Oh, GM. Sometimes I feel like there is no novel engineering challenge beyond GM’s grasp, and simultaneously no defeat that GM can’t snatch away from victory’s highly selective jaws. While I’m not exactly certain that this example represents a significant lost opportunity, it is yet another fascinating technical chapter in GM’s history, and once again is an example of GM developing novel technology only to completely abandon it. And, even better, it starts with one of GM’s most innovative and infamous cars, the Corvair.
I’m not sure exactly how I’ve never heard of this before, but somehow the fact that there were once serious plans for a FWD Chevy Impala powered by a horizontally-opposed 10-cylinder air-cooled engine had eluded me. But no more! And now I’m going to make sure you all know about this incredible weirdo, too!
Yes, a flat-ten air-cooled engine. Driving the front wheels, on a car developed way back in 1961! What is this madness, and why does it exist? The answer, like all worthwhile answers, has to do with the Chevy Corvair.
The Corvair, in case you’re unfamiliar with the car or perhaps dropped your copy of Unsafe at Any Speed into your hot tub as you were lounging and reading, was GM’s answer to the wildly popular Volkswagen Beetle and other small, imported cars. It borrowed the basic VW formula of rear engines, horizontally-opposed cylinders, and air-cooling, but did it with particular American style and scale.
The Corvair was nothing like other American cars of the era; it was much more like a European car technically, and, interestingly, stylistically managed to inspire a whole generation of cars from Europe and (to a lesser extent) Japan:
So, after the Corvair came out in 1959, GM was already thinking about ways to not just improve it, but about the possibility of leveraging Corvair-derived technology all across the Chevrolet line. The first thing Chevy wanted to do for the Corvair engine was to solve the persistent issues of head gasket leaks. To do this, they re-designed the cylinder “jugs” – remember, on an air-cooled engine, the finned cylinders are separate from the main engine block, and are bolted on. GM designed cast combined cylinder-and-head modules that solved the leak problem entirely, since the cylinder head and jug would be one unit.
By designing cylinders and cylinder heads into one unit, they also managed to give themselves the building blocks of a modular engine system; this Corvair Mark II engine design could be built in configurations ranging from two to 12 cylinders, perhaps even more, hypothetically. Flat-twin and flat-four versions were built and installed into mules made from Renault Caravelles and Alfa Romeo Giuliettas, driving the front wheels and targeted at competing with Ford’s small FWD car project, the V4-powered Cardinal.
The Cardinal project ended up becoming the Ford of Germany Taunus, complete with FWD and a V4, but it never made it to America, as originally planned. It was reasonably successful in Europe, though.
In addition to the flat-2 and flat-4 engines, a flat-6 was built, as that would be a direct successor to the then-current Corvair flat-6, and flat-8 and flat-12 engines were at least planned and considered. But it was the flat-10 engine that ended up actually being built.
Count the cylinder heads on the side there: there’s five, which means there’s five on the other side, which means, yes, ten. This modular, air-cooled engine used carburetors from a six-cylinder Chevy engine, and you can see the large horizontal cooling fan driven by a 90° belt, just like on the Corvairs of the era.
Each cylinder in this new modular engine family displaced about 29 cubic inches, so 10 of them would be 290 cubic inches, or about 4.75 liters for the flat-10. The six-cylinder variants put out about 120 horsepower (a good jump from the original Corvair’s flat-6 that made about 80 hp in naturally-asperated versions) so the flat-10 easily have put out well over 200 hp, pretty damn good for the time.
As to why they picked a flat-10 engine instead of a flat-8 or something more expected, the reason is one I can certainly respect, as told to Dave Newell, writing in the April 1995 issue of the Corvair Society of America’s magazine, Corsa Communique; the Frank mentioned here is Frank Winchell, who was in charge of Chevrolet’s Research and Development Group:
“Because no one had ever done one! It wasn’t considered seriously by anyone but us, but we were very serious about the family concept. The Impala was to demonstrate the flexibility of that concept.”
Because no one had ever done one is a fantastic reason to make a flat-10 family car, I think. The team took the four-cylinder and six-cylinder engines they’d been working with and combined them to make the flat-10, which they installed in the front of their Impala test car, driving the front wheels.
This is significant because it shows they were thinking about using these modular engines not just in the rear-mounted Corvair fashion, but also more conventionally up front, and less-conventionally (for the era, at least) driving those wheels up front. To fit it, the front end of the Impala required some stretching, which was accomplished with fiberglass filler panels. You can see it compared to a 1962 Impala here, and note the extra length in front of the front wheelarch:
Interestingly, the front axle is between the engine and the transaxle, which was borrowed from the Pontiac Tempest.
