(first posted 6/5/2014) Turbochargers are becoming ubiquitous. At the rate that manufacturers are adopting down-sized turbocharged engines across their model lines, naturally aspirated engines may one day be a quaint memory. The turbo revolution has had its ups and downs; or should we say boosts and lags, but here’s where it really started, in the Corvair Spyder, beginning in 1962. Yes, the Oldsmobile Jetfire came out a few months earlier, but its complicated systems soon had its maker pull the waste gate on it. The turbocharged Corvair was the first car to expose the masses to the joys of turbo boost.
The history of the turbocharger is almost as old as the internal combustion engine itself. The benefits of forced induction were understood by both Gottlieb Daimler and Rudolf Diesel, and they experimented with pump-driven forced induction on early versions of their engines in the latter years of the 19th century. But it was Swiss engineer Alfred Büchi who first patented the exhaust-driven turbocharger in 1905, although it would be some time before it was successfully built and used. Early uses were mainly airplane engines, to allow high altitude flying, and large diesel engines for stationary, locomotive and ship use. The first automotive application was the 1938 Swiss Saurer diesel truck.
So why and how did GM come to be the first to apply turbocharging to a gasoline-engined passenger car? They were no stranger to forced induction small engines; the 1951 Buick XP-300 concept had an aluminum 216 CID (3.5 L) V8, with a Rootes type supercharger that made some 339 hp. The GM labs were likely the greatest ones in the automotive world, so , undoubtedly they had experimented with turbocharging. And the first years of the 60s was a time of great innovation at GM.
The 1962 Jetfire aluminum V8 had similar displacement (215 cubic inches), and was rated at 215 hp. But it used a high 10.25:1 compression, ratio, which required the use of a water-methyl alcohol injection system to cool the fuel mixture as a deterrent to dangerous pre-combustion. The Jetfire quickly became a maintenance and reliability nightmare, and many were converted by dealers to convention four barrel induction. Few of the 9,607 built survived.
Wisely, Chevrolet took a more conservative approach with turbocharging its air cooled Corvair engine. Compression ratio was lowered to 8.0:1, which helped reduce the chance of pre-ignition. Maximum turbo boost was 10psi, not insignificant, and was essentially limited by the design of the exhaust system, which featured a very throaty low-restriction muffler and short and fat 9″ tailpipe. These turbo mufflers came to be used commonly as an aftermarket muffler on V8 performance cars of the era, and for some time, “turbo muffler” became almost a generic term.
The Corvair’s turbo was built by TRW, and hid under that chrome bullet-shaped cover on the right. A side-draft 1½” Carter YH carb fed the turbine, in a “suck through” system. The Spyder engine received many heavy duty parts, such as a special alloy-steel forged crank, stronger connecting rods, special pistons and rings, and tougher valves and seals, among others. Output jumped to 150 hp (gross), at 4,400 rpm from the 102 hp up-rated 145 cubic inch naturally aspirated engine. Torque jumped by 64%, to 210 lb.ft. @ 3200-3400 rpm. Chevy claimed that “usable power” increased by 90%, up to 3000 rpm; that would be after the turbo spooled up, of course.
Before we consider how well the Spyder engine worked, the question is why turbocharge it, instead of increasing power by the more conventional means. Chevy was certainly no stranger to extracting well over 1 hp per cubic inch; in 1962, the 327 V8 was making 340 hp with a carb and 360 with fuel injection. The reason was that the Corvair cylinder head was designed for an economy car, not a sporty one, and had quite small valves and ports. And most likely because of its being air-cooled, it may have been difficult if not impossible to change that, without a major re-design. Forced induction is the best solution for a poorly-breathing engine. Or at least an expedient one.
Here’s Chevrolet’s take on the Spyder, with some nice footage of it at work. The throaty engine sound is quite unmistakable, and there’s a nice shot of it being pushed hard into corner, creating a bit of smoke/dust from the rear wheels.
Car and Driver tested a Spyder in their May 1963 issue, and a reprint is on-line here, at corvair.org. The review is generally very positive, inasmuch as this Spyder really was as close as anything Detroit made to a Porsche, especially an affordable one. And with the Spyder package only costing $317.45, which included the four speed transmission, sports suspension, a new dash with full instrumentation, and other goodies, it was deemed quite the bargain. Which led to demand quickly outstripping supply for it.
