(first posted 6/14/2017) A ten cylinder Corvair engine installed in a FWD ’62 Impala? How’s that to get the juices of a hard-core Corvair air-head going?
One of the highlights for me of the recent Detroit trip was the little museum in Ypsilanti, in a former Hudson dealership. It was small, but a welcome reprive from the mega-scale of the greenfield Village and HF Museum. Here we could get intimate with the displays, and there were some gems, including a few Corvairs. And there was this modular Corvair engine display, including two actual six cylinder engines and info on the program. It was mostly new to me.
Here’s the basic info. In 1961, the Corvair was still deemed to play a significant long-term role within Chevrolet, so a development program on a gen2 modular engine was undertaken. The actual Corvair had a single alloy cylinder head on each bank of individual cast-iron cylinder barrels.
The mod engine used individual cylinder-head units, cast as a single unit, eliminating the head gasket altogether. There was no info, but presumably there was a cast-iron liner in the cylinder for wear, as the Nikasil system developed for the Vega presumably was still a distant (bad) dream.
Here’s a look at one of the engines on display. The cooling shroud has been cut away on this side to clearly show the cylinders.
Here’s the other side, with its individual valve covers and log intake manifold.
The bottom of the cylinder has a large rectangular base, which is bolted to the crankcase.
The view from underneath shows that each cylinder has its own integral pushrod case, rather than the leak-prone tubes in the production Corvair engine.
The real key difference of course is that it was designed to be modular, and everything from two to twelve cylinder versions were designed, although the eight and twelve cylinder versions were not actually built.
The four cylinder version was of particular interest to Chevrolet.
It was used in FWD prototype small cars, a configuration that was of course also used by Citroen (GS) and VW in Brazil (Gol).
I showed this image at the top, but it’s worth contemplating a 10 cylinder air-cooled FWD Chevrolet Impala again. Or maybe it shouldn’t ever have been contemplated. The text said that this powertain led directly to the Olds Toronado, but it’s well known that Olds had been experimenting with FWD cars from the late 50s, and gave serious thought to building a FWD car in about 1961 or so.
The proposed engine was for a 1964 introduction, but the expense in re-tooling was obviously not justifiable. And GM was moving towards a more conventional RWD approach with its small car development program that would eventually lead to the Vega, which had a very different type of engine. But if you’ve ever wondered why the Vega did have an aluminum block, it was largely to keep GM’s Tonawanda aluminum foundry going, after a huge investment for the original Corvair engine.
What might have been…which pretty much sums up the Corvair program.
The engine is fascinating! I’m almost as fascinated that it has existed for 50+ years (including 20+ years of the Internet age) and this is the first I’ve heard of it.
Likewise. And I thought I knew everything about the Corvair, given my 57 year obsession with them.
Thank you very much.
Wow, four MORE cylinders to leak oil out of every one of the many seals and eight more push rod tubes for oil to pour out of,,,,,, sounds like a winner!
Even the 6 cylinder version wasn’t known for particularly good gas mileage.
My best friends mom had a 62′ 63′ red Corvair coupe, (it WAS a good looker) and I remember the huge cardboard boxes flattened out and placed under that thing.
They were always SOAKED BLACK with oil.
At around 65000 miles that Corvair was a noisy, ticking,smoky, leaking pile of junk that looked almost new,,,, she traded it for a 73′ Nova with a 307 that had a lifter tick from the get go but was an excellent car overall for a decade.
Meanwhile my mom’s 62 Falcon just worked, year after year and was purring like a kitten when traded in in 72′ for a Maverick 2 door with a 302.
That Maverick was F U N !!
No pushrod tubes, they did away with that in picture # 7
Hey I missed that, I never understood why GM didn’t just quickly mod that on the existing Corvair engine because those tubes leaked like crazy even on young engines……
…as well as air-cooled VWs.
