Saturn S series Twin Cam cylinder head had now featured a new roller-rocker setup with hydraulic tappets and roller cams replacing the conventional bucket lifter setup of the previous engine in the S series. Also introduced for the 1999 model year S-series vehicles that were sold in California was a different type of an exhaust manifold that housed an upstream catalytic converter (this converter had heated up much faster than the conventional unit, and it had also decreased exhaust emissions faster as well), and it also had provisions for an air-injection reaction system (This had injected fresh air into the exhaust to reduce
Steam locomotive exhaust system reason the blower is often turned on in these situations, to counteract the compression effect. The aim of exhaust system development is to obtain maximum smokebox vacuum with minimum back pressure on the pistons. Little development of the basic principles of smokebox design took place until 1908, when the first comprehensive examination of steam-raising performance was carried out by W.F.M. Goss of Purdue University. These principles were adopted on the Great Western Railway by Churchward. Andre Chapelon made a significant improvement with his Kylchap exhaust which incorporated a "Kyala spreader" (second stage nozzle) and third stage cowl between the blastpipe