Muscle Cars You Should Know: Oldsmobile F-85 Jetfire

With the industry’s recent focus on reducing displacement and supplementing it with forced induction, it’s easy to think of the latter as a relatively new technology for production cars. Up until recently, the use of turbos in mass produced vehicles was considered fairly exotic, and the concept pairing up turbocharging with V8 power on an older vehicle would conjure up thoughts of the Ferrari F40 supercar for many enthusiasts.

Truth is, the idea goes back a lot farther than 1987. In fact, to find the first implementation of a V8 with turbocharging, we’d need to look all the way back to the early 1960s when – for a brief moment – a niche opened up in the automotive market that saw a number of American buyers shifting toward the smaller, more efficient vehicles that were popular in Europe.

Of course the Big Three weren’t too keen on forfeiting market share to overseas competitors. So they scrambled to meet the demand, debuting new compact offerings like the Plymouth Valiant, Chevrolet Corvair, and Ford Falcon for the 1960 model year. Oldsmobile responded a year later with the F-85, which shared its Y-body platform with the Buick Special and Pontiac Tempest. It was Oldsmobile’s smallest vehicle by a wide margin – some two feet shorter than the next-smallest model they had on offer, and was also their most affordable.

While the F-85 was originally conceived as a fuel-efficient compact model to compete with the likes of the Ford Falcon and Plymouth Valiant, Oldsmobile was keen to offer more performance in this small, light weight package. The trick to it was figuring out a way to do so without moving up to a bigger motor, which led the company’s engineers to turn to forced induction as a means of increasing output without the need for more displacement. Image: GM

It also came standard with V8 power courtesy of a 3.5-liter all-aluminum mill, good for 155 horsepower and 210 pound-feet of torque in standard configuration with 8.8:1 compression and a two barrel carburetor. Buyers looking for a bit more pizzazz could opt for the Power Pack, which yielded 185 horsepower by way of 10.25:1 compression and a four barrel carb.

But Oldsmobile still wanted more from the F-85, yet they weren’t willing to increase engine displacement or drivability to get it. Gilbert Burrell, Oldsmobile’s chief powertrain engineer at the time, had a wild new solution in mind.

The Jetfire

By the early 1960s America was enamored with the promises of the Space Age, eager to embrace new technologies and excited by the prospect of innovation. General Motors was particularly keen to capitalizing on the trend, diving into oddball developments like the mid-engined Corvair and numerous engineering exercises with the Corvette.

So it perhaps comes as little surprise that the first production application of turbocharging in the automotive industry would come from GM, arriving in the form of the Oldsmobile F-85 Jetfire and the six cylinder-powered Chevrolet Corvair Monza Spyder, both of which debuted for the 1962 model year and well before the likes of Porsche, Saab, or any of the other venerable European marques would decide to take the plunge.

The combination of high compression and turbocharging meant that spark knock became a concern during development. To combat this, Oldsmobile's engineers added a water-methyl alcohol injection system and dubbed the mixture Turbo-Rocket Fluid. The mixture was added into the intake system between the carb and the turbocharger to cool the intake charge and prevent detonation. A light on the center console boost gauge would let drivers know when the water-meth reservoir was getting low. Images: GM, Mecum

Burrell’s formula was to pair up the 3.5-liter V8 with a small-diameter Garrett T5 turbocharger that produced 5 psi of boost at 2200 rpm. Armed with 10.25:1 compression and a specially designed single-barrel carburetor, the Jetfire motor dished out a healthy 215 horsepower and 300 pound-feet of torque, which was the kind of grunt that would catch the attention of enthusiast buyers.

But during development the engineers discovered they’d need a way to prevent spark knock during hard throttle applications, so they developed a water-meth injection system which injected measured amounts of distilled water and methyl alcohol into the intake manifold to cool the intake charge. They dubbed the mixture Turbo-Rocket Fluid, and replenishing the water-meth reservoir became part of the Jetfire’s list of scheduled maintenance items.

