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CYLINDER HEAD BASELINE PROCEDURES

When we get ready to develop a new cylinder head porting program we use the following steps:

 PORT AREA

?      Measure valve diameter

?      Measure stem diameter

?      Length of port

?      Port volume in cc

We take the above data and insert into a computer program. This will give the area of a port which will help in a mathematical determination of port velocity.

This is determined by air flow in CFM and port area at a given lift to estimate port velocity.

FLOW-BENCH TEST

The cylinder head is installed on a flow bench, and both intake and exhaust ports are flow tested. We check air-flow at .050 lifts and at 28 inches of water.

PORT VELOCITY PROBE TEST

While the cylinder head is on the flow bench we test port velocity at the .300 lift and the .550 lift. On the intake test we use a u-shaped probe and on the exhaust test we use a straight shape probe. We check the port at nine points. We start at the top of port measure  top three areas of port, the middle three areas, and the bottom part of port. This information is inputted to the computer and a port velocity map is generated.

COMBUSTION CHAMBER

We measure the chamber volume in cc, this used to determine a correct compression ratio. Chamber volume is important to assisting in determining a cam shaft choice. Chamber volume and the intake closing number on camshaft assists us in this determination.

COMBUSTION CHAMBER SWIRL TEST

A swirl meter is a device that shows the direction of air-flow in the combustion chamber. This meter reads the air flow in rpm and in either a clockwise or counter-clockwise rotation. The idea here to make sure the air flow is directed to the spark plug. The higher rpm the more turbulent mixture in the combustion chamber.