The one sealing surface in Corvair engines that has NOT had a leak problem since about 1970 is the pushrod tubes. Very early on someone realized that the problem was the O-ring material turned hard and crispy at the temps the engines were seeing (not to mention acidity of hot oil). The solution was pretty simple–make the pushrod tube seals out of another material, which turned out to be Viton.
Now, that’s not to say that there weren’t hundreds of thousands of Corvair engines with this problem for many years after, but that mainly had to do with awareness, service / rebuild cycles, willingness to invest the $ for the work, etc.
2packs4sure,
Your post does includes no actual ownership and opinions from second and third party. How were those cars maintained?
You also failed to note that VW/Porsche/Corvair can and will leak oil. In case your are not aware, the venerable air cooled 911 flat six Porsche motor, has many more times the number of leak points than a Corvair motor; as each case bolt has two O-rings, since the case bolt is also the main oil gallery, plus the oil return tubes and twice the number of valve covers for the SOHC motor.
The Corvair has one valve cover per head, but I sure would trade that for the chance for having the SOHC Corvair prototytpe motor from the Astro show car.
GM failed to use Viton O-ring material and instead used buty which did not last as long, that was their mistake and accounts for your friends oil soaked cardboard. How an owner abuses or does not maintain their car is not the failure of the original design. Today a smart Corvair owner has changed those butyl O-rings to VIton.
Your mom’s Falcon was not an example of advanced 1960’s engineering talents, as was the Corvair. The Falcon was just a tired example of 1950 tired engineering, blue oval style.
Chevy/GM took the gamble and in many ways leading both design and engineering goals with the Corvair over other Ford, unlike the boring Falcon which then was used for the basic bones of the early Mustang. If I was you I would not be too proud of a Maverick, an ugly version of a Mustang II.
The 2nd generation Corvair was a good match for the newly released 1964.5 and 1965 Mustang in engineering, design and handling.
The Corvair was a sufficient marketing threat for a sporty car, that Ford rushed into production the Ford Mustang from Falcon bits and pieces. To Ford’s credit and the Corvair having started a desire for a sporty car market. Remember the Corvair was an entire model line from Chevy and included; coupe, convertible, sedan, truck and van all powered by the aluminum flat six Corvair motor. If you doubt the real facts, read lee iacocca autobiography, he was deeply concerned with the Corvairs popularity and the new market it helped create.
Ford with the Mustang took that market with a V8 power and cheap gas. The Corvair was introduced as an economy car and was/is today capable of 20mpg and better.
“If I was you I would not be too proud of a Maverick, an ugly version of a Mustang II.
The Maverick and Mustang II do NOT share a platform and have no common parts. The rear differential is similar, but the track is different, while the automatic transmission is common, but shared by many Ford models.
Mustang II had more in common with the “Pinto” . The “Maverick” had an entirely different platform.
The Maverick was more based from the Falcon platform in which the 1975-80 Granada also used as well. The original 1964-66 Mustang used that identical platform. The 1967-73 used note I mentioned similar not identical but updated platform from the 1964-66. The Pinto was an entirely different new platform for 1971 which shared with no other larger Ford product lineup. The Mustang II even though it was based on a stretched Pinto platform actually was modified to set it apart from the Pinto much like the 1975-79 Cadillac Seville with the 1975-79 Chevy Nova and 1970 1/2-81 Chevy Camaro or the 1975-80 Monza were to the 1971-77 Vega.
And more overhung weight at a greater distance, to take more weight off the front wheels.
GM’s various engineering labs of the early 1960s must have seemed like toyshops, where engineers went to play instead of work.
Although I had never heard of this program, I am not surprised as I have never been much of a Corvairhead. But what a cool idea! We will always be left to wonder how life might have been different if the 4 and 6 cylinder versions of this boxer engine had made its way into the Vega instead of the abomination that it actually got.
I’ve always found it interesting when GM would use a full size car as a test mule for something. In the 90s there was supposedly a box Caprice running around the GM proving grounds with a V12 out of a BMW installed in it as part of a test bed for greater than 8 cyl engines.
