General Motors produced the in-line four-cylinder engine for its line of Saturn S series automobiles from 1991 to 2002. It came in the single overhead camshaft (SOHC) and double overhead camshaft (DOHC) chain driven models. While the SOHC and DOHC engines used the same engine block, crankshaft and connecting rods and may appear similar, some striking differences exist between the two models.
Overhead Camshaft Differences
Like other SOHC engines, Saturn's version has only one camshaft in the cylinder header. Saturn's DOHC camshafts have two camshafts in the cylinder header. One of the camshafts operates the exhaust valves, and the other operates the intake valves.
SOHC cylinder heads operate on eight valves and incorporate a foam cast material. The DOHC engine has 16 valves in its cylinder head. In both engines, the camshaft is located in the cylinder head and functions off of a chain located in the front crankshaft sprocket.
Because it has a double overhead camshaft, the DOHC engine produces more overall power and runs more smoothly and efficiently. However, the SOHC produces more power earlier and is in turn more flexible and generally more economical. While the DOHC engines make an ideal choice for racing and performance vehicles, they cost more to fix than the SOHC engines.
- "Saturn S-Series: 1991 thru 2002 All Models"; John Hayes and Mark Ryan; 2003
- Nada Guidelines: Saturn S-Series Specs and Performance
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