Cruising RPM, Hrs, GPH, and longevity Tug and Cut diesels

[BB marine]

There have been threads asking how many hours do you have on your Tug or Cut? There have been threads asking what is your cruising RPM? There have been threads asking what is the highest RPM I can run my Volvo, Yanmar or Cummins at ? Threads about fuel efficiency, propping and speed performance. This thread is to combine all of them into one to see how Tug and Cut owners are operating their boats. What Tug and Cut owners are experiencing and expecting the reliability and longevity to be with diesel power plants installed and the way they are operating them.

We can ask a Volvo, Yanmar or MerCruiser representative, representing the company that manufactures and sells the engine. He is not going to tell you run it at 40 to 50% and you will significantly increase your longevity. Reason ? You will be upset at the boat manufacturer under powering the boat.

We can ask a Volvo or Yanmar or Cummins technician that works on the engines. Most of them are experienced at fixing oil leaks, component parts changing, troubleshooting day to day failures. There are not many that are tearing them down and rebuilding them. I have asked diesel technicians how should I run the D3? Most say run it hard! Diesels like to be run hard! I'll ask" even with an (open deck block) with high boost and high compression?" Sure Volvo says you can!

We can ask Fluid Motion technicians and customer service. They work with the selling engine manufacture to get the right engine that will achieve the advertised cruise speed and full throttle speed of the boat model. Unfortunately most of the Tugs and Cuts have to be run at 80% load to achieve those speeds. If you ask them what kind of longevity I can expect? They are perfectly honest, " you can run them at 90% of WOT, that is what Volvo is telling us and we are seeing good results" . Honestly that is really what they have to go on. Ranger Tug and Cutwater boats are one of the newest used boats in the Market. A 2008 model year boat is a fairly new boat in the used boat market. How many hours does a average 2008 boat have on it? 100 hrs a season average would be 1200hrs. Throw a couple of trips on the average boat use 12 year old boat may be 1500 hrs.

The small displacement diesels are built for the average recreational boater. Volvo, Yanmar and Cummins, run them at 80% load average 100 hrs a year you will get 12 or 15 years out of that engine easily.

Many Tug and Cut owners use their boats more than the average boater. Many use their boats year round. I know of a few owners that have over 1000 hrs on 2016 model year boats. I image there are many that do. That type of use is more than the average recreational boater. That is what this thread is about. I'm asking the boat owners not Volvo, not a diesel technician and not the Fluid Motion reps. How do you operate your Cummins, Yanmar or Volvo? What is your Max Rpm ? What Rpm do you cruise at and what is your fuel consumption at that cruise speed ? How many hours do you have on your engine ? Its not a debate or a right or wrong. Its a how do you run your boat?

My information
D3 220 HP 430 hrs +/- total,
slow cruise 2100 RPM
fast cruise 3400 RPM
Approximately 250 Hrs +/- 2250 rpm at or below average GPH 2.0. 180 Hrs +/- 3200 -3500 rpm average GPH 8.0.
My C26 runs best at 3650 rpm to 3700 rpm approximately 85% load. I rarely run that high.
Max rpm with the prop installed (17"X 17" 1.05" cup) high 4150 rpm and low 3980 fully loaded for a trip.
@2250 rpm average speed 8 mph. 7 kts. 2.8 gph
@ 3400 rpm average speed 14mph 12.2 kts. 8.7 gph
@ 3600 rpm average speed 16.5 mph 14.3 kts. 10.0 gph
@ 4130 rpm average speed 22 mph 19.1 kts. 12.0 gph

1150 rpm to gain 6 mph going from 20% load (estimate) to 70% load (estimate)
700 rpm to gain 8 mph going from 70% load " to 100% load. "

Reliability has been good with the exception of a Turbo hose and turbo failure at 400 hrs. I have all oil sampled after oil changes. Reports have come back within range each time. I did see higher iron count after taking a 700 mile trip and running most of the time at 3400 rpm my average iron particulates went fro 42 PPM to 64 PPM on this oil change 92 hrs. 64 hrs of run time total for the trip. The 64 ppm was on the high side of the range still considered ok. But advised to watch by Blackstone. I also had the reverse gear oil sampled when it is changed same time. This showed "Visible ferrous metal present in the oil sample. I was advised to resample in 75 hrs which I did and it was fine. My theory on this was higher rpm the wear increased slightly both engine and reverse gear. It would be interesting to see what others have experienced, reliability, Rpms , hours, Gph to get a better idea of what to expect from these smaller displacement diesels over time.

