Detroit switched to unleaded gasoline 50 years ago, here’s how power took a hit

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“We all know who we are pollute the atmosphere, “Alex Mair, Chevrolet’s chief engineer, told the New York Times.” But I think we got it in time, we can turn that around. “

Mair did not speak this month about GM’s electric vehicle program as a world leader met at COP26 to tackle climate change. He died in 2012. That quote comes from a 1970 story about GM’s decision to modify its 1971 cars to run on low-lead, unleaded gasoline.

The NYT speculated that other automakers would follow GM’s move (I was going to say lead, but that could be confusing), and that’s exactly what happened. Although car enthusiasts didn’t know this at the time, the V8 muscle it had peaked in 1970. Overall, Detroit reduced the compression ratios of nearly all of its 1971 cars to accommodate the lower octane content of unleaded gasoline. And that meant performance suffered.

Related: For the first time since 1923, no driver in the world can legally purchase leaded fuel

Regular cars with straight sixes and small V8s didn’t lose much because they often already had low enough compression ratios that allowed them to run on cheap gasoline. But some, though not all, of the hottest engines hammered. Let’s take a look at exactly how many horsepower they lost in the pursuit of clean air. To make useful comparisons, we are focusing primarily on the engines that were available in both years, rather than the replacement engines that were enlisted to correct the CV deficit.

AMC Javelin – Lost 5 HP

Credit: Mecum

American Motors’ Mustang rival gained a voluptuous new sheet metal for 1971, but lost some muscle in the process. The new 304 cu-in. The 210-hp (5.0-liter) V8 output was 15 hp less than the previous year’s 290-cubic equivalent. and the AMX the 360 ​​cu-in (5.9-liter) V8 carryover dropped 5hp to 285hp.

And despite the appearance of a new massive 401 cu-in. engine option delivering 330hp despite its 9.0: 1 compression without lead, the year before’s high-performance 390-cubic Ram Air engine still outpaced it by 10hp.

Buick GS 455 – Lost 35 HP

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The Buick GS 455 torque monster kept its 7.5-liter V8, including the high-performance Stage 1 option, but both had claws trimmed for ’71. The compression of the base 455 dropped from 10.0: 1 to 8.5: 1, bringing the power from 350 to 315, while the squish of the Stage 1 dropped to a modest 8.0: 1, resulting in a reduction in power from 360 hp to 345 hp.

Cadillac Eldorado – 35 HP lost

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Deciding that just 472 cu-in (7.7 liters) simply wasn’t enough, Caddy stroked its tiny V8 down to a whopping 500 cu-in. (8.2 liters) and introduced the result as an upgrade option on the Eldorado of 1970. That year it was rated at 400 horsepower and 550 lb-ft similar to a truck, but the compression ratio dropped a point and a half to 8.5: 1 for 1971, bringing power back to 365 horsepower.

Chevrolet Camaro Z / 28 – Lost 30 hp

Credit: Mecum

Related: 21 US states are urging the EPA to set stricter fuel economy standards

The ’67 -’69 Z / 28s he had used a short stroke 302 cu-in. (5.0-liter) V8 designed to conform to Trans Am racing rules, but for the 1970 Chevy’s street Z / 28 it borrowed the hot LT1 350 from the Corvette. Equipped with solid tappets, large valves, a lumpy cam and aluminum pistons giving a compression ratio of 11.0: 1, it produced 360hp (10hp less than the Corvette). But the compression dropped to 9.0: 1 for 1971, bringing the power to 330hp.

Chevrolet Chevelle SS 454 – Earned 5 HP

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The 1970 Chevelle SS 454 with the optional LS6 engine and skyrocketing 11.25: 1 pistons was rated at 450hp, the most of any car from the muscle heyday. But it was nowhere to be seen in ’71. However, the milder LS5 sibling is back, and despite compression dropping from 10.25: 1 to 8.5: 1, Chevy said it now produced 365 horsepower, up 5 from 1970.

But that was a smokescreen: the fact that it had developed that power 600 rpm earlier and produced 35 lb-ft less torque revealed the Chevelle Super Sport new character. And if not, the availability of a small 245-horsepower block with a pathetic single exhaust pushed the message home.

Dodge Challenger – 35 HP lost

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Compared to GM, Chrysler withstood more of its horsepower as 1970 switched to 1971. True, the 383 cu-in. (6.3-liter) V8 that was the base engine in many Dodge and Plymouth cars like this Challenger was now rated at 300bhp, down from 335bhp, but the Six-Pack, triple carb 440 has only dropped by 5bhp to 385 hp, Other the mighty 426 Hemi maintained its 425hp output for its final season.

Ford Mustang – Lost 10 HP

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Seventy-one was a mixed bag for the Mustang, and not just because the new style didn’t tickle everyone’s fancy, particularly when it came to the coupe. The 250 cu-in base. (4.1-liter) six split with 10hp he could hardly afford to lose, dragging peak power to 145hp and mid-range 351hp cu-in. The power of the V8 (5.8 liters) dropped from 10 hp to 240 hp.

Related: Mercedes again accused of cheating on diesel emissions, real figures allegedly five times higher than those reported

A Ford that reversed the trend was the new for ’71 Boss 351 Mustang, which brought the bird to low-lead gas with an insane compression ratio of 11.7: 1 and good power of 330hp. And a new 429 cu-in. (7.0 liters) replaced the previous year’s 428 and produced 375 hp, an increase of 40 hp, with the premium Super Cobra Jet trim.

Oldsmobile 4-4-2 – 25 HP lost

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Olds’ big hitter in the muscle car wars it was 4-4-2, which scored a PB of power in 1970 thanks to a new 455 cu-in (7.5 liter) V8 that produced 365 hp in base trim and was rated at 370 hp when equipped with the W30 hop-up kit racing. But those numbers dropped to 340hp and 350hp for 1971, respectively.

Pontiac Grand Prix – 50 hp lost

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The basic engine in the GTO and the Grand Prix was a 400 cu-in. (6.6-liter) V8 in both 1970 and 1971, but production dropped 50bhp to 300bhp for the second of those years, making them the biggest losers on this list.


It is worth saying that the power numbers from early muscle age it shouldn’t be taken as a gospel, particularly those before Detroit switched to more realistic net CV ratings for 1972, which we’ll come back to in another feature. Some have been overrated for looking good in advertisements, and some, like the Camaro ZL1 from 1969, hugely underestimated for insurance reasons, but it’s clear that most have lost power while preparing for a friendlier, low-lead, lead-free gas.

We just wonder if Alex Mair, whom we heard about at the beginning of this post, would have imagined that we would still be fighting to save the planet 50 years after his NYT interview.

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