The 340 Mopar Engine is still one of the most popular Mopar Engines from the ’60s and ’70s. Some Mopar Engines were designed for drag racing. They were heavy and bulky, but put-out high horsepower. This made them great for straight line races, but anything that involved curves they struggled. That’s were the quick-and-nimble 340 Mopar Engine found its calling.
The 340 Mopar Engine was developed in the 1960s and found its way to production by the end of 1967. It was close in cubic inches to the 318 Engine, but they differed in a whole lot more than just 22 cubic inches.
The 340 had: high performance heads, special carburetor and cam; New oil pump with a 90 degree adapter; 2.02 inch intake valves and 1.60 inch exhaust valves; Dual Time Chain with windage tray; high-rise dual plane intake.
Even with all of these performance features the top “horsepower rating” that any 340 Mopar Engine was 290 horsepower. This was the 340 Six Pack version debuted in the Dodge Challenger T/A and AAR ‘Cuda. Many believe that many Mopar Engines’ horsepower were underestimated to cut down the costs that buyers would have to pay for their insurance. So the actual horsepower of these 340 engines are most likely more than the rated 290 horsepower.
Stock 340 Mopar Engine Characteristics
Figure 1 show the performance characteristics (power curve) of the stock 340 engine. The maximums were at 281 hp at 5200 rpm and 328 lbs/ft at 3900 rpm. These numbers are right on target for the the factory ratings on the 340 high performance which were 275hp at 5000 rpm, and 340 lbs/ft at 3200 rpm.
Share Your 340 High Performance Modifications
How have you built up your High Performance 340 Engine? Share in the comments!