John Baechtel - Practical Engine Airflow

CarTech, Inc.

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2015 by John Baechtel

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Layout by Monica Seiberlich

ISBN 978-1-61325-157-7

Item No. SA308

Library of Congress Cataloging-in-Publication Data Available

Written, edited, and designed in the U.S.A.

10 9 8 7 6 5 4 3 2 1

Title Page:

A similar choke point exists on the exhaust side. It also represents the minimum cross section and typically has a larger radius to encourage smooth exhaust flow, which exits under high pressure.

Back Cover Photos

Top Left:

The throat area immediately above the valveseat is the controlling factor in airflow efficiency. Maximum velocity across the valve should be generated here.

Top Right:

Cylinder heads are the most influential component of an internal combustion engine. They are the gatekeeper that regulates the amount and quality of the air/fuel mixture entering the engine.

Bottom Left:

Naturally aspirated applications typically require much more flow-bench work to extract maximum performance for each application. Experience pays off, but it still may require long hours of trial and error. (Photo Courtesy Smithberg Racing)

Bottom Right:

Modifying port entry angles via specific port matching produces power. The match between the runner exit and the intake port entry should be almost seamless with no sharp edges or area change. Epoxy filling is sometimes required to accomplish the smooth finish. (Photo Courtesy Wilson Manifolds)

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Table of Contents

CONTENTS

To Louie Hammel

My amazing friend Louie Hammel had a fondness for the impossible, frequently offering simple yet profound quips about engine performance that made you stop and think and, more important, imagine. Louie suffered for many years from the debilitating effects of leukemia and has since passed on, but I will always remember the day he looked at me and said, You know, Im an engine guy and when I die I want to be cremated and have one of you guys pour my ashes through the carburetor on a screaming high-RPM big-block on the dyno so I can watch all this stuff we talk about first hand.

Unfortunately Louie never achieved his goal, but I often wish he had because his reports from the other side would have been awesome and unquestionably accurate. He always wanted a personalized license plate that read TORQUE, and he had a million ideas about ways to generate it and improve engine performance. Although I was busy with a career at Hot Rod and Car Craft magazines, Louie honed his skills testing and developing parts in the dyno rooms at Edelbrock and later became a researcher and dyno technician at McFarland, Inc., evaluating and developing high-performance components for Jim McFarland.

Later, after Louie became sick, he used to come by my dyno shop in the afternoons and weekends and we would bench race engine tech and theory endlessly. Whenever something stumped us, we immediately thought to ask Louie, whereupon he addressed our question with the thoughtful power of his amazing intellect. That made some people jealous, but he only sought to offer well-thought-out opinions, and he usually had a perfectly good explanation that solved our problem.

Louie was no poser. He never cared if he impressed anyone or what others thought of his ideas. He thought well beyond that and was truly immersed in the magic of engine performance and, in particular, the science of engine airflow. If Ive learned anything over all these years, much of it came from Louies remarkably thoughtful questions and subsequent discourse on said matters. Many of us miss Louie even to this day and cant forget the remarkable impression he left on us. And thus I dedicate this book to him, an exceptionally observant and knowledgeable man.

Somehow I think he still may have managed to find his way inside a running engine and he is still in there, taking notes and preparing reports for his old friends who still feel the need to ask Louie. R.I.P., buddy.

This photo was shot at Jim McFarlands think tank R&D shop in Torrance, California, in the early 1990s before Louie was diagnosed with leukemia. Thats an early GM ZZZ engine on the dyno. Left to right: Kevin McClelland, Rod Sokoloski, Louie Hammel, Keith Rudolph, and Jim McFarland.

Resources are the lifeblood of any tech book. Without them an author could never pull together all the relevant information that applies to the subject of the book. Very few authors can write this stuff off the top of their head. It takes a concerted effort and the unfailing cooperation of numerous people who also have lives, jobs, and other things to do. Sometimes they forget or take longer than expected, but they come through in the end and their contributions lend substance to the book. Many people contributed to this book by necessity as I am far from an expert on the nuances of engine airflow. Each of them has my profound gratitude for the effort they expended.