newmercman:
The L12 was an offering purely for the cheap low powered lorry that the Oil Companies desired, it also went in some other chassis for the same reasons, it was a Guy for the 1980s, a lorry that was meant to go from point A to point B and nothing else. As long as it met the HP/ton standards for 32ton nobody involved in the design, build or purchase of such a lorry gave a toss about anything else, there had been a significant demand for such a lorry for many years, in the case of Gardner powered versions people were prepared to pay a premium for a lorry that couldn’t pull the skin off a rice pudding, so why not pull the turbo off of an engine you already have the production line set up for and fulfil that desire with zero investment?
Also the TL12, was it designed or marketed to be a rival for a 2800 Daf or a Volvo F12? The answers are no and no, so what the hell have they got to do with anything?
This is exactly the point. In 1968 when Leyland were introducing the 500 engine and presumably had it in design for some two three years before, there was no reasonably predictable demand for for an engine producing in excess of 400bhp it would be in excess of some 30 years before this power output became required. Look back the same amount of time and we are talking pre war - an era when less than 100 bhp was the norm and much over that figure was the exception, the idea of requiring 200bhp would have been a pipe dream in 1938.
In 1968 for the 500 and still in 1978 for the 12.4L engine, Leyland was looking to meet mainly current demand from its loyal customers, and a reasonably predictable future demand from those same and a crystal ball supposition for what might be required in the next 10 to possibly 15 years time. They were led by the development of the UK Motorway network and speculative predictions regarding any increase in gross vehicle weights.
Above all they were concerned with what they could sell, produce themselves and not be reliant upon external component suppliers. As they progressed through these ten years (68-78) they had observed the ■■■■■■■ Vee engine debacle, knowing from their own experience the financial cost that multiple failures in service and product withdrawal can bring. They were anxious not to be put in the position of meeting warranty claims actually relating to a supplier’s product. They remained averse to proprietary engines while allowing their more or less specialist Scammell partner to provide feedback relating to Rolls Royce and Detroit and Guy with feedback from ■■■■■■■ and Gardner as well. They had watched the rise in market share of ■■■■■■■ inline engine at the expense of Gardner elsewhere and within Guy and were very glad to be free of the supply problems that any involvement with the latter company would have meant for their own production. They had also witnessed the continuing refusal of the very conservative home market to accept the thirsty Detroit and noticed similar resistance in some quarters to the inline ■■■■■■■ for the same reason.
It had been an extremely frustrating period trying to forsee power unit requirements for the future, they had had legal issues with patents, around a vee engine design, which they considered had contributed to their own vee’s demise and withdrawal. They had run into trouble trying to uprate their 11 litre engine by turbocharging. With a continuing somewhat strained relationship with their AEC partner they had decided that it was to be a Leyland clean-sheet 12 litre design to take them forward, but the V8 episode had left them in even more of a hurry. Meanwhile as a sop to AEC they would let them investigate uprating their 8.2 litre design for medium and medium - heavy weight vehicles. A realisation of the cooling requirements for their new baby under their existing cab caused a drastic rethink. They would cancel the 8.2 litre AEC upgrade and downsize their project to make it fit.
This left a somewhat disgruntled partner and a problem with how to replace their largest engine. A look at the overwhelmingly important aspect what was selling in their portfolio showed that their Freightline Beaver was outsold by AEC’s Mandator. So considering their view was that the Beaver’s engine upgrade had been unsuccessful and not worth persuing, then they would concentrate on the large AEC unit which seemed good to take them as far into the future as they could see. There was one manufacturer they had been observing from afar whose ideas might be worthy of possible consideration for their own experimentation - Mack and the concept of turbocharger tuning and torque rise. Their experimentation with the fixed head 500 engine had provided valuable knowledge, this would be used in the development of the TL12.
With the closure of AEC production in 1978 Leyland found GUY customers still loyal to an outdated product cab, but one which had offered proprietary engines. This provided an opportunity to market an updated Marathon utilising much that had been GUY, the option proved popular sowing the seeds for a potential abandonment of the TL12. Meanwhile Leyland were stuck with trying to develop and iron out production quality issue with the 500 series engine which they eventually more or less achieved with the final version, only to be taken over by DAF with the immediate substitution of that company’s 8.25 litre engine into the T45 cabbed chassis.
