Leyland Marathon...The "Nearly" Truck of The 1970s?

[carryfast]

railstaff:

Carryfast:
Did you read my previous posts.

Piston speed is related to the length of stroke ‘and’ engine speed.If you reduce the engine speed, for a given power output,by more than the increase in stroke,you get a ‘reduction’ in piston speed not an increase.While the increased leverage at the crank allows for more torque with less stress.More torque = more power for less engine speed.Usually to the point where the reduction in engine speed is greater than the increase in stroke.So I’ll do the figures again.

Engine A - ■■■■■■■ 335 280 hp at 1,600 rpm.Piston speed = 26.6 feet per second.

Engine B TL12 280 HP at 2200 rpm.Piston speed = 34 feet per second.

Let alone the same comparison with a 350 or a 320 Big Cam.

IE the ■■■■■■■ produces more ‘power’ for ‘less’,not more,piston speed. That being a function of its higher torque output at any given engine speed.Which is itself in large part a function of its longer stroke providing more leverage at the crank so more torque for a given force through the con rod.

As I said it’s not rocket science.

Why would anyone want to fast idle the ■■■■■■■ at 1,500 rpm ?. Oh wait that’s the only selective example which would show any advantage for the TL12’s shorter stroke.However engines generally aren’t designed on the basis of a selective comparison of piston speeds at silly unrealistic idle speeds.They are designed for optimum efficiency and to stay together under load.The definition of ‘efficiency’ and ‘staying together’ in this case being which can produce the most power for the least engine speed.

Can you read for starters?

If you can try reading a basic book on engine design and principles.

It was a theretical example which is FACT,ive not made it up.

I choose to keep the engine speeds the same for comparison reasons.Knowbody else as yet has questioned it but you,the majority seem to be happy with the theory.It is FACT.

Anybody who has any serious engine experience will understand what a fast idle refers to,if you care to look at ■■■■■■■ product care you will see it refered to quite often,mainly during the warm up procedures.Any engine speed over idle is refered to as a fast idle.

Just to clear up any misconceptions of a PT fuel pump running at 1500rpm steady and not running on to the governor,that is made possible by the VS and top throttle portion of the fuel pump.

Why do you continue to move the goal posts?

Ironically I’ve been arguing in favour of fast idle to warm up an engine v load elsewhere.But never heard of running the thing at 1,500 rpm to do it.

I didn’t move any goal posts.It’s obvious that you chose to rely on the only selective irrelevant comparison which would help the typical erroneous view that shorter stroke means less piston speed which is obviously a myth.As I’ve proved.

So what’s better fast idle the ■■■■■■■ at 1,000 rpm and have the benefit of the lower engine speed and with it lower piston speed at any equivalent power output under load.Not to mention less stress on the piston to component chain provided by the extra leverage at the crank.

Or reduce its stroke to 142 mm to match the TL12’s piston speed at any given engine speed at idle. Here’s a clue the TL12 was predictably taken of production during the early 1980’s because it couldn’t compete with the ■■■■■■■ or Rolls Eagle let alone TX.Remind us how long the N14 stayed in production to be replaced by an engine with a smaller bore and even longer stroke.

Which leaves the question why was Leyland so keen on using a known flawed inferior uncompetitive engine when the Rolls and ■■■■■■■ alternatives were available ?.The in house excuse doen’t cut it.I’m still going with conspiracy not ■■■■ up.

[zb_anorak]

Nobody who has worked in engineering in the past 50 years uses imperial units. Even the Americans use SI these days. The only time I use inches is when I am boasting about my manhood, and if I needed to raise any dimension of that to the fourth power- for whatever reason- I would convert to mm straight away.

[carryfast]

[zb]
anorak:
Nobody who has worked in engineering in the past 50 years uses imperial units. Even the Americans use SI these days. The only time I use inches is when I am boasting about my manhood, and if I needed to raise any dimension of that to the fourth power- for whatever reason- I would convert to mm straight away.

