View Full Version : Cummins vs Yanmar
I'm trying to decide between the Cummin's QSB5.9 (350hp) and the Yanmar 6LYA (370 hp) to put in a 31' downeaster. They both seem to be great engines but parts availability, price and service for the Cummins are a little better in my area. Another big consideration for me is noise. My friend has a 31 Duffy with a 1990 Cummins 300hp and it is very noisy. I think the new QSB5.9 is a lot quieter. Any suggestions, opinions, ideas would be greatly appreciated.
RANCHI OTTO
06-04-2006, 01:57 PM
Look at consumption curve...
Good engines both, but I prefer Yanmar, more modern and less noisy...
I would look at the three curves, power, torque and consumption and I would try to see what is the most favorable engine regarding performance and consumption at the power and rpm that you will use it most of the time, I mean, at your cruising speed.
marshmat
06-04-2006, 05:14 PM
Noise will be determined more by how you hook up and muffle the exhaust, than by the make of the engine. If quiet is an issue, mount big mufflers and wrap them in the appropriate sound-absorbing insulation. I agree with Vega's advice on comparing the rating curves, this is the best way to see what a given engine will do with your hull.
FAST FRED
06-10-2006, 08:48 AM
I would give both engine sellers a call and ask for the price of a rebuild, and the price of various parts you might need.
How much for a rebuild kit?
How much for injectors or the fuel pump?
And of course the hard question , how long would it take to get the repair stuff.
For a work boat the Cummins (or a Cat) would be first choice , for a 200hour a year fun toy the Yanmar might be lighter & cruise faster.
FAST FRED
For a work boat the Cummins (or a Cat) would be first choice , for a 200hour a year fun toy the Yanmar might be lighter & cruise faster.
FAST FRED
I guess you are talking about the big engines of Cummins Marine (above 15 liters), because the smaller engines (mercruiser) are very similar to the yanmar. As Ranchi Otto has said, the Yanmar is a more modern engine.
But I agree with you about comparing maintenance schedules and prices of pieces.
“Cummins Marine, a division of Cummins Inc, focuses on marine propulsion engines above 15 liters of displacement and auxiliary engines and gensets from 37 kW. Typically, these products are applied in commercial applications on a vessel that earns revenue.
Cummins MerCruiser Diesel, a joint venture between Cummins Marine and Mercury MerCruiser, focuses on marine engine applications below 15 liters for yachts, sport fishing boats, trawlers, military craft, commercial vessels and more”
http://www.gce.cummins.com/mce/mce_pages/productpage.htm?SMSESSION=NO
StianM
06-27-2006, 10:21 AM
Yanmar
dougfrolich
06-27-2006, 12:39 PM
I have been ivestigating a similar situation, I have looked at the Yanmars,Volvos,Cats, and Cummins and the Yanmar Is lighter for power from 370 to 500bhp, and has a lower profile than the others. So for my application a couple of extra inches in ht. and lower weight made the choice easier.
dougfrolich
06-27-2006, 12:41 PM
See Attatchements
FAST FRED
06-28-2006, 05:10 AM
http://www.steyr-motors.com/products/products.htm
These guys claim lots of power for very little weight , but their service life here in US is still unknown.
Any one ever been shipmates with one?
250hp at 322kg sounds light, with a Commercial rating!
FAST FRED
Frosty
06-28-2006, 05:59 AM
I considered the Steyr before I bought the yanmar 6 LP. They were cheaper and yes lighter. However I was put off by the fact that the engines I was looking at in the 250HP range had no cylinder head. It was a full casting in so much as the head was part of the block. Ok no head gaskets to worry about but a valve job would be a major overhaul. It also had some wierd alluminium housing that wrapped the engine,--- Na I went for the yanmar 6LP. I cant say that I would do so again, but for my use they have been ok. 3 years now and still only 160 hours, so with work like that Yanmars are ok.
They are a very high maintenance engine though, lots of zincs every 6 months and Yanmar talk of changing mixing elbows at 12 month intervals. I fresh flush so I have escaped that. There is also a cam belts to worry about needing changing at 1000 hours.
The Yanmar 6LP is a Toyota 1HD engine from the Landcruiser. So all you guys who think marine engines are special ??????
StianM
06-28-2006, 08:48 AM
http://www.steyr-motors.com/products/products.htm
These guys claim lots of power for very little weight , but their service life here in US is still unknown.
Any one ever been shipmates with one?
250hp at 322kg sounds light, with a Commercial rating!
FAST FRED
They are used in some MOB boats in the north sea and I belive the austrian miletary use them too.
They are that light because they are in aluminium alloy.
I considered the Steyr before I bought the yanmar 6 LP. They were cheaper and yes lighter. However I was put off by the fact that the engines I was looking at in the 250HP range had no cylinder head. It was a full casting in so much as the head was part of the block. Ok no head gaskets to worry about but a valve job would be a major overhaul. It also had some wierd alluminium housing that wrapped the engine
I't quite easy to remove.
How often is a valve job required? In My father's boat we had to remove the top's 3 times on the kad's and two times it was broken gasket and 1 time it was broken cylinder liner and piston and we just changet the whole engine since they where 5 years old annyway and it is a ambulance boat in frequent use.
If we where going to change engines again it would be the steyr with no doubt.
Monoblock is great since you actually newer nead to remove the top and if you are doing a valve job it's pobartly time for a full overhault annyway so you nead to take out the whole engine.
StianM, very interesting.
