Revisiting Tims thread re 2.1 L Merc 115

[Bushwacker]

Originally Posted by McGillicuddy

Thread revival from last August... Has anyone opted for this motor yet? Tim???
I'm really tempted to re-power the Seafari 20 with this choice. Its about 360 lbs and appears to get 5 mpg and 4 mpg @ roughly 20mph and 35 mph... Think i could keep my controls and props, making it more intriguing. 4-s silence at speed?

Until recently I've been 2-s d.i. or die with short looks at zuke 90 and 140. I think with etec weight on the rise and merc offering a 4s lighter than an opti, even with oil, mercs new 2.1 L is a game changer.

Com'on Terry of the 3 Lions, what say you 2-s faithful, does the torque curve allow consideration? What say you Bushwacker - it appears the valve lash issue is "history"...have I lost my way?

Bigshrimpin', oh Grand Pooh-bah of the phantom black, how doth thy opine?

Gillie, I agree that the new Merc certainly looks very competitive on engine weight now that the V-4 E-TEC has gained a lot of weight. One really needs to know a lot of technical details to do a good comparison, like how does the Merc lower unit compare to the robust V-6 lower unit they appear to have put on the newer V-4 E-TECs, but haven't been able to find much tech info on that Merc 115. The Merc web site only has basic stuff like weight, displacement, gear ratio, etc.

The weak link on all 4-stroke motors is burned exhaust valves and seats, and to a lesser extent, the exhaust manifold (corrosion issues). If anyone is building one that's really bullet proof, it'll have sodium filled exhaust valves and stellite (cobalt alloy) material for the valve seats, plus some very good alloy for the pistons. Nickle or cobalt alloy exhaust valves would also very durable, so that's info I'd want to know if I was gonna buy one! I suspect some of the supercharged Verados may have stuff like that because of it's extremely high specific power output (HP/cu. in.), but I doubt that you'll find expensive aircraft quality hardware in a cost-competitive outboard.

I ran across this thread on the 115 E-TEC vs. 115 Merc 4-S that might answer some of your questions. Forum member Huey is a dealer/tech in Sidney, Australia that's been selling both Evinrudes and Mercs for 40-50 years and seems to really know his stuff. He says that a 4-stroke needs to have 30-40% more displacement to match the torque of a motor having a power stroke on every revolution, so by that measure the new Merc needs to be about 2.2-2.4L to match the 1.7L E-TEC. I've seen a video of a BRP "identical boat tug-of-war" between the new Merc 150 4-S and the 150 E-TEC, and while the E-TEC didn't pull the Merc completely underwater like it did the 150 Yamaha, it still pulled it around pretty good, so I suspect that Huey is right, the new Merc is certainly a step in the right direction but it needs a bit more displacement to match the E-TEC's mid-range punch. As for durability, the E-TECs are well established by now and seem to have a very good record if installed and set up right, and BRP has an excellent record of standing behind them, even beyond the warranty period. Fr. Frank most definitely knows how to maintain a motor, but the 3 fuel system failures on his Opti and some horror stories documented by BoatUS on lack of customer support on the early Bravo 3 Drives would give me a little less confidence on the black motors.

[Bigshrimpin]

The 115 "command thrust" model has the same larger gear case as the Merc 150 four stroke. It's comparable to any v6 gear case. Those Etecs are nice motors for sure. I'm no expert on this motor . . . I'm still running a 1980's 2.4L merc and I can't justify a new engine until I blow all 6 spare motors.