When you know an engine inside out, it makes sense to stick with it, which is exactly how a 4G63 ended up powering Matt Rolley’s MX-5 NA. In his case, the block was sourced from a VR-4, while the head is off an Evo IV.
“They are the go-to four-cylinder Japanese engine, and, with previous experience tuning them, it made sense,” he explains. “It fits quite well dimensionally — a little tall at the front, but that was solved by shortening the oil-filler neck on the cam cover.”
Matt made a small cut-out to suit the cam-angle sensor and coolant outlet in the name of top clearance, work that he says wasn’t necessarily difficult just time-consuming. The sump was changed from front to rear to sit the engine where it needed to be without modifying the steering-rack position or the front subframe.
It’s backed by a CD009 six-speed that has been adapted from a Z33 Fairlady, Matt saying this was a very strong option that was cheaper than buying an R154 or the like. The rear end has been converted to an Evo diff with Legnum diff hat, Evo axles and drive flanges, and Ford Laser wheel bearings.
“It’s 1018kg now, which I don’t think has hurt the balance at all. The running gear would be at least 10 per cent heavier than the standard MX-5 stuff. However, it’s mounted low and reasonably well centralized. It’s a huge gain over a stock car; a solid performer. It’s not for the faint of heart, and it just doesn’t have the race prowess that it would if I was running a sequential box,” he says.
ORIGIN CHASSIS: 1996 Mitsubishi Evo IV CAPACITY: 1997cc CONFIGURATION: Straight-four BORE/STROKE: 85x88mm COMPRESSION: 8.8:1 POWER: 206kW WEIGHT: 160kg