Frosty
06-30-2006, 12:49 AM
Yes OK a valve job is not a very common occurence. However the Steyr is a belt driven cam, again Ok so is Yanmar,these can fail, not only for the belt falure but for tensioner failure.I am not sure if the Steyr is a safe engine in so much as it can tolerate a cam drive failure. I know the Yanmar cant, but if the yanmar split apart I can get a new head. I can also get spare parts and as I said in my last post it is a Toyota motor. I have never seen a Steyr dealer here where I do my boating.
I hate belt driven cams, just a 10 dollar bearing failure on the belt tensioner jocky wheel is a major disaster. I suspect the styer could be a throw away motor
I am not really a Yanmar enthusiast but it seemed to me at the time and still is the better choice.
The price is very attractive to boat builders and where I saw them at the Sydney boat show In 2003 they were really pushing them, they were offering them in all packages and gearbox configerations including a surface drive package.
If I was looking for a motor for a yacht, then I would reconsider my chioce. I also feel that the exta few thousand dollars for a Yanmar puts more onto its second hand sale value.
The Yanmar 6LP is a Toyota 1HD engine from the Landcruiser. So all you guys who think marine engines are special ??????
Jack frost, you mean that if I have a Toyota Land Cruiser engine, should be no problem to fit it to become marine engine ?I do really like Yanmar engine but I never know actually they are Toyota..!
FAST FRED
06-30-2006, 05:53 AM
"The Yanmar 6LP is a Toyota 1HD engine from the Landcruiser."
If true, that is GREAT news , Yanmar is almost as insane as Volvo in pricing parts , somthing an auto dealer could never get away with.
Our preference for 100-200hp or so for fish boats is the International DT 466.
Same engine has been made for almost 3 decades in power levels from 125 to 300hp.
Almost free at Truck junk yards as class 5 trucks are seldom if ever rebuilt after an accident , so a "new" truck with engine is really cheap.Std SAE bellhousing so fitting a rebuilt marine tranny is a bolt on.
We chose Kubota down for the small stuff , lawn tractor dealers cant get the INSANE prices the marine folks seem to think is their due.
FAST FRED
zorton01
06-30-2006, 06:41 AM
In my opinion,
I heard before that some people prefered Yanmar because it was more modern than Cummins. But Cummins offers the option of electronic control (shift and throttle), + other integrated systems like automathic engine syncro, and more data engine, as instant consumption, vessel range, depth, rudder position, temp, etc. This is not the case of Yanmar, that only offers the traditional engines with analog instrumentation, and the posibbility of installing a semielectric control for shift and throttle (electric control action, but mechanical shift and throttle action at gear and engine). It´s not an electronic engine like Volvo or Cummins.
You haven´t consider the Volvo or Cummins option. The D9 is not in the range we are talking about, you should think on a D6-370. Firts of all, it delivers 11 Hp more than Yanmar (at the same fuel temp). For me, the 6lya is not on the same level competition as QSB or D6. There are big differences between this two engines and Yanmar. QSB an D6 delivers more power, better torque at low revs. Yanmar delivers more smoke, and i´m not able to appreciate noise differences between them . D6 is common-rail inyected (less comsumption and smooth running). D6 is based on the EVC (CAN-bus tech). Wire installation is easier (one easy plug wire going from controls and panel to the engine). Cummins and Volvo can be installed multistation, not Yanmar.
The decision for me would depend on the quality of the engine service aftersale, not forgetting the performances. I would chice between Cummins or Volvo depending of the aftersale service in my port
QSB 5,9 6LYA D6-370
CILINDERS 6 6 6
DISPLACEMENT 5,9 5,1 5,5
RPM 3000 3300 3500
CRANKSHAFT POWER 380 359 370
WEIGHT 612 610 KG 677kG
FUEL SYSTEM DI DI COMMON-RAIL
CONSUMPTION *76l/h * 81l/h * 73l/h
*FUEL TEMP 40ºC
StianM
06-30-2006, 12:17 PM
Moust valves have lifters that will brake so the other components will not suffer. Aluminium has the advantage that it's easy to weld compared to cast iron so I suspect that steyr bring damaged monoblocks in for welding and machining and than ready to go.
All new european car's and some american has b elt drive, but how often do you hear about it snap?
The diference betwen chain/gear drive is that a belt has to be replaced once in a while. The reabilety is the same after my exsperience.
Frosty
06-30-2006, 12:19 PM
What ,--- the Yanmar 6LP is a Toyota is news? I have posted this before ,-- Yes gentlemen it is Toyota. I have had this confirmed from the 'Yanmar help' forum based in the UK. Both the 250HP engine and the 4 valve 300HP configeration is Toyota. It may have escaped your attention but this engine the 1hd is a very powerfull diesel engine and obviously impressed Yanmar too.
What ,--- the Yanmar 6LP is a Toyota is news? I have posted this before ,-- Yes gentlemen it is Toyota. I have had this confirmed from the 'Yanmar help' forum based in the UK. Both the 250HP engine and the 4 valve 300HP configeration is Toyota. It may have escaped your attention but this engine the 1hd is a very powerfull diesel engine and obviously impressed Yanmar too.
Thank you again..now I know how to cut my cost..Base on my experience with Yanmar engine..I.am really impressed..but Yanmar price is a bit stiff..used Toyota Land cruiser or trucks engine is easier to find(imported from Japan).
Frosty
07-03-2006, 02:34 AM
Ari,-- The Yanmar 6Lp is a converted truck motor but thats a very cruel descrption of it. The base engine is the Toyota but I hasten to add that yanmar put a lot of other bits on as well making a very capable marine engine.
