Carryfast:
railstaff:
Carryfast:
As I said the AV 1100 seems to have been lumbered with an impossibly ridiculous overall block height for its stroke measurement.Which would obviously have defeated any attempt by AEC to make the obvious move,suggested by cav,of combining the 1100’s and 690/691’s design for use in any type of general automotive use.Which is why I posted the MX example to show how it should be done and then some.
There are good reasons for the height of the block being what it was.(156 x 156)
Does that mean that it would have been possible to combine the 130 bore of the 690/691 with the 156 stroke of the 1100 without needing the space of a bleedin power station to fit it ?.
Why would the silly 156 bore size have needed such an equally silly block height ?. IE the big bore would be expected to put size on the length and width of the block not the height.
Just maybe to keep the engine smooth it required larger weights on the crank,to eliminate wear on the thrust side of the piston the skirts were larger,so the skirts didn’t touch the weights the conrod length was increased,so the pistons didn’t hang out the block face the height was increased and on it goes.
What technology would it take that wasn’t available then,to cast a block that could have allowed a 130 bore and a 156 stroke with the same,if not less,overall dimensions of the MX and which would have fitted under something along the lines of the ERF NGC or SA 400 cab ?.
Bearing in mind that’s a smaller bore and only 4 mm longer stroke than an 855 ■■■■■■■ and same bore and 4 mm longer stroke than the Rolls Eagle.In which case it wouldn’t/shouldn’t have been impossible rocket science by the standards of the day.
Oh wait according to AEC it was all about maximising the bore size because they thought that power was dependent on piston area not BMEP.
railstaff:
Just maybe to keep the engine smooth it required larger weights on the crank,to eliminate wear on the thrust side of the piston the skirts were larger,so the skirts didn’t touch the weights the conrod length was increased,so the pistons didn’t hang out the block face the height was increased and on it goes.
All that to get an extra 4 mm of stroke over a Rolls Eagle. 
So an engine the size of a house with bores the size of the Dartford Tunnel with at least a better stroke than a ■■■■■■■ 855 then a bleedin great big turbocharger bolted to it and around the same amount of power at 1,800 rpm as a non turbo 14 litre Detroit 12v71 in its lowest rating. 
There you go,that was what AEC engineers wanted.Again you quite clearly cannot grasp the idea of a duty cycle.Take a look at ■■■■■■■ KTA 50 or QSK 50.As the name suggests 50 litre vee sixteen,rated hp 2200hp but at sustained duty cycle that drops to 1800.So to put that into perspective the RNLI have just re engine their life boats with Scanias vee eight rated at 1200hp,but that is only 16 litre with just a difference of 600hp.It is a design feature.
Try looking at the standard AEC automotive sump, it is enormous. So big in fact that with certain front axles on a tilt cab chassis it will not come off unless the axle is dropped.
railstaff:
There you go,that was what AEC engineers wanted.Again you quite clearly cannot grasp the idea of a duty cycle.Take a look at ■■■■■■■ KTA 50 or QSK 50.As the name suggests 50 litre vee sixteen,rated hp 2200hp but at sustained duty cycle that drops to 1800.So to put that into perspective the RNLI have just re engine their life boats with Scanias vee eight rated at 1200hp,but that is only 16 litre with just a difference of 600hp.It is a design feature.
So would it be fair to say that in the era that we are discussing, (or attempting to discuss), that all the major engine builders that sold into various markets, i.e. automotive, industrial, marine, railcar etc. then they designed engines that had compromises in certain features so that the engines could be used in all their applications, rather than designing specific engines for duty cycles demanded by each separate application?
gingerfold:
railstaff:
There you go,that was what AEC engineers wanted.Again you quite clearly cannot grasp the idea of a duty cycle.Take a look at ■■■■■■■ KTA 50 or QSK 50.As the name suggests 50 litre vee sixteen,rated hp 2200hp but at sustained duty cycle that drops to 1800.So to put that into perspective the RNLI have just re engine their life boats with Scanias vee eight rated at 1200hp,but that is only 16 litre with just a difference of 600hp.It is a design feature.So would it be fair to say that in the era that we are discussing, (or attempting to discuss), that all the major engine builders that sold into various markets, i.e. automotive, industrial, marine, railcar etc. then they designed engines that had compromises in certain features so that the engines could be used in all their applications, rather than designing specific engines for duty cycles demanded by each separate application?
You,ve got it vicar,and lets not forget the average 13 litre engine wasn’t producing 500hp,the best of the heavy haulage Scammells had either CNFL8 rolls or 250 NHC,s( I could be wrong) horses for courses.
cav551:
Try looking at the standard AEC automotive sump, it is enormous. So big in fact that with certain front axles on a tilt cab chassis it will not come off unless the axle is dropped.
