Summary

In 1962 and 1963, Oldsmobile offered a short-lived turbocharged version of the compact F-85. Called F-85 Jetfire, it used a high-compression aluminum V-8 engine with a complex, troublesome fluid injection system. Chevrolet also developed a simpler turbocharger installation for the air-cooled flat-six engine of the rear-engined Corvair. The Corvair offered turbocharged engines from 1962 to 1966.

SIDEBAR: The Buick and Oldsmobile Aluminum V-8 Engines

Although the origins of the 215 cu. in. (3.5-liter) aluminum V-8 engines offered in the 1961–1963 Buick, Oldsmobile, and Pontiac senior compacts are reasonably well-documented, there is a surprising amount of confusion and misinformation about these engines, so it seems worth reviewing their basic features, which also provides an opportunity for us to correct a number of our own past errors.

The basic design for the aluminum V-8 came from the corporate Engineering Staff, but it was extensively redesigned by Buick engineer Joseph D. Turlay, Buick’s director of powerplant activity. There were two distinct production versions of the engine: the Buick Fireball V-8, whose development was overseen by Turlay along with Edward H. Holtzkemper and Cliff Studaker (who would later be responsible for the design of the larger V-8s that replaced the 1953-vintage Buick “Nailhead” for 1967), and the Oldsmobile Rockette V-8, developed by Gilbert Burrell and Frank W. Ball. (Pontiac also offered aluminum V-8 engines for the 1961–1962 Tempest, but these were Buick engines, modified only as needed to adapt them for the Tempest powertrain mounts.)

The “Fireball” name had appeared on Buick engines on and off for years, going back to the straight-eight days, but it never seemed to catch on in the same way the “Rocket” name did for Oldsmobile. From 1962 to 1965, Buick also applied the Fireball name to the cast iron V-6. (Photo: General Motors LLC)

Both versions of the aluminum V-8 used the same short block, which was manufactured by Buick. Unlike the aluminum engines offered by Chrysler and American Motors in this period, the block was not pressure die-cast. Rather, it was cast using semi-permanent molds, a process then quite new in the U.S., with reusable low-pressure metal molds forming the outer surfaces and tappet valley, non-reusable sand cores the internal passages. Cast in a high-silicon alloy (which GM called 4323M) and weighing only 60 lb (27.2 kg) bare, the aluminum block had centrifugally cast-in dry iron cylinder liners to protect the inner surfaces of the cylinder bores from piston scuffing. Bore spacing was 4.24 inches (107.7 mm), with a bore of 3.50 inches (88.9 mm) and a stroke of 2.80 inches (71.0 mm), giving a total displacement of 215.3 cu. in. (3,528 cc). Both engines used the same crankshaft, cast of pearlitic malleable iron (which GM called “Armasteel”), with 5.66-inch (143.8-mm) forged steel connecting rods. Buick and Oldsmobile also shared a common camshaft, although for some unaccountable reason, Buick opted to quote its valve timing including the clearance ramps, Olds without them, resulting in a purely nominal 20-degree difference in stated intake and exhaust duration. Valve timing was quite mild.

Each division made its own aluminum cylinder heads. Both the Buick and Oldsmobile heads were cast of GM 4323M alloy using semi-permanent molds, like the block; had pressed-in valve inserts (steel for Oldsmobile and sintered iron for Buick); and used rocker shafts on die-cast aluminum stands rather than the rocker studs used by Chevrolet and Pontiac V-8s. Oldsmobile heads had an additional head bolt per cylinder (all the blocks included provision for the extra stud, although it wasn’t used, or usable, on the Buick version), and there were various minor differences in oiling and valve gear. The Buick heads had a fully machined combustion chamber that aligned with the depression in the top of each dished piston to form what Buick called a “slanted saucer” chamber, with the ring-shaped topland acting as a quench area. The spark plug was positioned between the intake and exhaust valves, mounted close to the center of the combustion chamber for shorter flame travel. Oldsmobile went a different direction, using flat-top pistons and a more conventional wedge combustion chamber, with the spark plug angled toward the thicker side of the wedge. The Oldsmobile heads also had fractionally larger valves, although valve diameter was similarly modest for both engines: 1.50 inches (38.1 mm) intake and 1.31 inches (33.3 mm) exhaust for the Buick, 1.52 inches (38.7 mm) intake and 1.35 inches (34.4 mm) exhaust for the Olds. Each version of the engine had its own unique intake manifold and air cleaner assembly, although Buick and Oldsmobile both used the same Rochester carburetors.