But yes parts would be available at half the price at the Toyota dealer. I will certainly not be ashamed of myself for doing so. Incidentaly I had an issue with oil pressure when I first bought these engines, they had hardly 20 hours on them. It was more of a concern than in Issue really . However Yanmar Australia who supplied the engines said that I must use genuine Yanmar parts or the warranty may not be honoured. They suggested that my concern over the late oil pressure could be caused by after market oil filters and insited that i use only Yanmar filters. The thing was that the engines came deliverd in the crate with toyota filters on them. I informed them of this,-- it went very quite for a while and then they replied saying that ,--well errm they are Toyota engines and may well have had the Toyota filters on.
Stamped on the back of the front cover by the raw water pump is very clearly stamped for the world to see ----TOYOTA
The Yanmar dealer for Malaysia is a compny called CLLS
Ari --are you based at Admiral Marina ?
Admiral Marina is about 10 minutes leisurely drive from my house.My family used to spend our evenings there..lotsa boats..very comfortable place.. get to know some of the sailors that sail and circumnavigate..had you been here before Jack ?
Frosty
07-04-2006, 02:01 AM
Yes I have, I usually stop over at Port Dickson and then a leasurely sail round the corner to Klang. Is the immigration office still behind the Indian curry house?
I always sail close to the light house "cape Ricarda" or something I forget,-- But what a fabulous light house that is.
Yes I have, I usually stop over at Port Dickson and then a leasurely sail round the corner to Klang. Is the immigration office still behind the Indian curry house?
I always sail close to the light house "cape Ricarda" or something I forget,-- But what a fabulous light house that is.
My dear friend if you know where it is behind that curry house ..than you really know the place..! That light house called Cape Rachado..probably named after some Portuegese big shot who set up the light house there.The current in that region is very swift especially when it is change of tide - high to low or low to high..grave to a few Junk and Galleon..and those treasure hunters..bottom fishing there is fantastic..especially when one used handline..350lb strenght..the biggest congegation of brain coral..very steep rock wall..the channel is about 250 feet deep at some point and only inches..when out of it..I had stranded on those rocks one night with my brand new(5 hours) 24 footer fast fishing boat equip with 40 horses Mercury..lucky the fibreglass hull is strong enough..limp back home on the 6hp spare Suzuki..!Next trip around..feel free to inform me if you plan to stop by..
.. That light house called Cape Rachado..probably named after some Portuegese big shot who set up the light house there..
You are right...and you are wrong.
You are right because it is a Portuguese name and you are wrong because it is not named "after some Portuguese big shot". Portuguese were sailors and there are a lot of places around the world named by us, mainly places that are easily identified at that had worked as reference points. Many times the name is a sort of description of the place (for useful proposes) and that is the case. Rachado means : " almost split in two, but not completely", like the ass, Ari:p
Frosty
07-04-2006, 12:28 PM
Vega, You are right and you are wrong too!!
That fabulous light house that your ancestors were resonsable for is an absalutely beautifull majestic building on the top of a cliff. Now cliffs are not common in this part,-- why just 40 miles up further north you have mangrove swamps and 1 fathom bank. Any way this cliff and the surounding area does not have any thing as far as I can see that could be construed as splitting in two. Unless its because the light house is half way up the straights ( a wild guess)
Now I am not one to be a spelling guru here but an ass Sir is the animal that jesus rides about on. The arse is the big thing in the back of a fat ladies pants. But I think I know what you mean.
That fabulous light house that your ancestors were resonsable for is an absalutely beautifull majestic building on the top of a cliff. Now cliffs are not common in this part,-- Any way this cliff and the surounding area does not have any thing as far as I can see that could be construed as splitting in two.
Now I am not one to be a spelling guru here but an ass Sir is the animal that jesus rides about on. The arse is the big thing in the back of a fat ladies pants. But I think I know what you mean.
Hey jack I don't speack English very well, but take a look here:
ASS :slang for "backside," first attested 1860 in nautical slang:p
http://www.etymonline.com/index.php?term=ass
They certainly did not make the lighthouse, they just give the name to the cape.
In old Portuguese " racha de Vento" means strong gusty wind. So Cap Rachado can also mean Gusty cape. It makes more sense like that?
Frosty
07-04-2006, 11:04 PM
Any one who participates in a forum in a language that is not there mother tounge has my utmost respect. Jees I couldnt do that ,--not even to save my life.
Looks like I am right and wrong too then!! But I am not surprised-- the wife says I am wrong all the time,--Sigh
Hey jack I don't speack English very well, but take a look here:
ASS :slang for "backside," first attested 1860 in nautical slang:p
http://www.etymonline.com/index.php?term=ass
They certainly did not make the lighthouse, they just give the name to the cape.
In old Portuguese " racha de Vento" means strong gusty wind. So Cap Rachado can also mean Gusty cape. It makes more sense like that?
What ever it is..no problem..wether it is meant to be cape de Rachardo or racha de vento..both can be right..! it do really split the shore and create two big half moon bay with the thin cape protruding out about 3 kilometres from the shore..back side shape..talk about the wind..this is the "Sumatra" strong area..those who sail the straits of Malacca..understand this very well..At the times Portuguese conquer Malacca, the cape area which is Linggi is part of Malacca territory. Until today the cape still belongs to Melaka but the shore is Linggi which is part of Negeri Sembilan..my state.:)
Any one who participates in a forum in a language that is not there mother tounge has my utmost respect. Jees I couldnt do that ,--not even to save my life.
