GM LS Thumpr Cam - 275THR

The GM LS Thumpr Cam - 275THR by COMP CAMS is a hydraulic roller camshaft engineered specifically for GM LS-series engine platforms seeking aggressive street and mild performance characteristics. This camshaft delivers the iconic "Thumpr" lobe profile—known for producing distinctive valve train noise and enhanced low-to-mid-range torque delivery. Ideal for enthusiasts building LS engines for daily driving with noticeable performance gains, the 275THR bridges the gap between stock efficiency and serious racing hardware, making it a popular choice for truck, muscle car, and hot rod applications.

Featuring a 109-degree lobe separation angle (LSA) and hydraulic roller lifter design, this camshaft achieves 0.553-inch intake lift and 0.536-inch exhaust lift across a 275-degree intake and 295-degree exhaust duration window. The hydraulic roller design eliminates complex adjustment procedures while reducing valve train friction compared to flat-tappet designs, ensuring reliable operation across the 2000–6400 RPM power band. The aggressive lobe profile generates increased overlap and scavenging action, promoting cylinder filling and exhaust evacuation for superior breathing and responsive throttle character. The 109 LSA positioning optimizes powerband placement for street-focused performance without sacrificing low-end tractability.

This camshaft is compatible with all GM LS-series engines, including LS1, LS2, LS3, LS6, and truck variants such as L92 and L99 platforms, provided valvetrain geometry and pushrods remain stock-based or properly matched. Installation requires standard camshaft replacement procedures, valve lash adjustment via hydraulic lifter preload, and carburetor or fuel-injection tuning to optimize fuel delivery for the altered cylinder-filling dynamics. Builders pairing the 275THR with mild heads, long-tube headers, and a quality exhaust system typically see 15–25 horsepower gains over stock while maintaining streetable idle quality and cold-start reliability. The Thumpr signature is best appreciated with solid-mounted valve covers and an aggressive exhaust tone.