Earlier truck engines featured a small engine cover that was positioned over the throttle body. The throttle body on these engines also pointed upward (and a little forward) but was located at the center of the intake. (Photo Courtesy Fiat Chrysler Automobiles US LLC)
5.7-Liter Eagle 2009–2012 and 6.4-Liter Apache 2011–2012
These engines share the same front cover, which does not interchange with earlier models. The alternator and power steering fit earlier engines, but care should be taken to ensure correct interchange as there are concerns other than physical fitment, such as electrical.
Until the 1990s, most automotive intake manifolds were made of cast iron or aluminum. Manufacturers eventually made them of a composite or plastic material that was durable enough to survive engine use. The benefits of both lower weight and cost made them popular.
5.7-Liter Hemi (Truck/Durango) 2003–2008
These intake manifolds are made of a composite material and place the throttle body in the middle of the engine facing forward. They fit correctly only on pre-2009 5.7-liter heads. The MAP sensor is located at the front of the intake.
5.7-Liter Hemi (Car and Jeep) 2005–2008
This intake manifold is also composite but places the throttle body directly above the front accessory cover, parallel to the ground. This intake fits only pre–2009 5.7-liter heads. The MAP sensor is located at the rear of the intake.
5.7-Liter (Truck) 2009–2012
As with previous versions, this intake manifold is composite. It fits all square-port heads. Unlike previous truck intakes, this one places the throttle body at the front of the intake, at a 90-degree angle (facing upward).
These stock 5.7 car manifolds are barely adequate for a stock Charger, Challenger, Magnum, or 300, but you can add aftermarket bolt-on goodies, and forget it.
All Gen III Hemi intakes (except for the 6.1-liter) are of a composite design. This reduces weight and helps reduce intake-charge heat. This intake is for a 2008 or earlier passenger car. The passenger car intake varies from the truck intake, which typically has the throttle body in a different location and pointed upward.
5.7-Liter (Car and Jeep) 2009–2012
This intake is composite but looks and performs like that of the 6.1-liter intake manifold. The throttle body is located horizontally at the front of the intake, above the timing cover. This intake fits all square-port intake heads and the MAP sensor is located at the rear of the intake.
6.1-Liter Hemi 2005–2010
All applications use this aluminum intake. It is designed for square-port heads. It is a two-piece design with a removable plenum cover. This removable cover makes porting and polishing easy. The throttle body is located horizontally at the front of the intake above the accessory drive cover. This intake fits both 5.7- and 6.1-liter blocks, making it a great choice.
6.4-Liter Hemi 2011–2012
In all applications, this intake is composite. It features a variable-length runner design that is RPM controlled. The throttle body is located horizontally at the front of the engine, above the accessory drive cover, but is angled toward the driver’s side of the car. This intake fits all square-port heads, but may require the use of spacers.
Many companies offer transmissions for Hemi-powered cars. The following are the most popular among Hemi car owners.
NAG1/A580 2005–2014
With the merger of Chrysler and Daimler/Benz, it wasn’t long before some of the Benz parts began to appear in Chrysler vehicles. Enter the NAG1 automatic transmission. The NAG1/A580 transmission had advantages over existing Chrysler automatic transmissions. For example, it was more efficient than the previous 4-speed automatic that was used with less-powerful LX cars. Compared with the 545RFE 5-speed automatic transmission that Chrysler was using in their trucks, the NAG1/A580 had a wider gear range, was considerably smaller, and weighed less.
MAP Sensor
A 1-BAR MAP sensor reports barometric pressure, which is approximately 14.7 psi or 30 in Hg (inches of Mercury). As an example, a typical three-wire MAP sensor has 5 volts and ground to power the circuit. The signal circuit, or return voltage to the computer, is about 4.5 volts at a barometric pressure of 14.7 psi; this measurement is taken at key on, engine off. The sensor can withstand about 1.5 BAR of pressure, but the return voltage peaks at about 4.8 volts.
This type of sensor is designed for a normally aspirated engine to read a negative pressure, or vacuum, at a typical barometric pressure. A reading of 2 or 3 BAR simply means two or three times above barometric pressure.
Common MAP sensor readings are:
• 1 BAR is for a normally aspirated engine
• 2 BAR handles a forced induction up to 14.5 psi of boost
• 3 BAR handles a forced induction up to 29.0 psi of boost
A MAP sensor measures both vacuum and pressure. (Photo Courtesy Fiat Chrysler Automobiles US LLC)
If you ordered an automatic-equipped Hemi car, your shifting duties were handled by the Mercedes-Benz–derived NAG1 transmission. The NAG is an electronically-controlled 5-speed transmission that has a lock-up clutch inside the torque converter. A large 13-pin electronic connector located on the passenger’s side of the transmission (just above the fluid pan near the bellhousing area) identifies the transmission.
All rear-wheel-drive LX cars from 2005 to 2012 use an aluminum oil pan with a front sump. All 2003–2012 two-wheel-drive Ram trucks use a stamped steel rear sump pan (shown). Jeeps use a unique cast-aluminum rear sump oil pan.
The NAG1/A580 automatic transmission is an electronically-controlled 5-speed transmission that uses a lock-up clutch encased inside the torque converter. Fifth gear is an overdrive with a high-speed ratio, and the different ratios are actually selected by three planetary-gear sets.
The NAG1/WA580 was used in different cars, starting with the 2005 Chrysler 300 and Dodge Magnum with Hemi V-8 engines. Later, it was put into service in the Jeep Liberty, Grand Cherokee, Charger, Challenger, and eventually, the Ram truck. The NAG1/WA580 was built at Chrysler’s Transmission Plant II, in Kokomo, Indiana. Plant I built the 45RFE and 545RFE electronically-controlled transmissions starting in 1998.
Gear Ratios
Visually, the NAG1/A580 transmission can be identified by the round 13-pin connector located on