We’d previously stated that the Oldsmobile version of the aluminum engine was significantly heavier than the Buick version, but it now appears that we were misled by published reports that described the engines in different states of “dress.” Buick variously quoted the dry weight of its aluminum V-8 as 318 or 324 lb (144.3 or 147.0 kg) complete. In early 1961, Hot Rod Magazine actually weighed a complete Oldsmobile 215 and found it weighed 326 lb (147.9 kg) with all accessories, flywheel, and manual clutch. We conclude therefore that any actual difference in complete engine weights, when measured in like condition, amounted to no more than a few pounds.

The Oldsmobile version of the aluminum V-8 was most easily distinguished by its inverted soup pot air cleaner, but it also had its own manifolds and cylinder heads, with flat-top pistons rather than the dished pistons used on the aluminum Buick engine. (Photo: General Motors LLC)

The design differences between the Buick and Oldsmobile engines also didn’t amount to much from a performance standpoint, although Buick boasted a 10 lb-ft (13.6 N-m) torque advantage for its regular-fuel base engine. Initially, Oldsmobile claimed an extra 5 hp (3.7 kW), but Buick quickly adjusted its ratings so that both engines had the same 155 gross horsepower (115.6 kW) rating. By mid-1961, both the Buick and Oldsmobile versions were also available in premium-fuel versions, which had higher compression, Rochester 4GC carburetors, and bigger exhaust pipes; still higher compression ratios brought somewhat higher gross outputs for 1962 and 1963. Oldsmobile continued to offer these normally aspirated premium-fuel engines (which were standard on the Olds Cutlass and a $45.19 option on the F-85) in addition to the turbocharged Jetfire in 1962 and 1963.

For 1961, Pontiac offered the low-compression regular-fuel Buick V-8 as a rather pricey $216 option for the Tempest. For 1962, the 1961-spec Buick Skylark four-barrel engine replaced the regular-fuel V-8 as a Tempest option, still available only by special order. Either version was quite rare; only 2,004 1961 Tempests and 1,658 1962 Tempests were so equipped. (The 1963 Tempest offered only cast iron Pontiac engines.)

Gross output ratings of the various iterations of both the Buick and Oldsmobile aluminum V-8 engines are summarized in the following tables. (Please note that all the metric equivalencies are our calculations, NOT factory figures.)

**Buick Fireball Aluminum V-8 Engine, Gross Outputs, 1961–1963**
Applications	Carburetor	Compression Ratio	Power	Torque
1961 Buick Special (early announcement)	2GC	8.80:1	150 hp [111.9 kW] @ 4,400 rpm	220 lb-ft [298.3 N-m] @ 2,400 rpm
1961–1963 Buick Special (standard); 1961 Pontiac Tempest (optional)	2GC	8.80:1	155 hp [115.6 kW] @ 4,600 rpm	220 lb-ft [298.3 N-m] @ 2,400 rpm
1961 Buick Skylark (standard); 1961 Buick Special (optional); 1962 Pontiac Tempest (optional)	4GC	10.25:1	185 hp [138.0 kW] @ 4,800 rpm	230 lb-ft [311.8 N-m] @ 2,800 rpm
1962 Buick Skylark (standard); 1962 Buick Special (optional)	4GC	11.00:1	190 hp [141.6 kW] @ 4,800 rpm	235 lb-ft [311.8 N-m] @ 3,000 rpm
1963 Buick Skylark (standard); 1963 Buick Special (optional)	4GC	11.00:1	200 hp [149.1 kW] @ 5,000 rpm	240 lb-ft [325.4 N-m] @ 3,200 rpm

**Oldsmobile Rockette V-8 Engine, Gross Outputs, 1961–1963**
Applications	Carburetor	Compression Ratio	Power	Torque
1961–1963 Oldsmobile F-85 (standard)	2GC	8.75:1	155 hp [115.6 kW] @ 4,800 rpm	210 lb-ft [284.7 N-m] @ 3,200 rpm
1961–1962 Oldsmobile Cutlass (standard); 1961–1962 Oldsmobile F-85 (optional)	4GC	10.25:1	185 hp [138.0 kW] @ 4,800 rpm	230 lb-ft [311.8 N-m] @ 3,200 rpm
1962–1963 Oldsmobile F-85 Jetfire (standard)	RC (with turbocharger)	10.25:1	215 hp [160.3 kW] @ 4,600 rpm	300 lb-ft [406.8 N-m] @ 3,200 rpm
1963 Oldsmobile Cutlass manual (standard); 1963 Oldsmobile F-85 manual (optional)	4GC	10.25:1	185 hp [138.0 kW] @ 4,800 rpm	230 lb-ft [311.8 N-m] @ 3,200 rpm
1963 Oldsmobile Cutlass automatic (standard); 1963 Oldsmobile F-85 automatic (optional)	4GC	10.75:1	195 hp [138.0 kW] @ 4,800 rpm	235 lb-ft [311.8 N-m] @ 3,200 rpm