Looks like I am right and wrong too then!! But I am not surprised-- the wife says I am wrong all the time,--Sigh
Don't worry too much Jack the wife said that on purpose..so you will always refer everything to her..since she is the 'the right one'..! how do I know..? more or less same experience Jack..!:D
alex fletcher
07-08-2006, 08:57 AM
Just notice this "Yanmah LP6 the same as Toyota"? yes but no yes the LP6 is produced by the same moulds That Yanmar got from toyota. but Yanmah Added a Ladder Frame Crankshaft Base, Crown cooled Pistons, waste gate turbo, inter cooler and stuck with a mechanical injection pump it is a efficient and reliable system that work well a go option in my books an other option would be a small MAN high Speed Diesel.
catmando2
09-20-2006, 10:57 PM
Hi guys, don't know a huge amount about diesels, but i have fitted cummins to the cat i'm building.They are only 65hp ones though. At the time I got them Yanmars comparitive was 2 litre and spun arond 3600rpm, Isuzu was about the same but the cummins was a whopping 3.3 litre and reved at 2600rpm. we reckon we'd only need 50hp most of the time which is around1500 rpm from memory. Also had plenty of reports of how indestructable these little/big motors are which made me feel a bit better. Change in U.S.dollar vs Aussie dollar helped in the decision a bit as well. the ones we got have no electronics or turbo, sounds great to a ludite like me.
Interesting to see the new Yanmars are slow spinners now,so I believe.
Dave
brian eiland
10-14-2006, 12:46 AM
December 2005
YANMAR AND BMW ENGINE SUPPLY AGREEMENT
YANMAR CO LTD and BMW AG, German manufacturer of luxury vehicles, have agreed that BMW will supply four and six cylinder Diesel engines designed for high performance use to YANMAR MARINE INTERNATIONAL BV as the base engine for the new YANMAR MARINE product line.
This agreement enables YANMAR to have the most advanced marine engines for its product range. Customers will be in the position to benefit from the joint efforts of two of the most reputable companies in their respective fields of operation with a product that will set new standards in the Marine industry.
YANMAR is aiming to introduce this new fully electronic range of Premium Marine Diesel Engines in the market around mid-2006.
...more at http://boatdesign.net/forums/showpost.php?p=75304&postcount=138 (http://boatdesign.net/forums/showpost.php?p=75304&postcount=138)
....and even more auto engine marinization at
http://boatdesign.net/forums/showthread.php?t=650 (http://boatdesign.net/forums/showthread.php?t=650)
brian eiland
10-14-2006, 12:54 AM
Noted a fair amount of Steyr discussion here, so I thought I would reference this:
Steyr Integrated Flywheel Generator (IFG)
Here's an interesting new innovation from Steyr motors, an onboard AC generator located inside the engine's bellhousing. Another technology arising from the new 'permanent magnet' technology applications.
...couple of photos here http://www.yachtforums.com/forums/32761-post63.html (http://www.yachtforums.com/forums/32761-post63.html)
ABoatGuy
10-21-2006, 10:13 PM
The Cummins QSB5.9 is a common rail engine, the Yanmar is not. If the common rail technology is exploited the fuel can be introduced into the cylinder in multiple shots on each stroke. This eliminates the typical deisel rattle on each stroke. They sound more like gas engines.
Having installed both, I would go with the Cummins if your biggest criteria is noise. Naturally a good silencer etc. goes a long way toward any engines noise.
Which ever you pick, choose your gear ratio carefully. Watch the torque at the prop and choose the ratio accordingly.
The new Yanmar 6SY is a Steyr engine, the 6LY is not.
FAST FRED
10-22-2006, 05:51 AM
The RV folks seem to be very happy with the new GM Duramax diesels.
If you think a boat is always going "up hill," you have to drive an RV , where some throttle is required to maintain speed DOWNHILL!
Anyone marinizing these yet? Onlt 850 lbs for claimed 300hp.
FAST FRED
zzmeyer
11-01-2006, 05:04 PM
Yanmar. As my mechanic said "You take care of a Yanmar like you do a hard on. Don't f**k with it."
Frosty
11-01-2006, 08:10 PM
zzmeyer,---Change your mechanic to one that knows what he is doing.
zzmeyer
11-02-2006, 11:07 AM
I'll pass the good word along to him. I think what he was saying is that with good normal maintenance, which he does every 50 hours, these engines last a long time. I've only had it for 12 years without a problem so I'll have to wait a while and see.
Frosty
11-02-2006, 08:15 PM
Which Yanmar are we talking about?
Which Yanmar are we talking about?
Must be the older single,twin our triple cylinder.They do last very long..eventhough I did not understand what that mechanic means..my perception is 'do not modify the engine, keep it in original as per design'. It is normal to have the slow revving small horses Yanmar engine last that long.. :) They are slow..and their aging also very slow..!
zzmeyer
11-03-2006, 11:31 AM
4JH. My mechanic has said "the boat is yours, but the engine is mine". Keep the engine clean, check the fluids and filters, keep your batteries new and call me every 50 hours. We are religious in maintaining the engine. We replace on schedule, not when something breaks. My engine is clean enough to have a dinner party on and I might not be afraid to eat food I drop on the engine pan - a good place to look if you are having problems like oil or salt water leaks.
Dutchy
03-10-2007, 03:51 PM
Only the 6LP engine has a Toyota block as base engine.
