Table Of Content

CarTech®, Inc. 39966 Grand Avenue North Branch, MN 55056 Phone: 651-277-1200 or 800-551-4754 Fax: 651-277-1203 www.cartechbooks.com © 2010 by David Vizard All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without prior permission from the Publisher. All text, photographs, and artwork are the property of the Author unless otherwise noted or credited. The information in this work is true and complete to the best of our knowledge. However, all information is presented without any guarantee on the part of the Author or Publisher, who also disclaim any liability incurred in connection with the use of the information and any implied warranties of merchantability or fitness for a particular purpose. Readers are responsible for taking suitable and appropriate safety measures when performing any of the operations or activities described in this work. All trademarks, trade names, model names and numbers, and other product designations referred to herein are the property of their respective owners and are used solely for identification purposes. This work is a publication of CarTech, Inc., and has not been licensed, approved, sponsored, or endorsed by any other person or entity. The publisher is not associated with any product, service, or vendor mentioned in this book, and does not endorse the products or services of any vendor mentioned in this book. Edit by Paul Johnson Layout by Chris Fayers ISBN 978-1-61325-256-7 Item No. SA357 Library of Congress Cataloging-in-Publication Data Vizard, David. David Vizard’s how to build horsepower / by David Vizard. p. cm. Includes bibliographical references. 1. Automobiles—Motors—Modification. 2. Automobiles—Performance. I. Title. II. Title: How to build horsepower. TL210.V5184 2010 629.25—dc22 2009044104 Written, edited, and designed in the U.S.A. 15 14 13 12 11 10 On the Title Page: The dyno validates or disproves theory. Time spent here is worthwhile, but only if what is going on is largely understood. If results are misinterpreted, then much of what might be gained is forfeited. On the Back Cover Top Left: One of the Dominator carbs has been removed to show the internals of this Ultra Pro Machining ProStock-style intake. When fitted to a two-valve pushrod engine, power eclipsed the 165-hp-per-liter mark. All-out ProStock engines, as of 2010, are right around 175-hp per liter. Top Right: Here are the springs I favor for hydraulic applications. Note the small-steel beehive retainer is as light as a titanium one for a regular spring. Middle left: Shown here is the real-life lobe centerline angle for a small-block Chevrolet roller follower cam. Middle right: The “shear dam” to the right of the intake guide boss can be clearly seen here. A fuel rivulet arriving at the shear dam is sheared off and re-introduced into the air. From here, it mostly excites the valve in the 6 to 7 o’clock position, and in doing so, aids swirl production. Bottom left: The block is the primary component for any engine. The block needs to be strong and machined to fine tolerances if winning results are to be achieved. Bottom right: The intake ports of the cylinder head shown here are the subject of an intense flow-bench development program. The high-efficiency figures produced made it possible to develop more than 100-hp per liter from a 355-ci (5.8L) 10.5:1 CR engine running service-station 92-octane premium fuel. OVERSEAS DISTRIBUTION BY: PGUK 63 Hatton Garden London EC1N 8LE, England Phone: 020 7061 1980 • Fax: 020 7242 3725 Renniks Publications Ltd. 3/37-39 Green Street Banksmeadow, NSW 2109, Australia Phone: 2 9695 7055 • Fax: 2 9695 7355 CONTENTS Introduction Chapter 1: The Basics of Every Known Speed Secret The Dynamometer When Isn’t Bigger Better? Chapter 2: Primary Point Induction Air Temperature Ram Air: the Basics Practical Density Issues Significant Pressures and Flow Element Clogging Chapter 3: Fuel Delivery Systems Mixture Ratio Exhaust Pollutants Mixture Quality Carb Function Basics WOT Calibrations The Boosters Idle and Transition Circuits Acceleration Enrichment Carbs—How Big? Carbs Versus Fuel Injection Chapter 4: Intake Manifolds Length and Volume V-8 Intake Manifolds Tunnel Ram Intakes Chapter 5: Supercharging Supercharger Types Turbos and Centrifugal Turbine Superchargers Boost Curve Shapes Supercharger Selection Superchargers and Built Motors Getting the Cam Right Turbo Cams Fueling System Chapter 6: Cylinder Heads Optimizing Cylinder Head Airflow Valve Shrouding Practical De-shrouding Ports Port Evolution Cross-Sectional Area Applied Basic Porting Wet-Flow Testing Compression Ratio Chapter 7: Porting and Flow Testing Building a Really Trick Low-Cost Bench Flowing the Exhaust Porting Results Chapter 8: Ignition Systems Number-One Ignition Goal Spark Plugs Coils Ignition Timing and Curves Modified Motor Timing Requirements Modified Ignition Systems Expected Results Chapter 9: Real Camshaft Science Mechanical Attributes Simplified Hi-Perf Four-Cycle Engine Airflow Dynamics Choosing a Cam Chapter 10: Cam Event Criteria Overlap Optimal LCA Duration Valve Lift: How Much? Chapter 11: Valvetrain: The Physical Build Reading Cam Spec Data Valvesprings Tappets Timing Gears Cam Timing Rockers Chapter 12: The Short-Block Engine The Block The Rotating Assembly Connecting Rods Pistons Rings Lubrication System Chapter 13: Exhaust Manifolds Pipe Diameter Alternative Configurations Using This Header Tech Chapter 14: Mufflers to Tail Pipes Simple Steps to Success Cats and Mufflers Muffler Flow: How Much is Needed? Pressure Waves Crossover and Balance Pipes The Ultimate System? INTRODUCTION As I type this I am approaching my 52nd year modifying engines—the last 45 doing so in a professional capacity. I would like to say they have all been smooth but that is far from the reality. It was in England, my home country, and in 1966 that I had my first taste of building/modifying a V-8 engine. It was a Ford Flathead, the principal components of which I lucked into as an unfinished project. The gentleman I bought these cut-rate parts from was to be the guest of Her Majesty’s Government and so had no need of them for 10 years or so. A thick-wall block with a big overbore and a billet stroker crank resulted in a massive displacement, for a Ford Flathead of 301 cubes. A lot of porting work and the use of high compression, a race cam, triple Strombergs, and a whole lot of other high-performance moves resulted in 224 hp and 300 ft-lbs as measured on a dyno of unknown accuracy. Up to this point I had used only chassis dynos to prove the validity of my work. This was my first go around on an engine dyno and, as it has subsequently proved to be, the first of more than 250,000 dyno pulls over the next 42 years. At the time I was disappointed with the results from that Flathead, but 30 years later I was to find that this output was a relatively creditable result for a side-valve engine. But the disappointment of that engine was to be offset a couple of years later. Over the winter of 1968–1969, I was asked to port some small-block heads for a 302 small-block Chevy powering a Lola T70 sports racer. It seemed the heads used on the popular Bartz or Traco USA-built engines of the day had a propensity for cracking, and a new set of heads at a couple thousand dollars each (remember this is 1969 and a grand is more like $2,500 as of 2010) were needed for every race. I started with castings that I thought might do the job but were different from those used by engine builders in the United States. Here I am about to time-in the cam on a low-buck 5.0 Ford Mustang engine. What is being passed on to you in these pages is 50-plus years of experience building high-performance engines. After a few weeks of experimentation, on my very simple flow bench, I had some promising working heads. The dyno subsequently demonstrated this very much to be so. That, in conjunction with a few other moves, proved to be the formula for killer results. With what I learned helping out on that engine, I reasoned (with good cause) that I had a working handle on what it takes to build an international-level race-winning small-block Chevy. Over the next few years I was to amass hundreds of wins, lap records, and pole positions, plus a half-dozen or so championship wins— two at international level—all with European engines.