5 Mystery Muscle Motors of the 1960s that Detroit Never Sold in a Car

[TripleB]

1968 Ford 289 SOHC V8

Ford built three experimental 289 with a unique single overhead camshaft design that features a cam located in each of the cast aluminum valve covers (instead of on top of the cylinder heads). The lobes of each cam activate the cast iron rocker arms that open each valve. In the original camshaft position within the engine is smooth shaft whose role is to drive the distributor as well as the two overhead cams. The purpose of this project was to raise the maximum engine speed and with it peak power. The OHC 289 produced 300 HP at 6500 rpm.

 

[TripleB]

Oldsmobile W43 DOHC V-8


As part of the development of the Oldsmobile 455, Olds engineers wanted to take the design of the engine as far as possible. The ultimate version added a set of dual overhead camshaft cylinder heads to the mighty engine. A gear drive supported by roller bearings in an aluminum gear case at the front of the motor spun the cams, while a driveshaft was used in the standard camshaft position to transmit motion to the oil pump and distributor.

Toward the end of 1969 engineers dyno tested the DOHC W43, built with a very racy12.2:1 compression ratio, and recorded a very flat (and fat) torque curve. Peak power Olds engineers recorded was 700 horsepower at close to 7000 rpm.This was achieved using the standard cam profiles for the W43, ground onto separate intake and exhaust camshafts. At that point, no development had been done to optimize cam specifications to match the breathing of the heads.

But on January 1970, General Motors President Edward N. Cole announced that all GM divisions would lower the compression of their motors so 91 octane unleaded fuel could be used, and development stopped on the DOHC Olds.

 

[TripleB]

1964 Pontiac SOHC V8


Most likely prompted by its development of the Pontiac OHC six, the GM division built three different experimental SOHC 421 CID V8 engines in the early 1960s. According to the engineers who worked on the project, the SOHC 421 engines produced around 625 hp and were capable of turning 7,000 rpm.

One version of the engine featured camshafts driven off the front of the engine, another design had the cams driven by gears off the back of the engine. Apparently at least one of these engines survives under the hood of an engineer’s personal Pontiac.

 

[TripleB]

1967 Cadillac Eldorado V12

As part of the General Motors V-Future program, Cadillac developed an overhead cam V12 slated for production in the late 1960s. The V12 engine was to make its debut in the new FWD Eldorado in 1967.

Six prototypes engines were built in 1963 and 1964, all with a 60-degree architecture, chain driven overhead camshafts and hydraulic finger followers. The initial displacement was 7.4 L, but an 8.2 L was also tested. A number of different induction systems were tested, including a single four-barrel, dual four-barrel, and triple two-barrel carburetors, as well as mechanical fuel injection. Output ranged from 295 to 394 horsepower.

Based on the power output listed above you can see why the Cadillac V12 program was killed. Not only was horsepower disappointing, but GM was also concerned about the engine’s ability to meet upcoming mandated emissions controls.

 

[TripleB]

1969 Plymouth Weslake DOHC V8


It’s unknown whether this project was purely for racing, or Plymouth had the intent to offer the motor in a street car at some point. Keep in mind that the entire Chrysler group witnessed the excitement and positive impact on the brand when the previously race-only 426 Hemi was offered in production cars.

Following the 1968 season, Richard Petty announced he was leaving Chrysler and going to Ford for the 1969 NASCAR season. The money allocated for Petty was used to develop the Plymouth Indy DOHC V8. Design work began in February 1969 and running engines were provide to Andy Granatelli’s STP race team less than 90 days later.

The designer of the special cylinder heads was Harry Weslake, a British engineer best known for his expertise in gas flow through internal combustion engines. If you recognize the name, it may either be for his V12 engine in Dan Gurney’s 1967 Belgian GP winning Eagle, or the Gurney-Weslake cylinder heads used on GT40 Fords.

The engine lacked top-end horsepower necessary to compete at the high speed oval tracks, it had plenty of bottom-end torque which made it quite competitive on the short oval. In fact, Art Pollard drove the Plymouth-Westlake engine to victory at the 200-mile Indy car race at Dover, Delaware on August 24, 1969. This would turn out to be the only victory for Plymouth in the history of Indy Car racing.

 

[port austin pirate]

cool thread very interesting.never heard of these befor

 

[Sleek-Jet]

Being a big fan of the Rocket engines, I had heard about the W43, but pictures are very rare.

Lots of lore around that engine. Most of it comes down to GM didn't want any of the divisions to outpace Chevy, specifically the 'Vette. Besides the fact the engine would have cost more than the Cutlass it was going to be installed in. Hopefully they fixed the oil Gally issue.

I put a 455 in a 72 Cutlass, what a great combination.

 

[monkeyswrench]

I don't have my Midwest passport stamped...
I'm surprised no mention of the "Mystery Motor" Chevrolet. I've seen one, on a stand, sitting next to the Corvette it came in. I don't know the whole history and pedigree of the motor and development. The 'Vette was the Mickey Thompson deal. The motor looked like the offspring of a 409 and a 396...with some weird cast long tube exhaust manifolds.