Frosty
03-10-2007, 09:51 PM
6LP and the 6LA Are all Toyota --heads as well.
Thats the 2 valve head and the 300hp 4 valve head. Toyota.
FAST FRED
03-11-2007, 06:06 AM
6LP and the 6LA Are all Toyota --heads as well.
I understand the marinization also includes beef up like a crank girdle etc.
Just yanked from a car , and unmodified could it be used as a 200 hp engine , with 160hp taken out 5 hours a day as a max?
The Cummins 5.9 is really easy to find in US junk yards , but the engines are louder mechanically than any other engine UGH !! so I worry that any saving in engine cost would be offset with hundreds of pounds of expensive noise control products.
The new Electric ones are "better" , but how many control boxes would be needed to cruise in the "Florida, Lightning Capital" of the world is unknown.
FF
Fast Fred
The Cummings QSB5.9 common rail engine is one of the most modern and QUIET engines on the market. You must be thinking of the old 5.9l engines. These engines are no smoke at idle also. Comparing the Yanmar to this technology is not equal.
Frosty
03-11-2007, 11:34 PM
I personally dont weant any common rail engine in a boat that I am on.
If it stops there is really no point in even opening the engine room. If its not a filter forget it.
I dont think they will ever be popular in sea going private boats.
Ok Ok some yards may be fitting them but I dont want one.
FAST FRED
03-12-2007, 06:18 AM
The Cummings QSB5.9 common rail engine is one of the most modern and QUIET engines on the market.
Perhaps , but as most cruisers I can NOT take apart an electronic control and rebuild it with parts at hand at sea.
The mechanical engines may use 15% more fuel and be 3X as loud , but for CRUISING , Electric control is just not realistic.
A truck can pull over and await a tow and then spring $3000 for a black box, on a Cruiser a lightning strike might cause the Rescue tow to claim salvage , and OWN the boat.
Should one be someplace where there IS a tow service , perhaps 1% of the world?
FF
In my opinion the Steyr integral head-block is a very logical step forward It gives you a simpler, more rigid, engine with fewer parts. How common is a valve failure in a modern engine, anyway? The big bad thing is dropping the cap off a stellite-faced valve, but when that happens the block is coming out, so no big difference. However you drive the cam, it's subject to failure. Gear, chain, or belt. The difference that I can discern is that with a belt, if you observe the renewal interval you won't have troubles. But who knows when a gear is going to shed a tooth?
I remember when Cat came out with their first V8 bored-in-block engine, the family that became the 3208, and everybody said that it was a "throw-away" piece of junk because it wasn't a wet sleeve engine. But they worked out pretty well.
Steyr makes good stuff, whether it's engines or firearms.
The secret to a quiet engine is a good installation. Mufflers are important, but so is the enclosure. I've been around 6-71 Detroits that were very quiet when the enclosure was shut. Not a cheap undertaking, but it can be done.
FAST FRED
03-13-2007, 06:50 AM
Gear, chain, or belt. The difference that I can discern is that with a belt, if you observe the renewal interval you won't have troubles. But who knows when a gear is going to shed a tooth?
Most cruisers will go out after 100 hours of local ,( in range of the tow boat) cruising.
I have NEVER heard of an industrial engine marinized that lost the timing gear or chain.
A single belt between DISASTER (loosing the entire monoblock ) is not for most offshore boats .
I contacted Steyer about if the loss of a timing belt could cause loss of the valve train .
They claimed it was a rare event , but COULD bend the valves thru piston contact.
I would LOVE to be able to Spec a Steyer for the box keel project as light weight is important , but so is getting back to port.
FF
Three examples that I can think of right offhand:
Detroit Diesel 12=71, in a trawler, stripped a timing gear at less than a thousand hours time. Engine disabled, in the end had to be removed from the vessel for rebuild and to fully survey to develop an opinion of Proximate cause.
Cat 398 (or maybe a 399) V-12, anyway, in a small tug. I was not hands-on with this failure, but I think what happened was a bearing in an idler gear ran hot, wobbled, and broke the teeth on the idler.
Volvo B-18 (gasoline) in inshore lobsterboat. Stripped the teeth off the cam drive gear. This engine has a steel gear on the nose of the cranks, and a fiber gear on the cam. The fiber gear stripped. Engine stopped. Repair was just a question of removing the timing cover and renewing the gear.
The only engine that I'd guess is entirely immune to valve train problems is the Fairbanks OP, only because it doesn't have any valves or valve train. But on the other hand, Fairbanks engines don't have a reputation of much higher reliability than its Cleveland, Cat, EMD and Alco competitors. I can't back that up with any statistics.
I suppose that for at-sea serviceability nothing exceeds the EMD design with its welded crankbase and modular "A-frame" cylinders assemblies. It isn't unheard of for a twin-screw boat to change out an A-frame at sea while the other engine soldiers on. Since the EMD is a two-stroke the valve train is more limited than in a four-stroke, but has all the same elements.
Maybe the main issue isn't the configuration of the cam drive as much as it is whether an open valve impinges on the travel of the pistons. I remember with grim clarity screwing up the bolt-up of a Mercedes engine, getting the cam 180 degrees backwards. Half a crank, and a piston jacked a valve up into the cam, breaking the cam mounting pillars which were part of the head casting. New cylinder head time. Very sad day. Expensive way to learn the lesson to ALWAYS roll the engine over by hand before cranking it after a rebuild.
It seems that higher-lift cams are an essential design feature of higher efficiency, higher speed engines. This translates directly to lighter weight, both in the machinery and the fuel load.
