The 1970s were a tumultuous time for car lovers., especially in the United States. The decade began at the height of a fascinating power war between muscle car manufacturers, and ended with two oil price crises, new anti-pollution regulations that led to the arrival of catalytic converters, and cars that were a shadow of what they had come. to be very few years ago. One of the most unknown episodes is the day muscle cars lost over 100bhp overnight.
One of the most flagrant cases that explains what happened between the years 1970 and 1973 is the case of the Cadillac Eldorado. The Eldorado mounted one of the largest displacement engines ever seen in a passenger vehicle, a gigantic 8.2-liter displacement V8. A front-wheel drive car – yes, you read that right – that in 1970 it boasted a very remarkable 400 CV of power. In 1971, General Motors lowered its compression ratio so it could run on low-octane gasoline, but the car only lost 35bhp – manageable, right?
The marketing departments had started an announced power war with muscle cars that seemed to have no end.
However, the following year, in the MY 1972, this same engine announced a maximum power of only 235 CV. Where had those 130 hp gone? The sad reality is “they were never there”. The fact of the matter is the way in which the power of the cars was measured in the United States at the time. The horsepower advertised by a car was “gross” horsepower, measured according to a 1917 engine test manual.. Power was measured with a cold intake manifold, with the ignition and carburettor set to deliver maximum power.
In addition, on the test bench, the air filter was removed and the engine fan was disconnected, along with other accessories that robbed the mechanics of power. The result was that the engine gave its best on the dyno, but it did in conditions that were never going to be replicable in real life, when a person was driving the car. For this reason, California passed a law in 1970 that required car manufacturers to announce the net power of the vehicle as of the Model Year of the year 1972.
Gross power came to be measured with engines with free exhaust, without mufflers and without back pressure in the exhaust line.
The net power was calculated in a much more realistic way, according to the SAE (Society of Automotive Engineers) J245 standard. An engineer explained to the New York Times in 1971 the difference between gross power and net power very clearly: “A soldier delivers his raw power when he wears a tracksuit and sneakers, but his net power is delivered when he wears military boots, carries a 30-kilo backpack on his back, and a 3-kilo rifle in his hands. The army is not interested in how he performs almost naked”.
The big manufacturers in Detroit accepted the California law at face value, applied it nationally, and General Motors even went so far as to announce both the gross power and the net power of its cars for the year 1971. The president of the Detroit giant himself stated that the net power was what interested his clients, since it was the real power of the vehicle. Net power was measured with all engine accessories connected.with the intake manifold at operating temperature and with a conventional set-up.
In truth, car manufacturers had been considering this measurement change for some time, but their marketing departments advised against it.
It must be taken into account that the net power that the cars went on to announce was a power at the output of the crankshaft, which is the way in which cars currently continue to announce their maximum power. However, there is a noticeable loss of efficiency in the power to the wheels, which today we estimate at 15-20%. The practical result of the new net power standard was like taking the autotune off a modern artist.: revealed the true reality: overnight some engines lost up to 35% of power.
This was especially evident in the most performance engines, revealing how marketing had inflated the maximum power of some cars to unsuspected limits. The Cadillac Eldorado we are talking about went from delivering 365 gross CV to delivering 235 net CV. The 5.7 V8 of the entry-level Chevrolet Corvette now has 210 hp, compared to 270 hp, and its LT1 version went from 330 hp to 275 hp. The range-topping LT5, a 7.4-litre big-block, went from 365bhp to 285bhp. The Ford Mustang wasn’t spared from the power bleed, either.
The cars that lost the least power were cars that underreported gross power to keep insurance and politicians happy.
Accessible six-cylinder Mustang went from 145bhp to just 95bhp, and the 5.8-liter V8, which in 1971 boasted 240 CV, stayed at a timid 177 CV. The Dodge Charger didn’t suffer as much: its 3.7-litre six-cylinder went from 145bhp to 110bhp, while the 5.2-litre V8 promised 230bhp but actually settled for 155bhp. Although it stopped selling in 1972, the iconic 7.0 V8 (the mythical 426 HEMI) promised 425 gross hp, staying at a more than correct 350 net hp – however, it was still believed that that V8 hid much more power.
These are just a few examples, which helped the muscle car era languish to extinction. Not only this dose of reality contributed to this: the adaptation of low-octane gasoline engines and the arrival of the first anti-pollution systems, in addition to the first real efforts in road safety by the US government. marked the end of an era much missed by the most oilheads in the United States. It was not until the 1990s that the levels of power and performance lost in the 1970s would be recovered.
