Exhaust Manifold

Abstract

An exhaust manifold for attaching to exhaust ports of an engine, the manifold having a plenum and a plurality of exhaust runners each associated with a respective exhaust port, the plenum having a progressively tapering cross sectional area along its length as defined by the direction along which successive exhaust runners connect to the plenum and a connector at its larger downstream end, for connecting to further components of the exhaust system, characterized in that the lengths of the gas flow paths in all the exhaust runners, as measured from the end of each runner adjacent the exhaust port to an interior wall of the plenum opposite the other end of the runner, are substantially equal to one another.

I claim: 
     
         1 . An exhaust manifold for attaching to exhaust ports of an engine, the manifold comprising:
 a plurality of exhaust runners each having a respective exhaust port associated therewith;   a plenum coupled to the plurality of the exhaust runners, the plenum having a height, a length defined by the direction along which successive exhaust runners are connected to the plenum, and an internal wall, the plenum having a progressively tapering cross sectional area along its length, and a collector disposed at the largest cross section area of the plenum, the collector defining the downstream of the plenum, and runners being progressively upstream with increased distance from the collector;   the plenum and the exhaust runners define a plurality of runner respective gas flow paths defined at least from the end of the respective runner adjacent the respective exhaust port to the interior wall of the plenum, the length of all gas flow paths being substantially equal.   
     
     
         2 . An exhaust manifold as claimed in  claim 1 , wherein the height of the plenum, as measured in the plane orthogonal to the runners and a major axis of the plenum, increases in steps as each successive downstream runner opens into the plenum. 
     
     
         3 . An exhaust manifold engine as claimed in  claim 1 , wherein the height of the plenum, as measured in the plane orthogonal to the runners and a major axis of the plenum, increases linearly along the length of the plenum in a direction from an upstream runner towards the collector at the downstream end of the plenum. 
     
     
         4 . An exhaust manifold as claimed in any preceding claim wherein the plenum has at least a section of its length having an oval cross section defining a major axis and a minor axis, the length of the major axis increasing monotonically along its length between the furthest runner and the collector. 
     
     
         5 . An exhaust manifold as claimed in  claim 4 , wherein when fitted within an engine compartment of a vehicle, the major axis is substantially vertical and the minor axis substantially horizontal. 
     
     
         6 . An exhaust manifold as claimed in  claim 1 , wherein the plenum increases in cross sectional area as each successive runner joins the plenum from the farther runner at the most upstream end to the collector at the largest area downstream end. 
     
     
         7 . An exhaust manifold for attaching to exhaust ports of an engine, the manifold comprising:
 a plurality of exhaust runners each having a respective exhaust port associated therewith;   a plenum coupled to the plurality of the exhaust runners, the plenum having a height, a length defined by the direction along which successive exhaust runners are connected to the plenum, and an internal wall;   the plenum having a mid-section having the largest cross section thereof, the mid-section having a collector coupled thereto;   at least one of the plurality of exhaust runners being coupled on each side of the mid-section; and,   the plenum cross-section tapering away from the mid-section along the plenum length;   the plenum and the exhaust runners define a plurality of runner respective gas flow paths defined at least from the end of the respective runner adjacent the respective exhaust port to the interior wall of the plenum, the length of all gas flow paths being substantially equal.   
     
     
         8 . An exhaust manifold as claimed in  claim 7 , wherein the plenum cross section area decreases after each successive runner which joins the plenum farther from the collector. 
     
     
         9 . An exhaust manifold as claimed in  claim 7 , wherein the plenum cross section area decreases linearly away from the mid-section. 
     
     
         10 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 1 . 
     
     
         11 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 2 . 
     
     
         12 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 3 . 
     
     
         13 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 4 . 
     
     
         14 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 5 . 
     
     
         15 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 6 . 
     
     
         16 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 7 . 
     
     
         17 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 8 . 
     
     
         18 . A vehicle having an internal combustion engine utilizing exhaust manifold as claimed in  claim 9 .