Why are Diesel Engines so dear...

[ontheplane]

Been looking for a new boat as anyone seeing many of my old posts will see.

Some of the boats we've looked at have had new engines fitted.

Now, given the large cost of this, I was baffled why so many have been re-engined and yet still have petrol motors given the strong diesel bias of so many boaters.


So I made some phone calls to see what a new engine costs....

A new, not exchange, 4.3MPI from someone like Marine Repower costs somewhere in the region of £3000. Now given some bits probably aren't included in this (alternator etc) I guess the real cost is more like £3500 or £4k which gives about 220HP

Now - Looking on websites such as Coastal Rides, Lancing, etc It looks like a re-manufactured Volvo/Cummins/Yanmar or any other similar makes are about £12000 for the same power output - so what they are new is anyones guess!


Given a new car with a diesel is about £1000 more than the equivalent petrol I am really struggling to see why this is.

Now I know someone will say "because they can" but actually, is that true? If you could get a decent diesel for about £6k surely all the people who's engines broke would have re-powered with a diesel not a petrol. In fact, if the money was sensible, many people with big v8's would actually seriously consider removing them and putting the diesels in and selling the old good petrols for a grand each or so..... And if it's just because the manufacturers are making silly margins, surely someone somewhere would start a bit of a price war?

Many years ago (about 10) I had a really good relationship with a local Volvo Penta dealer. They were talking about being able to supply a new KAD32 with DP drive for around £9k - but this was very "hush hush" and I think the list price was massively more than that.... I also think I remember the Mercruiser 1.7DTI that had just come out (120HP) was about £5k as well - but that sort of price was only for boatbuilders or importers, not regular joe's.

So, can anyone in the industry tell me why?

 

[ontheplane]

Ok.. so you don't have to be in the industry... anyone can answer, that's fine...

 

[tinkicker0]

Ok.. so you don't have to be in the industry... anyone can answer, that's fine...

Diesel engines are chock full of big expensive bits like injection pumps costing 1000s.

Also economies of scale. A GM V8 petrol will be fitted into all sorts of cars, trucks, plant and industrials. As a result many millions are made and this reduces the cost added per unit for research and development greatly.
diesels will have a much less unit volume.

Same with internal parts. Place an order for 80 million pistons and you will get them much cheaper than placing an order for a 100 thousand. This is right down the supply chain to the mine / smelter ect.

Amount of material. A diesel piston will probably weigh twice as much as a petrol one. This is twice the material.

Manufacturing complexity: Diesel pistons are cam ground and contain alfin inserts to take the pressure on the rings and reduce wear.

Cars do not have these, nor do I believe are cam ground, although not up on car engines.

Times this by every part of the engine........

 

[ian38_39]

Because they can, or at least could. Doesn't stop there either, wait till you have to change a fuel pump on a diesel engine.

As you say in automotive there is about a grand between them and as many marine engines are automotive based, not just petrol, there is really no reason other than they used to be so much more desirable due to fuel cost.

In the past everyone ran red for boats, not just the UK, and red was about 25% of the price of petrol.

Old petrol engines didn't mix well with water in old boats (wet bilges etc.)

Stern drives came along and gave dry bilges, Red diesel disappeared across Europe eliminating most of the price differential and petrol engines became reliable. Why would anyone repowering a petrol boat do so with a hugely overpriced diesel unit that is also going to need a fair bit more than just the engine changing, when they can drop a new petrol engine in as a straight swap for sensible money.

All in my opinion of course and it is going to get worse for diesel given that the new multipoint fuel injected petrol's are producing similar economy and torque figures to diesel units and are still dramatically cheaper, If marinas start to put petrol pumps in it could lead to a major shake up.

In truth it very rarely makes any sense to change a petrol to a diesel as by the time the petrol engines need changing the cost of the diesel equivalent, especially if there are two of them, would be more than the boat was worth even with new engines. You will never recover the price in full of the new engines come sale time, petrol or diesel.

 

[oldgit]

When we got the wifes new Audi there was no difference between petrol and diesel price so we went diesel,as far more economical and due to lower emisssions.... no road tax.

 

[rafiki_]

OTP you raise a very good point on pricing differential, and the only honest answer, is that people continue to pay the asking price.

I source as many parts for my Merc (Isuzu) diesels from the local Vauxhall Stealer. They are very helpful, and keen to help. My requests are unusual for them, and could not be more helpful. So I recently paid £35 for a cam drive belt, rather than the £135 from Merc. The parts for the outdrive I source from the States, but cannot get the diesel parts from them.

The new DI petrol engines will be similar cost to equivalent diesel, with the control system and aftertreatment eating up the cost.

I'm still happier with the diesels, better fuel economy, safer, availabilityof fuel etc.