Performance was very considerably improved over the normally aspirated Monza, with 0-6 coming in at 11.7 seconds. Not bad, for a small sporty car for the times, and certainly better than plenty of genuine sports cars (MG and such). The very slow steering come in for criticism, as usual.
Obviously, there was turbo lag, since full boost didn’t come in until 3200-3400 rpm. And since the Corvair engine peaked out at or before 5000 rpm, keeping the Spyder in the boost was a bit challenging, especially in the first two gears, which were quite low (3.65; 2.35). The Spyder’s turbocharging was most effective and enjoyable at higher speed, in the top two gears. But C/D still found the Spyder to be quite pleasant around town, being perfectly tractable and no less responsive below its boost than the 102 hp engine, if not even better, oddly enough. For a first shot at mass-market turbocharging, the Spyder was a success. And the engine was tough enough to take it without ill-effects.
In 1964, the Corvair engine’s displacement was increased to 164 cubic inches (2.7 L), but somewhat oddly, the Spyder’s engine was still rated at 150 hp, although at a lower 4,000 rpm. Torque was up to 232 lb.ft.
But in 1965, along with a major body restyle and a new rear suspension borrowed (partly) from the Corvette, the engine line up changed, and the top level model was now called Corsa.
The standard engine on the Corsa (optional on other models) was now a new 140 hp, four-carb naturally aspirated engine. Chevy finally did revise the heads, and fitted larger valves and ports to it. The 140 engine revved higher, with its power peak coming at 5200 rpm. Its torque curve also shifted upwards, so that it felt a bit more lethargic at low rpm. Why did Chevy bother to develop the 140 hp engine? Presumably because of the cost of the turbo engine and as well as the complexity of keeping the turbo engine properly tuned and happy. The 140 hp engine became quite popular, and is generally the most sought after Corvair engine, but its additional power is really only felt at above 3000 rpm or more. Around town, the lower output engines are a better choice for most drivers.
The turbo engine was now optional on the Corsa, and packed 180 hp @ 4000 rpm. Torque was also up; a pretty healthy 265 lb.ft. @ 3200 rpm. Boost obviously was higher to accomplish that. It should also be noted that the 180 hp engine did not use the new better breathing cylinder heads from the 140 engine. Performance was up a bit, with 0-60 now coming in at around 10 seconds flat, depending.
Keeping a Corvair turbo engine in top tune can be challenging. Ignition timing, done strictly through mechanical advance, can be tricky to keep right on the numbers. The very old-school Carter YH, last seen on the 1953-1954 Corvette six cylinder, is also a bit of a tuning challenge, and is subject to heat soak given its location next to all that exhaust plumbing. Dedicated Soyder and Corsa owners have made a number of various improvements to their engines, including different carbs, fuel injection, modern ignition systems, etc., which has allowed both more reliable operation as well as increased performance.
I found this ’63 Spyder (wearing ’64 wheel covers) the other day in the driveway of a rental house in the University district. Zak (sp?), a student, was outside and I asked him if it was his. It turns out to be his grandmother’s, a fairly recent acquisition which she’s happy enough to share with him, for extended periods. Obviously, this car is not quite original, especially its paint and upholstery. But it’s a long term keeper which will be restored to its original condition, starting with the paint.
Zak gladly pulled it out to the curb for me, and the sound of the Spyder engine’s throaty exhaust brought back memories of some folks my parent knew in Iowa City that had a ’62 Spyder convertible. How I lusted over that when they parked in our driveway, and how impressed I was by that badge on the rear deck, and the big stubby exhaust (which I forgot to photograph).
And I hung in over the door to admire the Spyder’s comprehensive gauge cluster, which included a combination vacuum/boost gauge, and a cylinder head temperature gauge.
I can’t even fathom how someone could have re-upholstered a Spyder with this Broughamy cloth. Mind-boggling. But it will go too, as part of the long term improvements. The engine needed a new turbo, which obviously was a priority.
This Spyder is in good hands, and will likely become Zak’s someday. We should all have a grandmother who buys a Corvair Spyder and lets us take it to school.
Now that summer’s here, what better way to spend our long balmy evening than behind the wheel of a Spyder, waiting for that turbo to kick in.
And the wait is worth it, especially in a convertible, as the Spyder makes such nice sounds even before the the turbo spools up. If you’re going to experience a bit of turbo lag, this is the best possible place to do so.