Buick and Oldsmobile both dropped their aluminum V-8s at the end of the 1963 model year, although in 1964, Buick used the aluminum heads of the Fireball V-8 on the division’s new iron block 300 cu. in. (4,923 cc) V-8. (The latter adopted cast iron heads for 1965.)

In January 1965, the English automaker Rover purchased a manufacturing license for the Buick engine and put it back into production in 1967, with all-new tooling and various minor design changes. The early Rover cylinder heads were very similar to the Buick heads (albeit with some valvegear changes to permit a higher rev limit), but Rover redesigned the aluminum block for sand casting rather than semi-permanent molds and used pressed-in rather than cast-in cylinder liners. Rover-made blocks were also beefed up somewhat for greater strength and rigidity. The Rover engines used mostly British components and accessories, with a few notable exceptions, and had a new crankshaft and a new cam with greater valve duration.

Rover first used the reborn aluminum V-8 in its 1968 P5 models (which were known internally as “P5B” when fitted with the ex-Buick engine), replacing an old and underpowered 2,995 cc (182.8 cu. in.) F-head six. Although it had four doors, Rover called the body style of this 1971 3.5 Litre P5B a coupé, as it had a lower, faster roofline than the standard saloon. (Photo: “Rover 3.5 Coupe (1971)” by Steve Glover, which is licensed under a Creative Commons Attribution 2.0 Generic (CC BY 2.0) license)

Gross ratings for the initial 1968 version of the Rover aluminum V-8, with 10.5:1 compression and dual 1.75-inch (44.4-mm) SU HS6 carburetors, were 184 hp at 5,200 rpm and 226 lb-ft of torque at 3,000 rpm (equivalent to 137.2 kW and 306.4 N-m). Rover reported the engine’s net output as 160.5 hp at 5,200 rpm and 210 lb-ft of torque at 2,600 rpm (equivalent to 119.7 kW and 284.7 N-m), later restated as 152.5 PS DIN and 203.5 lb-ft (equivalent to about 111.9 kW and 275.9 N-m).

Neither Buick nor Oldsmobile published as-installed net output figures during this period. However, our guess is that the regular-fuel versions of both American-made aluminum V-8s made no more than around 120 to 125 net horsepower (89 to 93 kW), the premium-fuel versions something in the realm of 135 to 140 hp (101 to 104 kW). The net horsepower peak in both cases was probably no more than 4,000 rpm. (Unlike the Rover V-8, neither American engine was eager to rev past 5,000 rpm in stock form, and valve float became a serious risk at around 5,300 rpm with the stock camshaft and lifters.)

Pages 1 2 3 4 5 6 View All

14 Comments

Add a Comment

MrF

April 29, 2023 at 10:33 am

Pleased to see this. Impressive, as usual.

Reply
Andrew Buc

April 30, 2023 at 2:42 pm

There may have been an antidetonant for other applications at the time. If so, I’m betting that the manufacturer never explicitly marketed it to Jetfire owners.

Reply
1. Ate Up With Motor
  
  April 30, 2023 at 6:37 pm
  
  I’m not sure if Thompson was still selling Vitane by this point, but it wouldn’t have been ideal for the Turbo-Rocket V-8 anyway. At any rate, Oldsmobile literature most emphatically discouraged using substitute fluids, which was understandable, since using a different fluid risked either diminishing the effectiveness of the system or risking it freezing in cold weather.
  
  There were a number of technical papers published toward the end of WW2 summing up wartime experience and best practices with regard to fluid injection, which I suspect the engineers at Oldsmobile (or perhaps Rochester, who designed the final injection system) read and took to heart, as they followed those recommendations quite assiduously.
  
  Reply
Chris B

May 3, 2023 at 8:44 am

I remember reading that the F85 – in its earliest development stage – was to have a transverse 60 degree V6, and an automatic transaxle that used the hardware from the Roto-5 automatic but with three chains to connect engine to gearbox to wheels. It was killed early in the development stage – due to cost, of course – but we did get something useful from that project. The 60 degree V6 developed by Olds engineers sat on the shelf until the late 1970s when a narrow V6 was needed for the upcoming X car. The Olds design was handed to Chevrolet to get them started and then they finalized the engine for production. But if you look carefully at the 2.8/3.1 V6 from the early 80s, you can see details in the block – notably timing chain area – that look a lot like the small block Olds V8. In fact, it looks a lot more like an Olds motor than a Chevy.