 

[Deleted User YDKXO]

I think it's fairly simple. Diesel engines rely on compression to ignite the fuel so compression ratios and combustion pressures are much higher than a typical petrol engine. Because of this, the mechanical components of the engine have to be much stronger (and usually much heavier). Add highly sophisticated and expensive fuel injection components and a turbocharger or two and you get a much more expensive engine. Having said this, IMHO engine manufacturers seem to price diesel engines at the maximum that they think they can get away with given the better fuel consumption of these engines against petrol engines in many applications

 

[Assassin]

Not only that, but diesels last much longer and generate much more torque, this means other components such as transmission components have to be so much stronger to deal with this torque.

In respect of longer lasting engines, its down to marketing, if a petrol lasts 100,000 hours you sell a unit every 100,000 hours, if a diesel lasts 500,000 hours you sell one every 500,000 hours. Basic economics in simple terms.

 

[Latestarter1]

Much is volume related.

Traditionally the US has provided automotive V8 engines which come from pretty low tech high volume base. Typically GM/Ford small block long motors in the 200/250 hp node sell to marinisers for less than a thousand bucks.

We used to use mid range diesel engines in this power node where for example a Bosch P7100 fuel injection pump costs the engine manufacturer a thousand bucks before it is fitted on the engine.

Marinisation hang on components, exhaust manifolds, heat exchangers, water cooled turbochargers etc are low volume stuff with a heap of hand work involved in assembly.

Used to attend meetings to review profitability of certain engine platforms. Automotive, Industrial, marine. Golden rule was after manufacturing plant overhead and warranty accrual engines HAD to make 22% gross margin. It was always the marine guys which stuggled to make corporate gross margin.

The centre of gravity has now shifted in the 200/250 marine node with the introduction of LDA (Light Duty Automotive) chainsaw motors, Volvo D3, VW, BMW etc. The cost base of these motors is very similar to eqivalent gasoline motors. However a trip up using this this little stuff is real costly. Guys I know at Yanmar in the US claim that after about six years they are not making a dime out of the BMW based BY marine motors.

As to argument regarding list prices....Merely words on paper, once you get down to the nittly gritty negotiated pricing is hugely lower than list.

 

[lovezoo]

In respect of longer lasting engines, its down to marketing, if a petrol lasts 100,000 hours you sell a unit every 100,000 hours, if a diesel lasts 500,000 hours you sell one every 500,000 hours. Basic economics in simple terms.

And exactly how many boat engines drop dead from overuse?

 

[Jim@sea]

I am looking for a diesel powered boat. If it was November with 5 months to go before the boating season started again and I would quite happily buy a cheap petrol powered boat and have a Brand New Diesel Engine dropped in. In fact if I was still had my garage I would be considering doing this and selling the boats on as a business, as obviously the New Engine would have a manufactures guarantee,
I have considered an outboard boat but where I go boating the marina has diesel on the pontoon but the nearest petrol station is a mile away and I see people struggeling carrying 5 gallon drums of petrol down the steps, I would probably need 40 gallons to go to the Isle of Man.

 

[ian38_39]

A fair few petrol engines get replaced but I would guess that most of those are more to do with abuse than use.
Very rare that diesels get changed as their high cost means rebuilding is the only viable option, with petrol it is normally not much more to change it than rebuild and you know you are getting a brand new factory spec unit.

 

[ian38_39]

I am looking for a diesel powered boat. If it was November with 5 months to go before the boating season started again and I would quite happily buy a cheap petrol powered boat and have a Brand New Diesel Engine dropped in. In fact if I was still had my garage I would be considering doing this and selling the boats on as a business, as obviously the New Engine would have a manufactures guarantee,
I have considered an outboard boat but where I go boating the marina has diesel on the pontoon but the nearest petrol station is a mile away and I see people struggeling carrying 5 gallon drums of petrol down the steps, I would probably need 40 gallons to go to the Isle of Man.

Had an interesting chat once with quite a prominent engine mariniser who re engined a petrol Sealine 305 a good few years ago.
Despite having access to the engines at cost and their own boatyard facilities they still only just managed to break even on it.

The only time it would be worth while is if you are planning to keep the boat for a lot of years, so will benefit from the lower maintenance of new engines or if you can get hold of pair of good second hand units for peanuts.

Probably easier with a single as if someone does have a catorstrophic failoure on an engine they may replace the pair, leaving one good one for sale.

 

[lovezoo]

The only time it would be worth while is if you are planning to keep the boat for a lot of years, so will benefit from the lower maintenance of new engines or if you can get hold of pair of good second hand units for peanuts.

I can only see it being viable if the original petrol engine is knackered and you can get a cheap second hand diesel. You will never get the price back from a new one.

And I'm sure you have seen this thread where the guy has spent £17K rebuilding his diesel engine and still doesn't have a working boat.