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Michael T

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212rowboat

I'm not familiar with the Volvo, and not so much with the merc, either, but I know engines okay..

It's pretty easy to figure tq and hp.. you gotta know induction, flow rates, volumetric efficiencies, exhaust, and how well managed stoich ratios are.. then there is the big two which go hand in hand for a RELIABLE engine: compression (dynamic, not static) and spark advance...

If someone is squeezing a ridiculous amount of power out of a naturally aspirated engine, they are pushing the envelope somewhere.. I'd be curious to find where they've pushed it, and if it's at the expense of reliability and longivity.. I, personally, ain't willing to give those up..

mvn

Are these based on the GM 6.0L Vortec engines? 

Mark

Michael T

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Madcow

There's no replacement for displacement...lol

212rowboat

man, I find it frustrating when people or organizations aren't straight forward... this sounds like a good case of it..

there is no replacement for displacement, as Madcow said, and as you'll hear at the track over and over.. but there kinda is, and it's called boost.. if my 6.4lPSD drew no boost, it would likely top out at around 250HP and maybe 400# tq.. drawing up to 75lbs of sequential twin turbo, it dyno'd at 617hp and 1187#tq.. it ~can~ be done, and safely/reliably, depending on the build... cheap/fast/reliable... choose two, you can't have all three...

I appreciate what volvo is doing in the automobile industry- they are like lazereth rising from obscurity.. I don't know much about the marine industry, though... I'd hate to think they are relying more on twisted numbers than fact...

and I'd still like to know where they are getting the extra power from specifically.. higher rev's? maybe- but higher revving n/a engines have a lot that goes into them, and usually at the expense of bottom end- bigger valves, for one, which decrease flow velocity down low and make an engine fight for air.. higher lift/longer duration ground cam shafts for another- which if there is any overlap or too much air-in, causes really weird vacuum signals and makes power off idle near non-existent, and that is if you can keep it running at idle at all...

fuel trim is over-rated... there is no way they are getting that power out of playing fuel trim tricks.. 14.7:1 stoichiometric ratio is perfect- it's said 13.9:1 is perfect for power but noticeably rich at the pipe (would eat a catalyst alive in no time), and 15.3:1 is said to be perfect for economy, but it burns might hot- which is bad for valve seats, guides, gaskets, and such... which leaves boost..

you can safely boost an engine expressly built for high compression.. my diesel, for example, has a mechanical compression ratio of 17:1 stock.. there are very few gassers on the planet that achieve that kind of compression.. when you compress air and shove it into a cylinder, as you can figure, the compression ratio goes up right along with it.. which is why you'll find a lot of boosted engines running a mechanical compression ratio under 9:1- so they can handle as much as, say, 14:1 under full boost..

there is no replacement for displacement- true story.. you're getting that extra 'displacement' from boost.. 14.7 pounds is an additional atmosphere.. a 6L engine pumping 15#'s into the cylinders is moving air equivalent to a 12L engine.. Well, sorta kinda anyway- there are volumetric efficiencies and some other factors buried in there, but it's a close comparison..
 
if those engines were boosted, I'd wonder why someone boosted a marine engine, and not think much about it.. even 3#'s of boost would explain the output.. but they ain't advertised as boosted, which makes me think what Al presented is more than likely the truth of it..

Michael T

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212rowboat

variable valve timing is a neat little trick.. especially the Ferrari way of doing it: they use a cam shaft with an elongated lobe, and literally slide the camshaft forward or backward depending on RPM, using a very smooth 'grind' transition.. they can alter not only lift and duration doing this, but also do so in a manner that doesn't feel like an old four barrel edde 'quadrajet' carb opening up the secondaries.. it is a smooth transition from all vantages.. other folks using variable valve event timing schemes are having issues with rockers locking the active valvetrain, such as with a piston in the honda application, or the multiple camshafts others use..

the engine is a catalyst controlled engine.. which means they are monitoring o2 both before and after the catalyst, which means they can dial in air:fuel to the very edge of stoichiometric.. which is really good for longevity and economy.. I started out hating computer controlled engines, but now I love them..