Sorry Yamaha and Suzuki powered Tug and Cuts you are in a different league with your 6000rpm engines cruising at 4000 rpm on a plane! It would be interesting to compare your numbers too.

I'm running out of things to do during this social distancing :shock:

 

[Red Raven]

Here’s my data. I’m interested to see if any others have seen a reduction in performance like ours.

2014 R27 (purchased used with 30 engine hours in 2015)
Volvo D3-200
All numbers fully loaded

100 Engine hours (2015)
Slow cruise: 2250rpm 7.3kts 2.8gph temp 178F
Fast cruise: 3400rpm 14kts 8gph temp 183F
WOT 2015 4000rpm 19kts 10gph temp 189F

1180 Engine hours (2019)
Slow cruise: 2250rpm 7.3kts 2.8gph temp 178F
Fast cruise: 3400rpm 13kts 8gph temp 189F
WOT 2019 3850rpm 16.5kts 10gph temp 196F

As you can imagine I am pretty concerned about these numbers. The reduction in WOT has been consistent at about -50 rpm per year. I have removed nearly everything from the boat (over 1000lbs including the dinghy and spare anchor and chain etc.) as a test and only achieved a 50 rpm improvement. Changed the impeller, back flushed the heat exchangers and cleaned the running gear (it was not bad). No improvement. The boat lives inside on the trailer over each winter and thus the bottom is pristine at launch each season but the drop in WOT rpms continues.

The first 4 years we ran her pretty hard, fast cruise 80% of the time. Last year was the opposite with the trip up the inside passage. 90% slow cruise, 10 fast cruise. The years at fast cruise show iron count at the high end (at 200 hours). Last year with slower cruise average iron count was down to mid normal range (again at 200 hours). I fully service the boat myself per the Volvo schedule (at less than 200 hours). Never seen more than a small crack in the impeller at changeout.

A certified Volvo tech went out with me at the 2019 Rendevous and put his computer on it. He could find nothing wrong and said it must be bottom condition and/or load. I had already removed a lot of weight and the bottom had 6 months on it since cleaning but the performance had been the same all year.

This off season, to get the WOT rpms up, I have removed the cup from the 17x17 prop. I also ran barnacle buster through the raw water system and cleaned the turbo with one of those turbo spray cleaning products. I haven’t launched the boat this season to test these changes yet. If no improvement I plan to take it to a shop to have the injectors cleaned or replaced. Can’t think of what else to do.

Other than the WOT reduction issue the boat has been completely trouble free. Love the boat.

Curt

 

[Cutwater28GG]

Curt is your boat in the water all the time? Even if I have had a diver clean the boat, old vs new paint and type of paint can make a difference. Just a thought.

 

[BB marine]

Wow I was hoping for more input then this. Does this mean that most Tug and Cut owners do not monitor the performance of their engines ?

One other piece of information that should be included in the data that Curt included was coolant temperature. Additional data would be boost pressure. One that many have no concerns is engine intake air temperature from the compartment.

Additional data D3 220hp
2250 rpm 178 F 10 PSI
3400 rpm. 183 F. 22 PSI
3600 rpm. 185 F. 25 psi
4130 rpm. 193 F. 28 psi

When engine compartment reaches and operates at 140 F + during extended cruising approximate 10% loss of efficiency
Keeping engine compartment at or below 115 F no noticeable change in efficiency

Curt do you have recorded specs on you boost numbers at different RPM and WOT. I spoke with a 27 Ranger owner at the SWF rendezvous and his boost # 23 PSI WOT also experiencing a loss of RPM 3750 rpm max. 15.7 kts these numbers came from a screen shot off his Garmin that he sent to me. I know the 220 hp is 28psi I don't know max 200 hp I assumed the same as 220 hp

Let me know what you experience performance wise with removing the cup. I thought about doing this before leaving for Florida this fall. We will be loaded heavy, so an additional 50 to 100 rpm gain would be what I will be looking for.

