The Phantom P-30 was a 0.297 cuin. (4.87 cc) crankshaft front rotary valve (FRV) spark ignition motor whose production life spanned the WW2 years, going from late 1941 to early 1948. The engine was manufactured in Los Angeles, California by the Automatic Screw Machine Company and marketed through their subsidiary Phantom Motors Distributing Co.

The Phantom displayed a number of unusual features. The bypass passages were formed in unit with the steel cylinder by pressing them out from the interior prior to the finishing of the bore. The post-WW2 variants featured the twin exhaust, twin intervening bypass arrangement later made famous by Cox and others. These bypass passages permitted the use of a flat-topped piston having no baffle on its crown. 

The Phantom P-30 was an excellent performer by the standards of its day, as latter-day testing has demonstrated. It was made in substantial numbers, a good proportion of which evidently survive today.

A detailed review and test of the Phantom P-30 appears elsewhere on this website.