It makes no difference the end result is always going to be that the ■■■■■■■ and Rolls Eagle can produce more horse power,at less engine ( and piston ) speed and with less stress than the TL12 ( or DAF DK ).

The question then being why deliberately lumber the Marathon,let alone the T45,with the TL12 when Leyland would have known that from day 1 and the more ■■■■■■■ and Rolls engines they ordered the lower the unit cost would have been ?.In addition to the question why use the small cam ■■■■■■■ 335 instead of the even higher torque output of the 350.We can probably add to that the convenient late adoption of the higher output 300 + big cam options across the domestic industry.Which equally all too conveniently seems to have been the result of ‘type approval’ ‘delays’.

[gingerfold]

Most of the recent arguments and counter arguments have been completely irrelevant to the subject of the thread, which is not uncommon when CF gets technical. However even my non-technical and non-mathematical brain got Railstaff’s example of engine stroke relative to piston speed, and I do know from past conversations with AEC engineers that piston speed was always an important influence in their designs and calculations.

A formula for piston speed calculation freely available on the internet is: -

Piston Speed = stroke length x rpm divided by 6

Therefore the TL12 stroke of 5.59 inches x say, 1,500 rpm = 8,385 divide by 6 = 1,397.5 ft per minute

Taking a 6" stroke design, then 6 x 1,500 rpm = 9,000 divide by 6 = 1,500 ft per minute

So, the longer the stroke the higher the piston speed at any identical rpm.

Carryfast, I think that you owe Railstaff an apology because you have to take identical engine rpm. The TL12 was not driven at max rpm all the time, any more than the ■■■■■■■ or RR, or any other engine you care to mention. As a former driver you should know that.

And, for all the theoretical guff spouted in recent posts the TL12 was a very good engine. In practice it worked and worked well. There is no way that statement can be disproved.

Happy New Year!

[gingerfold]

Another double post

[carryfast]

gingerfold:
Most of the recent arguments and counter arguments have been completely irrelevant to the subject of the thread, which is not uncommon when CF gets technical. However even my non-technical and non-mathematical brain got Railstaff’s example of engine stroke relative to piston speed, and I do know from past conversations with AEC engineers that piston speed was always an important influence in their designs and calculations.

A formula for piston speed calculation freely available on the internet is: -

Piston Speed = stroke length x rpm divided by 6

Therefore the TL12 stroke of 5.59 inches x say, 1,500 rpm = 8,385 divide by 6 = 1,397.5 ft per minute

Taking a 6" stroke design, then 6 x 1,500 rpm = 9,000 divide by 6 = 1,500 ft per minute

So, the longer the stroke the higher the piston speed at any identical rpm.

Carryfast, I think that you owe Railstaff an apology because you have to take identical engine rpm. The TL12 was not driven at max rpm all the time, any more than the ■■■■■■■ or RR, or any other engine you care to mention. As a former driver you should know that.

Why would we ‘have’ to take identical engine speed when what matters is the engine speed relative to the comparable power output.IE you’ll have to rev the nuts off the TL 12 to get the equivalent ‘power’ output of the ■■■■■■■■

So the shorter the stroke the ‘higher’ the piston speed at any identical ‘power output’.

On that note remind us what was the power output of the TL12 at 1500 rpm v that of the ■■■■■■■ 335’s 265 hp let alone the 350’s ?.At that power output the TL12 will be revving closer to 2,000 rpm if not more.While if we’re happy with just the TL12’s output at 1,500 rpm then the ■■■■■■■ will be revving at far less than 1,500 rpm. In which case as a former ‘driver’ I know that the engine which can climb hills faster at a lower engine speed is the superior one.

Which is why railstaff had to selectively use a bs comparison of unrealistic identical idle rpm to make the figures work in favour of the TL12 and its why the ■■■■■■■ N14 was still in production in the 21’st century and the TL12 was all too late dropped in the early 1980’s.