While the Jetfire’s boost gauge wasn’t particularly informative – essentially just indicating whether the motor was on or off boost by way of a needle indicating Economy or Power – it sure looked cool. Image: Mecum

Because Oldsmobile knew that some buyers would neglect refilling the Turbo-Rocket Fluid reservoir, they also incorporated a valve assembly in the fluid path that would close if the reservoir was empty, in turn limiting boost pressure (and engine performance in turn) in order to  prevent internal damage. As the five quart reservoir neared depletion, the driver would be alerted to the situation by way of an Add Fluid light illuminating on the Jetfire’s console-mounted boost gauge.

Turbocharging Makes Its Debut

Thought the tech might’ve seemed like some sort of voodoo magic to buyers accustomed to there being no replacement for displacement, the benefits of Oldsmobile’s turbo implementation were undeniable. Although peak horsepower saw a substantial bump, it’s the torque numbers proved to be the real story, with twist going up by no less than 30 percent over the Power Pack-equipped F-85 models. What’s more, peak torque of 300 lb-ft was delivered by 3200 rpm while 280 lb-ft was available from just 2000 rpm, which greatly improved the urgency of the F-85’s acceleration and made it a clear performance standout in the segment in turn.

Serious high performance offerings were few and far between in the F-85’s compact segment in 1962. As a result, the Jetfire’s performance significantly outclassed the competition when it debuted, though its finicky operation and requirement for regular Turbo-Rocket Fluid fill-ups would relegate the Jetfire to niche status for the most part. Image: GM

Car Life magazine posted a 0-60 mph run in 8.5 seconds with a four-speed manual gearbox-equipped Jetfire, which was 2.5 seconds quicker than was seen with the 185hp motor and nearly twice as quick as the base model F-85’s 155hp engine. In terms of its competitive set, the F-85 Jetfire was said to be nearly 10 seconds quicker to 100 mph from rest than its next-closest competitor.

The F-85's muscle car look began to take shape when it received a significant refresh for 1963. Images: Mecum

But the performance didn’t come without its drawbacks. It was said that the Turbo-Rocket Fluid reservoir could go from full to dry in less than 250 miles with a lead foot behind the wheel, and this often led to owners refilling the reservoir with tap water rather than the proper water-meth mixture, as the Turbo-Rocket Fluid was only readily available from Oldsmobile dealers. This in turn resulted in scores of motors being sent to the boneyard due to cooling issues and detonation, and the complex injection system itself was said to be finicky in operation.

Legacy

While the mechanicals would remain unchanged from the previous year, the F-85 would get a significant aesthetic refresh for 1963 that beefed up its look and stretched its overall length by four inches, and sales increased in turn.

Though the Jetfire system delivered great performance for the time, its reliance on the water-meth mixture – which was only available through Oldsmobile dealerships at the time – resulted in a lot of frustrated customers. The performance landscape was also in flux by the end of 1963, and big changes were on the horizon. Image: GM

However, Oldsmobile’s turbocharging experiment would prove short lived. Reliability concerns due to both owner maintenance habits and the complexities of the system would lead to Oldsmobile offering owners the option to ditch their Jetfire’s turbo system completely and replace it with a tried and true performance intake and four barrel carb at no cost.

By the end of 1963 the automotive performance landscape was beginning to change as well. The following year would see both the Ford Mustang and Pontiac GTO enter the market, the latter of which packed 325 horsepower by way of a big, naturally aspirated V8 which would set the tone of the muscle car craze which would follow.

In 1964, the Jetfire would have to make way for a new F-85 performance variant: the 4-4-2. Image: Hemmings

By then Oldsmobile had a 330 cubic-inch V8 of their own as well, and they would tune it to crank out 310 horsepower and 355 pound-feet of torque in a new performance variant of the F-85 dubbed the 4-4-2. Perhaps unsurprisingly, the Jetfire option was dropped from the F-85 options list for 1964 after just two years on the market.

Oldsmobile’s turbocharged performance would be quickly overshadowed by the escalating horsepower wars going on both internally at GM and amongst the Big Three, a trend which saw engineers returning to big, naturally aspirated motors for power once again. Ultimately the Jetfire technology would simply prove to be way ahead of its time, as both turbocharging and water-meth injection have found their way back into production cars in increasing numbers over the past few years.

About the author

Bradley Iger

Lover of noisy cars, noisy music, and noisy bulldogs, Brad can often be found flogging something expensive along the twisting tarmac of the Angeles Forest.
Read My Articles

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