From 2010 GM Powertrain: https://docs.google.com/viewer?a=v&q...vvI_1JLj2RhozQ

The Vortec 3.7L I-5 carries over the VVT (variable valve timing) or cam phasing system employed on the 3.5L I-5, which was one of the world's first truck engines with this technology. The cam phaser changes exhaust cam lobe timing relative to the cam-drive sprocket, which in turn varies exhaust valve timing on the fly, maximizing engine performance for given demands and conditions. At idle, for example, the exhaust cam is at the full advanced position for minimum intake-valve overlap. That allows exceptionally smooth idling. Under other operating conditions, the phaser adjusts to deliver optimal exhaust-valve timing for performance, drivability and fuel economy. The result is linear delivery of torque, with near-peak levels over a broad rpm range, and high specific output (horsepower per liter of displacement) without sacrificing overall engine response or drivability. Because it manages valve overlap at optimum levels, cam phasing also eliminates the need for an Exhaust Gas Recirculation (EGR) system.

 

my brain malfunction,got egr and pvc mixup! this could be serious!!! just this morning,b4 posting i had a ct scan of neck/head for arteries!! i told my daughter i was having my head examined. guess i was right(about the exam)!! anyway.
oh my, dont get old

 

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lol bio that's spam. not a post

 

Moderators, PLEASE DELETE THIS GUY!