1971 Dodge Demon 340

Smaller-sized models with medium-size engines were an interesting subset of the muscle-car market. Their engine compartments could seldom accommodate the big-block motors that made the intermediates so potent, but their compact bodies were lighter and, combined with highly tuned V-8s, presented a tempting power-to-weight ratio for performance buffs on a budget.

1971 Dodge Demon 340
The 1971 Dodge Demon 340's high-revving 290-bhp 340-cid four-barrel
could jolt the 3200-pound coupe to sub-14-second ETs.

Dodge’s Dart GTS of 1968 and ’69 was a fine example, and equipped with the 383-cubic-inch V-8 or, in very limited numbers, the mighty 440, caught many more overt muscle cars napping.

For ’70, Dodge scaled back, offering only the Swinger 340 as its Dart performance entry. Over at Plymouth, the same 340-cubic-inch four-barrel V-8 went into the new Duster, a fresh compact with a strong, simple fastback body. Dodge got its own version of the Duster body for ’71 and after rejecting the name Beaver, christened it the Demon.

A near twin to the Duster, the Dodge version differed primarily in its vertically fluted “Frenched” taillamps and louvered grille. They were even less individualized inside, each carrying a dual-pod instrument cluster derived from the 1967-69 Barracuda. High-back bucket seats and console were options. So was a 6000-rpm tachometer and a 141/2-inch diameter thick-rimmed, three-spoke “Tuff” steering wheel.

Though Demon had no center roof pillar per se, Dodge called this car a coupe because its rear windows opened forward on hinges a couple of inches, rather than rolling down.

Demon came standard with the venerable slant six engine. Its base V-8 was the 318 two-barrel. The 340 was yanked from the Dart sedan and coupe and inserted into the new fastback to create the Demon 340. Tipping the scales at just 3165 pounds and starting at only $2721, here was a light, inexpensive performance alternative.

Its MoPar small block delivered 275 horsepower at 5000 rpm. With a 10.5:1 compression ratio, dual exhausts, hydraulic lifters, and a hot cam, the 340 churned out a healthy 340 pounds/feet of torque at 3200 rpm. A fully synchromesh three-speed manual transmission was standard; a New-Process four-speed or TorqueFlite automatic was optional. Buyers could choose from a wide range of axle ratios -- 2.94:1, 3.23:1, 3.55:1, 3.91:1, or 4.10:1 -- and a Sure-Grip differential also was available.

The standard Rallye suspension included heavy-duty front torsion bars and rear springs, rear anti-sway bar, and oversize shock absorbers. The drum brakes were larger than those on other Demons and so were the E70x14 Goodyear Polyglas GT tires.

“It’s a tough little devil,” declared the Dodge performance brochure for 1971. And while Dodge promised that “the performance is a lot more than painted on,” the Demon 340 did look the part. Chromed tips decorated the dual exhaust outlets. A twin-scoop black-out hood was optional, as were handsome Rallye wheels and spoiler packages.

Driven with skill, a three-speed-manual Demon 340 with one of the performance axle ratios could turn the quarter in 13.98 at 100 mph, though most ran in the high 14s at around 95 mph with their four-speeds and automatics.

Road Test tagged Demon as a car that “will change personality in an instant. When you stomp on this one, hang on and look out!”

Marketed as part of the Dart line, Dodge’s ’71 Demon sold well. With 69,861 base Demons and 10,098 Demon 340s built, it accounted for 32 percent of Dart-series sales.

Dodge carried the Demon name into 1972, again with optional 340 four-barrel V-8. The compression fell to 8.50:1, however, and atop the 340 for this, its fourth year, was the new Carter Thermo-Quad four-barrel. Because of the carb’s plastic body, fuel was less affected by engine temperature.

For 1973, Dodge exorcised the Demon designation, turning to “Dart Sport” until the design expired after 1976. A Dart Sport Rallye model with a four-speed manual, 318 V-8, handling suspension, and front disc brakes was introduced in mid-’73, and for ”74, the 340 was bumped to 360-cubic-inches, though the car was heavier by that time and the 360 never became the street threat a good 340 was.

In the big picture, Chrysler had the right car at the right time with the Duster and Demon. The Duster for a while was Plymouth’s best seller and the Demon, even in 340 and 360 form, sold well also. One key was the styling, another was the genuinely spirited performance, especially at a time when high insurance rates and general public criticism were taking a big bite out of big-block muscle-car sales.

Engine Type
Displacement (cid)
Horsepower @ rpm:
275 @ 5000
Torque (pounds/feet) @ rpm
340 @ 3200
Compression Ratio
Bore (inches)
Stroke (inches)
Valve Lifters


0-60 mph (sec)
0-100 mph (sec)
1/4-mile (sec)
14.56 @ 96 mph
Top speed (mph)
Axle ratio

*Source: Road Test (1971)

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