[cav551]

Carryfast:

cav551:

Carryfast:

[zb]
anorak:
Complete lack of reading/comprehension^^^.

Great feel free to describe all the points when a con rod is under tension.

Oh boy that ■■■■■.

I’ll word it better then maybe you can answer the question.In what way would increasing the stroke and therefore leverage at the crank have any major downside on any tensile loads.As opposed to beneficial effects of the increased leverage at the crank reducing compressive and shear loads,through the con rod,during the power stroke,for a given torque output.Bearing in mind that an increase in specific torque also generally means a net reduction in engine speed/piston speed for a given power output.

With apologies to Gingerfold and all who are bored to death with what has become digging up old ground. In order to keep this one on track, perhaps the mods could transfer the distractions from the title’s theme onto a new thread. However with this I have now had my say on the matter.

That is asking a different question. However increasing the stroke means increasing the crank throw (distance) so therefore adding to the leverage exerted by the crankpin upon the connecting rod, just as the leverage the piston exerts upon the crankpin via the connecting rod is increased. It follows then that when the connecting rod is subjected to tension that increasing the stroke will add to the tension load. In the NA engine the con rod is under tension during the induction stroke since there is no pressure on top of the piston. The turbocharged engine forces air into the cylinder under pressure creating a load upon the piston, however this is only considering what is happening in that particular cylinder. Other things are occurring, the cylinder has a twin. While air is being admitted under pressure to ‘our’ cylinder its twin is firing. The actual pressure inside that twin is greater than the pressure being pumped into our cylinder. Our piston is not being driven down by the incoming air, it is being pulled down by the rotating crankpin which is being driven by another cylinder; our rod is under tension, since the crankpin now have been made with a longer throw the tension has increased.

Disregarding lubrication failure and assembly errors, it is more common for a connecting rod to fail when under tension than when under compression unless an element of abuse has been introduced. Since the rod is constantly subjected to varying force, because the piston is never travelling at a constant velocity or acceleration, whether that force is compressive or tensile, it or the big end bolts will eventually fail from fatigue. Quite often that failure occurs when the engine is not under heavy load sometimes even when at low idle.

A reference to one of the performance enhancing chip manufacturers will reveal that specific torque can increase without a reduction in piston or engine speed. Now what they have actually done one can only surmise, however what is in no doubt is that there will have been no internal alterations.

chipexpress.com/products/iv … oxes/5235/

As for the Scania DC09 the company seems to have got itself muddled, the DC09 I referenced was to the dimensions mentioned, However Scania publicity department promoting their upgraded engine seem to have got their displacement calculations wrong since their dimensions produce a 10 liter engine. This is unlike Iveco whose 10 litre remains the same and their development is called a Cursor 11.

scania.com/uk/en/home/exper … nines.html

[carryfast]

cav551:
That is asking a different question. However increasing the stroke means increasing the crank throw (distance) so therefore adding to the leverage exerted by the crankpin upon the connecting rod, just as the leverage the piston exerts upon the crankpin via the connecting rod is increased. It follows then that when the connecting rod is subjected to tension that increasing the stroke will add to the tension load. In the NA engine the con rod is under tension during the induction stroke since there is no pressure on top of the piston. The turbocharged engine forces air into the cylinder under pressure creating a load upon the piston, however this is only considering what is happening in that particular cylinder. Other things are occurring, the cylinder has a twin. While air is being admitted under pressure to ‘our’ cylinder its twin is firing. The actual pressure inside that twin is greater than the pressure being pumped into our cylinder. Our piston is not being driven down by the incoming air, it is being pulled down by the rotating crankpin which is being driven by another cylinder; our rod is under tension, since the crankpin now have been made with a longer throw the tension has increased.

Disregarding lubrication failure and assembly errors, it is more common for a connecting rod to fail when under tension than when under compression unless an element of abuse has been introduced. Since the rod is constantly subjected to varying force, because the piston is never travelling at a constant velocity or acceleration, whether that force is compressive or tensile, it or the big end bolts will eventually fail from fatigue. Quite often that failure occurs when the engine is not under heavy load sometimes even when at low idle.

