Avanti engines were designated as R1 (non-supercharged) or as R2 (supercharged). The superchargers were manufactured by Studebaker's Paxton products division. The blower provides 5 lb. of boost and is accompanied by a lower compression ratio, 9:1, and a dual breaker ignition system. In addition to the R1s and R2s
, the 64 production models included 9 cars designated as R3s
. The R3s were hand built racing engines. R4s were a non-supercharged version of the R3s. Approximately 140 R3/R4 engines were made. The experimental "Due Cento" with the only R5 dual supercharged engine built by Paxton reached 196.62 mp.