Suitably sized and powered vintage replacement for our BMC 1.8

[Chop!]

Is there a torquy engine, suitable for powering a pair on rivers, that will fit in our BMC's engine 'ole?

[gazza]

Plenty, how deep are yer pockets?

 

Whats up with the BMC?

[MtB]

You currently have a BMC 1.8 in a proper engine room?

 

If so then yes, plenty, but it isn't just a case of dropping in a vintage pump. You'll need a much bigger propeller too. What is the biggest diameter blade your shell can accommodate?

[GUMPY]

what's happened to the BMC?

Are you moving the position of the engine?

How deep are your pockets?

[MtB]

what's happened to the BMC?

Are you moving the position of the engine?

How deep are your pockets?

 

 

Or more pertinently, how deep is your swim?

[Athy]

if you need a more powerful but similar engine, what about the BMC 2.2 (the traditional London taxi engine)?

 

I guess someone will be along soon to tell me that it's nothing like the 1.5 or 1.8, but it's just a suggestion.

[MtB]

if you need a more powerful but similar engine, what about the BMC 2.2 (the traditional London taxi engine)?

 

I guess someone will be along soon to tell me that it's nothing like the 1.5 or 1.8, but it's just a suggestion.

 

 

The OP asked for a more torquey engine, not a more powerful one.

 

Most vintage engines have more torque and a lot less power than a BMC 1.8.

[GUMPY]

 

 

Or more pertinently, how deep is your swim?

Not really a 1:1 box sorts that out

A friend of mine swapped his Mitsubishi for a lister CE and had a 1:1 box fitted even with the shallow swim it went well. Until years later the CE suffered the fate of 90% of CE and broke its crank.

 

At present Chop's engine is under what used to be a cruiser stern, hence my question is he moving the engine

Edited June 30, 2015 by Loddon

[RLWP]

Not really a 1:1 box sorts that out

 

At the expense of redesigning the propshaft from the gearbox to the sterngland. The flywheel on the vintage engine will be too large to permit the output flange of a 1:1 box to sit in the same place as the gearbox on the BMC. It will have to sit higher up

 

Richard

[GUMPY]

 

At the expense of redesigning the propshaft from the gearbox to the sterngland. The flywheel on the vintage engine will be too large to permit the output flange of a 1:1 box to sit in the same place as the gearbox on the BMC. It will have to sit higher up

 

Richard

Yes Bernard did have to do some modification when the CE was fitted can't remember exactly as it waS the best part of 15 years ago. Oh and it was a Vetus not a Mitsi

Its at the bottom here

 

http://www.cutweb.org.uk/members/lexa.html

Edited June 30, 2015 by Loddon

[mark99]

 

 

The OP asked for a more torquey engine, not a more powerful one.

 

Most vintage engines have more torque and a lot less power than a BMC 1.8.

 

 

But torque is related directly to HP so powerful = more torque.

 

I think what is meant is high power/torque available lower down in the rev range.

Edited June 30, 2015 by mark99

[Athy]

 

 

The OP asked for a more torquey engine, not a more powerful one.

 

Most vintage engines have more torque and a lot less power than a BMC 1.8.

I'm sure you're torquing sense. But I thought that the majority of vintage engines would occupy more space than a BMC and thus might not be suitable.

[gazza]

Yes Bernard did have to do some modification when the CE was fitted can't remember exactly as it waS the best part of 15 years ago. Oh and it was a Vetus not a Mitsi

Its at the bottom here

 

http://www.cutweb.org.uk/members/lexa.html

He's since fitted a socking great 3 cylinder Lister in there that makes its presence felt

[GUMPY]

He's since fitted a socking great 3 cylinder Lister in there that makes its presence felt

The CE made the boat go like stink goodness knows what its like now.

In the 90s I was looking at building a small tug with a CE Bernie "nicked" all my calculations for gearbox/prop etc when he did Lexa I did feel smug when Crowthers came back with the same figures. Oh and I was one of those taking the p when he broke down......

[gazza]

Its noisy and shakes the boat a bit! I understand Sandie is not as mad on it as Bernard is

 

My mate fitted it for him - same guy that's got the trick scow discussed in another thread. Shoe horning the new motor in was no mean feat!

 

As you may know Bernie was the commodore at MNCC hence me knowing him.

[gazza]

I'm waiting for chop to spill the beans as to why the BMC needs to go.....

 

Mr Hansen's work load sounds like it's going to increase

 

As far as more pokey engines go, a 2.0 Perkins Prima out of an old Austin rover Maestro/Montego or even a late Sherpa should bolt up to the existing adaptor plate.