 

[TripleB]

Here you go

Disowned by General Motors before it ever raced, the Chevy 427 Mystery engine became a legend in its own time. Here’s the story behind the story of this almost mythical V8.
The Z11 was developed strictly for drag racing, while the V8 that became known as the Mystery engine was intended solely for NASCAR.
Chevy enthusiasts will note that the Mark II V8 bears a strong resemblance to the familiar 396/427 CID Mark IV V8 (aka big-block Chevy) introduced in 1965-66—especially around the valve covers. Indeed, many have regarded the Mystery V8 as a prototype or version 1.0 of the big-block V8, but that’s not quite accurate. For one thing, no major components interchange. Meanwhile, the Mystery motor has also been described as an improved version of the 409 built on the same block, but that’s not accurate, either.
Probably the best way to regard the Mystery V8 is as a missing link between the 348/409 and big-block Chevy engine families, sharing aspects of both. The man responsible for the Mark II’s design is Richard L. Keinath, a key figure in the successful development of several Chevrolet V8s.
On the Mark II aka Mystery V8, the intake and exhaust valves are staggered, like on the 348/409, but also canted or tipped relative to the cylinder bores, a feature shared with the Mark IV V8. The bore and stroke are 4.3125 by 3.65 inches, identical to the Z11 V8, and the crankshafts are similar, sharing the same 2.500-in. and 2.200-in. main and rod journal diameters. (In comparison, the Mark IV 427 production engine employed a different bore/stroke combo, 4.251 by 3.76 inches, and larger 2.75-in. main bearings.)
However, the Mystery V8 required a totally different block casting with conventional, 90-degree cylinder decks. The decks on the Z11, as with all members of the 348/409 family, were cambered 16 degrees to provide a combustion volume in the cylinder rather than in the head—a brief fad in engine design also adopted by Ford and some industrial engine makers. The Mark II engine abandoned this unusual feature in favor of a traditional kidney-shaped closed chamber contained in the cylinder head.

 

[monkeyswrench]

Yep, that's it! Not a Chevy guy, nor a 'Vette guy, but the cool factor was impressive. I don't know if the same gentleman still owns them, but that is the pair I saw. The car had a 327 in it, and was a factory "white body". Me, not understanding cars of such pedigree, asked why the motor was on the stand. "If anything were to happen to that motor, it's really just another Corvette"

 

[old rigger]

Being a big fan of the Rocket engines, I had heard about the W43, but pictures are very rare.

Lots of lore around that engine. Most of it comes down to GM didn't want any of the divisions to outpace Chevy, specifically the 'Vette. Besides the fact the engine would have cost more than the Cutlass it was going to be installed in. Hopefully they fixed the oil Gally issue.

I put a 455 in a 72 Cutlass, what a great combination.

Always been an Olds fan but actually only owned 2.

When I was a kid my dad put a 425 out of a brand new wrecked car in his '56 Ford pickup. It was a runner.

When I was 16 I bought the running gear out of a '56 ford pickup that the guy drag raced only. This was in '72 and Lions had just closed so he wanted to make his pickup streetable. Perfect opportunity for a dumb kid, me. It was a 394, high rise manifold, dual carbs, vertex mag, big Joe Reath cam, 13 1/2 to one compression, fender well headers, 4 speed hydro, and in the deal I got the rear end with 4:56 gears. He ran 122 mph, 11.70's. I on the other hand could barely afford to put gas in it, let alone premium, but it was unbelievably fun to drive until I coughed it up street racing. Dad helped me rebuild with a little more friendly 10 1/2 to 1 slugs. Oh, I paid 300 bucks for everything and did the swap to my '56 pickup over a few weekends. He ran 'glass hood, front fenders and bumper and like an idiot I passed on the molds he had for all the parts.

Later in the late 80s when I was at Advantage I bought a 455, 410 hp, out of an old boat that we re-powered over the winter. I think I paid 75 bucks for it and it ran pretty good, we swapped in a BBC. Had it strapped to a pallet and in the corner of the shop. Nostalgic drags were a big deal then and I had my eye on a Henry J that I wanted to build for those races. Came in one morning and the boss had sold the Olds for scrap! That killed that project.

Anyway these scans are from a mag I bought through the mail back in the 80s offered by Petersen publishing.

 

[Carlson-jet]

I'm still dumbfounded sanctioning bodies in the racing field killed American technology and put us back 30 years.
OHC and 4 valves win out in Normally aspirated engines HP per cubic inch.
Cool thread.

 

[Flatsix66]

Amazing complexity to make power. Should spent more time developing the 12 Cyl Two stroke.

 

[Carlson-jet]

Amazing complexity to make power. Should spent more time developing the 12 Cyl Two stroke.