What hit the showrooms in late 1960 was fairly conventional, but looking at the MSRP that would be in the high $20k in 2023 dollars, there wasn’t much engineering magic they could include without pricing the car out of the market or losing a lot of money on every one they sell.

Reply
1. Ate Up With Motor
  
  May 3, 2023 at 10:41 am
  
  It’s true that Oldsmobile did experiments with FWD for a car the size of the F-85, but the timetable makes it unlikely it would have been for 1961. The first FWD test mule wasn’t built until early 1960, when the initial production F-85 was very close to pre-production. At that point, the FWD project was at a rather nascent stage (the test mule weighed about 600 lb more than a RWD F-85, the chain drive was still quite crude, they were still evaluating whether they needed two CV joints per side, and I think it was using pieces of an older four-speed Hydra-Matic), so even if the division had been enthusiastic and corporate management had signed off on it for production, I think it would likely have been for a second-generation F-85. There simply wouldn’t have been time to get it into producible shape for 1961.
  
  (There is some confusion on the timeline, stemming in part from the fact that both Oldsmobile Advanced Design Group and the corporate Engineering Staff were working on the project concurrently in different ways. (Oldsmobile asked Engineering Staff to develop a gear-drive transfer unit, which involved a Buick Dual Path Turbine Drive two-speed automatic.) However, Andy Watt, who was head of Advanced, said unequivocally that until early 1960, Oldsmobile FWD prototype development was still only at the stationary test rig stage.)
  
  I have seen Oldsmobile engineers attribute the Chevrolet 2.8-liter V-6 to the abortive Oldsmobile FWD project. However, I’m very skeptical of the idea that it “sat on the shelf” until the seventies or that an almost 20-year-old design for an unproduced Oldsmobile experimental engine would be “handed” to Chevrolet. Weird things happen sometimes, so I suppose it’s not outside the realm of possibility, but it seems more like a piece of internal folklore born of old divisional rivalries. I’ve never found any substantive details about the V-6 used in the FWD mules (neither the SAE paper nor the GM Engineering Journal articles about Oldsmobile FWD development even mention its displacement), and since that engine never got close to production, it’s not a claim that seems particularly verifiable. Also, the “small block” Oldsmobile V-8 — by which I assume you mean the 330/350/307 rather than the aluminum Rockette engine — didn’t yet exist as such in 1960 (the bulk of its initial development was in 1962 and early 1963), although it’s possible that the experimental V-6 previewed certain details later used on that engine. To the extent that the 2.8-liter V-6 looks “like an Olds motor,” it seems more plausible that the source of inspiration was the smaller Oldsmobile V-8, which WAS a production engine, and a very familiar one by the time the FWD X-body cars were in development.
  
  (At a glance, the most obvious resemblance between the 2.8-liter V-6 and the Oldsmobile V-8 is the way the block forms a kind of integral shroud for the timing chain. Oldsmobile said they did that because they wanted to be able to use a flat timing chain cover, while Chevrolet’s explanation was that it allowed them to avoid using a steel backing plate for the cam drive.)
  
  Reply
Gordon Malone

May 4, 2023 at 10:09 am

Aaron,

Great article as usual! Thanks.

Reply
Roader

May 4, 2023 at 2:26 pm

Not only did turbocharged Corvairs have a cylinder head temperature gauge, there was also an under-dash buzzer that alarmed if the head temp get too high. I’ve read that Chevrolet engineers were worried about sustained high loads like pulling a trailer or climbing a long, steep mountain pass and wanted an audible alarm to get the driver’s attention to back off the throttle.

Reply
1. Ate Up With Motor
  
  May 4, 2023 at 8:33 pm
  
  Some of the period testers noted that while there was a cylinder head temperature gauge, the gauge didn’t provide any specific indication of how high was too high, so supplementing it with a buzzer was prudent. That notwithstanding, adding the new instruments rather than simply an amber “HEAD TEMP” light in the existing panel was a worthwhile move, and suggested that despite the comparative simplicity of the Spyder package, Chevrolet engineers had a clearer idea of its potential market and what those buyers might want.
  
