posted 04-03-2015 04:01 PM ET (US)            

I believe the cut-off occurred sometime DURING model year 2014. There is a local dealer here with a leftover 2014 Montauk 170 with the old 1.7 liter engine rigged on it.

posted 04-04-2015 06:30 AM ET (US)            

I should have been more clear on that. The decal on the engine cowl has a slightyl different color scheme. But this is difficult to notice unless it's side-by-side with the old engine.

However, the cowl shape is distinctly different. There are lots of differences in shape, but the most conspicuous aspect is the way the rear side of the cowl rakes forward to meet the top surface of the cowl. Instead of a an almost 90* corner where the top and back sides meet, the new engine has a much gentler transiton due to the oblique angle.

Overall, the new engine has a more streamlined and much less bulky appearance.

posted 04-05-2015 10:22 AM ET (US)            

--a 1.596-liter in-line four-cylinder engine with a powerhead made by Yamaha. Mercury bought the power head from Yamaha, and attached it to a midsection and gear case made by Mercury. These engines had carburetors. There were notorious and chronic problems with the carburetors. These engines were called Merc-aha (as in MERCury combined with yamAHA) 90 engines, and were in production until c.2005.

[I thought there was a 90-HP model with EFI, but I think that's wrong. I can't find it listed in any of the old catalogues I have. The 115-HP was EFI but the 90-HP wasn't.--jimh]

--a completely new, all-Mercury model, derived from the basic in-line four-cylinder design of the VERADO, but without the supercharging. This engine had a displacement of 1.7-liter. Its cowling was quite unusual, as it had a rounded dome top. This family of non-supercharged engines derived from the VERADO were called the VERADITO (from Spanish, for little or petite VERADO), as a way of distinguishing them. These engines were made around 2006.

--another completely new, all-Mercury model, with some harmony with the newer 150-HP FOURSTROKE engine, which came out in 2014. This engine has 2.1-liter displacement. Like the 150-HP, it seems to be designed with simple maintenance in mind, and has a lot of displacement for the horsepower produced.

posted 04-05-2015 01:06 PM ET (US)            

These were introduced by Mercury in June 2014 and began showing up on some Whaler models (e.g. Montauk 170, w/ 90HP) during the late 2014 model year. But as noted above, most model year 2014s probably had the 1.7L engine. Presumably, the farther into the model year, the more likely the 2.1L engine was used.

Like the previous version, the 2.1L engine is offered in 75, 90, and 115 HP versions.

The 2.1L engine is significantly lighter than the previous 1.7L engine. The valve train is self-adjusting, to reduce maintenance requirements. Also, a new Command Thrust gear case is now optionally available, allowing these higher displacement engines to turn a larger prop.

One cause of identity crisis with these engines results from Mercury using an image of the old 1.7L engines when they issued their press release announcing the new 2.1L engine. Here is the press release, which unfortunately/confusingly uses an image of the old 115HP 1.7L engine:

https://www.mercurymarine.com/en/us/news/mercury-marine-unveils-new-lineup-of-fourstroke-outboards/?page=4&

And here is what the new 2.1L engine actually looks like. Notice how the rear side of the engine cowl rakes forward, and the lower seem of the engine cowl follows a curvaceous path, rather than a straight seem as on the old 1.7L engine:

https://www.mercurymarine.com/en/us/engines/outboard/fourstroke/75-115-hp/

posted 04-08-2015 04:21 PM ET (US)            

I ask because I am interested to see this technology trickle down - the weight and size savings in the smaller motors will be proportionally greater.

posted 04-09-2015 09:34 AM ET (US)            

BRIEF HISTORY OF MERCURY 90-HP FOURSTROKE OUTBOARD ENGINE

2001 TO EARLY 2006

The Mercaha or YamaMerc engines
--Mercury 90-HP FourStroke using Yamaha power head
--1.596-liter displacement, four-cylinder, in-line
--four-valve, dual overhead cam
--386-lbs
--carburetor fuel induction
--no SmartCraft electronic instruments
--cowing was squarish, and about the same size as a 200-HP two-cycle engine cowling.

The simplest method to identify a Yamaha engine sold as Mercury: they don't have SmartCraft electronic instrumentation.

Around 2006 Yamaha was offering their 90-HP four-cycle engine with EFI. In a 2006 Boston Whaler catalogue, the 170 MONTAUK boat is listed as having a Mercury 90-HP EFI engine, and the pictured boat has the cowling style of the Mercaha or YamaMerc engine. I haven't found a 2006 Mercury catalogue that shows this engine. There may be a few of these Mercury-brand Yamaha-block 90-HP EFI engines, or maybe not.

2006 TO 2014

The VERADITO engines
--Mercury 90-HP FourStroke using Verado block
--1.732-liter displacement, four-cylinder, in-line
--four-valve, dual overhead cam
--399-lbs
--simple electronic fuel induction
--SmartCraft electronic instruments
--cowling was taller and had a domed round top

IN 2014

The "New" engines
--Mercury 90-HP FourStroke using new block
--2.1-liter displacement, four-cylinder, in-line
--two-valve, single overhead cam
--359-lbs in small gear case model; 363-lbs in large gear case model
--simple electronic fuel induction
--SmartCraft electronic instruments
--cowling has new trapezoidal shape
--option of larger gear case called "Command Thrust" said to improve efficiency