are yanmar 370 engines ok, hope so !

[Hugin]

I suspect torque will destroy VP DPH drives without any thoughts about uprating.

Why is that?

If a Yanmar 370 is 5.2L and 370 hp then surely a VP D6-400 with 5.5L and 400hp would have even higher torque. I belive Volvo sells lots of D6-400 joined up with DPH drives (or am I getting the letter combination wrong here)

Not to mention that FPT offer their N60-370 in combination with a Bravo3 drive - and that's a 5.9L block

Makes me wonder which producer have the most powerful duoprop drive in terms of torque rating?

 

[Hugin]

Not to mention that FPT offer their N60-370 in combination with a Bravo3 drive - and that's a 5.9L block

Just checked and was a bit wrong here. The N60-370SD is a 5.9L - 370hp - 1050Nm package but the drive is not a Bravo3. It's an ordinary single-prop drive of unknown origin, but could look like a Konrad with it's sharp edges.

 

[Latestarter1]

Why is that?

If a Yanmar 370 is 5.2L and 370 hp then surely a VP D6-400 with 5.5L and 400hp would have even higher torque. I belive Volvo sells lots of D6-400 joined up with DPH drives (or am I getting the letter combination wrong here)

Not to mention that FPT offer their N60-370 in combination with a Bravo3 drive - and that's a 5.9L block

Makes me wonder which producer have the most powerful duoprop drive in terms of torque rating?

I stay away from VP stuff and certainly run a mile from outdrives.

D6 400 power curve is specially tailored to the re-designed DPH C http://www.ybw.com/forums/showthread.php?283081-Updated-Volvo-DPH-drive

FPT ratings are 3,000 rpm, torque curve unsuited to Bravo 3.

I had report on field test of Cummins 4B 3.9 250 Bravo 3 combination. The 3,000 rpm Cummins 4B regularly turned Bravo gears to mush and the project was canned. Years later Cummins Mercruiser released a QSB 5.9 230 Bravo 3 package, calibration was trimmed to suit the outdrive following experience with the 4B 250. QSB230/B3 was withdrawn from market after a year or so, make your your own conclusions.

Spannerman or Volvopaul will give you their heads up on DPH drive capability.

I my book engine/drive combinations living on the edge only lead to expensive grief.

 

[Hugin]

QSB230/B3 was withdrawn from market after a year or so, make your your own conclusions.

I have no knowledge about the mentioned combination, but I could imagine it being withdrawn for other reasons than mechanical problems....... lack of demand being the obvious. Why on earth would anyone want to merge a 600kg engine and a stern drive for only 230hp? There have for years been a handful other engine manufacturers offering much lighter and more powerful combinations of engine and duoprop outdrives. Since excessive torque can be a problem rather than a benefit in combination with outdrives it makes absolutely no sense to use such a big block unless the purpose is to max out horsepower.

Some powerful engine & duoprop outdrive combinations for comparison

Volvo D6-400 + DPH: 5.5L, 400hp, 970Nm/2000rpm (785kg total)

Mercury TDI 4.2L-370 + Bravo 3XR: 4.2L, 370hp, 782Nm/2750rpm (~500kg total)

Yanmar 8LV-370 + ZT370: 4.5L, 370hp, 810Nm/2250rpm (~550kg total)

The QSB 5.9-230 for comparison gives 690Nm/1600rpm so apart from the fact that the engine is much too heavy for the output of only 230hp I cannot see why it could not work with an outdrive. I think the most likely reason for it's withdrawal was that it just didn't sell because it was too heavy (and expensive?) for the modest output. The combination would be suitable for getting a relatively heavy boat up on plane, but top speed would suck badly

 

[Latestarter1]

I have no knowledge about the mentioned combination, but I could imagine it being withdrawn for other reasons than mechanical problems....... lack of demand being the obvious. Why on earth would anyone want to merge a 600kg engine and a stern drive for only 230hp? There have for years been a handful other engine manufacturers offering much lighter and more powerful combinations of engine and duoprop outdrives. Since excessive torque can be a problem rather than a benefit in combination with outdrives it makes absolutely no sense to use such a big block unless the purpose is to max out horsepower.

Some powerful engine & duoprop outdrive combinations for comparison

Volvo D6-400 + DPH: 5.5L, 400hp, 970Nm/2000rpm (785kg total)

Mercury TDI 4.2L-370 + Bravo 3XR: 4.2L, 370hp, 782Nm/2750rpm (~500kg total)

Yanmar 8LV-370 + ZT370: 4.5L, 370hp, 810Nm/2250rpm (~550kg total)

The QSB 5.9-230 for comparison gives 690Nm/1600rpm so apart from the fact that the engine is much too heavy for the output of only 230hp I cannot see why it could not work with an outdrive. I think the most likely reason for it's withdrawal was that it just didn't sell because it was too heavy (and expensive?) for the modest output. The combination would be suitable for getting a relatively heavy boat up on plane, but top speed would suck badly

You asked for an opinion, I gave you one....

You make your own mind up as to whether your proposal will work, however save my response as reminder when it ends in tears.

DPH C not DPH with D6 400 remeber not 425 what does that tell you?

Mercruiser VW and Yanmar are simply chainsaw motors with peak torque way up the rev range you only have to do the torque rise calculation.

Jury is still out on the Yanmar ZT drive and the Bravo 3XR for that matter.