A reference to one of the performance enhancing chip manufacturers will reveal that specific torque can increase without a reduction in piston or engine speed. Now what they have actually done one can only surmise, however what is in no doubt is that there will have been no internal alterations.

chipexpress.com/products/iv … oxes/5235/

As for the Scania DC09 the company seems to have got itself muddled, the DC09 I referenced was to the dimensions mentioned, However Scania publicity department promoting their upgraded engine seem to have got their displacement calculations wrong since their dimensions produce a 10 liter engine. This is unlike Iveco whose 10 litre remains the same and their development is called a Cursor 11.

scania.com/uk/en/home/exper … nines.html

Going by the logic that a longer stroke creates more tensile loads on a con rod during the inlet stroke than it reduces compressive shear loads during the power stroke there would have been no reason why the TL12 couldn’t have been boosted to more than the specific torque of the DAF DKS or even Rolls Eagle.Which as we know didn’t happen.While the last thing that ■■■■■■■ would have done would have been to replace the N14 with an engine based on a smaller bore and a longer stroke.Neither the ISX or the MX being known for con rod failures under tension.Probably because assuming an equivalent specific torque output,the inertial/tensile loading that you’re referring to can’t just be magicked away,when it’s still the same amount of force,acting through the crankshaft between the power stroke cylinder to the inlet stroke cylinder,just the same.In addition to the real world fact that the longer stroke motor will generally be turning over at a net less engine and piston speed for the equivalent output.

As for short stroke design the way I was told that’s got more to do with stopping con rod failure of high revving engines at BDC on the power stroke through the resulting inertial loadings,than potential tensile con rod failure on the inlet stroke.

While the idea of a truck diesel is to produce as much specific torque as possible at the lowest possible engine speed without breaking it through the resulting compressive and shear loadings on the piston to crank component chain.Which explains the short stroke TL12’s hopeless specific torque limitations.

As for the Cursor 11 v 10 the former is 128 mm x 144 mm while the latter was 125 x 140.Although admittedly both the exception which proves the rule with the engineering required to do it and why being anyone’s guess.

While the question of both the Marathon and the T45 both being deliberately crippled,to the advantage of the foreign competition for political reasons,is relevant to the topic.

[railstaff]

Carryfast:

gingerfold:
Most of the recent arguments and counter arguments have been completely irrelevant to the subject of the thread, which is not uncommon when CF gets technical. However even my non-technical and non-mathematical brain got Railstaff’s example of engine stroke relative to piston speed, and I do know from past conversations with AEC engineers that piston speed was always an important influence in their designs and calculations.

A formula for piston speed calculation freely available on the internet is: -

Piston Speed = stroke length x rpm divided by 6

Therefore the TL12 stroke of 5.59 inches x say, 1,500 rpm = 8,385 divide by 6 = 1,397.5 ft per minute

Taking a 6" stroke design, then 6 x 1,500 rpm = 9,000 divide by 6 = 1,500 ft per minute

So, the longer the stroke the higher the piston speed at any identical rp

Carryfast, I think that you owe Railstaff an apology because you have to take identical engine rpm. The TL12 was not driven at max rpm all the time, any more than the ■■■■■■■ or RR, or any other engine you care to mention. As a former driver you should know that.

Why would we ‘have’ to take identical engine speed when what matters is the engine speed relative to the comparable power output.IE you’ll have to rev the nuts off the TL 12 to get the equivalent ‘power’ output of the ■■■■■■■■

So the shorter the stroke the ‘higher’ the piston speed at any identical ‘power output’.

On that note remind us what was the power output of the TL12 at 1500 rpm v that of the ■■■■■■■ 335’s 265 hp let alone the 350’s ?.At that power output the TL12 will be revving closer to 2,000 rpm if not more.While if we’re happy with just the TL12’s output at 1,500 rpm then the ■■■■■■■ will be revving at far less than 1,500 rpm. In which case as a former ‘driver’ I know that the engine which can climb hills faster at a lower engine speed is the superior one.