I have removed the cup from the 17x17 prop.

 

[Red Raven]

Curt is your boat in the water all the time? Even if I have had a diver clean the boat, old vs new paint and type of paint can make a difference. Just a thought.

Hi Gavin,

The boat is pulled each fall and lives in the garage over the winter so only in the water for 6 months. The bottom is fully cleaned over each winter and was repainted with the same Seahawk AF33 bottom paint as new 2 years ago. There was no Improvement in performance with new paint.

Curt

 

[Red Raven]

Curt do you have recorded specs on you boost numbers at different RPM and WOT. I spoke with a 27 Ranger owner at the SWF rendezvous and his boost # 23 PSI WOT also experiencing a loss of RPM 3750 rpm max. 15.7 kts these numbers came from a screen shot off his Garmin that he sent to me. I know the 220 hp is 28psi I don't know max 200 hp I assumed the same as 220 hp

Let me know what you experience performance wise with removing the cup. I thought about doing this before leaving for Florida this fall. We will be loaded heavy, so an additional 50 to 100 rpm gain would be what I will be looking for.

Brian,

According to the Volvo tech the boost pressure for our boat during commissioning at was 23.8psi at 4000rpm. We measured 23psi on the water at 3850 that day. He said it was fine. I don’t have additional numbers but will be recording them in the future.

Yes, I’m hoping removing the cup will help. The prop shop estimated a gain of 100 rpm. I asked about re-pitching but they said it could not be done on that prop and still maintain the prop tolerance rating. They recommended removing the cup only. BTW, I forgot to mention before the prop shop also said there was a very slight bend in one blade that they fixed. They didn’t think it would account for the loss in rpm but maybe it’s possible? I will report back on performance once the boat is back in the water.

Has your performance remained the same over life? Did the performance change when you added the ventilation system?

Curt

 

[Cutwater28GG]

im a D4 260 in a cut 28. 2012
im 3 years into bottom paint and its at its end of life
boat is id say mid loaded with gear.
Hours 610.

I only measure temp from the volvo display. always a solid 185F once warm.

Speed to RPM ratio is tough to be accurate as I use in the sound and hyper local current can make big differences. also weight onboard has a huge effect for how much RPM is required for on plane use. 3 people vs just me is night and day.

typically run at 1200RPM for displacement speeds. around 5knots. Interestingly I do this mostly by ear and fuel burn. above about 1200 I can start to hear prop or hull cavitate (definite increase in bubbling sound) and it strikes me it less efficient.
Generally run on plane at between 2960-3100RPM This gives me about 18knots. - 9.5-11GPH and 1.7-1.8NMPG is typical

I occasionally push the engine for 10 minutes or so up to 3400-3450RPM. Ive seen 23knots.

I'm aware this is a leisure spec engine. my boat is 8 years old but only 600 hours. i expect the engine to outlast my ownership. I service religiously.

 

[NorthernFocus]

...Speed to RPM ratio is tough to be accurate as I use in the sound and hyper local current can make big differences...

GPS navigation is awesome but it does have its downside. What was once considered basic instrumentation, like boat speed indication, is no longer standard equipment from most boat manufacturers. A simple paddle wheel would eliminate the need to run up current/down current and average the readings to figure out true boat speed through the water.

We have the Mercruiser 150hp engine in a 2009 25 classic. The engine had nominally 300 hrs on it when we bought the boat. After five seasons we now have about 1400 hours on it. The first couple of years I routinely recorded all of the engine operating parameters. Now I just spot check. None of the meaningful parameters have changed with time. The only time I see any temperature variation is when the raw water intake gets dirty.

How we load the boat changes with every trip based on what we're doing and changes over the course of a given trip as we use fuel/water(we carry extra water every trip). Consequently at semi-planing speeds I operate the boat based on load rather than rpm. We have the lower pitch wheel (14 in pitch) that was an option back then.

