Engine Repower options....

10 years 11 months ago #283 by Gerry O'Donoghue
Engine Repower options.... was created by Gerry O'Donoghue
At the risk of offending anyone who doesn't want to share information ;-), can I start a thread about repower options for the Whitby 42 / Brewer 12.8. This is something I will be doing in the next year, so all ideas would be welcome. As many Whitby's are now hitting their 30yo mark this must be an option that some owners / new owners are considering. If we could possibly keep this thread separate from any rebuild ideas of the existing engines, it might make for some clarity.

Areas I am finding some difficulty with are;

1. HP requirements.
2. Turbo / No turbo
3. Exhaust diameter.
4. Mountings etc.
5. Transmission and access for removal etc.



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10 years 11 months ago - 10 years 11 months ago #295 by Derek Keeping
Replied by Derek Keeping on topic Re:Engine Repower options....
Gerry asked me to chime in on this “Engine Repower options....” forum so here it goes.

There are many things to consider when you are faced with your tried diesel engine.

Do you re-build or re-power?

Question you need to ask.
Do you like your engine? Has it be reliable in the past?
What is the cost of the rebuild parts and labour? Will you re-build the engine your self or have a engine re-builder do it? What about warranty?
How far do you go with the re-build: piston, liners, bearings, water pumps, coolers, fuel pump, injectors, hoses, engine mounts, gearbox, starter, alternator? What ever you do not re-build or replace will need to be replace sooner then later.
If you retain the alternator, starter, water pump, for example they will have an uncertain further life expectancy
Are parts available now, but more important will they be available in the future?
Do you have a large investment in spares starter, pumps, coolers, and other items?
The rule of thumb if the re-build will cost more than about 40% of the cost of a new engine then it may not be a good investment.

Will the value of our boat re-powered with a new engine increase enough to fully offset the cost of the new engine and its installation. The used boat market may not equal your investment if you sell the boat. The boat's value will increase, but probably not enough to fully pay for the re-powering. If you are considering rebuilding or re-powering you want to use your boat, not sell it.

The cost of the diesel engine is just the start.
What options do you need on the new engine?
Upgraded engine alarm and start panel with tachometer, gauges and warning lights or the basic panel with tachometer and alarm warning lights.
Larger alternator?
Mechanical or hydraulic gearbox? What ratios?
Do you need to re-prop? New coupling? New shaft?
Is the exhaust system adequate or must it be replaced? Most modern turbo charge engines requires a 3” exhaust.
Is the fuel system piping adequate?
Do you need to modify the engine mounts for the new engine?
What is the cost of replacing the spares I have for my old engine? Do you need the same number of spares for a new engine?

Most new diesels are very fuel efficient and lighter for the same hp.
Engine in the 70 to 80 hp are turbo charger to meet the new EPA tier VI standards.
Turbo charged engine are efficient, lightweight, and with modern materials used very durable. The turbo engines are best operated at medium to full load and at full operating temperature.
In general they do not like operating at idle or light loads i.e. “charging batteries” for prolong periods of time. The engine will not reach its optimum operating temperature and heavy carbon can form on exhaust valves, turbo, etc.

How much hp do you need to push a Whitby 42?
A number of vessels that have similar displacement and length to the Whitby 42 have between 50 hp to 75 hp a lot of the newer boats have 54 hp Yanmar. One of our members has recently re-powered with a Yanmar 54 hp.

If you are going to repower there are questions that must be answered.
How many hours will the engine be run a years?
What percentage of those hours will be running medium to full load i.e. motoring and what percentage with be light load used to charge batteries and run refrigeration? Do you have a generator for charging etc?
Do I need to upgrade the exhaust system new muffler, larger exhaust hose etc. for the new engine?
Do I need to upgrade the fuel system with large piping/hose from the fuel tanks to the engine?
Do you need to upgrade the drive train with a coupling, shaft, cutlass bearing, propeller?

Ocean Dove

When we purchased Ocean Dove in the spring of 2008 I knew that her Volvo MD30a had bad oil samples and was tried. It started and run but I knew I would be re-building or re-power soon.
I looked into the re-building but the cost of parts and the problems with the availability of some parts. I had with the replacement of a broken fuel injector piping which was not available from Volvo, the cost of having a new one made was 250% more expense.
I made the decision to repower with a new engine.

I started to evaluate Ocean Dove needs
Ocean Dove does not have a generator and depends on the wind generator (400amps), solar panels (174 amps) and 160 amp alternator on the Volvo to charge the 8 6 volts golf cart batteries 900+ amp/hrs.
I wanted a nature-aspirated diesel for charging the batteries
I wanted to retain the 60mm exhaust system and 1/4” fuel system.

Things I knew I don't want:
NO turbo charger (Yanmar 4JH4-TE, Volvo D2-75, Nanni N4.60)
NO computer controlled fuel system or starting system (VW, Volvo D2-55, D2-55)
NO rubber timing belt (Vetus VH 4.65 or VH 4.80)
NO belt driven sea water pump ( Vetus,)
NO Exhaust system greater than 60 mm (Beta, Westerpeke 64A, Yanmar 4JH4, Cummins B3.3 65)
NO fuel system piping greater than 6 mm (all of the above)
I need a engine that will fit the existing 60 mm exhaust system and 6 mm fuel system most modern engines are 75 mm (3") exhaust and 8 mm (3/8") fuel piping.
The cost of changing the exhaust to 75 mm is about $1000 plus my time and aggravation to install it.

Ocean Dove's new engine
I finally made a decision on a new engine for Ocean Dove. I purchase a Vetus VH4.80 80 hp @ 4000 rpm. The engine is based on a Hyundai industrial/truck diesel. The engine as upgraded hydraulic ZF25A gearbox and upgraded engine gauge panel and a 3-year warranty.
I made some compromises on my original specs for Ocean Doves new engine. It was price in the end and the trade in value the dealer gave me for the old Volvo than help me make my decision.
The things I compromised on were the belt driven sea pump and timing belt on the Vetus engine. Both items will require additional maintenance but as a marine engineer I can handle it. The other compromise was the exhaust system, Ocean Dove's original Volvo exhaust system is 60mm/2 ¼". The VH 4.80 requires a 75 mm/3" exhaust outlet.
The Vetus VH4.65 is a de-rated VH 4.80, the VH 4.80 is 80 hp @ 4000 rpm and exhaust outlet 72 mm/3", and the VH 4.65 is 65 hp @ 3000 exhaust outlet 60mm/ 2¼. So with that in mind I will install 3" hose from the engine to a new 3" wet exhaust muffler and step down after the muffler to the original 2 ¼ exhaust hose. I will monitor the exhaust back-pressure and only replace the exhaust hose 20' from the muffler to the overboard in the stern if the there is too much back-pressure.

I will be adding to my blog www.sailblogs.com/member/oceandove/ as continue with the re-powering

Last edit: 10 years 11 months ago by Derek Keeping.

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10 years 11 months ago - 10 years 11 months ago #305 by Derek Keeping
Replied by Derek Keeping on topic Re:Engine Repower options....
Access to the gearbox on many Whitby's is very difficult. When I first surveyed Ocean Dove I found the bulkhead between the aft cabin and the engine room behind the aft companion way stairs punkey with rot on the lower 2/3. I removed it this winter and will replace it with a removable panel so there will be better access to the back of the engine and gearbox. The new engine is shorter and the the gearbox is shorter then a Velvet Drive on some Whitby's. I will position the engine so the gearbox can be removed through the aft opening without moving the engine as Brian Stewart had to on "Pilgrim".

Last edit: 10 years 11 months ago by Derek Keeping.

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