Vehicle engines versus purpose designed marine engines.

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pcatterall

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The excellent thread by ianj detailing the fitting of the Marine Power Chinese engine has been of great interest.

Contessaman contributed with a post about using a standard vehicle engine and conversion parts from Lancing Marine.
Question.... are there significant differences between a 'dedicated’ marine engine designed ( I Guess) to work most efficiently at a certain opptimum RPM and a vehicle engine which may have to perform across a wider range of RPM and load??



I guess someone will say that many ‘marine engines’ ( such as my own 4108) or actually from road vehicle origin.
 
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pcatterall said:
The excellent thread by ianj detailing the fitting of the Marine Power Chinese engine has been of great interest.

Contessaman contributed with a post about using a standard vehicle engine and conversion parts from Lancing Marine.
Question.... are there significant differences between a 'dedicated’ marine engine designed ( I Guess) to work most efficiently at a certain opptimum RPM and a vehicle engine which may have to perform across a wider range of RPM and load??
Your 4108 was a bog std diesel engine used in generators, welding sets, forklifts, you name it it was used in it!
My MD22 was originally a BL petrol engine, converted by Perkins with a different head and bits in to a diesel! Then it was converted even more by VP but the bottom line, you can buy pistons, big ends etc for a refurb from a Perkins outfit, so not designed specifically for marine!
D



I guess someone will say that many ‘marine engines’ ( such as my own 4108) or actually from road vehicle origin.
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Specific marine versions of the 4107 were made with cylinder liners chrome plated on the outside to cut corrosion failure on the early raw water cooled units. Later 4108s of course had dry liners so that problem was solved but it shows that Perkins did in fact produce dedicated marine engines. On the point about using vehicle engines all my previous boats had ex truck engines and never gave any problems. My old Bedford 466 took me all round the UK in 1988.
 
I think marine engines tend to have a flatter torque curve as they have to perform well across the rev range. Also they often have a big flywheel to smooth out the running.
 
Almost all "marine" engines are based on industrial units, although Yanmar are primarily marine, but also used in industrial applications. Bukh still make engines mainly for marine use, but now rarely seen in yacht applications. In larger capacity engines most are derived from vehicle engines, but the last sub 60hp engine that came from a road vehicle was the now discontinued Perkins/Volvo unit that came from a BL car of the 1980s.

Fresh water cooling has removed the need for dedicated marine engines - that is designed and built for direct seawater cooling. Small industrial base engines are very lightly stressed in boating applications and are tuned to give modest power outputs compared with their potential. Some engines are offered (as in the past) with different levels of output depending on application. Bigger engines are built with a variety of outputs again depending on application and the depth of the buyer's wallet!

With the choice of properly marinised engines now on the market the marinising of secondhand vehicle engines has just about ceased, although parts are available for some older engines. Personally can't see the sense in marinising an obsolete diesel out of an old car or van.
 
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With the choice of properly marinised engines now on the market the marinising of secondhand vehicle engines has just about ceased, although parts are available for some older engines. Personally can't see the sense in marinising an obsolete diesel out of an old car or van.[/QUOTE]
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Probably the cost which is about 10% of a new comparable 'marine' engine.
 
PCUK said:
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With the choice of properly marinised engines now on the market the marinising of secondhand vehicle engines has just about ceased, although parts are available for some older engines. Personally can't see the sense in marinising an obsolete diesel out of an old car or van.
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Probably the cost which is about 10% of a new comparable 'marine' engine.[/QUOTE]

Not at all by the time you have bought all the marinising bits, gearbox etc. Yes, it may be a bit cheaper but why would you do it with an engine (like the one referred to above) which has been out of production for over 15 years? OK in the past when there was not the choice that is available today, but nobody has bothered to produce marinising kit for current engines because there is no market.
 
Many of the major engine makers have fingers in many pies. On Highway, Off Highway, Industrial, Construction, Agricultural and Marine represent typical market sectors.

Time for some generalisations.

Generally, the highest volume is the On Highway (truck) sector. This sector is also probably subject to the most stringent legislative requirements. It's hence likely that anything "new" will get the lions share of test and development including durability.

Most of the other sector engineering groups will base their products upon the truck version (another generalisation, of course). Fuel Injection Equipment is usually first on the list to change, then air delivery to match. This creates the required torque curve to meet the unique needs of its sector.

Other posts have talked about marinisation. Another point to consider is load and duty cycle. For example, the same marine engine displacement can be available with very different output power, depending upon application / duty cycle.

A 6 litre pleasure boat engine may be rated at, say, 250 bhp. The same engine in a work boat may be rated at, say, 150 bhp. The difference is duty cycle. The pleasure boat is expected to be run for 100 hours per year. The work boat may run for 2,500 hours per year. If you run the 250 bhp version for 2,500 hours you're more likely to break it, hence warranty claim in the making. Not what the OEM wants so he significantly reduces the power available.

Fascinating subject and I spent 20 enjoyable years working alongside as a supplier to the gas exchange groups.
 
4.107 marine engines also had more piston rings made from different material, the marine engines also were built from A grade components with B grade used for road vehicles and C grade used in compressors etc.
The crankshaft is normaly steel and better balanced to remove vibration.
Modern thinking (VP) is use what's in stock.
 
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Not at all by the time you have bought all the marinising bits, gearbox etc. Yes, it may be a bit cheaper but why would you do it with an engine (like the one referred to above) which has been out of production for over 15 years? OK in the past when there was not the choice that is available today, but nobody has bothered to produce marinising kit for current engines because there is no market.
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With an average engine and drive costing £20,000 a similar marinised truck engine will cost about £2000.
You don't need a marinising 'kit', just all the necessary parts.
Modern engines are less likely to be marinised due to the need for all the electronics to come off the same vehicle, not a lack of demand.
 