There was also supposed to have been a V12 Yukon prototype in the 2000s.
It was a V16 Cadillac engine in a Yukon/Tahoe.
Whoa, I am a Corvairhead and I’ve never heard of this before. JP is dead on.
Another stellar job by Curbside’s automotive detectives. Always thought of the Monza GT as a car that could’ve saved Corvair, sort of a 914/6 with Styling:
And then a decade later there was that Wankel mid-engine Corvette that really was on a 914 chassis to save development time, saved from the crusher at the last moment:
Towanda, or Tonawanda?
WNY pride compels me to ask. Otherwise, a great article about a brilliant and somewhat flawed engine! I know this type of innovation was not limited to the post war era, but Kudos to GM for trying.
Yeah,
As someone who grew up in Towanda, Pa. there is/was no GM foundry there. And whenever I would tell people I lived/grew up in Towanda….people assumed I meant Tonawanda, New York. Somehow I figured folks never made the same mistake about Tonawanda really being Towanda.
Tonawanda.
That foundry in WNY closed in about ’83 and, along with many others- auto and steel related- was devastating to the local economy. Tonawanda has a lot of history, and lies about half way between Buffalo and Niagara Falls.
Imagine what that 10-cylinder air-cooled engine must have sounded like!
Pretty cool I bet. I once heard the Corvair’s engine sound as being described as a “chain-driven vacuum cleaner”. That’s a pretty close description actually to to my stock 95HP/Powerglide Corvair. Higher horsepower versions, with a nice exhaust system, however, have a cool, distinctive exhaust note.
I guess there is a reason I am not a mechanical engineer, but it seems that a modular design for engines should be more common. I have read that most companies seem to be going for a 0.5 Liter per cylinder target on most engines now, and I am sure that bore and stroke are going to be different for various applications, but why not more modular designs? This seems like it would have been a great savings on development costs for different applications.
You’d be surprised how many modular designs there are.
Everything from the Cummins B-series (modular design in 3, 4 and 6 cyl variants, though I don’t think the 3-cyl was ever built) to the Ford modular families of the 1990’s (in IIRC 6, 8, 10 & 12-cyl variants) and VW (VR & W block engine family).
The new Mercedes Benz straight 6 engine was designed not for nostalgic reasons but cost issues – it is based on a new 4 cylinder design so I guess this new family of engines could be called modular.
They were fairly common from 1960 until fairly recently at General Motors. The first modular engines were the GMC big blocks for 1960 followed soon by Buick and Chevy in 1962. In the later 1970’s, Chevy small blocks started having two cylinders removed and even Oldsmobile did the same thing with the diesel V8.
The Atlas engines from 2002 (4, 5, and 6 cylinders) and even the LS V8 had a couple of cylinders removed for a V6 pickup engine.
Ford, Chrysler, AMC as well as Cummins had modular engine series. Continental also did the same thing with their vocational engines and airplane engines as did Lycoming (aircraft).
When Paul writes, “mostly new to me,” I perk up, ’cause I know it’s gonna be especially interesting.
I never heard an inkling of this, but figure GM then had money to burn, and so was flexing is research/engineering muscle on stuff like this.
Somewhere there’s someone still alive who worked on this—but how do you find these folks?
BTW, glad to hear the Ypsi museum was worth the (short) drive. I’ll have to check it out sometime.
Awesome post Paul! This is the stuff that keeps me coming back to CC. Thank you.
Just imagine what the could have achieved if R&D had continued.
My guess is that they were already seeing the limits with emissions and engine temperature management. I’m trying to imagine the cooling fan required to keep that thing from melting down if you ever got stuck in a traffic jam, and the thermostat control required to get up to and keep it at optimum temperature. I’m left wondering why the oil cooler wasn’t enclosed in the cooling tin…Water cooling was probably considered, and dismissed, due to size and weight issues. Even Porsche and BMW (motorcycles)- brilliantly engineered as they were- had to abandon the air cooling eventually.
