E IGHTEEN months ago Leyland raised the power and torque ratings
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of its turbocharged 11.1litre diesel, finally overcoming an apparent reluctance to join the manufacturing fraternity offering engines of 186kW (250hp) and above for 32.5 tonnes gross combination weight application.
As a result, the heavier end of the Cruiser range now has a choice of engines with 167 and 194kW(224 and 246hp) net outputs for use in artics of 28 to 35 tonnes gross weight and in drawbars too.
For this week's roadtest we have chosen the higher-powered 16.26 tractive unit, which since the 1984 Birmingham motor show has topped the Cruiser range — usurping the 16.23 which has now lost its 35-tonne plating.
Leyland's presence in the market for tractive units over 28 tonnes GCW is far weaker than in most other commercial vehicle sectors, although last year it doubled its tractive unit sales to 558 to give it a 10 per cent share. This put it just ahead of Mercedes-Benz, but well behind Volvo's 18.8 per cent, pars 14.1 per cent and Scania's 13.5 per cent.
Demand for Cruisers this year has focused on higher-powered versions and Leyland is confident that this trend will continue.
According to the company, the extra power of its 11.1-litre engine has been achieved simply by replacing the earlier CAV Majormee fitel injection pump with a Friedmann and Meyer unit. Thi move obviously has commercial advantages as Leyland has been using the Austrian-made equipment for over 12 years on the 400 series engines in th, Freighter, the TL11A, B and C engines and in its buses and coaches.
Also changed is the Holsett H2C turbocharger, which has been replaced by a Schwitzer. This is said to be more compatible with the new pump. And to help reduce the higher temperatures resulting from the increasi in power, Leyland now carries out an extra treatment of the cylinder heads. Any remaining sand residues from Casting are removed by Colene salt washing. This is necessary only on TL11C engines.
PERFORMANCE
Whatever the reasons behind the changes, they have had the desired effects, increasing maximum net power by 9.8 per cent and torque by 7.4 per cent, both at the original peak revs of 1,800 and at 1,3(X) respectively.
Our test vehicle, a demonstrator wit' barely 14,000km on the clock, and coupled to our fully-laden box van semi-trailer, certainly felt very quick an vigorous, both on the test track and oui on the roads.
Up to 80km/h it is a good deal quicker than Iveco's 165.24 and fairly comparable with the 3224 Cargo and Daf 2500. But its times through the gears show little improvement in performance over the Cruiser we tested two years ago. — a 16.23 with the I67kW TLIIB engine and plated at 32.52 tonnes (CM, December 17, 1983). That vehicle turned in an extremely well balanced performance around our Scottish route. It returned 38.86 • liti100km (7.27mpg) at an average speed of 65.38km/h (40.63mph) — quite a good result considering it was run at the earlier restrictive speed limits of 65km/h (40 mph) on dual carriageways.
Like the previous test, this week's trial was carried out during wintry weather. But whereas two years ago we had a little more than frost to cope with, the 16.26 had to contend with stronger, more variable winds and snow and slush-covered roads.
From Edinburgh southwards to Neville's Cross on the A167 our progress was hindered, with Carter Bar's southern side particularly hazardous. Although the snow plough had been through earlier it still .needed carefully controlled descent in 8th gear._
Strong side winds persisted for much. of the third day and, although we achieved good journey times, this was at the expense of fuel economy, as the results on page 56 bear out.
As expected, the 16.26's overall average speed of 67.23km/h (41.78mPh) was much higher than that of the 16.23,. although fuel consumption was worse, at 40.24 lit/100km (7.02mpg). its speed was identical to that of the Ford Cargo 3224 which set new fuel economy standards at 32.52 tonnes of 34.14 lit/1(X)km (8.04mpg) (CM, March 23, 1985).
