DFI or 4strk, best torque & acceleration

[LakeFever]

The four strokes don’t accelerate as quick as the two strokes in my experience but up top they work well. Plenty of 100mph plus boats but in the friendly drag races the two strokes are cleaning up. Even modded and tuned four strokes don’t accelerate like a stock 260 or 300 promax etc. at least not that I’ve seen

[DangerNewb]

I had a 25 Liberator with twin 300XS opti and another with twin 300R 4 strokes. The 4 stroke boat was stronger in acceleration and top end. About 7mph on top. Acceleration was seat of the pants. No hard measurement.

[JPEROG]

Sounds like some of these guys should have supported Caldwells efforts to make a new two stroke. I never thought that I would be a four stroke fan after watching the results of boats rigged with a single 2.6 Inline 6. My old 300X motors modified and stock would outrun all of them on a performance level but they were definitely more user friendly (dock manners) then my set ups. Since the release of the 4.6, there is no looking back. We also have an STV with a 3.4 that runs very well (not going to compete with an X), but the advantages of efficiency, smoothness, warranty, noise level, smokeless, and reliability outweigh the upside of just pure performance. We are not typical lake boaters that run a mile or two at a time-we have 40 miles between stops and used to have to carry fuel cans in the boat (maybe I am just getting old).

Joe

[David - WI]

That all makes sense, except that a "modern" two-stroke designed using state-of-the-art engine simulations, CNC machining, and advanced engine controls would be at least as efficient, smooth, reliable, quiet... and "clean" as any of the current four-strokes. Plus lighter, cheaper, and more powerful.

I think it will take a major disruption... recession, pandemic, terror attack, or maybe a war to force Mercury (or someone else) to lose enough revenue that they have to look at engines they can build and sell for less money without less performance.

[aj06bolt12r]

That all makes sense, except that a "modern" two-stroke designed using state-of-the-art engine simulations, CNC machining, and advanced engine controls would be at least as efficient, smooth, reliable, quiet... and "clean" as any of the current four-strokes. Plus lighter, cheaper, and more powerful.

I think it will take a major disruption... recession, pandemic, terror attack, or maybe a war to force Mercury (or someone else) to lose enough revenue that they have to look at engines they can build and sell for less money without less performance.

I'm with you.. Trust me I am. I'm an Allison guy.. But the efficient and clean emissions DFI outboards are very close in weight to the 4 strokes and the reliability is not on par.. Sadly, for the DFI 2 strokes to meet those fuel efficiency and emission standards they have to be run extra lean, like on the edge of death.. Any tiny particle of dust that makes it into the fuel system ends in a melted piston.. The 4 strokes don't have that problem, if they have an injector problem they just present with a misfire, replace or clean the injector and your good instead of rebuilding a powerhead.

If I'm going to pay new outboard money for a 2 stroke it better be significantly lighter than its 4 stroke competition and just as reliable.. Otherwise what's the advantage? You can rebuild an old lightweight Carb or EFI 2 stroke for less than 1/4 the cost of a new 4 stroke and it'll be bad on gas but it'll be light, powerful and reliable. The new stuff is just Crazy expensive. I'm a peasant, it would be really hard for me to justify that.

[LakeFever]

We run far too. Usually 80 mile runs. I can go about 85-90 miles on 25 gallons at 80mph+. My rig is slow compared to most guys I run with everyone else is in the 100+ club. One guy runs a Daytona with a 400r that is now off for a 450R next year. I believe his hull is 23’ long. Anyways he uses more than double the fuel I do but it is a giant boat and lord knows what it weighs.

The only real metric I can measure any of this too is the sleds where a 300mile day is not uncommon and the two strokes and four strokes are almost identical in range and the two strokes outdo the four strokes in most areas of performance. Again those etec motors rule the day. Rarely blow up and sleds go through far more extreme conditions than boats do. I’ve left on a run early am at -22F and come home at dinner time at +55F. Less than twelve hours to see that temp change. The carb motors would be very doggy without a rejet at those temps changes and no one out ripping stops mid day to rejet so it was what it was. Etec performance barely changes and runs safe low octane fuel hardly uses oil and so on. Plus iirc brp said their etec outboards were cleaner than the four strokes on market did they not? So the emission nonsense is a non starter.

Where BRP blew it imo with boats is where they win with sleds. You would think they would know this but a 300lb 300hp two stroke outboard ready to race that would embarrass any 2.5 production motor would have been a hard pill for any of us Merc guys to swallow or argue against. Hopefully this in turn would have nudged Merc to counter. Merc blew it with the mechanical pressure system imo. Too much gack when a stout electric system would have been superior. The irony too being that Kiekhaefer was Mr lightning electric man originally. It would have been great to see Meecury engineer the finest two stroke electric hpf tech and dominate the performance world with over achieving underweight two stroke outboards.