 |
|
|
| THE READ FOR SPEED by Ned Erkman |
| CHAPTER 3 |
|
Cylinder Head Power Production
To fully understand the performance capabilities of cylinder heads, a thorough understanding of the science is essential.
The fundamentals of airflow dictate that the power of an engine is directly determined by the amount of air that is consumed in the engine until combustion occurs.
Air flow is what determines fuel flow, as the volume of air is matched by the volume of fuel for the required air/fuel ratio. Fuel is also suspended and transported to the cylinder by air flow.
Power production depends on the quality of air and fuel flow, as dry air does not flow the same as wet air. Since fuel is denser and heavier than air, fuel flow through the intake port and combustion chamber takes a different direction than air flow alone. Cylinder head porting modifications and valve jobs that improve the quality of wet flow and increase air/fuel mixture velocity are what enhance power production.
Technically, proper cylinder head and intake manifold porting modifications that produce a (1) cfm (cubic feet of air per minute) increase of intake airflow can generate 0.25 horsepower per cylinder. Basically, this means that a one cfm increase in intake airflow can produce an additional two horsepower in a V8 engine. To further this example, a 30 cfm increase in airflow through the intake port can produce more than 60 hp with the right camshaft and compression ratio. Porting modifications that yield over 50 cfm improvement in airflow are possible when serious work is done to the heads and in accordance with the above formula, an increase of 100 horsepower can be attained with the right combination of engine components.
Another method that can be used to consider the power capability of a cylinder head is to determine the airflow of the cylinder head. For example, a cylinder head that flows 260 cfm of air has the potential to produce 100 hp over a head that flows 210 cfm. In addition, based on the two (2) hp per 1 cfm of airflow formula, a cylinder head that flows 260 cfm has the potential to produce 520+ horsepower, if the right combination of engine components is being used.
Ned Erkman
Author of The Read for Speed
Copyright © 2005 The Read For Speed. All Rights Reserved.
Reproduction in whole or in part without expressed written permission from the author
is strictly prohibited.
|
|
|
|
|
|