Styling studies were even undertaken for the flat-10, air-cooled FWD Impala, and it did have quite a different look than most Chevys of the era. Even with no radiator up front, a big grille was provided to provide ample cooling air for what would have been the largest air-cooled engine on a production car to date, I believe. So why didn’t GM give air-cooling more of a go? Were they in the pocket of Big Antifreeze? Or Big Coolant?
Of course, as we all know, in our reality GM never moved ahead with the idea of a Corvair-derived modular engine system that would have allowed such incredible machines as a FWD, air-cooled, flat-10 Impala to exist. It’s yet another example of how at times GM – huge, stodgy, ubiquitous GM – can somehow come up with fascinating and novel engineering solutions, ones that no other carmaker would likely even consider!
And then, of course, GM being GM, they also demonstrate an incredible ability to just abandon so much work and development, never to be heard from again, and we end up with the GM we have today, with a lineup that’s generally so dull it could be a viable competitor to Ambien.
Oh well. I still believe in GM’s ability to surprise, and I look forward to when it happens again, because we all know it will, even if it comes to nothing.
GM in those days was omnipotent financially. They had the resources to do all kinds of concepts like this. Someone needs to total up the number of different engines they actually had in production in the 50s and 60s.
Cannot stop considering that Impala with bagged suspension, wire wheels and custom paint.
Interesting that you brought up Dave Newell. Some 50 years ago I was a member of the San Francisco Bay Area CORSA chapter and I could hardly imagine anyone as passionate about Corvairs and their engineering as Dave was. We had monthly meetings in San Leandro, and he usually had some interesting content to contribute.
I used to hang out at a Corvair repair shop at 876 The Alameda in San Jose. One day the owner brought in an abandoned project that was started before thinking it all the way through.
The idea was to create a flat 12 using two 110 HP Corvair engines that were bolted in tandem to a 3/4″ thick slab of 7075 aluminum alloy. The connection to mate the crankshafts hadn’t been worked out yet, and the idea was to use a Jag V-12 distributor on one engine to provide spark to the 12 cylinders.
But after talking about it for awhile over a couple of beers, it became apparent to Jim, the owner and me why the seller gave up on the project.
The engine combination would fire simultaneously on each side, resulting in a vibration that could really limit the RPMs and power output..and if you clocked the crankshafts out of phase, who knows what you would end up with.
So the project died, but he ended up with 2 nearly new engines, which was why he jumped on the deal in the first place.
Fascinating stuff, I’d never heard of this before. Of course, my mind immediately goes to a flat-16 engine…
British Racing Machine (BRM) was ahead of you…
BRM built P75 H16 engine for its P83 racing car. People who heard the engine running were spooked out.
Wasn’t the BRM P75 H16 water-cooled, though? Porsche produced a handful of air-cooled flat-16 engines circa 1970-’71: https://www.autoevolution.com/news/i-bet-you-didn-t-know-porsche-built-a-16-cylinder-engine-156151.html
Yeah, Porsche did likewise, their minds went from a flat-12 in their 917s to a flat-16 where they built at least four such engines around 1970-’71 though none of those engines were actually used in races. The flat-16s actually worked but Porsche ended up going in a different direction with further development, which included turbocharging, of their other engines.
It’ possible they had some Wright R-3350 engineers come along and ask them if they realized what a goat-fuck that was until they worked their shit out, and did GM want to go through the same thing when a 283 small-block was working pretty well for a family car. I’m a’ thinkin’ the bean counters won that one for good reason.
“…To fit it, the front end of the Impala required some stretching, which was accomplished with fiberglass filler panels. “
Um – Nope – Look again
Those are entirely different fenders and hood.
And it looks fantastic.
I don’t know how GM spends so much time, effort and money on innovating things just to have them shoved into a bottom drawer somewhere. It boggles the mind.
I can see how this type of situation might have also been a setup for poor morale and quality of future work. Imagine you wind up spending months or years on projects that are close to production only to get shut down, so the next time you get on a project, you put kind of half-ass it – thinking it will never get green lit – just to see it get approved after all, but there’s so many issues with it that you don’t have time and funding to fix before it hits production.
That’s how Vegas happen.
OR, letting employees work on fun passion projects (which they know are not likely destined for production) is a great way to keep up morale because designing the same bland family sedans all day, every day is mind-numbing.
