These Big-Block Engines Pack Less Punch Than You'd Expect
The U.S. is known as the land of excess for many reasons. Take the automotive landscape, for example. You have big SUVs and even bigger engines. However, there was a time when engines in American cars dwarfed even the largest ones made today. We are talking engines displacing anywhere between 6 and 8 liters. The '60s and '70s were the true eras of excess, when big-block engines were popular among enthusiasts who believed in the bigger is better philosophy.
Then came the "Malaise" era, touted by many enthusiasts as a bleak period in the American automotive industry. The oil crisis hit in 1973, when Arab nations stopped exporting oil to the U.S. The entire nation reeled under gas shortages. Congress passed the Corporate Average Fuel Economy (CAFE) Act in 1975. This required carmakers to improve the average fuel economy of their lineup to reduce oil dependency. The Clean Air Act of 1970 required cars from 1975 onwards to have a catalytic converter and comply with stricter emissions.
Then came the Iranian Revolution in 1979, which brought about a second wave of gas shortages, reinforcing the need for vehicles with better fuel economy. While the Malaise era faded away by the early '90s, one of its effects could be seen in a few American cars. Horsepower plummeted due to two important factors. The switch for horsepower measurement from gross horsepower to SAE net horsepower ratings dropped the measured horsepower for most automobiles. Also, cars had to use unleaded fuel for the proper functioning of the mandatory catalytic converters. To accommodate unleaded fuel, carmakers reduced engine compression, dropping horsepower. The following examples are arranged by specific horsepower (horsepower per liter) and showcase the extremes manufacturers went to during this time.
Dodge Viper 8.0-liter V10 (50 horsepower per liter)
A poster car for many who grew up in the '90s, the Dodge Viper is mostly known for its massive 8.0-liter engine. The story goes that Bob Lutz, Chrysler's president in the '90s, wanted the carmaker to have its own sports car, inspired by his Shelby Cobra replica. Concepts of this all-American sports car used a V10 that was already under development for the Dodge Ram Pickup. That's where the similarities end. The production engine V10 was an all-aluminum block developed by Lamborghini, which was under Chrysler back then. It featured iron cylinder liners, an aluminum cylinder head, magnesium valve covers, and a forged crankshaft and connecting rods.
If you leave the displacement part out, the Viper offered good performance. It made 400 horsepower and 465 pound-feet of torque. It traveled from 0 to 60 miles per hour in 4.2 seconds, while the top speed was over 160 miles per hour. However, when you factor in its 8.0-liter engine, that's a specific power output of just 50 horsepower per liter — in the '90s, many respectable performance cars were pushing specific power outputs above 100.
Thankfully, later generations of the Viper witnessed performance gains. The fourth-generation Viper, launched in 2008, featured an enlarged 8.4-liter V10 engine, making it the largest production engine fitted in a modern car. However, it's nowhere close to the world's largest piston engine. The fifth and final-generation Viper, which came out in 2013, delivered 640 horsepower and 600 pound-feet of torque using the same engine.
Rolls Royce L410 6.75-liter V8 (31.1 horsepower per liter)
Also known as the 6 ¾ engine, the 6.75-liter V8 was used in both Rolls-Royce and Bentley cars. It was one of the oldest surviving production car engines in the world, last used in the Bentley Mulsanne. Debuting in 1959 as a 6.25-liter V8, this engine was seen in the Rolls-Royce Silver Cloud II, the Phantom, and the Bentley S2 Continental. In 1970, an enlarged 6.75-liter V8 was introduced, which went on to power Rolls-Royce and Bentley models for the next five decades and was last seen in the Bentley Mulsanne.