Generally speaking operating paramers are:

In calm water we make 5kts at 1250rpm. Manifold pressure not measurable. Coolant temperature 176-178(which is thermostat set point)

Typical low speed operation for us is 5.5-6kts(depending on conditions) at 1550rpm. I have to check my log book but by memory manifold at this rpm is 2.5psi. Coolant temperature 176-178. We operate at this rpm a lot because it's minimum rpm to get heat out of the "bus" heater or to generate hot water.

Semi-planing cruise at 80 percent load yields 3250-3350rpm at 10-11kts outbound, 11-12kts inbound. Again from memory manifold pressure runs about 15.5psi. Coolant temp 181-183. Inlet air temperature gradually creeps up as the engine room heats up at this engine load.

WOT when we ran the sea trial was 3850(vs 4000 name plate). With a typical load it runs more like 3650.

 

[BB marine]

According to the Volvo tech the boost pressure for our boat during commissioning at was 23.8psi at 4000rpm. We measured 23psi on the water at 3850 that day. He said it was fine. I don’t have additional numbers but will be recording them in the future.

That is interesting 23 PSI 200 hp, 28 PSI 220 hp with the VGT Turbo The boost is adjustable, controlled by the ECU. Same components operating at different parameters increasing HP.

Has your performance remained the same over life? Did the performance change when you added the ventilation system?

My performance loss as not been do to the engine. It has not been due to a fouled bottom. I pull the boat a couple of times a season and it is usually clean then (fresh water). I contribute the performance loss to a boat that is weight sensitive and under powered. If I add additional gear for cruising and the dingy I can see a reduction of 200 RPM then add some wind and disturbed sea's into the equation another 100 RPM. If I take all the gear out dingy off I'm back to my PDI 4130 rpm.

The compartment temperatures don't come into play until the compartment is "heat saturated". When ambients are lower this takes longer. Example Lake Michigan water temperature usually doesn't see much higher than 70 F. Air temperatures out on the lake usually high 70's on a day when it is 85 or 90 F on shore. It takes about an hour to see 140F compartment temperature at the engine air intake. Power loss was not really noticeable at most 20 to 30 rpm fuel efficiency over a 8 hour run about 5%. I did talk to a engineer from Volvo that works with Fluid Motion. Fluid Motion asked him to call me to explain engine longevity should not be effected by the elevated compartment temperatures. He did say though with compartment temperatures above 140F and the range I was seeing 155F to 160F engine performance "could be decreased slightly" "About 20 HP" I don't feel I saw a loss that high. I feel the ventilation is helping more with reduction of component temperatures, alternator, relays, any electrical components plus fuel temperatures. Plus cooler air in the engine induction increases engine efficiency.

I hope you see a increase in performance with the eliminating the cup. The less load put on these small displacement engines the better.

 

[BB marine]

As a side note to maintaining original performance. I saw this photo in my album. This is after second season of owning the boat and noticed a slight decrease in RPM and slight increase in operating temperature at WOT. I contributed this decease in the extra equipment and gear we added. The boat seems to get heavier every year. I took this photo after installing modified Drop fins (235 hrs) which helped in rpm ranges above 2000 rpm. Most noticeable 3000 rpm to WOT. With additional weight aft, dingy, outboard, heavier batteries, ( original batteries installed 44 lbs each, new Northstar 67lbs each) extra fuel tank 20 gals. The factory tabs which are marginal became useless. I had noticed my original 4130 decrease to 4000 to 4010 WOT with elevated bow attitude. The photo was during a sea trial with modified drop fin. Increase in rpm and temp dropped 6F. Less load on the engine when the stern is lifted out of the hole. Unfortunately when more supplies and weight are added for extended cruising the Rpm drops and temp goes up. I'm still able to keep the rpm with in manufactures specs. I contribute this to the trim tab alterations.

This is a photo after modified drop fin was installed.
gallery2.php?g2_itemId=54363
gallery2.php?g2_itemId=54369

 

[Chimo]

Did any of the 200/220 owners note their boost pressure at precisely 3000 rpm?

I spend a good deal of time at 1800 RPM and around 8 kn. The coolant temp is 172 – 174° F. Pushing above that is going over the hump and a good economical cruise comes at 2650- 2700. That's the 90% RPM point using 5.75 – 6 gph, around 80% of the 7.5 at WOT. Here I'm doing around 13 kn and coolant will go to 178° F. WOT is 3000 rpm and around 17.5 kn and temp 182 – 184 depending on season. I'm using that term "around" quite a bit because obviously weight and bottom condition matter.

