Powel Crosley and Crosley Motors weren’t afraid to innovate, as demonstrated by the COBRA engine—it employed sheet-metal construction.
Founded by radio and appliance tycoon Powel Crosley, Crosley Motors of 1939-52 wasn’t a terribly successful automaker, but the company did make its mark on automotive history with its clever engineering. (See our feature on Crosley’s pioneering disc brakes here.) However, one of its most memorable innovations, the COBRA engine, didn’t originate at Crosley. The concept was originally developed by of Lloyd M. Taylor, a talented California engineer and inventor who first patented the design in 1937.
COBRA was an acronym for COpper BRAzed, a manufacturing method in which the cylinder block and head were built up from a number of pressed steel parts that were secured in a fixture and then brazed together at controlled temperature. Working with Taylor through World War II, Crosley developed a number of prototype engines for the U.S. military using this process, which resulted in a production contract for a lightweight powerplant for field use. It was this inline four-cylinder engine that was adapted to the Crosley civilian passenger car for 1946.
With a bore and stroke of 2.5 inches by 2.25 inches, the COBRA displaced a mere 44 cubic inches, but it could develop 26.5 hp and weighed just 133 lbs. The cylinder block and head were constructed as a single unit, which bolted to a cast-aluminum crankcase with five main bearings. With no head gasket joint to compromise the structure, the sheet-metal assembly was sufficiently stable and rigid. .
The tube at the front of the unit housed the shaft drive for the single overhead camshaft with bucket followers, a light and rugged setup that allowed the COBRA to make peak power at 5,200 rpm. Both intake and exhaust passages were on the right side of the block, where a tiny Tillotson one-barrel carburetor supplied the fuel.
No, 26 hp doesn’t sound like much, but the Crosley automobile was small and light, especially the Hotshot sports car at less than 1,200 lbs. Tom McCahill of Mechanix Illustrated called the Hotshot “the poor man’s MG.” (Read about the Hotshot here.) But there was one problem with the sheet metal head/block construction: corrosion. In the late ’40s, antifreeze wasn’t what it is today in its anti-corrosion properties, and the cooliing jackets soon developed multiple leaks.
As a running production change on January 4, 1949, Crosley dropped the COBRA process and introduced the CIBA engine (Cast Iron Block Assembly) The engines are otherwise identical, and while the cast-iron block added 30 lbs, it fixed the leaks. Crosley ceased automobile production in 1952, but the engine lived on for many more years—in homebuilt sports racing cars and in marine use, in both inboard and outboard form.
Wow, that’s crazy. I had heard of the cobra engine but I never saw the pieces before. They must be really rare.
Yep just then you see it all something old is something new.
they made a odd sound running, you could tell one befor you saw it
The info I have for the CoBra motor is that the US military needed a simple and easy to repair/replace small 4 cylinder gasoline engine for us in generator sets and other equipment requiring a gas engine. {During WW2 there were 2 basic power plants; either electrical or gasoline, as Diesel fuel was still in it’s infancy, & hard to get for the European theater’s US Army, as it was used mostly as Navy ship “bunker fuel”.]
The CoBra was intended to run at fixed speeds, and one of the problems with using it in cars was the constant variable speeds it was exposed to, made for minute flexing of the block, leading to rapid engine wear, especially main bearings.
Plus, like much of WW2’s small equipment, the expected life cycle was around 30 to 90 days of use, and it was important that the engine could be easily swapped out of the generators by front line repair facilities, so the gen sets could be sent back into operation quicker than an entire replacement generator could be found. Because of their short life cycle, no consideration was given to the CoBra block’s cooling passages rusting out.
My understanding of the CoBra engine’s success in wartime and failure in peacetime is much the same as yours.
Powel Crosley, Jr. – who had a reputation for making affordable radios (and later TVs) with a minimum number of tubes, and a refrigerator that required no electricity – likely saw that the median continuous runtime for these engines before an overhaul was needed was around 1,500 hours, and equated that to four or more years of daily use, assuming one hour of driving per day. But as you pointed out, things didn’t work out that way when the engine was subjected to variable speeds, and there weren’t trained military personnel around to constantly monitor its operation around the clock.
(I’m also of the opinion that two unrelated engine designs also seem to work better at constant speeds than at the variable speeds needed for automotive use, namely the Wankel rotary engine and the turbine engine).
In the end, the decision to use the CoBra or CIBA engine probably wouldn’t have made much difference to Crosley’s eventual success or failure, since the Ford/Chevy price war of the early 1950s was the final nail in the coffin for most of the independent makes.
Re: the Constant Speed operation.
I have long thought that the Wenkel engine would be GREAT in a hybrid, running @ Constant speed to change the batteries when needed .
Very informative. Thank you!
My parents bought a new 1949 with the CoBra engine but Crosley replaced it under warranty with the cast version.
There was a man in Florida by the name of Sam Crooks, that at one time held a world record in a hydroplane that had a Crosley engine in it.
The Cobra was great for applications like generators – no cooling issues and they ran great at a steady rpm – not so much in automobile.
When Crosley ceased production of motor vehicles, the company sold the design to Airesearch, which continued to produce the engines for power generators and refer units for refrigerated semi trailers.
The Crosley Hotshot was the first “sports car” produced in the US, even though it was a tiny, 26hp rattletrap! And Crosley was the first production cars with 4 wheel hydraulic disc brakes. Before the CoBra engine, Crosleys were powered by Waukesha engines, which powered many vehicles during the first few decades of the 1900’s.
Thanks for posting this article. I had multiple Crosleys when I was in high school (including a 1946 sedan with the CoBra engine), and I still have a 1952 Crosley Super Sport convertible. I think Crosley was way ahead of his time.
back in the late 50s and early 60s we went to the 3/4 midgets and they were running the crosley engines then
Dad had a few 3/4 midgets with the Crosley engines he raced the early to late seventies
I would have liked to have seen pictures of the stationwagon. I saw MORE stationwagons than any other body style.
To my knowledge, these were used by pharmacies and grocery stores, etc. fur delivery purposes.
One Halloween we picked up someones Crosely Stationwagon & carried it up onto their Front Porch, then rang the doorbell, then RAN across the street & hid & watched.
When the owner was sufficiently @ wits end, we crossed the crossed the street & THANKED him for a Good Laugh, then proceeded to remind him that Next Halloween to put his car in the garage – & carried his Stationwagon badk down the STAIRS & set it down on the street.😁
Some years latter while attending Univ. of ILL.. We did likewise (Sping 1954) to a Pi Kappa Phi fraternity brlother. He couldn’t get into his Study Room & became Extremely Angry with whomever was holding his door.
We laughed, then removed the door hinges. & replaced his car onto the street. 😳
I believe the Outboard Motor – was branded – “FAGOL” (or something Very similar).
THANK YOU for Great Memories.
FRED (Fritz) STOTZ 8🎩
fritzstotz87@gmail.com
Pi Kappa Phi.
(Upsilon & Alpha Phi)
(773) 761 – 8888. 🎩