Beta/Nanni 10hp convert to 14hp?

Latestarter1 said:
Have to violently agree with Tranona. When I hear people saying this and that is too stressed it is all un-databased backside talk.
Click to expand...

Er...wasn't Tranona saying the opposite?

As for BMEP, I don't have sufficient figures to work it out for either engine, but the specific power output of the 14 is higher (If it were the same, the 14 would put out 12bhp rather than the 13.3 Beta claim).
Sailorman might be interested to note that according to Beta's graphs, at 3000rpm, the 10 puts out 10bhp (of course) whilst the 14 puts out 12. So, assuming it was propped correctly, for the same boat speed, the 14 would rev lower, which rather confounds his argument.
 
Last edited:
macd said:
Er...wan't Tranona saying the opposite?

As for BMEP, I don't have sufficient figures to work it out for either engine, but the specific power output of the 14 is higher (If it were the same, the 14 would put out 12bhp rather than the 13.3 Beta claim).
Sailorman might be interested to note that according to Beta's graphs, at 3000rpm, the 10 puts out 10bhp (of course) whilst the 14 puts out 12. So, assuming it was propped correctly, for the same boat speed, the 14 would rev lower, which rather confounds his argument.
Click to expand...

Ok Ok :)

what happens when the anode blocks the HE :D
 
sailorman said:
Ok Ok :)

what happens when the anode blocks the HE :D
Click to expand...

Does not have an anode. The Nanni has a cast iron heat exchanger - one of the things that differentiates it from the Beta equivalent. And you never run at 3600, typically at 2500. The purpose of having a higher revving higher output engine is so that you can with the right reduction ratio swing a big prop for a heavy displacement boat. My old Yanmar had a 3.1:1 reduction to swing a 15" prop and ran happily at 3200 all day long 'cos that is what it was designed to do. The Nanni with a 2.6:1 box swings the same prop but as it produces 40% more power than the Yanmar runs at lower revs to achieve the same shaft speed.
 
macd said:
Er...wasn't Tranona saying the opposite?
Click to expand...

No. He is agreeing with me. These engines are designed to run all day long in things like diggers, dump trucks, farm machinery, refrigeration plants etc. in the range of 2600-3000+. They have an easy life in a boat!
 
I am amazed the OP found the advice he asked for amongst all this slanging match!

There are a number of notable differences between the likes of an old Sabb or Bukh and current available models. The older designs were long stroke and ran much slower, but swung massive flywheels. As Dylan says in his article this month, the MD1 fired so slowly it seemed a miracle that the flywheel carried it through to the next power stroke.

Modern ranges are based on industrial engines and tend to be oversquare, relatively fast running engines which require a much smaller flywheel. As a consequence, they also tickover somewhat faster.

With either type matched properly through gearbox ratio and prop size and pitch, they are likely to suffer more from being under stressed in a yacht application. Work boats tend to hack around at full power and suffer less as a consequence. The recent post about a runaway was most likely brought on by glazed bores allowing the crankcase to pressurize, blowing the oil into the air intake through the breather. This can happen to any engine if it is not worked hard enough.

When choosing a new engine, chances are it will be a third of the weight for the power output and smaller boats have to move ballast around to get balanced again! I've known owners who have found the sail plan unbalanced after an engine change until they moved everything they could toward the stern.

Rob.
 
Last edited:
sailorman said:
i took out a 4108 & replaced it with a 4 cylinder Nanni, both rated @ 3000 RPM
Click to expand...

Various other Nanni models are rated at 3,600 and 4,000 rpm, though. Unsurprisingly, as they are the same base engine as the Beta, the Nanni 10 is rated at 3,000 and the 14 at 3,600.

Of course, I have no objection at all to whatever preferences you have for your choice of engine, but it's just not true that a faster revving engine is unsuitable for a displacement boat, or necessarily more stressed than a lower revving one (e.g. piston speeds and centrifugal forces far greater on our Bukh 10 hp single at its 3,000rpm max than our Beta 14 twin at its 3,600 revs).
 
You must log in or register to reply here.

Share this page

Top