XYZ Racing Racing Spec Coilovers — Maserati BITURBO SI φ52 welding (PCD: 4X98) 1986-1991

The Biturbo’s rear-wheel-drive, twin-turbo V6 layout was radical for a mid-1980s Italian GT, and the factory suspension was never built to soak up the weight transfer that comes with sorting out the SI’s boost delivery under real load. The XYZ Racing Racing Spec coilover for the Maserati Biturbo SI φ52 Welding (PCD: 4X98) replaces that ageing geometry with a track platform sized directly to this car’s 52mm strut welding spec and 4×98 hub pattern.

Racing Spec sits at the top of the XYZ Racing coilover range, built for cars heading out for serious track and time-attack sessions rather than fast-road duty. On a car this old, matching spring rate and damping to the actual mass and turbo-lag characteristics of the Biturbo matters more than chasing a generic stiffer-is-better set-up.

What this coilover does for your 1986-1991 Maserati Biturbo SI φ52 Welding (PCD: 4X98)

Fitting Racing Spec to a 1986-1991 Biturbo SI addresses the two things that show up first on circuit: body roll under the V6’s turbo-driven torque swing, and the vague, worn-out damping that decades-old factory struts can’t avoid. Correct spring rate for the platform keeps the nose settled under trail braking into slower corners, where a stock Biturbo tends to dive and load the front outside tyre unevenly. Because the strut is built to the car’s own 52mm welding diameter and 4×98 bolt pattern, the geometry stays correct rather than adapted from a donor platform, so camber and roll centre behave the way the chassis was designed to. The result on a car this light is a suspension that reacts to the twin-turbo’s power delivery instead of lagging half a second behind it through direction changes.

About the Racing Spec coilover

Racing Spec is the damper XYZ Racing builds specifically for circuit racing, and the base valving comes from real competition work rather than a desk exercise – the settings trace back to XYZ Racing’s direct involvement in touring car racing at WTCC level. For cars carrying heavier modification, such as a Biturbo running upgraded turbos, a stiffer roll cage, or other factory-racing-style changes, XYZ Racing also offers a bespoke build: send over the car’s upgraded parts list and the circuit it will run, and the damper gets valved to that specific combination rather than a generic Biturbo spec. That custom-order route exists because a heavily modified Biturbo behaves nothing like a standard one once turbo boost, weight and aero are all changed, and a shelf damper can’t account for that on its own.

Fitment for the Maserati Biturbo SI φ52 Welding (PCD: 4X98) (1986-1991)

This kit is built for the Maserati Biturbo SI variant fitted with the 52mm ("φ52") strut welding spec and 4×98 bolt pattern, covering cars produced from 1986 to 1991. Confirm your car matches this strut diameter and PCD before ordering, since Biturbo variants across the model’s production run used different top-mount and hub specifications.

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Configure your spring rates and confirm strut fitment for your Biturbo SI below.