This find is an impressive one indeed – as others have said, I have never heard of it after many years of Corvair watching. I would love to learn more!
It was a fabulous little museum. I enjoyed seeing what the drive chain on a TH425 looked like.
Rhe know nothings that comment on oil leaks haven’t heard of Viton seals. My 64 4dr doesn’t leak a drop.As for the gas mileage qip, my Monza’s mileafe IS down due to the alcohol content of the fuel. There are a lot of uninformed people out there. I have owned and driven. Corvairs since ’70. My current one is a barn find with 33,000 miles on it.
I wish I’d known about that viton stuff back in the 70’s- it would have saved me all kinds of grief. Well, I was just a kid… How well did it work on corroded push rod tubes and engine cases ate up by road salt?
If only the Chevrolet engineers had heard of Viton seals: they would not have had to redesign the engine….
The story I heard was that Chevrolet engineers were aware of Viton or similar compounds, but decided on regular rubber seals after research found the Viton like alternative did not seal as well in severe cold weather.
I resealed my 72k mile, oil leaking, Corvair engine with Viton o-rings and after 20k miles and some 100+ temp days, I’m very happy to say its finally been taught not to mark its territory when we’re visiting friends.
A Corvair-knowledgable 2009 article here with interesting tidbits, including today’s engine sorta-mentioned in #20: http://articles.chicagotribune.com/2009-07-12/news/0907090687_1_chevrolet-corvair-motor-trend-heater
While it seems the Flat-Twin and Flat-Four versions of the modular engine were used in 2/4-seater prototypes that were presumably equipped with FWD.
It would have been interesting seeing the Corvair joined earlier on in the 1960s by a pair of smaller related rear-engined models with similar styling, mainly sold in both North and South American markets (the latter where Volkswagen’s rear-engined models dominated for decades).
One GM sub-Corvair model being a Flat-Four engined 4-door 4-seater along the lines of the Volkswagen Type-3/4.
The other GM sub-Corvair model being a Flat-Twin (or low-displacement Flat-Four) engined 2/4-door 2+2/4-seater loosely akin to the earlier Peter Brock designed 2-door 2-seater 1956 GM Cadet, though possibly of similar dimensions to the BMW 700 if not closer in size to the Simca 1000 and NSU Typ 110 for US tastes.
Great article Paul, on a subject new to me.
Thank you for it.
Dr.Gino Donatelli was a G.M. engineer from 1959 to 69, showed blue prints of a single overhead and dual overhead cam six, and a single overhead cam 8 cylinder, air cooled, with healthy size oil coolers.
Some info and pictures on other factory experimental Corvair 3rd-gen engines can be found here:
http://corvaircenter.com/phorum/read.php?1,197075,page=1
One more little postscript–Popular Mechanics “Detroit Listening Post,” Feb. 1961:
Wow! Where can I get one of those. They pulled the plug too fast on that one. I have a 64 Monza that weighs in at 2000 lbs. Not Muscle car territory but not slow. Great article!
The Vol 1 book by John Wipff has an article in it from an old CORSA (I think) and the author had purchased at least one complete 6 cylinder version of the modular Corvair engine plus parts. IIRC he was from Colorado but his name escapes me… Ron Nordquist maybe?. He had the engine in his coupe. It had no head gaskets b/c the cylinder+head were 1 piece, and the valves were parallel (to allow machining and inserts via long tool reach into the head from the chamber side. The drains for the rocker arm lube were through cast chambers under each cylinder. One problem not related to the modularity is that GM engr Adelbert “Al” Kolbe had to design a flexible flywheel to decouple crankshaft bending modes due to the reduced number of main bearing webs. The Corvair engine cases uses 4 main bearing webs, and that’s not nearly as rigid nor as massive (from weight) in aluminum than a 7 web in cast iron would be. Porsche learned from that and used a 7 web in their 6 cylinder engine (designed after the Corvair),so if you really wanted to build a 8- or 10-cylinder flat Corvair engine, you would be wise to learn from those lessons especially if you have a custom crankshaft made.
