Milliken’s combination, the only one of its kind in X275, is a 6.8-liter Cummins (based on the production 6.7-liter) with an LSM billet aluminum block of full internal factory dimensions, bored .040-inches over. It sports a factory 6.7 Cummins crank, billet steel rods of stock dimension, Diamond pistons, a Hamilton roller camshaft, and Manton roller rockers. Wagler Motorsports provided the likewise factory dimension billet cylinder head with a factory exhaust manifold design, factory valve design, injectors, and injector feeds, and so on. Per the X275 rules, Milliken is permitted to use two power adders: a four-stage, .122-inch solenoid dry nitrous system coupled with an 88mm Garrett turbocharger.
“We’ve been running the same fuel quantity and power output for three years now, and we were just adjusting shocks or shift points or fuel cuts to fit the chassis setup,” he says. Milliken and team eventually figured out their anti-roll bar lengths were too short and also switched to two-inch longer extension shocks and it made all the difference — instead of tip-toe’ing through the early part of a run, they could get more aggressive like their peers.
“I wasn’t expecting nor prepared to go that quick. I hauled to this race thinking we might get lucky and hit a hail-mary and make the field — I didn’t expect to go number six and run quicker than the previous world record,” Milliken says.
Milliken is well aware of the attention his combination drew after its 4.28-second performance, noting, “No one has said anything direct, but I heard a guy in a video say, ‘that thing needs more weight thrown at it.’ But I checked with John Sears and per the track’s scales, I was the heaviest X275 car on the property. We were 3,435-pounds (his minimum weight is 3,350). Putting any more weight to my chassis would make it more dangerous and make it more difficult to race, since we’re on leaf springs.”