If someone were to ask for the most reliable, most repairable engine possible, I might suggest a plain old NA Detroit 71 series. They're cheap, parts are available all over the world, everywhere, cheap. The unit-injector system is a lot simpler to repair than a Bosch-style, certainly than an electronic common-rail. Once the mysteries of the Woodward governor are mastered, it's not that hard to set up.
But talk about heavy, hot, oily, and smoky! Puking, slobbering, and drooping, with an exhaust snarl that proclaims itself for miles around.
FAST FRED
03-13-2007, 11:54 AM
I saw a 4-71 aluminum block on E bay and was REALLY tempted , but I'm not sure '71 parts are that easily found anymore.
Sure there loads in Boats #Harbors and lots of rebuilding stuff seems aviliable, but a near by boat needed an early style Gov and had to buy an entire engine to get one!
OK, it was only a grand , and he got a load of spare stuff, to use in the future , but the writing is on the wall for the 1936 DD 71 series.
I'll probably not have hassles with the 6-71 in our lobster boat or the 8V 71 in our Greyhound bus conversion , but the clock IS ticking.
Any suggestions for a engine choice 200hp rated with expectations of 160hp for 10% , 100hp for 75% and 15% spent at high idle in wake zones.
Only 300 hours a year in pleasure service.
I LOVE the Intl DT 466 as there cheap and bulletproof ,but at 1400lbs, plus tranny.
The 4 cyl Cummins comes closest , although the 5.9 from light trucks would also work , but are so DAMN LOUD!!!
FF
brian eiland
03-13-2007, 02:15 PM
...In my opinion the Steyr integral head-block is a very logical step forward It gives you a simpler, more rigid, engine with fewer parts.....I remember when Cat came out with their first V8 bored-in-block engine, the family that became the 3208, and everybody said that it was a "throw-away" piece of junk because it wasn't a wet sleeve engine. But they worked out pretty well.
Steyr makes good stuff, whether it's engines or firearms.
I've heard good reports about Steyr as well, and they certainly weight in at a good figure for use on multihulls.
I included Steyr as an option on my latest motorsailer...look towards the bottom of the web page:
http://www.runningtideyachts.com/dynarig/
Conventional Propeller Drive: For those clients concerned about the new diesel-electric technologies, there are several conventional propeller configurations:
1)Tradition shaft drive from 'canoe stern' hull form (not shown)
2)Outdrive style drive leg with chain-belt driving single or dual props
3)Conventional propeller propulsion could be augmented with Steyr engine/generator combo-units to dispense with auxiliary generators.
http://www.yachtforums.com/forums/15453-post14.html chain drive
http://www.yachtforums.com/forums/32761-post63.html Steyr unit
Fastfred,
I think the 6-71 you're talking about is either a Greymarine or a very early "low-block" Detroit. The later "high block" engines came out, maybe in the '60's, and were built in the thousands upon thousands for marine, industrial, generator, pump, oil-field, truck, and tractor service. Every engine rebuilder that I know of and most auto-parts stores stocks parts for them.
I remember going into a bar in Petersburg Alaska once, a block up from the salmon cannery we unloaded at. Behind the bar there was a jar of pickled hard-boiled eggs, a jar of pickled pigs' feet, a jar of Slim Jims, and a neat array of detroit injectors, Jabsco impellers, and a sign that read "we have 4 & 6 cylinder head gaskets. Ask your waitress."
Of course you're right, someday Detroits will disappear, just like Model A's disappeared. But I'm pretty confident that for around-the-world parts availability, ease of repair, and solid balls of torque, a 6-71 will be the world champ for years to come.
A later-series 3304 Cat with turbo would probably fit your power requirements. Lobstermen around here pretty much use the B model Cummins, John Deere/Lugger, or the Volvo 60 series. It's possible that a turbo/intercooled 4-cyl. B model would be enough power, but you'd be running it right at the peak of its power curve, I think.
I personally do not like Cummins engines, but it is an ancient prejudice that springs from a traumatic experience with a VT1710 engine. The C models have a good reputation, and after a rough start with lots of fuel-injection problems the B model seems to be okay. What can you say about a company that would fit their engines with CAV injection. I think CAV is part of the far-flung and infamous Lucus (Prince of Darkness) Electric, LTD. Source of the old joke, "Why do the English drink warm beer?"
My prejudiced impression is that the "400 hp" Yanmar is a pretty short-lived engine at that power setting. I mainly see them in yachts, where their quiet running is a big plus. And, I don't know about now, but in years past it was pretty easy to get a dealer's medallion for Yanmar, which means that low-volume builders may pitch them pretty hard because their mark-up is better. The opposite extreme of that used to be Caterpillar, which seemed to not like to sell engines to almost anyone. These are ancient opinions of mine, in New England, and may not bear any semblance to current reality.
The answer to the joke is "They have Lucus Refrigerators."
seo
This is a possibly interesting bit of trivia about Steyr engines. A few years ago I surveyed a 35' Canadian-built yacht with a diesel engine that said "BMW" on the label. I said that getting parts might be a problem, because BMW had gotten out of the marine diesel business (remember the BMW I/O drives?). The seller (I was working for the buyer) told me that this was a BMW engine from a BMW truck, and Germany was teeming with them. I've been to Germany, and had never seen a BMW truck, but didn't argue. I also knew that back when BMW tried to get into the sailboat auxiliary business their little one and two cylinder engines were made by Hatz, and Austrian company. Nice engines.