I know the cars used a VW box but I'm sure the Sherpa didn't change boxes from B series to O series - the Prima being a development from the O series engine.

They were a good powerful economical unit, a bit noisey but well on the road to diesels become useful power trains in the automotive world.

Once turbocharged they really did go well.

 

Not much, if any off the shelf marine bits for it so you need a tame fabby for manifolds and heat exchangers.

They are also getting old so may not be easy to find a donner vehicle for the lump - most having rotted to oblivion years ago!

 

Other than that, take your pick and get your wallet out

[Sabcat]

 

 

But torque is related directly to HP so powerful = more torque.

 

I think what is meant is high power/torque available lower down in the rev range.

 

Torque is related directly to power but more power doesn't have to mean more torque and in the context of engines often doesn't. More power could mean a lot less torque and a lot more speed. Horsepower is torque x rpm / 5252.

 

Generally older engines make more torque but less power because they have a longer stroke (a bigger level) but run much more slowly in terms of rpm because the pistons are moving further.

[Chop!]

Sorry Gazza, I am working at mo & can't get online so often.

The BMC has a tendency to overheat, especially going upstream, apart from that I'm a vintage everything enthusiast, Even wondered if I could chuck in my spare BSA 1000 v-twin lump! (Only joking)

I like something that goes thump but, no Julian, SWSBO says I'm not allowed to move my engine, so, as you say, It's a squeeze under the former cruiser stern.

I still has it's skintanks, even though it's now raw water cooled so space is limited.

[MtB]

 

 

But torque is related directly to HP so powerful = more torque.

 

 

This is plain wrong. Or more accurately, only half the story.

 

Power is product of angular velocity and torque, rather than being proportional to just torque.

 

When torque rises, angular velocity tends to fall in a diesel engine so more power does not necessarily equal more torque as you allege.

[gazza]

Sorry Gazza, I am working at mo & can't get online so often.

The BMC has a tendency to overheat, especially going upstream, apart from that I'm a vintage everything enthusiast, Even wondered if I could chuck in my spare BSA 1000 v-twin lump! (Only joking)

I like something that goes thump but, no Julian, SWSBO says I'm not allowed to move my engine, so, as you say, It's a squeeze under the former cruiser stern.

I still has it's skintanks, even though it's now raw water cooled so space is limited.

Sorry, I didn't mean to sound impatient

 

If the BMC is otherwise sound I'd go for sorting the cooling out, swapping the motor out for something else won't cure it.

 

You want to be looking for restrictions in the pipework, blocked tube stack and poor design - the seacock should be 1" as should all pipework to the raw water pump, avoid elbows where possible.

How big is the heat exchanger?

 

I'd think about an engine oil cooler as you can eject a fair bit of heat from the oil.

We have one on out 1.5, it's a sandwich plate design that sits behind the oil filter housing.

 

Another option is to reinstate the keel cooling and add another external tank mounted wet side of the uxter plate, Pat Buckle of Stibbington does this regularly, its not an approach I'm keen on but does work well.

 

A couple at MNCC have had this work done by Pat and were pleased with the results. That was on a boat that had a tendency to get hot under the collar when asked to work a bit.

[mark99]

 

This is plain wrong. Or more accurately, only half the story.

 

Power is product of angular velocity and torque, rather than being proportional to just torque.

 

When torque rises, angular velocity tends to fall in a diesel engine so more power does not necessarily equal more torque as you allege.

 

 

I never said they (Tq and HP) trend with each other or follow all the way along the curves (you need to look at the engine curve (Tq and HP vrs revs) characteristics to determine when each "peak" or at at good levels for your use.

 

My statement stands: in that:

 

HP = Torque * constant/RPM

 

If you increase power for a given RPM the torque must rise.

 

I was, I admit, being a little mischievous in that the engine Tq and HP curves are characteristic of piston diameter, fuelling/energy released (leading to mean effective pressure on piston) and conn rod length.

 

Big stroke/big displacement type engine will give you torque low down in rev range.

Edited July 1, 2015 by mark99

[Athy]

Is Pat Buckle still in business? I know he used to build boats but I haven't heard of him in maybe ten years.

[gazza]

Is Pat Buckle still in business? I know he used to build boats but I haven't heard of him in maybe ten years.

Yeah, still busy there every time we go past

[Neil Smith]

Has it got to be water cooled?

 

Neil

[gazza]

Has it got to be water cooled?

 

Neil

Ohhhh, I like the cut of your jib - a Lister SR/ST should go in the hole.

 

I think chop! Is evolved in music so probably won't mind the din