1. The Vega 2300 was not a “Nikasil” plating, it was hypereutectic aluminum, Reynolds A-390 alloy that includes 16% silicon that crystalized as the molten aluminum cooled. The aluminum was honed away leaving the partially-embedded silicon crystals as the bore wear surface.
2. The museum text says the modular engine/’62 Impala led INdirectly to the Toronado, not “directly” as in your text.
Nice article. I had no idea this existed.
Speaking of the GM Tonawanda engine plant, besides the Corvair and the Vega engines, whose blocks were all cast there, that was also were all the Chevy 366-396-402-427-454-496 and 502 big block car and truck engines were built. I remember once sometime in the early-or-mid-1970’s driving on the QEW highway somewhere between Hamilton and Toronto Ont. passing a chromed-up NY-plated GM Astro 95 cabover tractor pulling a 48 ft. trailer with large lettering down the sides with the words “GM Tonawanda”. Some grafitti artist had underneath the official signage, hand spray painted the words “Home of the Rat Motor!” Thinking back that truck was probably hauling a load of brand new big block Chevy engines to the now, as of 2019 stated to close after more than 100 years of auto production GM Oshawa assembly plant.
Between the Corvair, the Buick 215 V8, and the Vega, you’d think GM would have learned enough about aluminum that the HT4100 and Northstar wouldn’t have been so problem-prone–or not aluminum blocks.
You probably know that newer versions of these engines had few problems. So GM did solve the issues eventually. Even Rover with the Buick 215 solved the issues.
This time around, something rung a bell in my head. The Franklin Company made air-cooled engines for their cars prior to The Great Depression. The company failed during the Depression and was bought out by some employees, and renamed Aircooled Motors in 1937.
They made air-cooled flat engines with individual cylinders, and the same “modular” H-4/6/8/12 concept, VERY much like this stillborn Corvair engine, starting in 1937.
I wouldn’t say the engines Chevrolet built were a direct crib, but you can sure see the impetus of the idea. I wouldn’t necessarily say that Franklin/Aircooled *invented* the idea – I’m not sure who did it first – but the Chevrolet design certainly wasn’t original.
https://www.wingsofhistory.org/franklin-199-e3-90-hp-engine/
Interesting side note… in 1947, Aircooled Motors was bought out by Preston Tucker with the idea of producing engines for the ill-fated Tucker automobile.
As lid in “60’s-70’s, wstrn PA”. Franklin Company was glass manufacturer. “Plant in “Butler PA” was a decaying relic far back as I can remember.
Went down for good in “early 70’s”.
According to the Wikipedia article, the company was sold to a Polish firm and continues operations there to this day.
The Corvair was not the first air cooled Chevy. The “copper cooled” Chevrolet of 1923 was.
Aluminum heads on cast iron blocks have been common on American engines with good results. Early Datsun Zs had that set up with good durability. The HT 4100 had cast iron heads on an aluminum block. These developed many problems, but later development improved the engine in the 4.5 and especially the last 4.9 models. The same concept but with much better engineering. GM wisely canned the HT moniker, I was not aware that the later engines were just improved designs, I thought that they were a new engine. The 4.9 is the one to get. That didn’t help my middle aged co workers with DeVilles, Sevilles, and Eldos that blew their head gaskets. My ’94 Northstar only had problems with oil leakage as it aged.
My Dad had a Corvair van back in the early ’60’s and later a Monza with a four speed. It ran pretty good, but I imagine that the engine was too expensive to build and use on only one model range. Existing V8s and sixes were cheaper and proven technology.
Imagine this fitted into a ’62 Impala. Right? Now try and do a valve job.
I did not hear the corvair powered RV mentioned.
They were built in Hutchinson Kansas, and the owners used to meet there on occasion.
https://ultravan.org/ultra-van-brief-history/#:~:text=Corvair%2Dpowered%20Ultra%20Vans%20were,end%20of%20the%20Ultra%20Van.