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You are watching: How much horsepower does a 3.9 v6 have

The Neglected 3.9 V6 Dodge Truck EngineThanks to Vince Spinelli, Gabriel Couriel, Dan Stern, Vincent Roberts, and Mark P.The 3.9 V6 was a close relative of the 318 V8, even keeping the bore and stroke, created because the upcoming Dodge Dakota needed a V6 engine. Creating a new V6 would have taken too much time and money.

On the 1994 Dakota and Ram, the exhaust manifolds were shrunk to 1 5/8" and the exhaust was reduced to 2.5" from 3", eliminating 5 horsepower but no doubt saving some money. The greater efficiency of the system led engineers to drop EGR on the 1996 trucks.In 1997, the 3.9 received sequential multiple-port fuel injection, where each injector fires as the cylinder is drawing in air (in the older multiple-port injection systems, the injector often fired against a closed valve). Aided by a larger spark plug gap, the system increased responsiveness, though horsepower and torque ratings remained the same as in 1996: 175 hp
Displacement239 cubic inches / 3906 cc
Bore and stroke3.91 x 3.31 (90 degree V6)
ValvesOverhead - 12 valves, roller followers, hydraulic lifters
Fuel injection1987: None, Holley carburetor1988-1991: Single-point electronic1992-1996: Multiple-point1997-end: Sequential, returnless multiple-point
ConstructionCast iron block and heads
Compression ratio9.1:1 (1997)
Redline5,250 rpm (1997)
Fuel 87 octane unleaded regular
Oil, coolant4 quarts oil, 14 quarts coolant
Emissions3-way catalyst, two heated oxygen sensors (1997)
EPA mileage(1997 Dakota)16 city, 22 highway (2WD, manual transmission)15 city, 18 highway (4WD, automatic transmission)

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Common repairs forum member Dean C. found that his 2002 3.9 van would stumble and idle poorly, a few minutes after a warm restart. When the throttle was blipped, it popped; when given a lot of throttle, it revved and ran normally. The stumbling lasted up to a couple of minutes; if driven, it would hesitate, sputter, and pop for several minutes unless given full throttle. After a couple minutes, it would be fine until the van was shut off for 5-15 minutes. Cold starts were normal.Bob Lincoln wrote that the the 3.9L V-6 often had a vacuum leak at the "belly pan gasket" on the intake manifold, which could cause stumbling and poor idle after a warm restart, and "pops" when the throttle is "blipped." Bob wrote that another indicator of this problem is oil consumption; the owner can check for black residue, either wet or dry, at the bottom of the throttle body."Whitevanguy" added that there can be problems with weak or intermittent grounds causing "weird electrical issues." Bad MAP sensors can also cause similar problems.(repair tips | performance tips | the men behind the 3.9 V6: Willem Weertman | Pete Hagenbuch)