Which is why railstaff had to selectively use a bs comparison of unrealistic identical idle rpm to make the figures work in favour of the TL12 and its why the ■■■■■■■ N14 was still in production in the 21’st century and the TL12 was all too late dropped in the early 1980’s.

Seeing as though were debating about torque and not meaningless hp.Does the TL12 not make its full 800lbs ft at 1300rpm,just a shade behind a 290 855?Can we please keep things in perspective.
The fact of the matter is the TL12 done a perfectly acceptable job back in the day.Simple.

[carryfast]

railstaff:
Seeing as though were debating about torque and not meaningless hp.Does the TL12 not make its full 800lbs ft at 1300rpm,just a shade behind a 290 855?Can we please keep things in perspective.
The fact of the matter is the TL12 done a perfectly acceptable job back in the day.Simple.

Does it matter when for the purposes of that comparison even the small cam 335 is already putting out 900 lb/ft at 1,300 rpm let alone the 350.While in the case of the Marathon the TL 12’s max torque only seems to have been 780 lb/ft anyway ?.IE it was never going to scare DAF.Unlike putting a 350 then a 320 big cam under an SA 400 type cab would have done.Thereby saving all the development and production costs of Marathon 1 and 2 and the T45 Roadtrain.

Probably as I’ve said because neither the Marathon nor the T45 were ever meant to put DAF out of the frame in the UK market as opposed to helping them.

[zb_anorak]

railstaff:
Seeing as though were debating about torque and not meaningless hp.Does the TL12 not make its full 800lbs ft at 1300rpm,just a shade behind a 290 855?Can we please keep things in perspective.
The fact of the matter is the TL12 done a perfectly acceptable job back in the day.Simple.

The TL12’s early 1970s reputation for speed is explained here. It was approximately as powerful as a 14 litre ■■■■■■■■ at any engine speed.

Regarding the Marathon’s bad ride, was this completely cured on the Marathon2? I doubt it, given the slating the Roadtrain got, for precisely the same failing.

[carryfast]

[zb]
anorak:
The TL12’s early 1970s reputation for speed is explained here. It was approximately as powerful as a 14 litre ■■■■■■■■ at any engine speed.

Going by the figures it was more ‘approximately as powerful’ as a 240 Gardner than a 14 litre 335, let alone 350,■■■■■■■■■■■ guess all the rest was blind reference to and belief in dodgy road test results.

[railstaff]

[zb]
anorak:

railstaff:
Seeing as though were debating about torque and not meaningless hp.Does the TL12 not make its full 800lbs ft at 1300rpm,just a shade behind a 290 855?Can we please keep things in perspective.
The fact of the matter is the TL12 done a perfectly acceptable job back in the day.Simple.

The TL12’s early 1970s reputation for speed is explained here. It was approximately as powerful as a 14 litre ■■■■■■■■ at any engine speed.

Regarding the Marathon’s bad ride, was this completely cured on the Marathon2? I doubt it, given the slating the Roadtrain got, for precisely the same failing.

And not forgetting better on fuel economy than the SC855,one of the two reasons ■■■■■■■ went big cam.

[carryfast]

railstaff:
And not forgetting better on fuel economy than the SC855,one of the two reasons ■■■■■■■ went big cam.

Firstly going by the examples of the results of the Euro ‘tests’ it would be fair to say that there are too many anomalies to trust the results to the point of in many cases being unbelievably pessimistic in the case of the opposition in terms of explaining journey times v fuel consumption v the available torque.

What is clear is that even with the most optimistic view of the TL12 powered Marathon it was still only around just 0.5 mpg ahead,of the most pessimistic view of the ■■■■■■■ SC 355 in the Transcon,overall.

