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Yamaha 350 v6 rumors

Old 10-18-2015, 01:08 PM
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Default Yamaha 350 v6 rumors

I have heard a rumor from a reputable source that yamaha is testing their new 350hp-V6 on a 25 tidewater in a southern state. Anyone heard of this new motor?
Old 10-18-2015, 03:13 PM
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No
Old 10-18-2015, 03:14 PM
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Can't imagine why other than for weight purposes. The yamaha has a torque advantage and i can't imagine a v6 being able to offer something like that
Old 10-18-2015, 03:24 PM
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Originally Posted by 305seahunter View Post
Can't imagine why other than for weight purposes. The yamaha has a torque advantage and i can't imagine a v6 being able to offer something like that
Maybe because their current rendition has a flywheel problem ??????;?
Old 10-18-2015, 07:10 PM
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I have alsp heard that.
Old 10-18-2015, 07:12 PM
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^^^ From where?
Old 10-18-2015, 07:20 PM
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If they offer a v6 in 350 they will certainly have to offer the v8 in 400+.....
Old 10-18-2015, 07:55 PM
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Originally Posted by redseacraft View Post
If they offer a v6 in 350 they will certainly have to offer the v8 in 400+.....
And the v8 will require flywheel replacement every 10 hrs at cruise.
Old 10-18-2015, 08:14 PM
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I heard the same (350 v6 getting close) from a good source.....second hand. For what it is worth. Do I believe it?? Not sure pre Miami and Ft Lauderdale show a lot of BS artists start talkin!
Old 10-18-2015, 10:57 PM
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Nup.

300HO to compliment the HO lineup, offered with the big leg.

The 4.2 is pretty close to max efficiency in 300 guise while still providing levels of reliability consumers expect of the brand, expect of the factory engine.

Little to be gained in turning them harder, volumetric efficiency begins to fall at high fives. They will spin harder, but power production isn't climbing.....

Ignition timing is set to allow for shit fuel when (not if) it gets fed to the engine. No one can guarantee the fuel quality they pump into their tanks, and most don't really care anyway. The factory tune has to cater for this scenario while offering a few years of warranty....

If it was a race speck competition orientated model different story. But that ain't Yamahas deal is it.

More fuel, through pump or injectors, doesn't make power contrary to popular myth. Lean combustion mixtures make power, provide economy (particularly on cruise, light loads etc) and most manufacturers are so close now to optimal, that pulling more fuel out (leaning mixtures) will push the combustion temps beyond acceptable long term condition.


Melting pistons and rings has been done before, (HPDI anyone) so that's not a place the brand is likely to go again.

On that last point, every manufacturer is running so close to AFR induced power v reliability, they're all so competitive in fuel consumption terms, if any of them "blow the others away " with fuel burn comparisons, surely the question MUST be asked if such efficiency gains come at the expense of long term durability...?



My own view is that indeed it must. Pretty much takes a given amount of juice to make a given amount of power. All things being equal.

Any manufacturer that manages to blow the competition away,,, well, let's see how that particular model is going with thousands of hours under its belt. In the real world. Operated with varying, and often questionable fuel quality.

flashing ECMs via aftermarket hardware while viable and worthwhile with many automotive applications, remains questionable and provides little gain in a modern, factory, marine aspirated application.

The current factory state of tunes are that good. They have to be, otherwise the model gets roasted on THT lol.

So, where does that leave us. forced induction? Probably.

Should Yamaha do it?

personally I hope not. And I'm a believer in it (FI) as I have had highly modified V8 engines in my motor cars courtesy of Kenne Bell and FORD GT 40. Boost is good

But do I want to strap a grey coloured FI engine to the transom of my boat? Nup.

Cube it up if needed, and let others venture beyond 350, 400 or whatever if FI is the only Option.

But given development mules of the 5.3 have been wracking up substantial hours making significantly more than 350, I think Yamaha will stay their current course.

Last edited by Gun smoke; 10-18-2015 at 11:09 PM.
Old 10-19-2015, 03:43 AM
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Originally Posted by Argon View Post
And the v8 will require flywheel replacement every 10 hrs at cruise.
BS artists like this ^^^???
Originally Posted by Flatout71 View Post
I heard the same (350 v6 getting close) from a good source.....second hand. For what it is worth. Do I believe it?? Not sure pre Miami and Ft Lauderdale show a lot of BS artists start talkin!
Will be interesting to see what new lines may be at the shows
Old 10-19-2015, 03:59 AM
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Ahh rumor season has started. Rumors used to be F400 V8, now its F350 V6.
Old 10-19-2015, 04:23 AM
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I heard the new engine will be a 425 HP, 2 stroke, supercharged V8.
Old 10-19-2015, 04:54 AM
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350hp from the 4.2L is still about the same HP/L as the old 3.3-250, so tit seems like the engine will do it. However, I think they will need a new gear case as the old one is marginal with LH rotation.

Regarding the V8, a boat manufacturer told me earlier this summer they were told to prepare for a 425hp next year by Yamaha.
Old 10-19-2015, 05:03 AM
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^^^ And let the HP wars begin!
Old 10-19-2015, 06:12 AM
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Originally Posted by haneyrm View Post
I heard the new engine will be a 425 HP, 2 stroke, supercharged V8.
I heard it was a 435, direct injected, 4 stroke at cruise and 2 stroke while accelerating. It will also have a super charger for low end and a turbo for top end and cruise.
Old 10-19-2015, 06:47 AM
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Originally Posted by Troutman561 View Post
I heard it was a 435, direct injected, 4 stroke at cruise and 2 stroke while accelerating. It will also have a super charger for low end and a turbo for top end and cruise.
What are you trying to say?

A turbocharger (if that is what you mean by turbo) is a supercharger. Are you suggesting that both a mechanically driven supercharger and a turbine driven supercharger both be used? Will the mechanically driven supercharger be a single speed or a multiple speed supercharger? Will it be driven by belts, gears or is it direct drive?

Why not turbo-compounding as well? Think of the space that an intercooler and an aftercooler would take up.

I am still contemplating the intake system that would be needed to shift from a two stroke mode to a four stroke mode. Got to get my mind right.
Old 10-19-2015, 06:50 AM
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motor manufactures make a lot more then 350hp with 4.2l of displacement, kinda comical to see people think Yamaha can not do it.

Would expect to see Yamaha upgrade there fueling system and injectors in the very near future. While there system is very reliable the market is pushing for higher HP, lighter more fuel efficient motors. Yamaha uses simple computer systems with very basic injectors. They can make more power from all there outboards with an upgraded fueling system and still be natural aspirated motors. If they are going to do it, guess we will have to wait and see.
Old 10-19-2015, 06:59 AM
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Originally Posted by Jeepman View Post
motor manufactures make a lot more then 350hp with 4.2l of displacement, kinda comical to see people think Yamaha can not do it. Would expect to see Yamaha upgrade there fueling system and injectors in the very near future. While there system is very reliable the market is pushing for lighter more fuel efficient motors. Yamaha uses simple computer systems with very basic injectors. They can make more power from all there outboards with an upgrade fueling system and still be natural aspirated motors. If they are going to do it, guess we will have to wait and see.
Name a motor manufacturer that makes more than 350 HP out of 4.2L displacement where that motor is connected to a single speed transmission. Just one. Thanks.
Old 10-19-2015, 07:03 AM
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Originally Posted by Whaler27 View Post
Name a motor manufacturer that makes more than 350 HP out of 4.2L displacement where that motor is connected to a single speed transmission. Just one. Thanks.
Mercury

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