And the Rolls Royce E220, not as deep in the sump, but very similar in appearance to the AEC
railstaff:
…the RNLI have just re engine their life boats with Scanias vee eight rated at 1200hp,but that is only 16 litre with just a difference of 600hp.It is a design feature.
I’ve never understood boats. Why are their engines more powerful than lorries? If anything, the duty cycle of a boat may be more severe than a road vehicle- there are no speed limits in the sea, so what is to stop the driver wedging a plank of wood against the accelerator, and running his engine on the governor permanently?
Whatever, those lifeboats must make a sound to die for .
Edit- this might answer my question:
scania.com/content/dam/scan … _846kW.pdf
There is a proviso about the use of maximum power at the bottom of the spec. sheet.
Interestingly, they still provide specific fuel consumption figures, about a quarter of a century after that information disappeared from road engine specification sheets. The sfc of that engine is rubbish, compared to those old lorry engines. IIRC, the first intercooled 14 litre engine, from the same maker, was under 200g/kWh, in 1982. Equally interesting, the sfc is worse at full load, suggesting some over-fuelling is going on.
Which lifeboat stations have these? I fancy a trip to the seaside. Rev it up, mister! 
Which class is being repowered? only the Shannon is listed as scania powered and that not by the 1200bhp engine.
rnli.org/what-we-do/lifeboats-a … boat-fleet
Quite a change from the days of the RNLI using their own design of engine.
[zb]
anorak:railstaff:
…the RNLI have just re engine their life boats with Scanias vee eight rated at 1200hp,but that is only 16 litre with just a difference of 600hp.It is a design feature.I’ve never understood boats. Why are their engines more powerful than lorries? If anything, the duty cycle of a boat may be more severe than a road vehicle- there are no speed limits in the sea, so what is to stop the driver wedging a plank of wood against the accelerator, and running his engine on the governor permanently?
Whatever, those lifeboats must make a sound to die for
Edit- this might answer my question:
scania.com/content/dam/scan … _846kW.pdf
There is a proviso about the use of maximum power at the bottom of the spec. sheet.Interestingly, they still provide specific fuel consumption figures, about a quarter of a century after that information disappeared from road engine specification sheets. The sfc of that engine is rubbish, compared to those old lorry engines. IIRC, the first intercooled 14 litre engine, from the same maker, was under 200g/kWh, in 1982. Equally interesting, the sfc is worse at full load, suggesting some over-fuelling is going on.
Which lifeboat stations have these? I fancy a trip to the seaside. Rev it up, mister!
You do realise that you are about to open up a new can of worms that will be meat and drink to our learned friend Carryfast 
. Co-incidentally I have just started reading a book about the British T Class submarine of WW2 and I did go to bed last night pondering about what designers consider when deciding on the power of the engines. The T Class boats weighed about 1100 tons fully fuelled and armed and they had two diesels of 1,250 bhp each, so a power to weight ratio of 2.27 bhp / ton, if that has any relevance at all, and that gave 15 knots surface speed. Torque figures aren’t quoted, thank goodness, 
so presumably it must all be about horse power with a marine engine? Then I suppose the diameter of the propeller(s) must come into the equation.
gingerfold:
[zb]
anorak:railstaff:
…the RNLI have just re engine their life boats with Scanias vee eight rated at 1200hp,but that is only 16 litre with just a difference of 600hp.It is a design feature.I’ve never understood boats. Why are their engines more powerful than lorries? If anything, the duty cycle of a boat may be more severe than a road vehicle- there are no speed limits in the sea, so what is to stop the driver wedging a plank of wood against the accelerator, and running his engine on the governor permanently?
Whatever, those lifeboats must make a sound to die for
Edit- this might answer my question:
scania.com/content/dam/scan … _846kW.pdf
There is a proviso about the use of maximum power at the bottom of the spec. sheet.Interestingly, they still provide specific fuel consumption figures, about a quarter of a century after that information disappeared from road engine specification sheets. The sfc of that engine is rubbish, compared to those old lorry engines. IIRC, the first intercooled 14 litre engine, from the same maker, was under 200g/kWh, in 1982. Equally interesting, the sfc is worse at full load, suggesting some over-fuelling is going on.
Which lifeboat stations have these? I fancy a trip to the seaside. Rev it up, mister!
