About: Under the Hood: Engine

Induction Manifold Header Head/Port Valve Diameters Compression Ratio Bore/Stroke Camshaft Advance/Retard Lifter
Induction Induction is the airflow into the engine. Flow ratings range from 300 cfm 2-bbl carburetors to 1100 cfm 4bbl or 8bbl (or multiple carburetors) pre-defined configurations. You can also type in a custom Flow.
Manifold An intake manifold is the pathway for the incoming air (and fuel if non-fuel injected). Generally, the smoother, larger and more tuned an intake is, the more power that can be produced.
Fuel Various types of fuel combust differently and produce different power results. Most dragsters run on racing gasoline or on alcohol.
Header You can choose between an exhaust manifold or header configuration. There are a variety of configurations to choose from. Generally the larger and more tuned the exhaust is, the more power that can be produced.
Head/Port The head design and porting type affect the way the fuel is mixed and the exhaust is pushed out. For high power, port and value size should be as large as possible.
Valve Diameters Choose from several "standard" sizes from a drop-down menu or have Hotrod automatically calculate the optimal value sizes. In addition, you can input the value sizes directly into the Intake and Exhaust boxes. Valves should be as large as possible for optimal power.
Compression Ratio The compression ratio is a comparison of the volume that exists in the cylinder when the piston is located at BDC (bottom-dead-center or the lowest point in the stroke) to the "compressed" volume when the piston reaches TDC (top-dead-center or the highest point in the stroke).The compression ratio can range between 6:1 and 16:1. There are several predefined choices or the user can enter a custom one in the Ratio box.
Bore/Stroke This is the size of the engine. You are presented with many pre-built configurations through the drop down menu but can also select a custom configuration by inputting the data directly in the Bore, Stroke, and # Cylinders boxes. The calculated size of the engine will be displayed. It is well known that the larger the engine, the more power that can be produced.
Camshaft Hotrod allows you to select a camshaft type, configuration, and timing. There are several pre-defined configurations but the user can input the valve events in either the 0.050-inch lifter-rise or the seat-to-seat methods. Many racing camshaft manufacturers publish this data and it can be used to simulate the effects of the cam.
Advance/Retard This is an offset to represent the ignition timing. The timing of the spark can be adjusted to occur later or earlier in the stroke of an engine. You can use this to move the torque and horsepower curve up or down the RPM range.
Lifter The lifter is the connection between the camshaft and the valves. In general the roller-type lifter produces more horsepower.