Click here to see the Brennan Imp: Brennan Imp 3 Main Engine
Okay, maybe venerable is a strong word to use, but the Brennan Imp is something special. The engine itself has been covered in some club news letters, but unfortunately I only have a copy of one issue discussing this. From what I have gathered, the Brennan was one of several companies that utilized the Bantam engine for commercial use. The other primary industrial application for these engines being water pumps.
The relationship between Bantam and Brennan seems to begin with the second two main variation of the Bantam engine and lasted through to the end of Bantam civilian production. Where it gets interesting is in 1940, after getting out of civilian car production and without a need to continue producing the Hillmaster, Bantam appears to have relinquished control of its engine to Brennan Standard Motors, of Syracuse to continue its life as a “Brennan Imp.” The Imp began its 3-main life as shown above, nothing more than a car engine converted to marine use. Unlike most marine engines, it retained the transmission at the flywheel.
It’s unclear how long this iteration of the Imp continued, but somewhere in the late 40’s Brennan reengineered the Imp and complimented it with the “Imp Jr.” The Imp Jr. was based on a Crosley, so one would naturally assume that it would have taken over and the Bantam based Imp would have been forgotten. As it turns out, the reengineering process retained the vital specs of the Bantam Hillmaster, but updated the crankcase to a new configuration more suitable for marine use. The engine retained a bellhousing and a timing cover area similar to the original bantam, but the areas were utilized differently. The transmission was mated to the front of the block, and an odd flywheel was fitted to the rear. With the updated crankcase, Brennan took the opportunity to fit the engine with insert bearings and presumably standard bearing caps. (I haven’t opened mine to see). With these updates, the Imp outlived the Imp Jr and became a go to engine for small home builders of inboard boats.
The Imp was actively advertised through 1966, with every ad touting improvements and higher horsepower. During the 1950’s, the Imp saw it’s horsepower rating go from a paltry 25 hp to 35 hp. In the 60’s, the Imp supposedly made 40-45 hp. By that time, the engine was fitted with an alternator and may have been produced until the demise of Brennan Standard Motors in 1972.