Tamd 71b / Tamd 63p

[ian38_39]

Hi All,

Currently looking at an advert for a boat with 63p's, boat is abroad and a couple of years younger than a UK boat the same but with 71b's.

Both of the engines claim the same output but is there a major difference and which is best?

 

[kashurst]

I've had both engines in different but similar sized boats.
The 71b is a simpler engine and very easy to work on (subject to access). bit smoky when cold, no turbo wastegates to worry about, most coolant hoses between intercoolers etc are metal so they don't burst. I think they are a 7 litre block.
If very cold they can take a bit of spinning to start up, sound a bit agricultural at idle when cold. Power seems to build more progressively as revs rise

63Ps - lots of rubber hoses and pipes, turbos are wastegate controlled, 5.5 Litre capacity. The raw water impeller can be a sod to get out without the correct volvo 63p extractor (cheap)
Start like a car engine, smoother running at idle - immediately regardless of hot or cold. Power builds rapidly from 1500 to 1800 revs very noticeable - but fun.

Overall performance very similar, fuel consumption very similar (subject to boat). If you download the volvo data sheets they will give you the torque /power curves. From memory the 71b has more torque lower down the rev range. No doubt VP will be along later and give the various foibles - but for my money I would be happy with the 71Bs (obviously service history test etc needs to be done for your potential purchase). I'm assuming this boat is at least ten years old so if everything else was the same I'd probably pick the boat with the 71Bs because there is less to go wrong on an older engine design.

 

[ian38_39]

The boats are 1994 and 1996 so yes they would fall well into the older boat category.

I'm all for an easy life though so have always shy'd away from anything with lots of electronics to break.

Would I be right in assuming that the 71b's are also lower revving and as such less stressed?

 

[Latestarter1]

Would I be right in assuming that the 71b's are also lower revving and as such less stressed?

No certainly not a correct assumption. I have no clue where this 'less stressed' perception comes from, particularly when we never wear diesel engines out in recreational operation.

The only measurement I can think of when people talk of 'stress' is piston speed...

Volvo 60 Series 98.4 X 120 stroke with rated speed of 2,800 rpm. Piston speed = 11 MPS
Volvo 71 Series 104 X 130 stroke with rated speed of 2,000 rpm. piston speed = 10.98 MPS

Piston speed of both engines is awash. Considering CAT C18 pretty much holds the piston speed record at an eyewatering 14 MPS where does all this 'stress' talk come from?

I would have thought cold start performance, general sociability, ease and cost of servicing are the issues. Would rather have a sociable but more complex motor any day.

Interesting to hear what VP says.

 

[ian38_39]

Would it not follow that given that the rated speed is 800 rpm less on the 71 that all bearings are going to be turning at a slower speed?

I do not have your understanding of engineering within a combustion engine but I assumed that if things turned slower that they would wear less?

 

[kashurst]

electrically speaking both engines are very similar, just a few relays and circuit breakers. There isn't any computers or tricky sensors to worry about. Servicing costs are pretty much the same. When I mentioned smoke when cold - its not a lot, we are not talking ford mermaids where you need to untie before you start up to avoid the neighbours.

 

[Who]

Two of my friends boats with 71b are both smoky and sooty.

My 1997 63p are very clean. Minimal smoke and then only on start up and NO soot.

My last boat kad42 on shafts, was sooty and a pain to clean the back after every run.

It's the soot I can't stand.

 

[volvopaul]

No certainly not a correct assumption. I have no clue where this 'less stressed' perception comes from, particularly when we never wear diesel engines out in recreational operation.

The only measurement I can think of when people talk of 'stress' is piston speed...

Volvo 60 Series 98.4 X 120 stroke with rated speed of 2,800 rpm. Piston speed = 11 MPS
Volvo 71 Series 104 X 130 stroke with rated speed of 2,000 rpm. piston speed = 10.98 MPS

Piston speed of both engines is awash. Considering CAT C18 pretty much holds the piston speed record at an eyewatering 14 MPS where does all this 'stress' talk come from?

I would have thought cold start performance, general sociability, ease and cost of servicing are the issues. Would rather have a sociable but more complex motor any day.

Interesting to hear what VP says.

Sorry Paul but 71 a and b is rated at 2600 rpm, 357 the 71a and 380 the 71 b.


As for an answer for Ian id go for the much newer 63p only because the smoke of the 71 is bad, but the achilles heel on those old motors are the heat exchangers and intercoolers, the tube stacks are over a grand a piece and there are 4 of them, the nasty alloy bodies they sit in area around £400 a piece and they rot away if not looked after as there was no provision for an anode.

There you go make your choice!!

 

[Latestarter1]

Sorry Paul but 71 a and b is rated at 2600 rpm, 357 the 71a and 380 the 71 b.


As for an answer for Ian id go for the much newer 63p only because the smoke of the 71 is bad, but the achilles heel on those old motors are the heat exchangers and intercoolers, the tube stacks are over a grand a piece and there are 4 of them, the nasty alloy bodies they sit in area around £400 a piece and they rot away if not looked after as there was no provision for an anode.

There you go make your choice!!

Sorry 2,000 rpm was a typo for the 71, teach me to butt in on Green engines! However the point is well made by you regarding drawbacks of the hang on's with aging and socialbility being key pre purchasing factors.

Certainly none of this highly stressed nonsense, base engines are never subject to wear out in recreational use. The factors highlighted by VP are typical of the factors in a buying situation not discussing the semantics of base engine design.

 

[ian38_39]

Have witnessed heat exchanger problems on an old princess 33 and it is a good point, are they different on the 63 or just newer?
The boat with 63's in is the preference even with mega hours on the clocks but the other one is a UK boat so the buying logistics are easier.
Paul if i can get something sorted with the broker I will give you a shout to have a look for me if you don't mind, will involve getting on a plane though.

 

[oldgit]

Have also had problems with the VP 40A cooling on my old P33 with the early square heat exchanger box.However even after 32 years the alloy outer box was in excellent condition and the internal brass matrix merely required soldering,nothing to do with corrosion but purely metal fatigue along one of the joints.

 

[asteven221]

FWIW my I have 63p's and compared to the 61a's in my last boat they run with minimal smoke from cold or hot. No soot. They seem smoother. I hate tempting fate, but they start first time every time, no pre heaters and even from freezing cold. That's the kiss of death, now that I have said that and no doubt will not start next time!!!