Perhaps you should talk to product planners at Mercruiser as to the wisdom of their package, apparently QSB 230/Bravo 3 was done for Willard RIB's U.S. Navy order. Peak torque down at 1,600 rpm gives gears a hard life.

 

[Hugin]

You asked for an opinion, I gave you one....

For the record it was "ubatuba" who proposed to experiment with Yanmar 370s and outdrives.... I merely found the topic interesting and I would agree with you that any one-off garage experiment will most likely end in tears if not for one reason then for some other.

In conclusion, judging from VPs use of D6-400 but NOT D6-435 it seems around 1000Nm is the current limit of abuse you can throw at an outdrive.

I'm not sure I can see your point about "chainsaw motors" having peak torque way up the rev range, Yes, smaller displacement engines generally reach higher revs than bigger displacement engines.... nothing new there. But all the engines mentioned here and many other I can think of have peak torque at 57-65% of max rpm and big block QSB5.9 is actually the bad guy here at 61-65% depending on version.

apparently QSB 230/Bravo 3 was done for Willard RIB's U.S. Navy order.

Well, there you have the explanation for the quick market withdrawal...... very few market participants have the same requirements and needs as the U.S. Navy. No point keeping a product on the market when the only likely costumer is already done shopping.

 

[Latestarter1]

For the record it was "ubatuba" who proposed to experiment with Yanmar 370s and outdrives.... I merely found the topic interesting and I would agree with you that any one-off garage experiment will most likely end in tears if not for one reason then for some other.

In conclusion, judging from VPs use of D6-400 but NOT D6-435 it seems around 1000Nm is the current limit of abuse you can throw at an outdrive.

I'm not sure I can see your point about "chainsaw motors" having peak torque way up the rev range, Yes, smaller displacement engines generally reach higher revs than bigger displacement engines.... nothing new there. But all the engines mentioned here and many other I can think of have peak torque at 57-65% of max rpm and big block QSB5.9 is actually the bad guy here at 61-65% depending on version.



Well, there you have the explanation for the quick market withdrawal...... very few market participants have the same requirements and needs as the U.S. Navy. No point keeping a product on the market when the only likely costumer is already done shopping.

Hugin,

As I said earlier I generally stay away from Volvo Penta, plenty of knowledge regarding that stuff around here.

On the subject of Green Engines, take D6 370DP motors with DPH drives (Which hardly have a stellar reputation) have a totally different torque/power curve to their shaft drive brethren, which must be linked to mechanical limits of the drive. Both D370 ratings are relatively low torque rise (18%) motors.

If you consider say a Cummins QSB 5.9 380 a bad guy with 28% torque rise a bad guy then I will go with bad guy every time.

By the term 'chainsaw motors' I refer to LDA (Light Duty Automotive) diesel engines. LDA engines in marine applications have a colorful history, BMW based Yanmar BY, Volvo D3 and VW Marine, now Mercruiser are responsible for more than their fair share of heartache. When trouble strikes LDA engines in boats become 'throw away' engines and are of little interest to me.

Bravo 3 now replaced by Cummins QSB 6.7/Konrad set up which is SUPPOSED to have a far more robust nature. ZF still working away on their new drives which they claim will surpass all the competition.

 

[burgundyben]

By the term 'chainsaw motors' I refer to LDA (Light Duty Automotive) diesel engines. LDA engines in marine applications have a colorful history, BMW based Yanmar BY, Volvo D3 and VW Marine, now Mercruiser are responsible for more than their fair share of heartache. When trouble strikes LDA engines in boats become 'throw away' engines and are of little interest to me.

Tell me, what are the key differences between an LDA engine and a medium duty one? Bearing areas? Thermal capacity? Load ratings?

 

[Latestarter1]

Tell me, what are the key differences between an LDA engine and a medium duty one? Bearing areas? Thermal capacity? Load ratings?

High speed Diesel engine classification is useful when making accurate comparisons for marketing and engineering product reviews as well as an aid to product planning. Originally conceived by the late Stan Hartshorne who was the recognised industry source of accurate technical engine information for many years with his publications sold throughout the world. Boundary between classes have become blurred over the years.

LDA Engines below .7 litre per cylinder and below, conceived for motor vehicle and light van operation relatively small bearing area for given displacement. Modern LDA engines are rarely re-buildable as they a generally capable of lasting the economic life of the vehicle in which they are installed, hence my term 'throw away engines'.

Mid Range engines are are a large group .8 liter per cylinder and above, potentially more durable than LDA and are largely used in trucks and buses of 7.5 tonnes and above as well as having construction and industrial uses. Top end of the Mid Range group, 9 litre engines now perform tasks once the province of Heavy Duty engines, these engines are often referred to a super Mid Range.

Heavy Duty engines of 1.6 liters per cylinder and above offer the highest levels of durability in the most arduous applications.

High Horsepower engines are high speed engines developing 1,000 hp and above, however duty cycle comes into play, for example CAT C32 and many MAN V engines drop into the High Horsepower category as their internal dimensions tend to be those of Heavy Duty engines, however when continuously rated they would fall into into the Heavy Duty. High Horsepower engines are characterised by CAT 3500 Series, Cummins QSK Series, certain MTU models and Mitsubishi S Series, all capable of achieving at least 25,000 hours life to overhaul at very high load factors.