1978 Buick Regal Sport Coupe: Unrestored First-Year Turbocharged Regal, 1978’s “Performance Car Of The Future”

Today, turbocharged cars and trucks are very common, but back in 1978, turbos were still rare and fairly exotic. The only U.S. manufacturer offering turbocharged engines in production cars was Buick, which introduced two turbo versions of its familiar V-6 engine for the 1978 LeSabre and the new Regal Sport Coupe. This well-equipped, highly original 1978 Regal is the first of a line of turbo Regals that culminated in the legendary 1987 Buick GNX.

According to the EPA, about 45 percent of all new cars and light trucks sold in the U.S. in the 2025 model year had turbocharged engines — more than 6 million vehicles. Back in 1978, the total was more like 60,000. The only manufacturers who offered turbocharged cars in the States back then were Porsche, Saab, and Buick, joined late in the model year by Mercedes-Benz with the new 300SD, the first turbodiesel passenger car.

Turbos weren’t new in 1978, of course. Chevrolet had introduced the world’s first turbocharged production car, the Corvair Monza Spyder, back in April 1962, followed in very short order by the Oldsmobile F-85 Jetfire. Turbochargers had started becoming popular in some forms of racing in the late ’60s. However, getting turbocharged spark ignition engines to work well enough for passenger cars was tricky, and most automakers had had other fish to fry.

Buick turbocharged its 90-degree 3.8-liter V-6 engine for its 1976 Indianapolis 500 pace car, and then decided to create a production version of its latest “even-fire” V-6. This posed a problem: how to keep the turbo V-6 from blowing itself up under boost on regular gasoline. Porsche and Saab had dealt with that by lowering their engines’ compression ratios and using port fuel injection, but Buick didn’t have the budget for injection, and they wanted to retain the stock 8 to 1 compression ratio for better gas mileage and better performance “off-boost.”

So, Buick came up with an electronic control device that would detect engine detonation and automatically retard the ignition timing in 2-degree increments until the detonation stopped. The detonation sensor was an electromagnetic gadget mounted atop the thermostat housing that generated an electrical voltage related to engine vibration; uncontrolled detonation would produce a voltage spike that the “Turbo Control Center” would read and use to continuously adjust the spark timing. Today, turbocharged engines have piezoelectric knock sensors that do something similar, although modern engines have much more sophisticated computer controls.

There were actually two of these turbo V-6s in 1978: The standard LC5 engine had a two-barrel Dualjet carburetor, while the optional LC8 version had a modified Rochester Quadrajet and different wastegate settings that allowed a little more maximum boost (up to 8.8 psi, compared to a maximum of 7.9 psi for the LC5). The LC5 engine had 150 hp and 245 lb-ft of torque, the four-barrel LC8 had 165 hp and 265 lb-ft. That’s no great shakes today, but back then, the normally aspirated (non-turbo) 3.8-liter V-6 had only 105 hp and 185 lb-ft of torque, so the turbo offered a big increase in power and torque while adding only 51 lb to engine weight.

Cutting weight was a central theme of the 1978 Regal, one of GM’s newly downsized A-body intermediates. Compared to the outgoing 1977 Regal coupe, the 1978 car lost 10.2 inches of overall length, almost 4 inches of wheelbase, and about 600 lb of curb weight.

You can decide for yourself how the new Regal looked on the outside, but it was definitely more efficient — despite its reduced heft and smaller dimensions, it was roomier inside, particularly in back.

This year, the new turbo engines were exclusive to the Regal Sport Coupe in the A-body line and the LeSabre Sport Coupe in the larger B-body line. Both models came standard with 150 hp LC5 turbo engine; the four-barrel engine was just $50 extra.

Although a 4-speed manual transmission was optional with the normally aspirated 3.8-liter V-6, the turbo V-6 engines were offered only with TH350 Turbo Hydra-Matic, specially calibrated with a new higher-stall torque converter and different shift points. The sole axle ratio with the turbo engines was a tall 2.73.

Buick unfortunately didn’t find it in the budget to add a boost gauge or even a tachometer.

However, there were “Turbo Power” indicator lights on the instrument panel to tell you when the turbocharger was doing its thing.

“You should be advised that Buick will not be marketing its turbocars as muscle machinery,” warned Car and Driver editor Don Sherman. “Instead, the philosophy will be one of utmost flexibility: a small, efficient engine for day-to-day cruising with a big motor’s potency on demand.” The turbo V-6 had some turbo lag, which were still an endemic problem with turbochargers, but it wasn’t a peaky engine, tuned for mid-range passing thrust rather than high-end power.

