1964 - 1990 Experimental 455 Engines
Aluminum 2 Valve 455
The aluminum Can-Am motor you are refering to is actually an aluminum version of the pushrod 455 block and heads! The motor was used in the McKee Can-Am cars of the 60s (one of which was sponsored by the Smothers Brothers, who also sponsored a series of 442 Super Stock class drag cars in the late 60s).
The Smothers Brothers Can-Am car was actually offered for sale in the March 96 Hemmings, complete with the aluminum Olds motor for $125K. The twin-turbo injected 455 on display at the REO museum is, I believe, one of these Can-Am motors (note that it is NOT a DOHC motor).
Aluminum DOHC 4 Valve 455
There was also a Can-Am all aluminum engine which had double overhead cams and was a very serious engine; huge port area for serious breathing. The DOHC version was intended as an all-out drag and marine race engine. It was all-aluminum and used a gear drive for the cams. For a very nice article on these engines, track down a copy of the May 1971 Hot Rod.
Aluminum 2 Valve Turbo 455
The twin-turbo injected 455 on display at the REO museum is, I believe, one of the Can-Am (see "Aluminum 2 Valve 455" in this section) motors (note that it is NOT a DOHC motor).
Iron, Aluminum 2 Valve 455 Hemi (W-45)
The W-45 was an experimental engine that Olds developed to compete with the Chrysler Hemi. It was a overhead cam of some sort. The engine (pushrod version) was developed in the mid-60s for anticipated introduction in 1970, but was killed in late 1967 as a result of the coming emissions controls and the insurance industry putting the screws to muscle cars. There were some cars installed with this engine for testing.
The cast iron version (with aluminum heads) that was meant to be the production engine (W-43) has true pushrod hemi heads. The block is different from the standard ones in that the camshaft was raised higher than normal to give the proper pushrod angle to the heads and cam (which would have also had to have been different because of a different bank angle). This explains the rounded top of the timing cover.
The pushrod version had a raised cam, to improve the pushrod angle as a result of a lot of bent parts early in the development program. The block actually had a dummy camshaft in the normal position to drive the distributor and oil pump, with a separate, bolted-in cam carrier in the raised position for the real cam. The block had 4 bolt mains as well.
Iron 4 valve 455 Hemi (W-43)
There was also an engine coded W-43 in 1969 to 1970, though it was never offered as a production unit. It was a four valve per cylinder 455 CID engine. It was developed in 1969 and 1970 by John Beltz, Lloyd Gill, Joe Jones, and Frank Ball. It was rated at 500 to 550 hp at 6500 rpm with a single Rochester Quadrajet on an aluminum manifold. It was constructed with a cast iron block and heads as well as an aluminum block and heads, which shaved 75 pounds of the 455 CID production engine weight. The engine had narrow valve angles for super-efficient combustion chamber design, central spark plugs and could be adapted for chain or gear driven overhead camshafts.
The 455-inch-configuration block has 4.625-inch cylinder centers, 4.125-inch bore and 4.250-inch stroke. Making use of 3.00-inch main bearings and 2.50-inch rod journals, the engine was fitted with a specially-prepared cast crank fitted with SAE-1140 forged steel rods, forged 10.20-to-1 pistons and riding on Morraine 400 bearings. The four-bolt-main block boasts two additional 5/8 inch oil drain holes.
Topping off this unique engine is a pair of four-valve heads with 1.750-inch intake valves (SAE-8460 steel) with 22-degree stems and 1.375-inch exhausts (214-N stainless steel) with 15-degree stems. Special Stellite seats, bronze-alloy guides, o-ringed plug tubes, 14-mm spark plugs, 3/8-inch pushrods, and aluminum rocker arms complete the head treatment.
Aluminum 4 valve 455 Hemi (OW-43)
There was an experimental engine based on the W-43, coded OW-43. It was designed for road racing applications. It had the same basic configuration as the W-43, but the materials were different. The block was cast from Reynolds-356 alloy and fitted with pressed in dry steel cylinder liners for the forged 12.2 to 1 pistons. It used billet steel connecting rods and a machined forged steel crank.
The OW-43 was developed at the same time that Chevrolet released its all aluminum ZL-1 427 engine, but the Olds engine was far more advanced and exotic than the Chevrolet engine. It had a redline just under 8500 rpm, and put out 300 HP at 3000 rpm, and 600 HP at 6000 rpm. The top output recorded for this engine at the Lansing dyno facility was 700 REAL horsepower at 6800 rpm. Tests were run with both carburetion (four Weber 48-IDA two barrels) and injection (three-inch ram stacks), with injection showing the most potential over 6000 rpm.
[ Thanks to Joe Padavano, Dave Paulison for this information ]