whats new on the 09 hemi
Grand Champion
Joined: Nov 2005
Posts: 6,258
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From: Charleston, SC
RE: whats new on the 09 hemi
From Allpar:
40% of Ram buyers opt for the Hemi, which has gas mileage similar to the 4.7 liter V8 but much more power. For 2008, the Hemi was revised to improve engine breathing and gas mileage, with the addition of variable cam timing; a higher compression ratio; higher-flowing heads, intake, and exhaust; and an active intake manifold that switches from long runners to short runners, to optimize the engine for either better high-end horsepower or better low-end torque.
In addition, the MDS system has been updated so the engine will spend more time in four-cylinder mode, saving fuel. Numerous other hardware upgrades were implemented to build on the quality, reliability and durability reputation of the HEMI engine, including crankshaft structural upgrades, a dual-mass crankshaft damper, floating pin piston design, valve spring design, and oil pump capacity increase.
The results of all this work are a 10% boost in power to 380 hp (283 kW) and 404 lb-ft of torque (548 Nm), up from 345 hp and 375 lb-ft. At the same time, gas mileage increased by nearly 5%. The Dodge Ram R/T rear-wheel-drive model, with a short bed, regular cab, and 4.10:1 gears, can reach 60 mph in a mere 7 seconds, making it faster than the PT Cruiser GT or V6 Dodge Charger. The variable cam timing (VCT) reduces the engine’s pumping work by closing the intake valve later, and increases the expansion process of the combustion event. This allows more work to be transferred to the crankshaft instead of being rejected out of the exhaust port as heat. VCT improves engine breathing, which improves engine efficiency and power.
The MDS system, which shuts off or restores four cylinders in a small fraction of a second, has, according to Chrysler estimates, saved nearly 100 million gallons of gasoline since 2005, along with reduced carbon dioxide (CO₂) emissions of close to a million metric tons. When MDS is operating, it is indicated by a “Fuel Saver†readout in the 2009 Dodge Ram’s Electronic Vehicle Information Center.
In addition, the MDS system has been updated so the engine will spend more time in four-cylinder mode, saving fuel. Numerous other hardware upgrades were implemented to build on the quality, reliability and durability reputation of the HEMI engine, including crankshaft structural upgrades, a dual-mass crankshaft damper, floating pin piston design, valve spring design, and oil pump capacity increase.
The results of all this work are a 10% boost in power to 380 hp (283 kW) and 404 lb-ft of torque (548 Nm), up from 345 hp and 375 lb-ft. At the same time, gas mileage increased by nearly 5%. The Dodge Ram R/T rear-wheel-drive model, with a short bed, regular cab, and 4.10:1 gears, can reach 60 mph in a mere 7 seconds, making it faster than the PT Cruiser GT or V6 Dodge Charger. The variable cam timing (VCT) reduces the engine’s pumping work by closing the intake valve later, and increases the expansion process of the combustion event. This allows more work to be transferred to the crankshaft instead of being rejected out of the exhaust port as heat. VCT improves engine breathing, which improves engine efficiency and power.
The MDS system, which shuts off or restores four cylinders in a small fraction of a second, has, according to Chrysler estimates, saved nearly 100 million gallons of gasoline since 2005, along with reduced carbon dioxide (CO₂) emissions of close to a million metric tons. When MDS is operating, it is indicated by a “Fuel Saver†readout in the 2009 Dodge Ram’s Electronic Vehicle Information Center.