That’s how mid-engine Corvettes happen.
Mid-engine Corvettes have only been in the works since the 1960’s.
Entire careers have begun and ended in that time – including Zora Arkus-Duntov’s
https://www.hagerty.com/media/automotive-history/chevrolet-took-52-years-to-put-make-the-corvette-mid-engine/#:~:text=To%20top%20it%20all%2C%20the,he'd%20committed%20so%20much.
Good grief can you imagine the fucking racket this thing makes. Like a Beetle, but much, much worse.
Did they forget the copper cooled Chevrolet engine debacle of 1923?
Too bad GM didn’t build it. They could’ve called it the Chevy Impair.
200HP good for the time; I still haven’t owned a vehicle with more than 200HP.
Filler panels to make the vehicle longer, just what the 1960’s needed.
The styling study really reminds me of the 58 Plymouth Fury. Probably because of the double round headlights and the shape of the bumper.
This is really fascinating.
“the GM we have today, with a lineup that’s generally so dull it could be a viable competitor to Ambien.“
I’m plenty critical of GM when deserved, and if this statement were directed only at their mass market stuff, I’d call it defensible, but I’d take GM’s niche/exclusive vehicles over just about any other company.
You can buy a 500 hp mid engine supercar from them for less than a 2.0T vinyl seat sedan from the German luxury brands!
Oh, and if there was any doubt, the H10 Impala is V10omous approved.
Interesting idea, but as someone who lives in below-zero land, I’ll stick with liquid cooling, thank you very much.
Eh, as long as the heating system is properly fettled (extremely important, as it’s all too easy to let things slip by and end up with a poorly functioning heating system) or the vehicle has something like an Eberspächer fuel-powered pre-heater most air-cooled vehicles actually do just fine even in polar conditions. If air-cooled vehicles actually did so poorly below zero then Beetles wouldn’t ever have reached the levels of popularity they did in Canada and the Arctic Circle countries.
Here’s a picture of a lovely red Beetle, actually stock in Scandinavian spec as per how the factory sent Beetles to dealerships in countries around the Arctic Circle, just chilling (ha) with some friendly penguins in Antarctica: https://www.clubvw.org.au/assets/images/austhistory/Antarctica11.jpg
Here’s a good write-up about the Beetles used by scientists stationed in Antarctica: https://www.clubvw.org.au/vwreference/antarctic-vws/
And here’s an excellent video that digs deeper into the Beetles used over the years in Antarctica: https://youtu.be/hqr7t7nBIVA?si=lhcpQUED5BjVMTkh
There is a huge gap between the air cooled engine operating well at low temperatures, and the heater working well at low temperatures. Soichiro Honda was a fanatic about his engines being air cooled until some engineers showed him just how much faster and better the liquid cooling made HVAC.
Yeah, to be sure, it’s a lot easier to engineer heating systems with liquid-cooled engines; it’s just that the idea that air-cooled vehicles are unusable in cold climates is all too common and is all too often played up for hyperbole. Decades of poorly maintained or rusted-out air-cooled VWs have unfortunately reinforced such a misconception (rust in the heater channels does tend to let the heat out before it reaches its destination, ha.) When everything is properly sorted or an Eberspächer heater or the like is installed then such vehicles are just fine in the cold. Might take a little longer to heat up but once the heat gets going it’s all good. In fact, I actually had the soles of my Converses melt from the heat coming from the floor vents of my family’s then late-model (and not rusted) Beetle on more than one occasion; I’ve never had that happen with liquid-cooled cars, go figure…
First car was a 58 vw bus. I lived in Saskatchewan which gets world class cold in the winter. The bus was fine in the winter, no problems with heat or starting. It was at the time I owned the same age as i was.
My grandmother had a Corvair with a gasoline powered heater.
That’s the problem, it’s an extra layer of complication. Liquid heat is just so much more practical.
I see the stories of people keeping warm with VWs and Corvairs, but that wasn’t my experience back in the day. Everyone I knew who had one hated the “heat”, my buddy had to park his 911 convertible when it could get below freezing.
Yeah, seems like your experiences (and your buddies’ experiences) were with poorly maintained or rusted-out VWs/Porsches, unfortunately. (Plus, convertibles aren’t exactly renowned for being toasty warm in the wintertime, ha.) In addition to all those stories of people including these Antarctic scientists keeping warm I can testify myself that having experienced properly maintained and rustfree VWs I know how well the heat can work even in New England winters.