It’s my guess that,as in the case of the 335 version,let alone the Volvo F12,both the average speed comparisons and fuel consumption figures,in favour of the TL12 can’t be relied on.With the opposition’s figures being damaged by whatever means ( excessive unnecessary use of low gears and revs ? ) so as to provide the required unbelievable figures and credibility for the TL12,bearing in mind the torque advantage held by all three of those competitors.On that note it’s my bet that the NTC 355 powered Transcon and the Volvo F12 would have been expected to beat the TL12 both in terms of journey times and fuel consumption.With the figures provided regarding the F12 v TL12 at least being totally unbelievable.

While in the real world the SC 355 as fitted in the Transcon would have made a perfectly good competitor to the DAF DKS until the BC 320 etc arrived on the scene in good time and not allowing progress to be hindered by ‘type approval’ ‘issues’ thereby also being in place to sort out the F12 too.That obviously not being Leyland’s agenda as proved by 1987.

[gingerfold]

This is my last post on comparative engine data and i will go back to the launch date of the Marathon in 1973 and concentrate purely on the standard engine fitted i.e. TL12, and the options that became available a few months later, that is the ■■■■■■■ NHC 250, and the RR E220 Mk. 3. The ■■■■■■■ NTC 335 became listed in 1976. No other engine type is relevant to the discussion as the topic is purely and simply about the 1970s.

TL12, 12.47 litres 273 bhp @ 2,200 rpm. 780 lbs ft @ 1,300 rpm

■■■■■■■ NHC 250, 14.00 litres, 228 bhp @ 2,100 rpm. 648 lbs ft @ 1,400 rpm

RR E220 Mk. 3, 12.17 litres, 209 bhp @ 2,100 rpm. 598 lbs ft @ 1,400 rpm

■■■■■■■ NTC 335, 14.00 litres, 328 bhp @ 2,100 rpm, 1,000 lbs ft @ 1,300 rpm

So, all four engines are to within 100 rpm of each other at max. bhp, presumably all of them fitting CF’s description of them as high revving “screamers”.

And if you care to do the maths then at whatever rpm value you care to choose the TL12 always has the lowest piston speed.

To keep banging on about engine developments that were 15, 20, 30 years in the future in 1973 is totally irrelevant, futile, and meaningless.

[carryfast]

gingerfold:
This is my last post on comparative engine data and i will go back to the launch date of the Marathon in 1973 and concentrate purely on the standard engine fitted i.e. TL12, and the options that became available a few months later, that is the ■■■■■■■ NHC 250, and the RR E220 Mk. 3. The ■■■■■■■ NTC 335 became listed in 1976. No other engine type is relevant to the discussion as the topic is purely and simply about the 1970s.

TL12, 12.47 litres 273 bhp @ 2,200 rpm. 780 lbs ft @ 1,300 rpm

■■■■■■■ NHC 250, 14.00 litres, 228 bhp @ 2,100 rpm. 648 lbs ft @ 1,400 rpm

RR E220 Mk. 3, 12.17 litres, 209 bhp @ 2,100 rpm. 598 lbs ft @ 1,400 rpm

■■■■■■■ NTC 335, 14.00 litres, 328 bhp @ 2,100 rpm, 1,000 lbs ft @ 1,300 rpm

So, all four engines are to within 100 rpm of each other at max. bhp, presumably all of them fitting CF’s description of them as high revving “screamers”.

And if you care to do the maths then at whatever rpm value you care to choose the TL12 always has the lowest piston speed.

To keep banging on about engine developments that were 15, 20, 30 years in the future in 1973 is totally irrelevant, futile, and meaningless.

The SC ■■■■■■■ 335 and 350 were both ‘available’ from at least 1972.The BG ‘range’ was ‘available’ from 1976.All before and/or within the Marathon’s production life.The turbocharged Rolls Eagle also being available within that period.The belated adoption of the latest technology and full use of the available output levels in that regard is one of the issues which I’ve explained as being part of the obvious plan to run down the Brit truck manufacturing sector and to sell out to the foreign competition.In large part owing to conveniently ( for the Euro imports ) applied ‘type approval’ obstacles.