The engine wasn't made for high power outputs, netting just 210 horsepower. That's a specific power output of about 31.1 horsepower per liter. Thankfully, it delivered a respectable 288 pound-feet of torque, so all was not lost. Also, the engine had potential. Further revisions, like the addition of fuel injection and, later, a turbocharger, saw power figures jump to 297 horsepower and 450 pound-feet of torque. In its last iteration under the hood of the Bentley Mulsanne, the 6.75-liter V8 produced 530 horsepower and 811 pound-feet of torque in the Speed trim. Big engines are a fad that's not going anywhere anytime soon. In fact, these are the largest engines currently on sale.
Ford 460 V8 (26.7 horsepower per liter)
The Ford 460 V8 was a 460 cubic-inch or 7.5-liter monster and the carmaker's trump card in the high-displacement engine wars. Introduced in 1968, this 385-series big block engine was developed for the luxury Lincoln cars.
Launched in the pre-malaise era of 1968, in the Lincoln Continental Mark III, the 460 V8 initially delivered a robust 365 horsepower and 485 pound-feet of torque. At first, the engine was exclusive to Lincoln cars. However, by 1973, it was offered in Mercurys, as well as Ford cars and trucks. Then, the engine got a new head design, a new camshaft, and reduced compression. Power dropped to around 200 horsepower and torque to under 350 pound-feet. That's a specific power output of around 26.7 horsepower per liter. By 1978, Ford offered the 460 only in its trucks and vans and dropped it from these lines as well in 1997.
The Ford 460 was quite an underrated engine, a fact realized by hotrodders and performance specialists. It was an overbuilt motor, and according to experts, you can produce 800 horsepower using the stock engine block. The 460 has found a niche for itself as a performance engine. It is easily available, given its plentiful use in Ford trucks and vans. There is a huge availability of aftermarket performance parts, and the engine's low and flat design means it can fit under the hood of many project cars. Let's not forget the availability of Ford Performance 460 crate engines.
Cadillac 500 cubic-inch 8.2-liter V8 (23.2 horsepower per liter)
During its era, the Cadillac 500 cubic-inch V8 was the largest production car engine. It arrived in 1970, in the Cadillac Eldorado, a front-wheel drive land yacht. At debut, the motor did impress with its performance numbers, delivering 400 gross horsepower and 550 pound-feet of torque from a 500 cubic-inch or 8.2-liter V8. It was the definition of American excess.
Then the Malaise era hit, bringing along new SAE horsepower measurements, emission control, and the switch to unleaded gasoline. By 1976, the 500 V8, now seen in the Cadillac Eldorado and DeVille, dropped to a paltry 190 horsepower. This, among other things, was mostly thanks to a reduction in engine compression from 10.25:1 to 8.5:1. That's a specific power output of roughly 23.2 horsepower per liter. One can only imagine the uninspired driving feel. Thankfully, Cadillac discontinued the 500 cubic-inch V8 the following year — better a quick death than a life of ignominy.
General Motors Detroit Diesel 8.2-liter Fuel Pincher V8 (15.9 horsepower per liter)
We had to have a diesel engine here. The consensus with diesel engines is that they are large-capacity, torque-rich motors with respectable horsepower outputs. While you are mostly right, some engines truly underdeliver. Launched in 1980, the 500 cubic-inch or 8.2-liter Detroit Diesel V8 was General Motors' attempt to create a diesel engine for the medium-sized truck segment, which primarily ran on gasoline engines. That's in comparison to today, where modern diesel engines outsell gas engines in heavy-duty trucks. The idea behind this "Fuel Pincher" engine was to offer better fuel economy, which became an important consideration during the time.
The engine did offer good fuel economy, but it fell short in other areas such as longevity, reliability, and performance. Some versions of the naturally aspirated V8 diesel produced a paltry 130 horsepower and around 350 pound-feet of torque. That's a specific power output of roughly 15.9 horsepower per liter. Some turbocharged versions of the 8.2-liter engines did push power up to 250 horsepower and 500 pound-feet of torque. Compare that to a modern GM Duramax 6.6-liter V8 that produces 470 horsepower and 975 pound-feet of torque, and you'll realize just how far the goalpost has moved.