Detroit 2 stroke diesel was amazing for it's time. Turbos blowing into a Supercharger. A bit heavy but effective. Tree huggers killed it. It took 30 years to make that time up as well.

 

[monkeyswrench]

Detroit 2 stroke diesel was amazing for it's time. Turbos blowing into a Supercharger. A bit heavy but effective. Tree huggers killed it. It took 30 years to make that time up as well.

30 years to build the power and rpm, but the sound will never come back

 

[Sleek-Jet]

Detroit 2 stroke diesel was amazing for it's time. Turbos blowing into a Supercharger. A bit heavy but effective. Tree huggers killed it. It took 30 years to make that time up as well.

Do you watch Bus Grease Monkey on YT? I've been hooked on that channel for a while, it is amazing how simple and powerful the DT was.

 

[HydroSkreamin]

The Astro-I was equipped with this experimental Corvair engine, with a bore and stroke of 3.56 and 2.94 inches, displacing 176 cubic inches. It was air-cooled, but unlike the production engine, used three tandem centrifugal blowers on a common shaft above the engine to blow cooling air over the cylinder blocks. Designed as a high output unit, the engine produced 240 horsepower at 7200 RPM. Specific power was 1.4 horsepower per cubic inch! Each side of the engine was fed air and fuel by using a Weber style 3-throat carburetor on a special light alloy head with a single overhead camshaft. The cylinder heads had nearly hemispherical combustion chambers and inclined valves. Camshafts were driven by Gilmer-style belts from the crankshaft.(cut and pasted from Corvair Corsa.com) I’m becoming a bit of a Corvair geek, as I’m restomodding a 68 Monza for my wife. The above engine was way before its time. Don’t the runners look akin to an 8.1 truck intake? GM had multi-cylinder flat prototypes to run development chassis when they were developing the FWD Toronado. Kind of genius, as the cooling system on the air-cooled is simple. Power limited, but simple.​

 

[monkeyswrench]

View attachment 852080

The Astro-I was equipped with this experimental Corvair engine, with a bore and stroke of 3.56 and 2.94 inches, displacing 176 cubic inches. It was air-cooled, but unlike the production engine, used three tandem centrifugal blowers on a common shaft above the engine to blow cooling air over the cylinder blocks. Designed as a high output unit, the engine produced 240 horsepower at 7200 RPM. Specific power was 1.4 horsepower per cubic inch! Each side of the engine was fed air and fuel by using a Weber style 3-throat carburetor on a special light alloy head with a single overhead camshaft. The cylinder heads had nearly hemispherical combustion chambers and inclined valves. Camshafts were driven by Gilmer-style belts from the crankshaft.(cut and pasted from Corvair Corsa.com) I’m becoming a bit of a Corvair geek, as I’m restomodding a 68 Monza for my wife. The above engine was way before its time. Don’t the runners look akin to an 8.1 truck intake? GM had multi-cylinder flat prototypes to run development chassis when they were developing the FWD Toronado. Kind of genius, as the cooling system on the air-cooled is simple. Power limited, but simple.​

Belt driven centrifugal blowers for cooling...I think that's what looks like the 8.1 runners? The head setup looks like the unholy offspring of a Porsche and a tri-ported 110 or 140 head. I really like Corvair motors. They have a neat sound when cammed. Weird though, only motor I can think of I've had to lap the cylinders to the head.

 

[HydroSkreamin]

Yeah, those are the blowers.

They do have a cool sound cammed. I’m jonesing to hear what this 3L I’m building sounds like with 20 lbs of screwcharger boost at 6500...

 

[monkeyswrench]

Yeah, those are the blowers.

They do have a cool sound cammed. I’m jonesing to hear what this 3L I’m building sounds like with 20 lbs of screwcharger boost at 6500...

As long as it doesn't sound like a spoon in a blender!
With the blower, the cam could get to be interesting...I assume you have a cam grinder that does custom stuff. Are you going to run the screwcharger up top? If so, what type of cooling setup are you going to use for the barrels?

 

[HydroSkreamin]

I’m going to have to be strategic about it, that’s for sure.

It’ll either be right above the fan with clearance, or off to the passenger side where the spare tire well is. No matter what I have to take engine movement and thermal expansion into consideration. Width-wise the Corvair engines grow a lot due to thermal expansion of the aluminum cases and heads, and the cast iron cylinders.

It’s probably going to get a custom ground hydraulic roller (big$) but that’s what it’s going to take for the performance I want.

Exhaust will be custom mandrel bent stainless tubes replacing the stock straight tubes; basically starting the header at the cylinder head and not after the straight tubes.Each pipe will lay in order with a V-band flange, then the rest of the tube length and collector (also V-banded) will be attached. Most headers either turn really sharp or hit the ground; my goal is neither. Borla or MagnaFlow stainless mufflers will be on each side, might notch the valance for old school bell-mouths straight out the back, otherwise a baloney-slice parallel with the valance 1” out.