That was powered by the Cummins LT10-250, an engine which Leyland already offers with the Constructor 2 (8x4) alongside its own TL11C, Gardner's 6LXCT and Perkins' (nee Rolls-Royce) 265L3. Although the LT10 is also a regular production option on Roadtrain models Leyland has no intention of offering it with the Cruiser range, sticking instead with its own Preston-built T1. engines.
DRIVELINE Leyland specifies the 10-speed Spicer SST 8010 as standard behind the TL11 C. with the rime-speed Fuller RTX7609 optional. An unchanged final drive ratio of 4.778:1 gives it a geared top speed of 110km/h (68 mph).
The ratios are well spaced out, with each gear separated by about 450 rpm. This means that on acceleration gears can be changed at about 1,650rpm, and when the next gear is selected the engine will pull strongly away at 1,200 rpm.
Driving away from rest on level ground can be done quite easily using 3rd, 5th, 7th and then consecutive gears. On gradients, 2nd and 4th are necessary.
Pulling maximum motorway speeds in top gear has the revs up at 1,800, while dual carriageway work at 80kni/h (50mph) allows the engine speed to sit in nicely at about 1,500rpm, where its torque will take care of most rolling inclines.
Running on A-roads in top gear is only possible on the flat or downhill. At the first hint of a slope it is best to split to 9th where the engine speed rises to about 1,500rpm.
With familiarity, many drivers revert to the rev counter to check road speed. Colour coding of the dial gives an instant indication to the most economic use of the engine's torque. Why Leyland does not add coloured segments is a mystery, as is why no exhaust brake is offered either as standard or as an option.
BRAKINC There are many parts of our test route where an exhaust brake can usefully check the vehicle's speed and several places where it is sometimes necessary to use it in lower gears, helped occasionally by the service brakes.
As well as being a safety feature, al exhaust brake liberally used will exto the life of brake linings.
Not that the Cruiser's brakes were lacking; full pressure stops at 65km/h (40mph) on a track that was still dryi out hauled the combination up straigl with hardly a trace of wheel locking.'
In normal conditions the brake ped needs only a moderate pressure and it operates with a firm progressive feel.
This is in contrast to the clutch. peci which is spring and hydraulically operated. It seems quite heavy compa with others and would probably be tiring on urban deliveries.
The accelerator pedal, too, is stiff a high engine speeds. This became mor apparent as the speed increased on motorways and hill climbs, and was possibly owing to the new pump's mechanical all-speed governor with boost control.
CAB COMFORT These criticisms apart, the T45 cab is well designed workplace. It gives a hi level of comfort without being lavish Its single-berth accommodation is more than adequate for the odd overnight stop, although some form separate heating should be fitted.
The firm and supportive airsuspended Isringhausen seat (standard for the driver) damps out low levels cab bounce and compliments the cab' four-point suspension.
Driving at low speeds in congested areas highlights the effectiveness of th ZF powered steering. It allows the driver to make the best use of the Cruiser's tight turning circle; at 12.7n kerb-to-kerb it is among the best.
Here, the cab's rear quarter windov are most valuable, especially on acute turns. Its large electrically-heated nearside mirror helps too, at least tint: the dirty .spray begins to bake on to it Light rain or frost quickly evaporates, but only a wash gets rid of the road dirt. But this criticism is not confined the Leyland Cruiser.
SUMMARY
Leyland says that its TL11C-powered 16.26 Cruiser is becoming more popular. Certainly, it offers a good le, of performance in all weathers at 32.5 tonnes gross. And at this weight it giN a good payload, handles well and has very comfortable cab.
In spite of seasonal conditions that marred this operational trial it achieve good journey times, but its fuel economy is disappointing. Even with better weather we doubt that it would better that of the 16.23 version.
The 16.26 is 0,000 cheaper than a comparable Scania, but £2,200 more than the Cargo 3224 and Iveco's 165.2 000 above the Daf 2500 and £500 ma than a Mercedes-Benz 16.25.
With such strong competitors in this sector of the market, Leyland's 11.1-lit engine could be more economical.
• by Bryan Jarvis