To end a long story, it turned out that the BMW six-cylinder was made by Steyr. Parts were marginally availble by ordering from Europe. The prices were astounding; like $700 for a piston, not including the rings or wrist pin.
FAST FRED
03-14-2007, 03:57 PM
That aluminum 4-71 is sounding better & better!
Our Greymarine came out of the Can , when in '95 the gov decided to sell off the "war reserve".
As the Navy was more than chopped in half , 600 ships to 230 by BJ Bubba , I guess they ran out of ca$h.
The 3-1 Twin Disc was made by Oliver Farm Tractor and shows no wear.
Great long lasting stuff , but the 6 at 2800 lbs is far too heavy for the next boat.
FF
FAST FRED
03-14-2007, 04:00 PM
Cummins 4B-250, rated for 200 hp continuous at 2800 rpm.
IS faster turning than I would like , but the power matches up with the requirements fairly well
The top speed is a minor deal as most cruising would be ay about 100hp /5gph for economy.
Any Idea how these hold up?
FF
Fast Fred,
It sounds like the engine you have is a Greymarine, not a Detroit. They are on the one hand nearly twins, but on the other hand they are not organ donors for each other.
As a former Navy civilian employee involved in testing newbuilds, the reserve of stocks of antique weapons and machinery seemed absurd. Why keep a fleet of 400 hp tugs built in the 1940's? I'm sure than when the Army's horses and mules were sold that many saw it as a dark day, but I don't think it worked out that way.
I've never seen an aluminum-block 4-71. My guess is that it was for use in a minesweeper. I have seen a non-magnetic 12-278a Cleveland, and a stainless steel Baldt anchor, and other interesting artifacts of the minesweeper fleet. The comments I heard on the Cleveland is that it was somewhat different from a plain iron one, and a real pain in the neck.
My main question is how much weight you'd save. My guess is a hundred pounds or so.
I've never seen a turbo-charged and intercooled 4-71, but the pistons and rods from a 6-71 might work. As I remember it the big name marine tweak-shop on 71's was called Johnson & Towers. I once had some experience with a boat that had a pair of high-output J&T 12-71's. Thank goodness that the USN was paying the repair bills. They had a short life-span at 100% power settings. Velocity impingement of the cylinder sleeves, mainly.
I think you'd have the same luck with a Cummins 4-cylinder B model as with the six. They are not works of art, but do okay. I'm surprised that they sell a marine model with a 200hp continuous rating. Is that commercial or yacht power curve? My cynical rule of thumb is that if you want to know how much power and engine REALLY puts out, look at the operating speed & output rating of the electrical generator version of the engine.
There's a lot of money to be made by hyping the kw outpput ratings of propulsion engines, particularly for yachts. On the other hand there's nothing sexy about a generator that craps out after 800 hours.
FAST FRED
03-16-2007, 05:57 AM
In order to really figure the worth of any particular engine a BMEP or fuel map is best.
But the mfg only want to release max hp curves and "ideal" propeller curves.
Almost useless.
Is there a way you have found to get a fuel map from the mfg?
I haven't!
FF
Fred,
I have to admit that I approach this from the point of view of 1) a grubby knuckle engineer, and 2) someone who advises on modifications to existing and stock vessels.
In that role, I pretty much observe what has worked in sister or similar vessels in the past. Particularly if I can get good data on 1) fuel consumption in gph vs speed vs shaft rpms then I can get a pretty good idea of how much power the engine is actually putting out, and a crude but maybe workable resistance curve of the hull.
The problem that I've encountered is that there's always a tendency on the part of the client to bump the engine up one size, just so he knows he's got enough power. He can always throttle down a too-big engine, which is a lot cheaper than hot-rodding or re-powering an underpowered boat. I guess that's not really a problem.
One hare-brained scheme that I've thought up is to make a gizmo that would fit between the halves of the propellor shaft flange, essentially a very short hydraulic cylinder with a rotating-seal coupling on the outside. The propellor shaft pushes forward on the rear flange, squeezing my custom spacer/coupling. The amount of hydraulic pressure that the squeezing produces in the spacer/coupling should convert directly to the amount of thrust the propellor is producing, which is the final object of propulsion machinery, right?. In combination with a good boat-speed log, fuel-flow metering set-up and engine tachometer, this might give you all kinds of interesting information.
On the other hand, N. G. Herreshof's son L. Francis describes in one of his books his father's method of testing rigs on his America's cup boats. That was to first test the rigging wire in a testing machine so there was an accurate stretch vs strain graph, and then down near the deck put pairs clamps on the various shrouds and stays. The pairs of clamps were a set distance apart, measured by micrometer. When underway, the micrometer would measure the distance between the clamps, and the stretch of the wire rope indicated the strain that the shroud was under. This was a hundred years ago. NGH was an MIT-educated marine engineer.
This example leads me to the idea that if you put a propellor shaft into a testing machine, and tested its compression-vs-thrust characteristics, you could do more or less the same thing that NGH did with the wire rope.
By machining a pair of grooves around the shaft you could have a way of measuring compression, or delongation, or whatever you'd call it. At various speeds, with different propellors, you could measure the distance between the grooves on the turning shaft, you could get a figure for shaft compression, which would convert directly to propellor thrust.
How's that for pie-in-the-sky?
Practically speaking, the Cat industrial engine manuals have pretty complete sets of curves, including fuel burn vs power output vs engine speeds. If you had an engine with gear, and felt like taking it to a shop with a dynomometer, and rigging it up with juice, fuel, and cooling, then you should be able to produce your own curves. But that wouldn't be cheap.