As for you keeping on about pointless engine speed comparisons.Yes the peak power and torque ‘points’ are more or less in the same points of the rev range.But the equivalent ‘output figures’ are what matters.In which case how can you possibly compare 780 lb/ft with over 900 lb/ft and ‘over’ 1,000 lb/ft in the case of the 350 SC and why are you making silly comparisons with NA examples when we’re comparing turbocharged engines in all cases.When the fact is the ■■■■■■■ at least could provide more power,for less engine and piston speed,than the TL12,at any point in its rev range.

IE the same 280 hp at 1,600 rpm as opposed to 2,200 rpm.The fact that it could also provide 328 hp at a slightly higher piston speed than the TL12’s at peak power was a bonus.But which would obviously have rarely,if ever,have been used if the driver wanted to keep is job bearing in mind the finer points of the SFC curve and pointless wear and tear to the engine.Just as in the case of the TL12’s pathetic 280 hp.Those figures also being the smoking gun which proves the absolute bs contained in those road test results suggesting that the TL12 could not only outrun far more powerful machinery but also do it for less fuel consumption.

[zb_anorak]

Carryfast:
.The BG ‘range’ was ‘available’ from 1976.

It was only available in GB chassis from 1978. We’ve already been down this route, and I’m not going to dig out the same stuff twice for you. The Marathon 2 was launched in 1977 or '78, and was available with the E290 at some stage.

[carryfast]

[zb]
anorak:

Carryfast:
.The BG ‘range’ was ‘available’ from 1976.

It was only available in GB chassis from 1978. We’ve already been down this route, and I’m not going to dig out the same stuff twice for you. The Marathon 2 was launched in 1977 or '78, and was available with the E290 at some stage.

The fact that the Brits were adopting available technology unnecessarily late and when they did limited,to the advantage of the foreign competition,is my point.In this case obviously allowing DAF and Volvo for two examples to get an early foothold with superior products.Although you obviously won’t accept that the DAF 2800 was a better truck than a TL12,let alone 250 NA ■■■■■■■■■■■■■■■ Marathon.As opposed to an SA 400 type cab with a ■■■■■■■ 350 under it.

Oh wait we’re supposed to believe that it would have been slower and thirstier,with a supposed more fragile engine,with 280 hp + produced at around 1,500 rpm,than the TL12 producing 280 hp max at 2,200 rpm.If not the lie that a 335 let alone 350 ■■■■■■■ didn’t even exist.

Who were they trying to kid and why.On that note remind us what the TL 12’s piston speed was at 2,200 rpm and its SFC at peak power v the ■■■■■■■■ at 1,600 rpm and therefore how could the thing possibly have provided a better overall journey time,at a better overall fuel consumption,at a lower piston speed,than a ■■■■■■■ 335 let alone 350.

[erf-ngc-european]

No need ^^^ to get too carried away with the ■■■■■■■ 350 of that period as it was only a SC 335 with an after-cooler - ie a modification. Robert

[carryfast]

ERF-NGC-European:
No need ^^^ to get too carried away with the ■■■■■■■ 350 of that period as it was only a SC 335 with an after-cooler - ie a modification. Robert

To be fair it seems to have been the basis of the ‘355’ specced in the Transcon providing a not inconsiderable boost in specific torque over the 335.Which then leaves that question how could something producing more than the TL12’s peak power output,within the optimum point of its SFC curve,possibly have been slower and thirstier,than the TL12 powered Marathon putting out less power in the worst part of its SFC curve ?.

IE the TL12 is going to need some miraculous SFC figures at 2,200 rpm,to beat either the 335 or 350 ■■■■■■■ or F12 all running at around 280 + hp still within the optimum points of their SFC curves,let alone the even bigger miracle of then also returning a better journey time with less power.Such a result would have had to have taken some creative driving methods to sabotage the Volvo’s and ■■■■■■■■ fuel consumption and journey time figures.