on an engine that maintains a very static and predictable operating temperature (which they all rely on a thermostat to do, but some monitor them better than others) spark advance can be toyed with.. once getting the air in there, getting the air out (which covers everything from air-hat to prop exhaust, including intake manifold, heads, valve size and timing, exhaust design..ect) and fuel trim is addressed, just about the only thing to do to a n/a engine to get more punch is with timing of spark..

my 4.3l merc requests 10*... that is a safe knock free engine.. and it's rated 190hp could likely generate (i'm guessing) as much as 220hp by simply advancing the spark to around 30~40*.. if I had an EFI, adjusting the fuel sync/squirt to advance maybe 5* would likely push the engine to around 240~250... just playing with spark and sync, mind you... but it ain't safe for the engine.. it wouldn't survive the inevitable pre-detonation but for a little while..

not being able to control the temperature, and not having the engine controlled by a computer which can alter sync, and spark advance dependent on environmental condition in microseconds is asking for serious issues with it's longevity and reliability.. maybe they have cracked that code with their proprietary cooling system, and computer controls- but here is the punch line that no manufacturer will present in plain language:

the same system that allows the engine to toe the edge and press for performance, will also reduce the engines performance if they aren't ran in the conditions they were engineered to run in... which is why computer 'programming/tuning' is such a big business- they remove the safety barriers makers implement, and do it somewhat safe because they are altered (if done correctly) based on the specific environment the user uses it in most often..

in a perfect world, they may produce the advertised power... no doubt they do on paper (described in post #2 here)... in reality and practical application, though, there is no telling what they give you.. and also- if they intended to be transparent about it, they would provide a graph demonstrating the complete power band from off idle to redline, demonstrating consumption and output...

I'm certainly not saying they aren't on to something, but there is a big ol' cloud about it..

212rowboat

a good steady gain to rpm is dang near necessary with marine engines, i'm thinking.. sorta like:

700 rpm  40hp
1000 rpm 45 hp
1300 rpm 55hp
1600 rpm 80hp
1900 rpm 110hp
--
4800 rpm 350hp
--
5000 rpm 330hp .....

certainly not;

700 rpm  30hp
1000 rpm 40 hp
1300 rpm 45hp
1600 rpm 50hp
1900 rpm 75hp
--
4800 rpm 200hp
--
5000 rpm 350hp
6000 rpm 420hp
6200 rpm 380 hp

the yellow would be g2g... the red is great for a racer in an expected and sustained range (up high), but it's bad for a cruiser... as it is, though, the only figure folks gotta advertise is the peak- and that only tells the headline of the report, the most important part of the report is it's contents, in that analogy..

tkrfxr

All of this is theoretical...the test of truth will come when these engines are put into the boats and the boats are used in a variety of conditions....

Stay tuned to this story....we shall see what the engines can do within the next couple of years.

Volvo has been an innovator in the marine industry before...for better or worse.....remember the XDP drives....

JoeStang

I'd say the Volvo380 is in reality an upgrade to the Merc 6.2 instead of a replacement for the 8.2.

On my boat (2013 276 Cuddy) the Volvo 380 is a $5300 premium over the 377Mag. The 8.2 Mag is another $760 on top of the Volvo380.

The Merc 8.2 comes standard with FWC and Bravo 3X drive, and I'm not sure if the Volvo comes standard with similar items.

I would definitely opt for the 8.2 for the extra $700, but I went the cheap route and stuck with the 350Mag/B3. I wouldnt mind another 5-10mph and FWC, but mine will still cruise 30mph @ 3500 rpm and has gotten great fuel mileage. Plus the 8.2 was close to $10k more. :O

212rowboat

you're right, tkrfxr... could be they're on to something.. i'm anxious to see how they did it.. maybe they are using some sort of variable valve event system that allows a good steady climb.. maybe they are using a silly high injection pressure which allows multiple injections per cycle.. (skinny early, fat before tdc after spark, and a lil on the pistons way down to increase tq numbers)...

212rowboat

if performance is your huckleberry, the same things being done to the vp small block can be approximated with the merc big block, but with even more power... sometimes it pays to watch the competition, huh?

Michael T

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