In 1926 AAA introduced new regulations that limited engine size to just 91 in³ (1.5 liters) to slow the cars. Harry Miller, an American race car designer and builder, who build single-seater race cars and engines since 1919, had to create a new engine for his new cars and his existing customers. To make up the lack of displacement, Miller and his team fitted a centrifugal supercharger. Some of the very first blown Millers appeared in 1925, on the 122 in³ engines. By the time the 91 in³ formula was set, Miller could already produce more power from the smaller displacement. With nearly 250 bhp on tap, the 91 could top out 171 mph. Miller produced both a rear-wheel drive (RWD) and front-wheel drive (FWD) version of the 91. At least 10 FWD and at least nine RWD cars were built. Millers 91 dominated the AAA races and filled most of the Indianapolis field from 1926 to 1929, winning the 500-miler in 1926, 1928 and 1929.
In the 1929 Indianapolis 500 the battle for the lead went between three Millers driven by Louis Meyer and Loo Moore, the previous year 1-2 finishers, and by Ray Keech, runner-up of the 1928 AAA National Championship. Finally Keech coasts to a six-minute 24 seconds victory over Meyer. Keech competed in his second 500. He debuted in the 1927 AAA season, won the first race at the Michigan State Fairgrounds Speedway in 1928, and finished in second place in the season points in the AAA National Championship with three wins. Keech dies just two weeks after his Indy 500 win in a racing accident in AAA championship event at Altoona, Pennsylvania.
The scale models of 1926, 1928 and 1929 Indy 500 winning Millers were made by Replicarz in a limited edition series.
| Season | Series | Event |
| 1929 | AAA National Championship | Indianapolis 500 |
| Driver | No. | Entrant |
| Ray Keech | 2 | M.A. Yagle |
| Chassis | Engine | Car Name |
| Miller | Miller | Simplex Piston Ring |
| Scale | Manufacturer | Collection |
| 1:43 | Replicarz | |
| Cat. No. | Quality | Rarity |
| RA43014 | 
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