As for extra layers of complication, plenty of people even in the far north were fine without the likes of Eberspächer heaters, plus they didn’t have to deal with making sure the coolant was the correct mixture of water and coolant (not to mention making sure it was the right kind of coolant lest the mixture turn into a congealed mess or corrode the engine’s materials or both) or making sure the rubber radiator hoses were in good shape or making sure the radiator or heater core wasn’t clogged or making sure the blend doors inside the HVAC ducts were functioning properly, etc, etc. Between all that and making sure the VW’s heater channels and heater exchangers weren’t rusted, the cable connections were intact, the flexible hoses were connected, etc, etc, it’s kind of a wash between air-cooled and liquid-cooled with perhaps a slight edge towards air-cooled for relative simplicity and *especially* when one has to replace a bad heater core. Those of you who have ever had to disassemble an entire dashboard and half of the car’s interior just to reach the heater core (& deal with draining and disposing of the coolant, etc, etc) know all too well just how much of a hassle it can be.
In any case, an air-cooled ten-cylinder engine is going to produce a heckuva lot more heat than a four-cylinder engine, whether it be air-cooled or liquid-cooled, that’s for sure!!
It’s kind of moot, anyway, since it’s harder to achieve emissions control standards with air-cooled engines due to the greater variance in engine/exhaust temperatures typical of air-cooling whereas liquid-cooled engines tend to maintain a more constant operating temperature which is more conducive to the current technology of emissions control. Porsche held out for a long time with air-cooled engines but eventually changed to liquid cooling for that very reason.
The Taunus name was used for several cars but the one shown above is the wrong series for the V4 engine and FWD. This one instead has a straight four and is RWD.
Also, that generation Taunus *was* sold in the US, but in limited numbers. Our mutual racing friend “Spank” Spangler had one for a while and I saw it at his place. I noticed it because I had never seen one with sealed beam headlights, a requirement for the U.S.
In fact in the course of trying to find a photo of a US Taunus, I found an article which I think is referring to the actual specific Taunus that Spank owned.
https://rustybuttrusty.com/2014/02/18/fomoco-tuesday-1962-ford-taunus-17m/
holy crap, that sealed beam conversion!
Based on the comments in that post, it appears that may be a homemade sealed beam conversion, but here are more details on US-market Taunuseseses.
https://www.enfostuff.com/forum2/viewtopic.php?t=30
I believe you’re thinking of the plural of that other similarly-named Ford:
https://www.2040-parts.com/_content/items/images/90/890890/003.jpg
What, Lamborghini 350 GT headlights aren’t good enough?
Crap! Sorry, I fixed it!
Thanks! I once saw a Taunus of the type you originally used (a “Badewannetaunus”) here in the US, although not the one that LTDScott mentioned as belonging to our mutual friend, and I still recall the disappointment of realizing I wasn’t seeing the original home of the V4 used by SAAB.
I feel like GM engineering deserves the description “ambitious but rubbish” even more than Top Gear. GM’s history is littered with innovative stuff that either flopped,, never hit production, or hit its stride the year they discontinued it.
The only thing worse than a GM engineer is a Chrysler engineer. The only engineers worse than them are the people who design refrigerators.
“The only engineers worse than them are the people who design refrigerators.”
So… Nash-Kelvinator Engineers… which became AMC… which became Chrysler… which became DaimlerChrysler… which became FCA… which became Stellantis?
I very wholeheartedly disagree with this statement. The engineers at GM are second to none. Unfortunately, so are their accountants.
You’re not wrong, the Vega could have been a decent car if it hadn’t been relentlessly cost cut. The other classic GM bone head move was protecting the Corvette, which hamstrung the Fiero and killed the Banshee
The standard GM model is to introduce a fundamentally good idea slightly half baked, accrue several years of negative publicity and poor sales, spend a lot of money to fix everything, but get the improved model onto the market after everyone has already stopped caring, and then discontinue it almost immediately.
At this point I wouldn’t call GM ambitious, just curious. They rarely have the guts to produce something innovative, but they can’t help themselves developing it anyway just to see what it’s like. Even when they do produce innovative stuff, they quickly become embarrassed for putting themselves out there like that and retreat to their comfort zone.
I currently drive one of those products! The Volt is an incredible feat of engineering. It never ceases to amaze me how well they executed that thing. However, after the inital hubbub of the first generation, I feel like they sort of…forgot about it? The second gen (which I drive) is a massive improvement, but I barely remember anything from when they came out.