Some of this cock-eyed thinking I developed while sailing on ocean trips on an old diesel-electric drive tug. We ran 24 hours a day, and the captain was willing to humor me by allowing fluctuations of engine speed for a 4 hour period. The engine room day-tank was well graduated, so fuel burn was easy to figure. Engine output was measured in kw of electricity, which is simple. Boat speed was measured a) by the Loran and b) by dropping a half-full soda can overboard opposite the galley door, and timing it until it went past a certain point on the towing deck. It was great fun, and produces notebooks full of figures (this before the laptop era).
FAST FRED
03-16-2007, 02:28 PM
Your boats might be rather large for the exercise but a simple tow rope and scale will work for most folks.
Out fishing one day and the operator got too friskey with the throttle in an attempt to get back to a pot line.
Spun the prop clean OFF ,
the AMAZING thing was his kid came out and towed us in, with BOTH boats (45ft) on the plane!
Talk about oversized engines!
FF
This was in ebay today:
http://cgi.ebay.com/ebaymotors/Steyr-Diesel-6-Cylinder-250-Horsepower-Marine-Engine_W0QQitemZ190095460690QQcategoryZ50441QQrdZ1QQcmdZViewItem
Listing on a 250 hp Steyr
brian eiland
03-26-2007, 05:09 PM
Seo & Fast Fred
You two fellows appear to have quite a knowledge of diesel engines.
Is there anything in that older posting of mine that you care to elaborate on??
http://www.boatdesign.net/forums/showpost.php?p=110174&postcount=33
Well, reading the press release over again, they seem to be saying that the "BMW" diesel engine is actually built by Steyr, which company is actually owned by BMW? Makes sense. As I mentioned in a previous post, "BMW" labeled boat diesels back in the '80's were Steyrs. Whether BMW owned them then, or owns them now, I don't know.
But at this site:
http://www.x-raid.de/index.php?id=59
BMW’s Engine Plant in Steyr has been an elementary part of the BMW Group’sworldwide production network since 1979. Forming the largest engine plant withinthe Group, Steyr is also the worldwide competence centre responsible for thedevelopment of all BMW diesel engines. The ground was broken for BMW’s Steyr Plant in UpperAustria in 1979. Engine production then started in1982, and today more than half of all BMW engines arebuilt in Steyr. The Steyr Plant builds four- and six-cylinderdiesel engines as well as six-cylinder petrol power unit
So, it looks like BMW and Steyr is one. Does this make sense? Sure. Do I like BMW stuff? Well...I have to admit that I always like Mercedes machnes better.
A step up from Toyota? well...probably lighter, quieter, smoother. Possibly also more expensive out of the box, and for overhauls.
seo
brian eiland
03-26-2007, 07:49 PM
I was referring to the relationship developing between Yanmar and the BMW more than the relationship of Steyr and BMW
According to a couple people I knew who worked for BMW in their short-lived boat foray, they got burned at it, and resolved to stick to their knitting from there forward. So they didn't build boat engines or trucks or aircraft engines or turbines or bulldozers or any of that cool stuff. Just cars.
Now here comes Yanmar, wanting to buy engines, and apparently BMW is selling them.
Historically, what does that mean? If you took the example of John Deere/Lugger, or Perkins/Westerbeke, you might say it doesn't mean much. Yanmar will figure out the details of marinizing the engine, and then BMW will say thank you very much, plaster their sticker on them, and they'll be in business.
Or perhaps the deal will be like GM/Mercruiser, where the two grew closer over time. Mercruiser quit building its own 470 engine, quit using Fords, didn't it? And for their part, I don't know if it's true, but I was once told that the engines for the biggest-horsepower bigblock Corvettes were actually bolted up by Mercruiser.
Right now BMW seems to be in quite deep with their investment in VW, and they're probably going to be concentrated on that.
It would make sense that a car maker with all their dealerships and distribution networks could see, supply, and service boats like crazy. And they've tried it. Dodge Watercar, Chrysler boats and outboard motors, Crosley motors, Chrysler motors (remember the Golden Lion? beautiful sounding exhaust), Volvo I/O's. Funny thing is, for some reason it never seemed to work out that the car dealership got into selling motors or stocking parts. Why? dunno.
brian eiland
03-26-2007, 11:58 PM
I was told that the 6 cyl inline engine was the most naturally balanced configuration of all the internal combustion engines??...and certainly BMW has to be one of the foremost builders of inline 6's.
So if I were seeking out a good 6 cyl source for a certain displacement engine line, they would have to be at the top of the list, and if they were willing to build some for me.
Hopefully an automobile engine builder would not be so misguilded to enter the miniscule boat market themselves
FAST FRED
03-27-2007, 06:56 AM
I was told that the 6 cyl inline engine was the most naturally balanced configuration of all the internal combustion engines??
Its 3 cylinders that work very well together so a 6 or 12 works even better.
Hopefully an automobile engine builder would not be so misguilded to enter the miniscule boat market themselves
As the Air Police seem intent on using downtown LA as a world goal , we will be having fewer and fewer engine Mfg as time goes by.
Unfortuniatly for Diesel marinizers the newest truck units use 15% MORE fuel since the exhaust MUST be cleaner than the inlet air in some locations.
Cat , Cummins, Kennworth have had huge layoffs as the big truck companies plan on running "old stuff" as long as there are parts to be had,"Forever " if they can.
FF
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