Oldsmobile’s experimental W-43 engine is surrounded in myth, legend, and a tall tale or two. Let’s see if we can sort it all out.
Here at Mac’s Motor City Garage, we’re grateful to the World Wide Web for rediscovering so many wonderful stories in automotive history and bringing them to public attention. Still, we have to note that that often, the info isn’t always totally accurate—which is only natural, we suppose. After all, the internet could be described as the biggest and longest game of Telephone in history.
Take this fascinating engine, for instance: the Oldsmobile W-43, an experimental V8 developed in 1967-69. Various sources have described this engine as a hemi (it isn’t) or a Can-Am engine (that was never its purpose) or a double overhead-cam design (nope). In truth, the W-43 was a conventional overhead-valve, pushrod V8, in the classic Motor City style, but with special cylinder heads and valvetrain that provided four valves per cylinder.
To the average car enthusiast, a four-valve head with pushrod operation—that is, each rocker arm and pushrod operating a pair of valves—may seem like an outlandish setup, but in the diesel truck world it’s fairly commonplace (Cummins and Detroit, to name two). It looks cumbersome but it works just fine, especially where high engine speeds are not required.
The W-43 was indeed based on a standard 455 CID production block, but with some key modifications, including four-bolt main caps and special valve follower retainers that bolted into the lifter valley. The spark plugs were buried in tubes in the center of the valve covers, which no doubt fed the stories that the engine was a hemi. Bore, stroke, and other significant specs were identical to the production 455 CID V8. There was also an aluminum-block variant of the W-43 designated the OW-43, and the program eventually produced an experimental four-cam, 32-valve V8 based on the production engine’s architecture.
With four valves per cylinder, the combustion chambers of the W-43 were not hemispherical but rather a classic pentroof layout, utilizing shallow valve angles in the Cosworth style. Intake valves were 1.75 inches in diameter and 1.375 inches on the exhaust, providing 43 percent more intake valve area than the production 455 two-valve heads. According to a feature in the May 1971 issue of Hot Rod magazine, the W-43 was good for 440 horsepower at 4600 rpm in a relatively mild state of tune. And given the improved volumetric efficiency enabled by the far greater valve area, that figure seems downright conservative.
Reportedly, the W-43 V8 was at one point considered as an across the board replacement for the standard two-valve 455 CID V8, but as we know, that never happened. Various theories have been proposed to explain why, including stricter emissions regulations and corporate infighting with the far more powerful Chevrolet division at General Motors. But as we see it, the four-valve version’s considerably greater size, weight, and manufacturing cost would have been more than sufficient to kill the program. At least two W-43 prototype engines still exist, one of them incomplete, but their current whereabouts are unclear.
Update March 2, 2024 :James and John Kryta of Romeo, Michigan have restored one engine to running condition and installed it in a 1970 Olds 442.
Yep, bean counters are a definite buzz kill in the auto industry. “It cost how much???”
Indeed. However, the bean counters keep the lights on and everyone paid.
Cool stuff
I was wondering if this was the 455 EXP aluminum block, but nope.
Valley head service has built BBC heads like this for many years.
RE Olds museum has one.
I was there yesterday and it was gone. The museum director wasn’t sure but he thought the engine went back to GM.
I have seen a Aluminum block 455 engine about 15 years ago .
valvetrain weight would negated any performance advantage. Just a bad idea all around. No currently made big cube performance motor utilizes 4 valves per cylinder. It’s all about valvetrain weight. Take a look at a state of the art Pro Stock motor that turn nearly 11,000 RPM.
the four valves per cylinder would make each valve lighter since they are smaller by a bunch. The importance of weight is per piece. the RPM range was probably limited by the spring tension on each valve which was probably minimal because there was one pushrod per every 2 valves. If they would have doubled the lifter bores that would have necessitated a new block and higher volume oil pump. Cool design tho.
As they said it was a low rpm motor achieving its hp @4600. And deisel engines have been and still utilize this design with millions of miles on them. It’s nice to compare 50 to 60 year old technology to state of the art builds. But its unrealistic. Why don’t we compare a model t 4 banger to a modern day 4banger turbo.
That’s a good looking engine!
Oldsmobile was a torquemaster and in the present, all of Mondello Oldsmobile racing . engines are t or q u e of monsters. Oldsmobile came out with the first Hemi engine or had a prototype before Mopar which was approximately rated at 700 ft lb of torque and over 600 HP. There was naturally aspirated for 55 and 1968 6970 who were easily making 10 and a half seconds 11 seconds in a quarter mile.
Yeah, not likely. Chrysler’s first hemi came out in 1951. Corvette guru Zora Arkus Duntov actually made hemi head conversions for the Ford flathead in the late 40s.