You do realise that you are about to open up a new can of worms that will be meat and drink to our learned friend Carryfast
The most important thing being the length of the stroke no doubt 
gingerfold:
You do realise that you are about to open up a new can of worms that will be meat and drink to our learned friend Carryfast
I think the torque is proportional to the slip speed of the propeller, so that means the boat engine does not need a high torque peak at low speed, like a lorry engine. You would have to specify the engine to suit the propeller size, like you choose the diff ratio of a lorry/car. I know bugger all about boats, so these are just my idle deductions.
The boat you describe goes well for its power output, considering the drag of the water on the hull. 2.27bhp/ton is the equivalent of a Gardner 5LW in a 44 tonner. I reckon such a vehicle would have to be geared for a top speed of about 30mph, so boats aren’t far behind.
cav551:
Which class is being repowered? only the Shannon is listed as scania powered and that not by the 1200bhp engine.rnli.org/what-we-do/lifeboats-a … boat-fleet
Quite a change from the days of the RNLI using their own design of engine.
Total ‘combined’ not each.
While they’ve used everything from MAN to CAT.No surprise I’m biased and Scanias won’t sound like this.
[zb]
anorak:
Edit- this might answer my question:
scania.com/content/dam/scan … _846kW.pdf
There is a proviso about the use of maximum power at the bottom of the spec. sheet.Interestingly, they still provide specific fuel consumption figures, about a quarter of a century after that information disappeared from road engine specification sheets. The sfc of that engine is rubbish, compared to those old lorry engines. IIRC, the first intercooled 14 litre engine, from the same maker, was under 200g/kWh, in 1982. Equally interesting, the sfc is worse at full load, suggesting some over-fuelling is going on.
Which lifeboat stations have these? I fancy a trip to the seaside. Rev it up, mister!
What was the SFC ( let alone piston speed ) of a TL12 at around 1,000 hp.
cav551:
Which class is being repowered? only the Shannon is listed as scania powered and that not by the 1200bhp engine.rnli.org/what-we-do/lifeboats-a … boat-fleet
Quite a change from the days of the RNLI using their own design of engine.
Fast carriage boat 2.
Ok since I last took any interest in the project they seem to have switched from the DS16 which was rated at 1200 hp to,two DS13 rated at 650hp each,combined of 1300hp with a twin disc gearbox.
The main difference over a normal marine application is that is uses water jets instead of a propeller and if your lucky a defuser so it can operate in low tide.
This kind of horsepower is a lot for its size and weight,maybe 40 ton and 25 knots in bad weather is a lot to ask.Quite a few of the 100 ton and above trawlers utilize VT28 and 3412 as main propulsion at around 900 hp.I think we will leave that were it is.
From the engine room scenes on the deadliest catch tv show, it looked to me as though the ships were using regular truck/marine engines.
I know the marine version of the C15 CAT in my truck puts out 800hp. A few guys run the marine cam in their trucks, along with some other mods to the ECM and turbo and they’re putting around 650hp to the ground.
Sent from my SM-G950W using Tapatalk
I remember when the 15.6 litre Scania V8 came out, and it was a bit marginal on cooling, IIRC. Even now, it seems that they are reluctant to give the 16.4 version any more than 730bhp, while those scruffy louts to the West have had 20 more boastable horsepower for some time now. I reckoned that the V8 was probably a bit dodgy at 800bhp, and that was why they were content to let Volvo have the lead, while they sweated like pigs to try and get the DC16 reliable enough to be the first 800bhp truck engine. I’m not too sure now. Maybe it’s the gearbox?
[zb]
anorak:
I remember when the 15.6 litre Scania V8 came out, and it was a bit marginal on cooling, IIRC. Even now, it seems that they are reluctant to give the 16.4 version any more than 730bhp, while those scruffy louts to the West have had 20 more boastable horsepower for some time now. I reckoned that the V8 was probably a bit dodgy at 800bhp, and that was why they were content to let Volvo have the lead, while they sweated like pigs to try and get the DC16 reliable enough to be the first 800bhp truck engine. I’m not too sure now. Maybe it’s the gearbox?
Marine cooling is night and day with truck air to water cooling,that sea is one hell of a big radiator.
railstaff:
Marine cooling is night and day with truck air to water cooling,that sea is one hell of a big radiator.
Is that the difference, applicable to all marine vs. road applications? Rather than duty cycle/durability expectations, the main factor is an infinite supply of coolant at <20 deg. C?
Basically yes.Keel cooling is very effective as long as the hull is submerged in water of course.Keel cooling consists of piping around the hull and the coolant is pumped through the pipes.Also heat exchanger which uses a raw water pump on the engine to send it through a heat exchanger and expel it normally out the rear of the vessel.