V8 TURBO TIPPEI
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CHALLENGER
Perkins' turbocharged TV8 diesel, driving through a Fuller rangechange gearbox, gives Renault's Dodge G24 tipper lively acceleration and fair fuel economy too . . .
)ODGE re-entered the sixwheeler market two years ago after an absence of 10 years. The v model was offered with a Perkins urally aspirated V8.540 engine rated 127kW (170hp).
;ince it acquired Dodge, Renault ick Industries has worked towards mgthening the make's position in the ':. market by offering a more nprehensive range, and at last year's ■tor Show new developments were .inised.
Jur test vehicle this week is the mination of those plans and is Nered by a turbocharged version of Perkins V8 diesel engine on the
-8. It is an option on the Dodge G24 I gives a power-to-weight ratio of
re than 9.5hp/ton.
Aore than 1.5 million vehicles rldwide (62,000 are in the UK) have kins engines. Their outputs range m 41 to 194kW (55 to 260hp) and lude four, six and eight-cylinder ;ine groups. The largest one is a V8. gines in this range, it is claimed, can over 600,000km (373,000 miles) 'ore needing a major overhaul.
n spite of the considerable increase in mer and torque provided by turbocharging, the Dodge G24 retains the Fuller RI' 6609 range-change constant-mesh gearbox used with the naturally aspirated version. Also kept is the original drive line incorporating Eaton axles with cross axle differential lock and inter axle differential lock. But Allison MT 653 five-speed automatic transmission is offered as a special option. With the manual box largerdiameter twin clutch plates have been introduced to ensure the necessary positive drive between engine and gearbox. Several years ago Dodge models reverted to mechanical clutch operation using the Bowdenflex cable. This consists of a low-friction linear ball bearing enclosed within a flexible outer casing.
Over two years ago Renault began tests at Dunstable of the Norde rubber suspension. Today it is offered as a lighter alternative to semi-elliptic leaf springs, saving 159kg in payloard capacity.
The chassis frame is of conventional bolted and riveted constriction. It has tlitched longitudinal channel side rails linked with top-hat crossmembers, on to which the optional Dodge bighline cab is mounted. This cab includes a fully adjustable driver's suspension seat with blue brushed nylon cloth upholstery and blue trim.
Our test vehicle had die shorter of the two -wheelbases — 4.3m and 5.1m (14ft lin and 16ft 9in). The turbocharged V8 engine gives a welcome increase in power to the Dodge 24-tormer, but still falls well short of what is offered by some of the current competition in the weight range. None of the more powerful machines; however, are able to match the G24 on a body/payload of 18.09 tonnes as tested.
Over CM's exacting on/off-road tipper route the power formula paid off, giving the second best fuel return ever achieved by a six-wheeler — 42.35 lit/100km (6.67mpg) at a high average speed of 39.48km/h (24.53mph). This must have been assisted by the higher speed allowed over the only short section of dual carriageway included in each of the 20km circuits. Off setting this small advantage were roadworks at two sites which undoubtedly slowed down the journey overall.
PERFORMANCE The smooth running TV8.540 and easy Fuller range-change gearbox produced a lively acceleration. Most of the driving could be done with engine speeds confined between 1,500 and 2,000rpm, coinciding with maximum torque. Alternatively, when required, the engine pulled willingly down to about 1,200rpm and up to 2,500rpin. Starting from rest on the flat nude some of the ,gears superfluous; only second and fourth were used for the quickest getaway.
Pulling away on a hill was quite different. At the Motor Industry Research Association test track at Nuneaton I needed the extra low 10.61 crawler. This gave an easy restart on a 1 in 5 hill. Full depression of the clutch pedal activates a clutch brake, so for clean changes on the move this is to be avoided.
Norde rubber suspension contributes to a very firm but level ride. Though it is initially more expensive than the standard steel springs, Dodge engineers are adamant that benefits in servicing costs will give an early payback. On the rough off-road track the vehicles suspension did little for driver comfort and it was there that I appreciated the extra luxury of the Cox suspension seat.
CO COMFORT Cab entry, with two steps placed ahead of the steering axle, is easy. The Hi-line cab, although compact, allows relatively unrestricted cross-cab access.
A dual passenger seat provided as a regular production option must be tilted to gain access to the oil filler and dip stick. For other less frequent checks the cab tilts forward through 45 degrees.
Instrumentation and the general standard of trim, incorporating a heavy rubber floor cover, are basic but adequate. The rev counter very much an afterthought might be placed higher within the binnacle to the driver's advantage. General visibility, with the deep corner windows, is excellent.
Power assistance makes light work of the steering, which I found to be particularly precise. Commonly on sixwheelers, the rear wheels have an overriding effect and exert a degree of understeer on the front axle, but there was no such influence here.
There is some body roll, but the suspension seems to give so far and no further.
Considering that the engine is located close beneath the cab floor pan, in-cab noise recorded at a maximum of 77dB (A) on full chat in seventh geat-=.is very good.
GRAKING Brake tests, carried out on a hot dry track, produced smooth controlled stops under full pedal application. Good overall decelerations without wheel-lock were accompanied by consistent peak readings of 0.7g. But during the test a delay in brake release developed. This was quickly diagnosed as a restriction in the foot valve exhaust. The plastic pipe had ridden up and blocked Back at Dunstable two days later, engineers were already re-tooling to cut• the vent pipe at an angle so that on future vehicles the problem should not recur.
An exhaust brake, available with many other models 03 the Dodge Commando range, is not fitted with the TV8.540 engine.
OFF ROAD
At this time of year it is difficult to find a good muddy site to try out offroad traction. What there was could be driven through without engaging the diff locks. Ground clearance below the rear suspension balance beam looks shallow, but is not much less than the clearance under the differential.
An extra not normally included was the Telehoist automatic grease lube system. Whatever may be thought of the messy deposits, the system certainly prevents dirt and grit entering the bushes.
SUMMARY' While there may be a large number of Perkins engines in use in the UK they are not everybody's first choice for heavier vehicles. The TV8.540, however, performs very smoothly, giving the 24-ton G24 a high power-toweight ratio.
A relatively wide rev band at near maximum torque assists economical driving without detriment to journey times.
Rubber suspension gives a firm ride with little roll, but has sufficient crossaxle and fore and aft articulation to keep the drive wheels firmly on the ground in most off-road conditions likely to be encountered.
Having only recently been re-entered in the 24-ton market, the Dodge marque will take some time to become reestablished there. The Perkins engine, in spite of its qualities, may also slow its progress because conservative tipper operators, who are accustomed to a big straight-six engine, will be deterred by the unknown maintenance aspects of a V unit. Moreover, Perkins does not have a strong presence in the heavyweight sector of the market. WORKSHOP TIME
Replace clutch centreplate 3 Reline brakes front two --,
—
rear four 5 Remove and refit ein.,xiiie (straight swap, not including-ancillaries) 18
Remove and replace gearbox 5 Remove and relit eight injectors 1 Remove and relit steering box 1 Change head gaskets 11
PRICES Manufacturer's parts prices (retail excluding vat)
Windscreen (front,laminated, clear,
excluding fitting) 1 complete set brake linings (linings only, not shoes) 1 door(untrimmed) 1 radiator (exchange price) 1 front spring 1 rear suspension rubber 1 head gasket set 1 half-shaft