How much power did a Leyland TL engine have ?

[Justin Smith]

Does anyone know how much power the Leyland TL11 engine had ?
I believe it was a 6cylinder 11.1 litre turbocharged unit, but the power specs I keep finding are all over the place !
From a quoted 170bhp at 1850rpm (for a 1978 Leyland Titan bus), through 205bhp at 1950rpm (for a 1980 railbus), to 210bhp at 1850rpm (for a 1987 Leyland Lynx bus).
Or are they all correct and the engine was just continually upgraded through its life ? If so one wonders why Leyland kept the same name !

 

[randyrippley]

It's not a definitive statement, but this post regarding the end of production of the TL11 may answer as it indicates there were various power ratings

TL11 to be dropped | 28th February 1987 | The Commercial Motor Archive

'TL11 to be dropped' first printed in the 28th February 1987 issue of Commercial Motor

archive.commercialmotor.com

The Tiger is the model which will be most seriously affected by the deletion of the TL11, which is currently rated at between 127 to 194kW for PSV applications.

 

[GusB]

Does anyone know how much power the Leyland TL11 engine had ?
I believe it was a 6cylinder 11.1 litre turbocharged unit, but the power specs I keep finding are all over the place !
From a quoted 170bhp at 1850rpm (for a 1978 Leyland Titan bus), through 205bhp at 1950rpm (for a 1980 railbus), to 210bhp at 1850rpm (for a 1987 Leyland Lynx bus).
Or are they all correct and the engine was just continually upgraded through its life ? If so one wonders why Leyland kept the same name !

The engine still had the same capacity regardless of power output, hence the TL11 name remaining the same. For the Leyland Tiger, outputs were initially 218 and 245 bhp, with the de-rated (170bhp, I think) option added later, along with a 260bhp version.

Presumably this was achieved by tweaking the turbocharger, although engine tuning definitely isn't my area of expertise!

 

[ac6000cw]

Or are they all correct and the engine was just continually upgraded through its life ? If so one wonders why Leyland kept the same name !

It's very common for engines to be slowly uprated over their production lifetime, and to some extent engine manufacturers allow for that when doing the original base design. Eventually the 'development life' of the engine is reached, and it's time for a new design (if it's worthwhile in business terms).

If an engine has been in production for a long time, especially older designs that started out as non-turbocharged engines and were later turbocharged, the power output of the final versions can be much higher than the earliest version. As an example of engine development, the 148.6 litre EMD 567 series V16 diesel started out in 1938 as a non-turbo engine at 1350hp (@800rpm) and the final turbocharged version produced 2500hp (@900rpm) 25 years later. Having reached the end of its development life it was replaced with the 13% larger capacity 645 series design in 1965, which as a turbocharged V16 went from 3000hp to 3600hp over 14 years. That in turn was replaced by the 10% larger capacity 710 series in 1983, which as a turbocharged V16 went from 3800hp to 4300hp over 12 years (and eventually 4500hp).

 

[Justin Smith]

Surely it'd have been much simpler if Leyland had adopted Gardner's nomenclature and slightly altered the name as the engine was uprated ? ! ?
Like this

Gardner 6LX - 10.75 litres - 150bhp at 1700rpm - 1957 on - 13.9hp/L - Still in production as 6HLX in 1968 ?, "derated versions available"
Gardner 6LXB - 10.75 litres - 180bhp at 1850rpm - 1966 on - 16.7hp/L - As fitted to Sheffield Transport [ > SYPTE] Daimler Fleetlines
Gardner 6LXC - 10.75 litres - 195bhp at ????rpm - Late 1970s on - 18.1hp/L
Gardner 6LXCT - 10.75 litres - 230hp at ????rpm - ?? - 21.3hp/L - Turbo variant, 6LX production ceased in 1992.

 

[ac6000cw]

The TL11 may have been available to order in several different ratings in its later years, this page on a Leyland truck - https://motor-car.net/leyland/item/22050-leyland-constructor - mentions 181, 209 and 260 hp versions, but the versions may only have been differentiated by Leyland product/order codes. Just because Gardner did it their way is no reason for a different company to use a similar naming system.

Presumably this was achieved by tweaking the turbocharger, although engine tuning definitely isn't my area of expertise!

Maybe by different settings for the injection system (to limit the maximum amount of fuel injected) or governor (to limit maximum rpm)?

 

[Justin Smith]

The TL11 may have been available to order in several different ratings in its later years, this page on a Leyland truck - https://motor-car.net/leyland/item/22050-leyland-constructor - mentions 181, 209 and 260 hp versions, but the versions may only have been differentiated by Leyland product/order codes. Just because Gardner did it their way is no reason for a different company to use a similar naming system.


Maybe by different settings for the injection system (to limit the maximum amount of fuel injected) or governor (to limit maximum rpm)?

Interesting, and that Leyland Constructor / T45 was a good looking truck !

>> Gardner did it their way is no reason for a different company to use a similar naming system.<<

No, but it'd certainly make it easier to work out how powerful an engine is !
I do think it odd that there are so many different power ratings of the "same" engine, has any other manufacturer done something similar ?

 

[ac6000cw]

I do think it odd that there are so many different power ratings of the "same" engine, has any other manufacturer done something similar ?

I think it's pretty common, especially for engines used in a wide range of sectors e.g. truck, bus, rail, construction machinery, mining, power generation, pumping etc.

Just picking the current version of the Cummins L9 truck and bus engine - https://www.cummins.com/engines/l9-2024 - it comes in eight different ratings from 260 to 380 hp:



...and the larger X12 'heavy duty' truck engine has an even longer list of ratings between 350 and 500 hp - https://www.cummins.com/engines/x12-2024?v=4641&application=Heavy-Duty Truck

 

[randyrippley]

Often though the power setting is simply just down to the state of tune of the individual engine, nothing to do with how it was built.......same engine, different tuning for different buses and routes.

I can remember being told by drivers at Lancaster City Transport back during the early days of deregulation when they were competing with Ribble on routes to Preston/Blackpool/Southport how during layovers at Preston bus station they'd surreptitiously get Preston bus fitters to retune their Altanteans for more power........Something that was kept quiet from the LCT management who presumably were more interested in fuel consumption than driveability.

 

[Justin Smith]

I think it's pretty common, especially for engines used in a wide range of sectors e.g. truck, bus, rail, construction machinery, mining, power generation, pumping etc.

Just picking the current version of the Cummins L9 truck and bus engine - https://www.cummins.com/engines/l9-2024 - it comes in eight different ratings from 260 to 380 hp:

View attachment 146027

...and the larger X12 'heavy duty' truck engine has an even longer list of ratings between 350 and 500 hp - https://www.cummins.com/engines/x12-2024?v=4641&application=Heavy-Duty Truck

Interesting.
I can understand why they do it like that, for example, I assume, L9 260 is the L9 base engine at 260hp ?

 

[ac6000cw]

I assume, L9 260 is the L9 base engine at 260hp ?

I assume that too.

If you don't need the extra power, the lower-rated versions should be cheaper to run and last longer between overhauls as they are less stressed.

 

[Justin Smith]

I was looking through some info we got from the Commercial Vehicle Museum (in Leyland) - great place to visit BTW - and in there they have an immaculately restored Leyland Buffalo 2, apparently the last one ever made. Of possible relevance for this thread it is reported as having a Leyland TL11A engine (i.e. it has an additional type letter) of 11.1 litres and with 209bhp at 2200rpm.