A 1978 Regal Sport Coupe weighed about 3,500 lb, so the LC8 four-barrel turbo engine ought to have produced respectable performance, but Car and Driver managed only an unspectacular 11.2 seconds 0 to 60 mph and a standing quarter mile of 18.2 seconds at 77.4 mph. For 1978, 11 seconds to 60 mph wasn’t bad for a six-cylinder intermediate, and Buick insisted either turbo engine was faster than the 5.0-liter LG3 V-8 offered on the Regal (a Chevrolet 305 with a two-barrel carburetor and 145 hp). The LC8 four-barrel V-6 might still have had a slight edge over the four-barrel LG4 V-8 that became optional during the year, which had 160 hp and 235 lb-ft of torque. However, the Corvette-eating acceleration of the later GNX was not yet in evidence.

Believe it or not, the 1978 Regal Sport Coupe actually scored better in handling than in straight-line performance. Buick included its FE2 “Rallye ride-and-handling” suspension with firmer underpinnings and a rear anti-roll bar. The Regal Sport Coupe also had bigger 205/70R14 tires and standard power steering and power brakes. Buick claimed that this car could pull 0.76 g lateral acceleration, which was very good back then. You could order the FE2 suspension and tires on the standard Regal, though, which would let you combine them with a V-8 engine.

Buick sold 236,652 Regals for 1978, 135,917 of them with V-6 engines, but Regal Sport Coupe production totaled a modest 30,507. (Production of the turbocharged LeSabre Sport Coupe totaled only 8,139 cars.) That wasn’t too bad for a flagship model, and Buick turbo production capacity was still quite limited anyway, but it was a modest start.

Buick expected that over the next few years, they would begin weaning customers off of V-8 power in favor of the turbo V-6. It really didn’t work out that way, and Buick turbo sales remained rather slow. As long as V-8 engines were still available, there wasn’t any strong reason for most buyers to choose the turbo V-6. Surprisingly, in the Regal, the turbo engine wasn’t any more economical than the 5.0-liter V-8. (In 1978, the two-barrel LG3 V-8 and the turbo engine had identical EPA ratings, and the four-barrel LG4 actually had a 1 mpg edge over both.)

The RWD Regal survived with several facelifts through 1987. For a while, Buick also offered the turbo V-6 in several other models, including the Century and Riviera; it also showed up briefly in the Chevrolet Monte Carlo in 1980–1981. However, the idea that the 3.8-liter turbo could become a bread-and-butter replacement for V-8 engines never really clicked, and after a while, Buick decided to just focus on making the turbo Regal the muscle car they originally said it wasn’t supposed to be. The 1984–1987 Regal Grand National was one of the more muscular domestic models of its era, and the final Car and Driver road test of the close-out GNX (suspiciously underrated at 245 hp) managed 0 to 60 in a blistering 4.7 seconds, night and day compared to its 1978 predecessor.

When these turbo cars were launched in fall 1977, Buick chief engineer Lloyd Reuss called the Regal Sport Coupe “the performance car of the future,” and C/D‘s Don Sherman boldly proclaimed, “This is the car that will lead Detroit down the road to turbocharger happiness.” That proclamation turned out to be premature: After 1987, GM decided that Buick (now absorbed into one of Roger Smith’s new multi-division supergroups) didn’t belong in the turbo business, and the popularity of turbocharged engines in the U.S. market waned greatly during the ’90s and early ’00s. It wasn’t until about 2011 that the market share of turbocharged gasoline engines really began to rise again, although they’ll probably become increasingly common as long as internal combustion engines are used in passenger vehicles. The entire 2026 U.S.-market Buick lineup is turbocharged. So, Reuss wasn’t exactly wrong, but the future he anticipated took a lot longer to arrive than anyone expected.

Surviving first-year Regal Sport Coupes aren’t quite as scarce as I had thought they might be — I found sale or auction listings for at least five in reasonably original condition. The gold car pictured here has the LC8 four-barrel engine, which most Regal Sport Coupe buyers ordered (the two-barrel LC5 sold in very limited numbers), and a couple of interesting options, including the $625 T-top “hatch roof” and the rare $99 “Designers’ Sport” polycast wheels (a one-year-only option). Its mileage isn’t super-low (it was up to 93,984 miles by the time of the auction), but it’s unmolested and supposedly mostly original. It sold for a healthy $26,400 at Mecum Indy in May 2025.

 

Related Reading

1978 Buick Regal: The Extreme Moderate (by Eric703)

Vintage Review: 1979 Buick Century Turbo Coupe – This Wild Turkey Tried To Fly (by GN)

Rare Survivor: 1981 Chevrolet Monte Carlo Turbo V6 – Forgotten Chevy Still In Great Shape (by Rich Baron)

COAL: 1987 Buick Regal Grand National – Rock and Roll All Night, Broken Every Day (by Lt Dan)

Vintage R&T Review: 1987 Buick Grand National GNX – Muscle Car of The 1980s (by yohai61)

Turbos for the Turnpike: The Turbocharged Oldsmobile F-85 Jetfire (at Ate Up With Motor)