM

Originally Posted by home made tunnel

Here's what I know of the 2 motors in that test.
125 Optimax - Max Rpm: 5750 / Weight 375 lbs / 3 cyl Inline / 1.5 Liter / Bore & Stroke: 3.63"x3" ratio=1.21 / Gear ratio 2.07:1
115 Pro XS - Max Rpm : 6300 / Weight 359 lbs / 4 cyl Inline / 2.1 Liter / Bore & Stroke: 3.5"x3.2" ratio=1.09 / Gear ratio 2.37:1

Being that the 115 has a longer 3.2" stroke vs the 125's 3" stroke, that there will tell you it should have more torque than the 125. Also, because it's a 4 banger vs the 3 banger of the 125 puts more power out of it. And it revs 500rpm more

I think it's a good comparison. Nope, not great for drag racing like the 2.4's out there... but the performance for most boaters is advantageous in this weight class so far w/ the 4 strokes.

re the longer stroke, you are forgetting the other is a 2 stroke so another cylinder has fired 120 degrees after the first one which is why in general terms a stroke has more torque for same capacity same no cylinders than a 4 stroke.
Getting the 4 strokes lighter and more cubes is what has moved them forward but wait till the 4 stroke has a cat con in it to make it as clean as the 2 stroke.
If global warming is created by Co2 the 4 strokes produce about double in the mid range and idle

**Dingie 2** · 06-10-2017, 08:35 AM

Yamaha SHO 115 has all kinds of low end power .Does anyone have a dyno sheet on the Yamaha SHO 115 . Max RPM 6300 - Joe R

**David** · 06-10-2017, 02:31 PM

I have not run a 4 stroke but I have run my 115 HO and a 100 cross flow on the same boat, 16' Baja.Cross flow max speed, 56, would barely pull out a 180 lb slalom skier (different props for ski and speed)115 HO 64 mph with no engine height experimenting, would barely pull out a 210 lb slalom skier, again different props for speed and skiing. Way more power from idle to the rev limiter. And it burns a lot less gas and oil.Where is Bass and Walleye Boat for a comparison test?

**FMP** · 06-10-2017, 03:29 PM

Sure but is that 100crank vs at least 115prop??

**FMP** · 06-10-2017, 03:45 PM

Originally Posted by RSWORDS

The newer ones do. Mercury's 3 liter 150 is an absolute monster. The 2.1 liter 115 is no slouch either. I run one on our work skiff. 19' Carolina skiff, running a 21 enertia I've seen a best of 51 on the GPS on the limiter. I have a 115 proXS sitting in the show room that I'm kicking around tossing on.

3 L making only about 170 crank. Where's the graph on that? Sorry Merc underrated.

**Risco** · 06-10-2017, 06:25 PM

Originally Posted by home made tunnel

Here's what I know of the 2 motors in that test.
125 Optimax - Max Rpm: 5750 / Weight 375 lbs / 3 cyl Inline / 1.5 Liter / Bore & Stroke: 3.63"x3" ratio=1.21 / Gear ratio 2.07:1
115 Pro XS - Max Rpm : 6300 / Weight 359 lbs / 4 cyl Inline / 2.1 Liter / Bore & Stroke: 3.5"x3.2" ratio=1.09 / Gear ratio 2.37:1

Being that the 115 has a longer 3.2" stroke vs the 125's 3" stroke, that there will tell you it should have more torque than the 125. Also, because it's a 4 banger vs the 3 banger of the 125 puts more power out of it. And it revs 500rpm more

I think it's a good comparison. Nope, not great for drag racing like the 2.4's out there... but the performance for most boaters is advantageous in this weight class so far w/ the 4 strokes.

Even with that small gear ratio difference means the 125 opiti will go faster with same size prop and 500 less rpm. They need higher gear ratio because 4s don't make the torque.

**FMP** · 06-10-2017, 06:47 PM

Never mind

**FMP** · 06-10-2017, 08:31 PM

We'll get around the cc lubrication with a closed system, misting pump sprayer and point injection , cylinder walls, bearings and recirculating. We'll supercharge the fresh air intake charge to a transfer port shared manifold, ultra high pressure timed injection. We'll time the direct injected again ultra high pressure Hydrogen charge with multiple points into the chamber for optimum effect and light the thing to the moon. Short circuiting fresh air will only help purge the cyl and freshen the exhaust. We'll have a two stroke that does it all. Lol

**David** · 06-10-2017, 09:16 PM

My 100 cross flow was prop rated

**FMP** · 06-10-2017, 09:25 PM

So the 115 kicks, if you even the pitch and gear! They don't do a 15"?

**Wayne Cammidge** · 06-11-2017, 01:34 AM

I would like to see this comparison versus the old 2 stroke 125 2+2 Merc.
That thing had monster torque out the hole and pulled hard.
Just a very low top end RPM
I know the fuel difference would be huge.

**FrenchPhil** · 06-12-2017, 04:22 AM

If you want to see who has the fastest mid-sized engines look at the recent UIM records:
Offshore 3A : Mannerfeld Veehull & Etec 115ho : 73.47 mph
Offshore 3B: Twister Cat & Merc 115 proxs 4 stroke : 85.05 mph

**home made tunnel** · 06-12-2017, 06:35 AM

Originally Posted by FrenchPhil

If you want to see who has the fastest mid-sized engines look at the recent UIM records:
Offshore 3A : Mannerfeld Veehull & Etec 115ho : 73.47 mph
Offshore 3B: Twister Cat & Merc 115 proxs 4 stroke : 85.05 mph

whats the difference in 3A and 3 B ??