I keep the boat in a boathouse of the bottom doesn't get too fouled. [no daylight equals no growth]. if I haven't been out for a week or so it takes about half an hour cruising to slough off the bit of slime and I'll notice a change in speed. I haul the boat in May and November to change zincs and do a quick check. What I did notice when I hauled was that the stern was picking up some real growth. That's logical because the sunlight comes under the boat house curtain. This year I have dropped a tarp with weights off the swim platform rails and the growth has been virtually eliminated. I tried WOT before and after the haul out and wash last year and the numbers went from 2970 to 3010, same weight.

I did add a remote temperature sensor near the air intake after reading Brian's comments. In a nice cool PNW it takes a long time to get up to 110 and 2 to 3 hours at 2650 RPM will only get me to 115° F.

Since we have essentially the same hardware between the 150, 202 20 [maybe a different Turbo?] the difference is software. The torque from the 150 at 3000 is obviously the same as the 200 at 4000. I asked the Volvo factory application tech at the last rendezvous whether my wear rate [think life] was lower at WOT than a 200 unit at 80% RPM and he smiled. We had quite a chat. Essentially, they choose the 90% number based a lot on fuel economy. Maintenance and use [or lack of] are big factors when it comes to life.

Back to COVID nap

 

[Red Raven]

David,

Just to clarify for all, these numbers are for a D3-150, correct?

It is amazing how different the numbers are for different software! Of course the boat size contributes a lot too!

Curt

 

[Chimo]

Hi Curt

That's correct.

Logically your 27 would have a higher hull speed but I see you're cruising around 2200 - 2300 rpm. I find that doesn't get me much more speed than 1800, just burns fuel pushing water. I suspect weight is the big difference. The spec. sheet for the 25 and the manual for the 27 both have 6200 lbs as displacement but to me the 27 has to be heavier to start with. The factory performance sheet for the 25 shows 5700 lbs dry weight but I don't think any of these numbers are gospel. My figures do seem somewhat in line with that sheet. I'm also fortunate that I can keep the boat relatively light having boathouse storage for all the "Stuff" that accumulates.

Did you ever see the graphs from Nellie II ?

David

 

[NorthernFocus]

...The factory tabs which are marginal became useless. I had noticed my original 4130 decrease to 4000 to 4010 WOT with elevated bow attitude....

I seem to recall you posting about your experience with the drop fins on the tabs. May need to give that a try. The tabs on the 25 push the bow down a bit but any improvement in speed/performance is marginal at best. Which isn't surprising because when they're down the tabs plow quite a furrow in the water. I may have to put the drop fins on the ole to-do list.

 

[Red Raven]

Hi David,

Yes, at displacement speeds the waterline length (LWL) becomes the most important factor. For our R27 the LWL is close to 25 ft which gives hull speed of 6.7kts. For your boat it would be closer 23 ft and 6.4kts. At 8kts you should be already pushing quite a bit of water. For our trip up the inside passage it was a trade off of efficiency, time, and range. We had to run 7.5kts to make the trip in a reasonable time frame and yet still achieve the required range between available fuel. We are definitely starting to push water at that speed. Anything faster up to about 12kts feels sluggish and inefficient. 7.5kts should feel about the same as 7.2kts or so on your boat. It looks like you run much lower rpms to get that with your set-up.

We are nearly twice as efficient just below hull speed as follows:
1600rpm, 6kts 1gph, and 6nmpg 176F

We use this slower cruise speed (1600rpm) if the day’s run is short. Otherwise it just takes too long. If I had the range, the partner boat could keep up, and the engine wear wasn’t an issue I would run at 14+kts all tIme! Much more efficient time wise and not bad fuel wise either. Our happy medium ends up being about 2300rpm and 7.5kts.

Weight doesn’t seem to make much difference at or below hull speed. It’s a big deal at higher speeds. I’d bet we are over 9000lbs fully loaded with passengers, fuel, water, gear and dinghy.