  Reply
  1. Roader
    
    May 6, 2023 at 6:48 pm
    
    I think it had all three: a gauge, an idiot light, and a buzzer. I’ve never driven a Corvair turbo but I’ve had several Corvairs and all had a combination head temp/oil pressure idiot light. As far as I know the turbo kept that and added the gauge and buzzer.
    
    Your extensive follow up on later turbocharged cars was fascinating, especially the point about Porsche not producing a 911 turbo until 1975, 13 years after the Corvair turbo. It seems as if the Corvair wasn’t so much a poor man’s Porsche, rather, the 911 turbo should rightly be considered a rich man’s Spyder.
    
    Reply
    1. Ate Up With Motor
      
      May 6, 2023 at 8:25 pm
      
      Porsche’s 1978 SAE paper on their turbocharging development makes clear that they were aware of the Spyder and Jetfire (as one would expect), but were not terribly familiar with them, asserting, for example, that they were made only in 1964 and 1965.
      
      At any rate, what’s distinct about how Porsche approached turbocharging was that it was an offshoot of their racing efforts; their first turbocharged 917 was for the 1972–73 Can-Am series, and the development of the 930 and 935 followed that. Competition has shaped a lot of automotive turbocharging development, and so it’s notable that it WASN’T a factor in the creation of the Jetfire or Spyder. Oldsmobile didn’t develop the Jetfire as an homologation special, and while Chevrolet created the Spyder in large part to try to bolster the credibility of the Corvair Monza as a sporty car, it was neither developed for or as a street version of any racing project.
      
      Reply
Schurkey

May 22, 2023 at 9:29 pm

Marvelous. As usual.

I am–again–impressed with both your research and your ability to write about it.

Thank you.

Reply
Chris In Australia

June 23, 2023 at 1:20 am

Another great article, and I thank you for it. BMW and SAAB both claiming ‘firsts” annoys me. Once again Detroit doesn’t get it’s due credit

Reply
jiro

December 18, 2023 at 2:21 pm

Stellar work Aaron! Thank you very much for the depth and breadth of your research and excellent explanations. I feel blessed to be able to read your work. As a warm up to another comment I might make on the Tempest article, a recycling of ideas I have about GM, don’t feel obliged to read closely.

I find GM an interesting corporation where short term profit, and lots of it, were so important and yet long term engineering development seems only to apply to the largest and cheapest construction engines and chassis. I like the idea of turbo’s, but both applications seem suspect. The Corvair, with it’s limited cooling ability, is somewhat suspect as a turbo candidate. The Olds, with excellent cooling and a strong enough block is much better. I like the ADI concept, but I don’t understand the requirement for alcohol in the ADI in areas that don’t freeze! Certainly in the summer it’s not freezing anyway. Given the technology they had available, perhaps more development might have reduced the issues, but as a mass market engine the Jetfire seems like a significant misunderstanding of the American motoring public. Of course, that same misunderstanding would occur again with the Vega and its lack of a coolant reservoir…

Thanks

Reply
1. Ate Up With Motor
  
  December 18, 2023 at 3:31 pm
  
  In principle, if you lived in a climate where it never dropped below freezing, you might have been fine just running distilled water, but even in desert areas, low nighttime temperatures might make that dicey. Also, trying to change the fluid type based on climate seems troublesome: For instance, if you had been running distilled water in the ADI tank, but planned a trip into the mountains to go skiing, how would you get back to a suitable water/alcohol mixture, short of draining the tank and refilling it with the recommended fluid? I’m sure Oldsmobile engineers reviewed some of the extensive wartime data on ADI systems (there were several SAE papers on that subject), which found that a 50/50 water/methanol mix offered better detonation-limited power as well as resistance to freezing, and concluded that would be the best compromise for year-round use.
  
  I just don’t think ADI is very practical for general-use passenger vehicles. It’s one more maintenance item to keep track of, and it requires too much knowledge for the average owner. If you use it regularly, the added cost of the fluid is a hassle (unless you throw caution to the wind and run distilled water), and using it infrequently increases the risk of something going wrong, even if that just means “not noticing when you finally run the reservoir dry.” I don’t see any real way around that; it’s a conceptual shortcoming rather than a problem of flawed execution (although in this case the execution was a bit flawed as well).
  
  The Vega’s lack of a coolant reservoir was the opposite problem: It was a disastrous cost-cutting measure that could (and should) have been completely avoided!
  
  Reply

Turbos for the Turnpike: The Turbocharged Oldsmobile F-85 Jetfire

Summary

14 Comments

Leave a Reply Cancel reply