40 year old needs new engine.

Hi!

I have an 40 year old Swedish made boat called Albin 25.
Its a 25ft 1.6ton fiberglass hull which is hybrid construction between dicplacement and planing (semi dicplacement).

The engine is the original one called Albin AD-21 a 4 stroke Diesel and it produced 22hp SAE (17hp DIN) and ~64Nm @2400 rpm when it left the factory almost half a century ago.

It still works and at maximum speed it produces enough power to give me around 7knots today (@ ~2200rpm via a 2.04:1 reduction and a 3 blade 16,5 x 12 propeller).

But...it's starting to get expensive and hard to find spare parts and it always feels a bit scary to rely on such an old engine.

Buying a new engine like Lombardini, Solé or Vetus costs a fortune and I simply don't have that budget. I was thinking of converting a VW 1.5L/1.6L Diesel engine instead and using Bowmans heat exchanger. I will also need a reduction of some sort.

My goal is to get a engine that is reliable,easy to mantain and powerful enough to run the boat. If possible it would be nice to increase the top speed to around 10knots.
I'm also thinking of installing an Aquadrive system (cv-shaft + thrust bearing) to quiet things down a bit. I would also like to have a lower minimum speed. Today I get around 3knots which is a bit too fast for some manouvers and also too fast for trolling.

I know my way around an engine and have friends that are mechanics. I know how to weld (Mig/Tig).

Have any of you done this conversion or similar?
Any input would be much appreciated!

Br
Jens

 

Hi Jens,
The VW Rabbit engine seems a good choice to me. Millions have been made and Ebay is an endless source for spare parts.
Whether or not your gearbox fits I do not know; if it doesn't you could consider a small Technodrive with an SAE adapter plate and an engine coupler.

For the conversion with a Bowman manifold you need lots of rubber hoses with 90 degree knees if you can get them, or use copper knees and hose clamps. The VW engine has a dry and a wet side but the conversion requires both sides to be "wet". I converted one engine with mainly hoses and a few straight 50 mm stainless tubes, but the supplier had run out of bent hoses so I used copper knees on the other one. You can of course also weld or solder these parts together.

I could compose a complete list of what you need, but I don't have it available right now.

 

Hi CDK!

Do you have another heat exchanger than Bowmans that you recommend ?

Any technical information on the engine would also be very helpful as I don't have any measurments on it.

A list would be very helpful but no hurry, I don't have a engine yet

What sort of water pump should I use ?

/J

 

No, I used Bowmans as well. The casting is a bit crude, but it fits. The alternative is one from VW marine at almost twice the price. I bought mine from Mesamarine in the US, they were cheaper than our English friends.
For raw water I used the smallest Johnson pump, belt driven from a pulley you have to add to the existing one driving the water pump and alternator. Plenty of space for a bracket and a 300x9.5 mm belt.

 

I would be very interested in seeing your list too. Marinizing a VW economically has been an interest of mine for some time now.

 

I had a look at the Bowman heat exchanger on CDK's pictures.
How tall is that reservoir ? I looks like it sticks up quite a lot over the engine !

If I remember correctly there is a version of the heat exchanger for keel cooling that doesn't have that hugh reservoir. Can I use that one and mount an reservoir in some other place ?

...also I'm off looking at a donor motor today, is there any particular weak spots I should check for ?

 

Pushing an Albin 25 to 10 knots will require a lot of power. At 7 knots, you're pushing 1.5 S/L which is what you'll get with the small HP engines you've got envisioned. Trying to get 2.1 or 2.2 S/L will be asking a lot without tripling the available HP.

I can get a new 3 cylinder, 22 HP, Kubota diesel, with manifolds, pumps and transmission for about $6K, ready to install as a marine power upgrade (no conversion). Of course this is in the USA, I'm not sure about availability in your area.

 

Hi Par, thanks for replying!

The 1969-1972 Albin 25 hade the same engine that I have (AD-21) producing 22Hp.
Top speed for these boats were (are) 8knots. "Economical" speed was 7knots.
Mine does just above 7knots today with the original motor.

From 1973 and onwards the 2 cylinder AD-21 was replaced with a Volvo Penta 3cylinder MD3B (later a MD17C at the same power) rated at 36hp which gave it a top speed of 10knots and a economical speed of around 9knots.

Also there were some smaller changes to the rear of the hull to better support the larger engine output. These changes contribute somewhat to the increase in speed.

The 10knots goals is not THAT important, the goal with this swap is to get an reliable engine as cheap as possible.

The Kubota prices you mentioned was really cheap!!
Do you have a link to the seller?

 

The filled cap of the header tank is the highest part of the engine now, approx. 15 mm above the casting where the EGR valve was installed. Originally the plastic oil filler neck was the highest part by far, but I cut it in half and machined the two parts so one could slide into the other.

As you will find out, it is very difficult to discern a good engine from a bad one by just looking at it, but there are some tell tales.
Look at the flywheel and the engine face under it: they should both be free of oil residues, otherwise you start with an oil seal replacement that is very time consuming.
Watch for signs of wear on bolt heads from using pliers or ill fitting tools; it means some hobbyist has done repairs or "improvements".
There should be a cap on the main adjustment screw of the Bosch pump, a sign it was not tampered with.
An aftermarket oil filter also means that service wasn't done by VW.

The best donor engines are those from company cars. Some recycling firms have a surprisingly well information system that can tell you a lot about previous ownership.

 

Are you familiar with this Albin group on yahoo:

http://groups.yahoo.com/group/AlbinCruisers/

1525 members, searchable threads, very helpful bunch. Lots of repower topics.

No cost to join

Steve

 

Yes, I have visited that forum but it was along time ago.
Perhaps time to pay them a visit again

Thanks Steve!

 

I think I have found the power map for the VW 1.6L NA Diesel.
As CDK mentioned in another thread the torque curve is really flat.

 

Try www.dieselenginetrader.com You might find something.

 

Send me an email and I'll send you the link for the Kubota.

 

I had a conversation with a fellow Albin owner here on the forum.
He have converted to electric drive which I also was thinkig about.
The only problem I have with that at the present is I have no access to electricity at the dock in my port so it seems I'm still going with the diesel.

...anyways, he was very kind and gave some really excellent figures on power consumtion and speed. From the figures one can easily see where things is starting to draw power.

Power Speed
0,7Hp 3kt
1,3Hp 4kt
2,0Hp 4,6kt
2,6Hp 5,0kt
5,0Hp 5,8kt
6,2Hp 6kt

This is surley no news to you guys but I was amazed to see that one only needed 1Hp to get almost 4kt of speed. Of course these power ratings are estimates as they seem to be (Amps x Voltage) / 746 = Hp.

In the old handbook for the Albin 25 there is an hand drawn diagram showing power and fuel consumption.