I have seen other performance charts here on Tugnuts. Not sure if I have seen the “Nellie II” chart.

Take care,

Curt

 

[BB marine]

Thanks for posting David. I was interested in seeing some numbers from a D3 150 to compare. The D3 from 110 hp to 220hp same components, same turbo just different perimeters in the ECU. What are your boost numbers at WOT ? At 3000 rpm my engine will come up to 22 psi boost and settle in at between 19psi to 21psi. The boost is controlled by information the ECU is receiving with a base max output based on HP rating. Using the VGT turbo, the same way the waste gate controls the boost on the Yanmar's.

Since we have essentially the same hardware between the 150, 202 20 [maybe a different Turbo?] the difference is software. The torque from the 150 at 3000 is obviously the same as the 200 at 4000. I asked the Volvo factory application tech at the last rendezvous whether my wear rate [think life] was lower at WOT than a 200 unit at 80% RPM and he smiled. We had quite a chat. Essentially, they choose the 90% number based a lot on fuel economy. Maintenance and use [or lack of] are big factors when it comes to life.

This is an interesting point. To sum it up nothing is for free. The WOT max tongue values are very similar from 150 HP to 220 HP D3 Volvo. 150 hp and 200 hp both close to 260 ftlbs and the 220hp 285 ftlbs. 200hp and 220 are @4000 and the 150hp @3000 Both the 200hp and 220 hp have much higher torque at 3000 rpm 200hp 313 ftlbs and 220 345 lbs. Same displacements just more fuel and air for more power. There is no doubt that the smile was "yes". Its all marketing. A D3 which I think is an awesome engine is a perfect engine for a boat that requires 160 hp to push it to its advertised high cruise speed. If any more hp is needed a larger engine is required for long term longevity.( 4000 plus hours) The R25 is in my opinion the perfect boat to have the D3, Mercruiser 150 hp or the Yanmar 150hp in it. It will get a greater longevity even if it is pushed to its max. At 7.5 gph your WOT 150 hp D3 is running at about 92% load using just under 140hp pushing the boat at 17.5 kts. The high speed cruise @ 6GPH is about 70% load.

Now the D3 220 hp in a C26 same everything, displacement block, same internals as the D3 150 hp. Burns more fuel and gets more air from the Turbo to develop more HP. To cruise at 13kts I'm running at 3500rpm 9.5 gph is just under 80% load, using about 174 hp, To cruise at 17.5kts 11 gph 3800rpm using 202 hp 92% load . With a little throttle left I can push 12 gph turn 4000 + and push it to near 100% load making close to the advertised 20kts. The numbers match up but the variable is wear! Nothing is for free. There is no way the D3 220Hp in a C26 is going to see the same longevity if run at manufactures marketing cruise performance charts. The D3 220 hp in the C26 is a perfect engine for the 100 hr a season boater. The average boater. Its a max 1500 to 2000 hr engine in that boat. Honestly if I can get 1500 hrs+ and run the engine hard at 80% load for many of those hrs I guess it has served me well.

I find that if I run at my hull speed 6.5 kts, 1800rpm 1.8 gph yields me just over 4 mpg about my best.

 

[Cutwater28GG]

Brian, what do you anticipate the failures to be on the 220 limiting its lifespan to 2000 hours? actual block/cylinder failure or ancilliary parts?

if you believe these prices (without install labor) that puts each hour on a 220 at $9.
http://lengimarine.weebly.com/volvo-inboards.html

 

[SkookumR29]

Hey guys, this has been a very interesting string of posts to follow and I wish I had some input to share - coming soon. My wife and I closed on a 2011 R29 Classic with the Yanmar 6BY2-260 engine back in November and it has been on the hard every since - hard to take. Just moved it to the CSR Marine boat yard in Des Moines WA for bottom paint, an ELCI breaker upgrade, galvanic isolator and a few other details before we move it in to our permanent slip in the Des Moines marina.

I am very eager to start logging data for my own knowledge and to share it out with those of you on Tugnuts. I really appreciate the detail you all have provided; and even though nobody so far has contributed data specific to our R29, this string and my mining of the Tugnuts archives has given me some good baselines. Hopefully there is an R29/R31 Classic owner or two out there that will jump on board.