This period of engine development at GM was pretty interesting. The W-43 is a bit like the Pontiac Ram Air V program. At least Pontiac was able to get 400 cid RAV parts out the door but too bad the small displacement program for Trans Am racing never made it.
Boy do I miss my Olds and Pontiacs!! I’ll settle for my Caddy n Buick though!
’11 Cadillac CTS Sportcoupe Turbo 6.2 and ’10 Buick LaCrosse CXS 3.6 AWD.
That 3.6 is a horrible engine Tom, hope you don’t have to put a timing chain in it or head gaskets, unless you have the money to burn, no offense brother
This with the proper 4speed gear ratio and rear could easy make 10 sec 1/4 ,s my 68 442 wide ratio 4 sp 342 rear 350 up was Oldsmobile,s best 1/4 mile st car the gearing , put all the torque at the shifting points if they did that w -43 could easy make it in 10 sec area!
Torque monsters
I think the aluminum one was put into a 442 ins sold at Barrett Jackson within the last 10 years. Surprisingly it didn’t break the bank. There’s an old hot rod magazine article from the 70s that shows all the experimental Olds engines on the cover including TwinTurbo’s and other wild configurations.
OK, so here goes. My Dad managed a Oldsmobile dealership in North Hollywood, CA. for 26 years. I was working there as a “lot boy”. I washed the inventory, and did about everything else including new car detail/prep. My Dad calls me into his office and says “My rep says he’s got this 442 that was a test car, with a really souped-up 455 in it. He said it’s from the Michigan plant”. I said “how much?” He says “It’s $1,400 but it has a blown turbo-400 hydramatic, but maybe you can Cal (transmission mechanic) can rebuild it on a weekend”. Well, a brand new 442 was over $3K (which I didn’t have) but I *did* have $1,400. So – I bought it. Well, one day the transport arrives and the driver says “I got one that runs but no trans”. So, he starts it, gets help to get it going backwards from one of the mechanics and me, and it rolls off in Neutral (4-speed gearbox of course). So, I grab Cal and Smokey (line mechanic) and Cal opens the hood and says “Randy, what the f__k did you buy?”. I said, ” I don’t know, but Dad says he’s told it’s really fast”. So, Cal said “hey, look at the badges on the side”. I look, the heavy pot metal cast badge (chrome and black) says “442-500”. The engine in blue. We push the sucker over to the parking area next to the transmission rack. That Saturday Cal rebuilds it (back in those days we had the keys to the parts dept). Well, we rebuild it. Cal says “wow, this things only go 160 miles on it and the turbo400 is tore up”. What made this car look different (besides badging on sides and trunk) was it had a really cool looking air cleaner. BIG carburetor, really bid secondaries.So, I drive this thing and it’s a MONSTER. BTW, this takes place in late 1969. I get 3 tickets in less than 4 months and my Dad says “sell the piece of s__t”, you’re gonna drive my insurance off the charts”. (I was on my parents policy. So, I sold it to my High School class mate who solo-wrapped it around a tree (passenger door side), totalling the car. What a damn shame. WAY too much power. No, I don’t know what it was, other than what my Dad told me that he was told. “that there were 3 or 4 made”. It had fully rallye pack instruments, SSII wheels, etc. HUGE radiator, I remember that. No, I do not have any photos. At 17, I didn’t think of that back then. Anyone who might have information on WHAT I had, please chime in.
This sounds like total BS for so many reasons
Very negative Jack.
I was only 17 Jack. Geez
442’s had 4-speed gearboxes. This car had a turbo-400 trans.
I worked for GM for almost 20 years on their antique car collection better known as the Heritage collection. The other engine you speak of was sitting a stand at the Heritage center. That was 6 maybe 7 years ago. I no longer work there (retired from wrenching). When I saw it, I thought I didn’t know Old’s built a hemi. There wasn’t info with it because it wasn’t on display at time. It sitting in back in storage.
Well, the car I had either had the experimental 500 CID Cadillac engine, or the Olds experimental hemi. It was beyond fast.
There were several experimental 455,s besides this one. There was a true hemi- head pushrod based : olds licensed their con rod design to dodge in exchange for license to use the hemisphere ical combustion chamber.
Can you tell me more about the various experimental 455’s? I don’t exactly know what I had in my car back then, but any information would help.
Years back,we bought a m 5 tank chassis that had a wild motor in it.it wuz an 1,100 c.i.block w.32 valve twin overhead cams,hemi,w dual mags,fuel injected ALL ALUMINUM. PRETTY CRAZY but we couldn’t seem to dial it in so we yanked it and stuck a bbl 460 ford in the trunk and went and crushed cars long live ” Cantankerous”
Thank you God bless