Aus­tralia’s fastest truckie

He’s hop­ing to top 300km/h in SA dash

Big Rigs - - PROFILE - Brent Dav­i­son

TOUCH­ING 200km/h in a mod­ern sedan is il­le­gal but do-able, run­ning 250km/h in a high-per­for­mance sports or mus­cle car is not too dif­fi­cult and hit­ting 300km/h is a dod­dle in a su­per­car but in a truck? Never. Un­less that truck is Diesel Ar­row, a one-off, land speed record-grab­bing mega-truck built to go ul­tra-fast (and then some) at Dry Lake Rac­ing Aus­tralia’s an­nual Speed­week event on South Aus­tralia’s Lake Gaird­ner salt flats.

In 2010 owner/builder Gavin Man­ning pi­loted Diesel Ar­row to the na­tional Un­lim­ited Class record with a 251km/h (156mph) pass on the Lake Gaird­ner salt – and with plans to take the record north of 300km/h (186mph) next March he is in no hurry to give it up.

The brain­child of the self-taught en­gi­neer and go-fast guy, Diesel Ar­row is based on an early 1990s Ford Cargo con­verted for truck rac­ing. Over the years it has mor­phed into a mon­ster that would look right at home on a Mad Max movie set.

The staunchly up­right Ford cab is land­fill, in its place a low, cen­trally mounted sin­gle-seat cab sit­ting for­ward of the front axle line with the mas­sive 23-litre, six-cylin­der, Cum­mins-based en­gine bolted right be­hind.

That huge, twin-tur­bocharged en­gine, mid-mounted in the chas­sis for op­ti­mum weight bal­ance, de­vel­ops an es­ti­mated 1500-kilo­watts (about 2000 horse­power), enough to push the eight-tonne, 8.0-me­tre long, 2.5-me­tre wide and 1.9-me­tre high rig to a po­ten­tial 340km/h (210 miles per hour) top speed.

Man­ning, Diesel Ar­row’s de­signer, de­vel­op­ment en­gi­neer, builder and test pi­lot, built his Cargo cir­cuit racer for the Aus­tralian Truck Rac­ing Cham­pi­onship in the late 1990s, giv­ing it a space­frame rear end, quick-change dif­fer­en­tial and coil-over sus­pen­sion to help achieve the kind of han­dling needed to com­pen­sate for its lack of sheer grunt against the big­ger outright trucks.

“The level of chas­sis so­phis­ti­ca­tion in Diesel Ar­row comes from its race truck days. It doesn’t need all of that to go fast in a straight line but it was there, so we kept it,” Man­ning said.

The quick-change diff, a sim­ple al­ter­na­tive to swap­ping gear­boxes to achieve ra­tio al­ter­ations is, he says, the big­gest quick-change any­one is ever likely to see.

When truck rac­ing went into de­cline, the first steps were taken to con­vert the Cargo six-shooter into a ballsy bal­lis­tic mis­sile. A 12.7-litre turbo-diesel was bolted-in, a few aero mods made and Diesel Ar­row Mark One headed for the 2005 Dry Lake Rac­ing As­so­ci­a­tion’s Na­tional Speed Tri­als.

“We learned a lot about what we shouldn’t do on that first trip to the salt and when we got home we started all over again, keep­ing the ba­sic chas­sis and pretty much chang­ing ev­ery­thing else,” Man­ning said.

Since then, the sin­gle-seat “aero” cock­pit went on, the 23-litre en­gine re­placed the “small” donk and a sec­ond turbo was added.

The truck sprouted wide aero­dy­namic side­pods to both keep it stable and en­close the coolant tanks for the mul­ti­ple ra­di­a­tors used to cool the en­gine, au­to­matic trans­mis­sion and tur­bocharg­ers.

Tyres from a Boe­ing 737 air­craft were fit­ted up front and 747 rub­ber went on the back, filled with ni­tro­gen and pres­surised to 200psi to man­age both the speed and heat that would de­stroy con­ven­tional tyres. Aero­dy­nam­ics, in­clud­ing a full un­der­tray and side­pod rear end­plate ex­ten­sions, were used to max­imise straight line speed and sta­bil­ity.

“A big rear wing might have looked good and given us down­force but it would have slowed us down. We have about two miles (3.2km) of track to build speed so we use the truck’s weight to keep it on the sur­face and keep it stable,” Man­ning said.

Diesel Ar­row was sched­uled to run at Speed Week in March this year but a work­shop ac­ci­dent just days be­fore the event threw a gi­ant span­ner in the works and ruled Man­ning out of pro­ceed­ings.

But ev­ery cloud has a sil­ver lin­ing and the ex­tra time – a full year be­tween

❝ The level of chas­sis so­phis­ti­ca­tion in Diesel Ar­row comes from its race truck days. — Gavin Man­ning

runs – has al­lowed even more de­vel­op­ment on the weapons-grade mon­ster truck.

The “cargo bed” has sprouted an aero­dy­namic cover and a Jab­sco ma­rine wa­ter pump has been fit­ted to flow even more coolant through the gi­ant en­gine.

“Warm­ing it up,” says Man­ning, “will be our big­gest prob­lem and it’s an ex­cel­lent prob­lem to have.

“If the ra­di­a­tors are right and the oil’s at the right temp we’ll let the rest take care of it­self.”

The long break has also al­lowed more en­gine run­ning time on a rolling road dy­namome­ter, giv­ing Man­ning’s small crew time to run sys­tems checks, a lux­ury sim­ply not avail­able in the harsh, 38-de­gree South Aus­tralian out­back.

Un­for­tu­nately, the dyno is un­able to be used to find ex­tra power and torque be­cause it is sim­ply not able to han­dle the en­gine’s mam­moth out­put, what­ever that may be.

“When we get it on the salt in March next year we’ll just run it, see what sort of speed we get and go from there,” Man­ning said.

PHO­TOS: CONTRIBUTED

INNOVATOR: Gavin Man­ning, Diesel Ar­row’s de­signer, de­vel­oper, fab­ri­ca­tor, en­gi­neer, builder, test pi­lot and tea lady.

Stripped of its pan­els, Diesel Ar­row re­veals what lives be­neath its aero­dy­namic side­pods. The tanks hold en­gine coolant and trans­mis­sion ra­di­a­tors as well as the tur­bocharger in­ter­cool­ers.

Diesel Ar­row’s en­gine room. The 23-litre en­gine de­liv­ers its plen­ti­ful power to the back wheels through an au­to­matic trans­mis­sion.

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