K I W I M A D E end casting, in that we are getting significant power from what is essentially a domestic V8 engine.” There isn’t a whole lot of circuit racing in New Zealand that appeals to Nelson from a business standpoint. “We restore the occasional classic car engine and do a bit of machining for GT and Sports Cars. Most of that has open rules, so there is not a whole lot to be gained by doing more maths, you just simply make the engine bigger and anybody can do that,” says Nelson. “On the flip side, everthing else is based around a one-make series. Where we are strong is extracting the most out of a tight, but slightly open set of rules. I guess that’s why my brother and I were so successful in Formula Ford”. Sprint Cars are a very American formula – the engines are about 900bhp, they have no gears or clutches – drive is straight from the crankshaft to a truck sized differential and rolling starts are the norm. Both front and rear has live axles. The wheels are various sizes with the largest being on the back right hand corner (as the tracks are counter-clockwise) and they are usually staggered to allow for maximum traction round a 12-14 second lap or less – basically a suicide ride on an oval dirt track. Brendon drove Nelson’s Sprint Car once and reckoned it was more of an adrenaline rush than an F1 car. And as Nelson puts it, “Sprint Car racing is the only international, high-end motorsport formula 20 February 2016 where I can build my own car without the need of a $1million and it’s available to anyone crazy enough to partake.” The traditional Sprint Car chassis is a birdcage of chrome moly 4130 tubing with very little cross bracing, so that in its traditional form, there is considerable chassis flex, under the loads imposed by a 900bhp motor and very large low-pressure ATV type tyres. This constant flexing over a period of season makes the tubing work harden, as the season progresses, so the torsional flexibility decreases over time. So much so that drivers who like the flexibility of the early chassis, have been known to make judiciously placed saw cuts in the tubing in order to regain the flexibility! Nelson on the other hand wants more predictability, so he’s gone for a stiffer setup and prefers to condition his kinematics with adjustable and innovative suspension -- he rebuilds and modifies his own shock absorbers and has a shock dyno to calibrate the performance, which helps. The three spring arrangement on the rear is an attempt to introduce some innovative suspension design into the traditional Sprint Car setup. The top spring controls the ride height and allows more spring rate on heave (up and down) and less on roll, instead of having massive anti-squat angle changes. “When we end up on a slick track you have to increase the anti-squat angles using SolidWorks CAD models of the monocoque front section.
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