The boat is immaculate with low hours (495) - could not have purchased from a better previous owner. Was never moored and always lived on a trailer. After cruising, the power plant was religiously flushed with SaltAway, so I imagine the raw water side is in pretty nice shape for a nine year old boat. My biggest concern however is the low hours, particularly the past couple. I have read plenty on Tugnuts and elsewhere on the internet that these diesels like to work hard regularly, so I am hoping there are few surprises.

Only about a week before splashdown - target is before Opening Day here on Puget Sound! I look forward then to share my experiences.

Jerry

 

[BB marine]

Brian, what do you anticipate the failures to be on the 220 limiting its lifespan to 2000 hours? actual block/cylinder failure or ancilliary parts?

if you believe these prices (without install labor) that puts each hour on a 220 at $9.
http://lengimarine.weebly.com/volvo-inboards.html

The marinized D3 by design is a 3000 to 4000 hr engine. The base line is 10% of its total run time @ 85% to 100% load and 90% of its run time between 84% load to 20% load. The marinized D3 Volvo Penta is an automotive engine (named D5). It had a 5000 rpm red line and the highest production output was 205hp @4000rpm with a 5 speed transmission. It was designed to operate at highway speeds in the 2000 to 3000 rpm range where the highest engine torque was provided and 40% to 50% load.

The engine design is a lightweight (open deck) aluminum block with grey iron cylinder liners, aluminum head and a strong bottom end with 6 main bearings. The open deck design gives better cooling around the upper portion of the cylinders but can be the weak link on an engine that is run in a higher load consistently.

An engine that is run at 80% load consistently that is also rated at its highest designed HP range is just going to wear out quicker. Think of every revolution of an engine as being a cycle. Compare two engines, same components, block, cylinder walls, crank shaft, rods, pistons and head. One engine has a max rated hp of 150 hp @ 3000rpm the other engine has a rated hp of 220 hp @ 4000 rpm. The 150 Hp was installed in a boat that required the engine run at 80% load (based on HP) (2700rpm) to maintain designed and advertised high cruise speed. The 220 hp was installed in a boat that required the engine run at 80% load (based on hp) (3600 rpm) to maintain designed and advertised high cruise speed. The base engine, designed longevity is based on 3000hrs. Are both engine going to have the same longevity? My opinion is no.

Example:
Two boats cruise together at the same speed for 6 hours 150hp at 2700 rpm , 220 at 3600rpm. At 900 rpm more the 220 hp powered boat under an 80% load (Based on Hp) made 324,000 more cycles than the 150 hp. powered boat under 80 % load (based on HP)

I would not expect an erupt failure at or around 2000 hrs but I would expect experiencing symptoms of a worn out engine, higher oil consumption, increased blow-by, harder starting, increased signs of soot, power reduction. I would expect the higher out put D3 would be more prone to cylinder head gasket failures, and cracked cylinder walls do to higher load stresses. All of this is just my opinion and I hope I am wrong. It would be great to have a Volvo engineer chime in. Or boat owner operating a high output D3 run at higher loads that has experienced a different outcome.

Gavin, Nothing is for free! The engines are pricy. My winter storage boat neighbor has a 47 Sea Ray powered with a pair of QSB5.9 Cummins 425hp @ 3000 rpm same rated use recreational as the D3,D4 and D6. He runs it hard. Blew the port engine at 650 hrs replacement cost 38000.00 plus installation. The Cummins rep told him average life of that engine run hard 1500 hrs to 2000 hrs. ( his didn't make that) If run at 50% load you could expect up to 10,000 hrs.

I have way to much time on my hands these days!!!

It would be great to see more input to see how most operate their Tugs and Cuts!

Only about a week before splashdown - target is before Opening Day here on Puget Sound! I look forward then to share my experiences.


Jerry

Jerry, congrats on the purchase of your Ranger R29 awesome boat! looking forward to seeing some 6BY2 data.

 

[TomFin]

I see a lot of discussion and speculation about this topic but has anyone had a block or engine failure that would have been caused just by use? I figure at average 30 mph a car engine runs 6000 hours easy granted at lower load.