I know a boat that has a 1.8 litre Ford diesel of the type used in the late 1980's Ford Escort. It is currently being overhauled in Turkey. Parts for it are easy to source and very cheap compared to Volvo or Yanmar parts. Its an engine that only developed 60 bhp in car use, and I suspect that the real reason that car engines are not now marinised in any great numbers is that even the smallest new car diesel engines are just more powerful than required for yacht use and fitted with emissions control gadgetry like EGR valves and particulate filters that we don't need.
 
PCUK said:
>>>>>>>>>>>>>>>>>
Not at all by the time you have bought all the marinising bits, gearbox etc. Yes, it may be a bit cheaper but why would you do it with an engine (like the one referred to above) which has been out of production for over 15 years? OK in the past when there was not the choice that is available today, but nobody has bothered to produce marinising kit for current engines because there is no market.
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With an average engine and drive costing £20,000 a similar marinised truck engine will cost about £2000.
You don't need a marinising 'kit', just all the necessary parts.
Modern engines are less likely to be marinised due to the need for all the electronics to come off the same vehicle, not a lack of demand.
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This thread started about small engines where vehicle derived engines are almost non existent. However, I agree it is possible to marinise truck engines, but as you say it is likely to be an older type which is mechanical rather than electronic. The example quoted earlier of the Ford XLD, which was popular as a marinised engine 20 or 30 years ago has been out of production for 15 years and although basic engine spares are still available this is unlikely to be maintained in the future. It was popular the because there was a "hole" in the ranges of marine engines in the 30-60hp categories that were light and modern. That hole no longer exists.

Given that the typical life of a small yacht auxilliary is 20-30 years, it seems a bit short sighted to spend money installing an engine that is already way out of date.
 
davidjackson said:
...... Another point to consider is load and duty cycle. For example, the same marine engine displacement can be available with very different output power, depending upon application / duty cycle.

A 6 litre pleasure boat engine may be rated at, say, 250 bhp. The same engine in a work boat may be rated at, say, 150 bhp. The difference is duty cycle. The pleasure boat is expected to be run for 100 hours per year. The work boat may run for 2,500 hours per year. If you run the 250 bhp version for 2,500 hours you're more likely to break it, hence warranty claim in the making. Not what the OEM wants so he significantly reduces the power available.

Fascinating subject and I spent 20 enjoyable years working alongside as a supplier to the gas exchange groups.
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Also short term duty cycle.
A car engine will develop 100bhp while accelerating, then back off to cruise after a minute or whatever.
A marine engine may be run at or near full power for hours on end.

Outboards illustrate this, a 1 litre bike engine is probably good for 120+bhp, but a 100 horse outboard will be 2 litres or more.
 
Tranona said:
This thread started about small engines where vehicle derived engines are almost non existent. However, I agree it is possible to marinise truck engines, but as you say it is likely to be an older type which is mechanical rather than electronic. The example quoted earlier of the Ford XLD, which was popular as a marinised engine 20 or 30 years ago has been out of production for 15 years and although basic engine spares are still available this is unlikely to be maintained in the future. It was popular the because there was a "hole" in the ranges of marine engines in the 30-60hp categories that were light and modern. That hole no longer exists.

Given that the typical life of a small yacht auxilliary is 20-30 years, it seems a bit short sighted to spend money installing an engine that is already way out of date.
Click to expand...

Having an XLD, as has been said elsewhere, these are NOT necessarily just the marinised Escort/Fiesta diesel. Uncle Henry produced them as an industrial engine as well, (continuous use at steady rpm) as is evidenced from the fact that they come in three power ranges, none of which would suit a car (35 bhp, 47 bhp and 54bhp IIRC). I have a mid power XLD and am very happy with it and Lancing's ongoing support of it - plus the cost of standard spares - even the injection elbow that gave up a couple of weeks ago and is custom made was only £70 delivered
 
Gladys said:
Having an XLD, as has been said elsewhere, these are NOT necessarily just the marinised Escort/Fiesta diesel. Uncle Henry produced them as an industrial engine as well, (continuous use at steady rpm) as is evidenced from the fact that they come in three power ranges, none of which would suit a car (35 bhp, 47 bhp and 54bhp IIRC). I have a mid power XLD and am very happy with it and Lancing's ongoing support of it - plus the cost of standard spares - even the injection elbow that gave up a couple of weeks ago and is custom made was only £70 delivered
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Was not saying they were bad engines as they definitely filled a gap in the market at the time. What I was questioning was the wisdom of re-engining a boat now with an obsolete design (which would inevitably be a converted secondhand road engine) when there are much better alternatives available from all the major marine engine manufacturers.
 
There are certainly issues with modern car engines. Even bigger ones. For the most part they are just not robust enough. Another major issue isthe complexity of the average fueling system now. The average Joe on the street can not hack the programming in any economical manner. Dual mass flywheels, exhaust filters and such things as belt driven timing all raise issues. As previously stated the only easy way to do it is to use obsolete engines and that raises it's own problems.
I don't think it's beyond the capability of a good home engineer to marinise a small industrial engine though. However I would only recomend it if you were doing it for the challenge as economically it would be cheaper to buy an already tested and backed up engine from the likes of Mermaid or Beta. They have the scale to make marinising economical and spend a lot of effort sourcing suitable base units such as Mermaid's JCB and Kohler( used in small JCB plant) and Beta's Kubotas.
 
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