The design and tuning of competition engines

The Design and Tuning

of Competition Engines

Philip H. Smith

Sixth Edition Revised by

David N. Wenner

The Design and Tuning

of Competition Engines

$14.95

Rewritten from its formerly British view￾point, this sixth edition covers the compe￾tition engine in America. Oval track, drag,

and stock car racing are discussed, whereas

earlier editions were concerned with "road

racing only". Part I (Theory) covers ther￾modynamics, engine construction mate￾rials, and fundamentals of engine design.

Part II (Practice) describes techniques used

in engine preparation, including cylinder

head modifications. Part III (Engines and

Applications) has seven chapters on modi￾fying specific engines: American V8s,

Formula Fords, Formula Vees, Formula

Sup"r-V",,~ (inrlllr!ing water-cooled), D:>.t￾suns (fours and sixes), Twin-cam Fords,

and Mazda rotaries. This virtually all-new

book is an indispensable reference for any

person involved (or just interested) in

racing.

David N. Wenner's revision of this

classic marks a complete and major update,

focusing on the American racing scene.

More than ever, it is a book anyone inter￾ested in racing competition should have."

-Autos Unlimited.

Updated, completely revised 6th edition

The Design and Tuning

of Competition Engines

The Design and Tuning

of Competition Engines

BY

Philip H. Smith

SIXTH EDITION REVISED BY

David N. Wenner

ROBERT BENTLEY, INC.

872 Massachusetts Avenue

Cambridge, Mass. 02139

First Edition 1954

Second Revised Edition 1957

Third ~evised Edition 1963

Fourth Revised Edition 1967

Fifth Revised Edition 1971

Sixth Revised Edition 1977

10 9 8 7 6 5 4 3 2

© 1977 Robert Bentley, Inc.

Library of Congress Catalog Card No. 77-78834

ISBN 0.8376.014°.1

Manufactured in the United States of America

Acknowledgments

Basic to the requirements of a comprehensive book on any

subject is suitable illustrative matter. Philip H. Smith, deceased,

the original author of this book, and T.C. Millington, who edited

and revised the Fifth Edition, were fortunate to have cooperation

from many sources. Some of their original illustrations remain in

the present edition-notably drawings that were provided by IPC

Transport Press Ltd., British publishers of Autoear, Automobile

Engineer, and Motor Trader. In addition, one or more illustra￾tions were provided by the following:

The Alexander Engineering Co. Ltd., Haddenham, England

Robert Bosch G.m.b.H., Stuttgart, Germany

V.W. Derrington Ltd., Kingston on Thames, England

Ken Lowe Accessories Ltd., Slough, England

London Art Tech (Motor Sport), London, England

Joseph Lucas Ltd., Birmingham, England

Dr.-Ing. h.c.F. Porsche, Stuttgart, Germany

Renold Chains Ltd., Manchester, England

Rubery Owen and Co. Ltd., London, England

Shorrock Superchargers Ltd., Wednesbury, England

Wade Engineering Ltd., Brighton, England

Soc. p. Az. Ed. Weber, Bologna, Italy

Mr. Douglas Armstrong, Reading, England

Mr. Michael Porter, Brooklyn, N.Y., U.S.A.

v

In the preparation of this Sixth Revised Edition, it has been

our pleasure to use a number of illustrations made available

through the courtesy of American Motors, Chrysler Corporation,

the Ford Motor Company, and General Motors-America's "Big

Four". Special thanks are also due the Champion Spark Plug

Company of Toledo, Ohio, whose excellent Service Corner pub￾lication has been the source for several of our illustrations. The

vast support given to racing by these American companies is well

known to all.

Our thanks are also extended to Volkswagen of America, Inc.,

and British Leyland Motors, Inc., with whom it has been the

present author's privilege to work in the preparation of official

service manuals. Both of these representatives of European manu￾facturers maintain very active racing programs in the U.S.A. Our

appreciation is likewise extended to Fiat, both for making avail￾able the basic art for our dust jacket, and for bringing high-per￾formance overhead camshaft engines within reach of the average

motorist.

It is with particular pleasure that we express our appreciation

to Datsun, Honda, Mazda, and Toyota-four auto manufacturers

based in Japan who have in recent years brought new excitement

to racing and to highway motoring in America. Only one or two

illustrations have been provided by each of these carmakers, but

their contributions to the modern automobile have been monu￾mental. Toyota has lent great financial support to Grand Prix rac￾ing in America-in addition to building fast and durable cars.

Honda and Mazda have made outstanding contributions to racing

and are especially noteworthy for having developed radically new

engines-showing that they represent the forefront of automobile

engineering today. Datsun, of course, wins races (which is what

this book is really about) , and has been given an entire chapter

as an indication of its important place in American competition.

Finally, we are indebted to the Moser Engine Corporation of

Monterey Park, California for providing us with photos of their

beautifully designed four-cam racing engine. Undoubtedly, this is

the last word in the development of America's favorite competition

powerplant, the small-block Chevrolet VS.

VI

Preface

Revised Sixth Edition

This sixth edition of The Design and Tuning of Compe￾tition Engines remains a carefully-proportioned amalgam of the

timely and the timeless. It includes both the laws of thermo￾dynamics, as immutable today as in 1954 when Philip H. Smith

included them in the first edition of the book, and a wealth of

information on present-day engines and the tuning methods

that form the cornerstone of racing in America.

When the first edition was published, the sidevalve engine

still occupied an important place in motor competition. In

America the immortal Ford flathead V8 was a major staple in

all forms of racing, and in England the 1098-cm3 Ford Ten

was propelling unknowns such as Colin Chapman and Eric

Broadley to their first tastes of racing glory. The overhead cam￾shaft engine-which today is used in well over half the makes

of cars sold in the United States-was, in 1954, a piece of pure

exotica reserved for Grand Prix cars and a few expensive Gran

Turismo machines.

Not only have many of the "glory" engines of 1954, 1957,

1963, 1967, and 1971 passed into obsolescence and obscurity,

most of the racing classes that these engines participated in

have also fallen by the way-superseded by new racing classes

that are more in tune with the times. Who could have predicted

m 1963 that the underpowered Volkswagen would find a hil>tory￾vii

VIII PREFACE

making place in Formula Vee COmpetItIOn-not to mention in

drag racing, where outputs of 200 bhp are not unheard of? For

that matter, who could have predicted in 1971, when the fifth

edition was published, that there would be a racing class for stock

Volkswagens-with watercooled engines mounted at the front?

But though the engines used in racing have changed, the

fundamental principles have not. Because of this, some of the

obsolete engines are mentioned here; occasionally they were

the last applications of principles that may someday be revived.

The 1935-1940 V16 Cadillac, for example, is discussed not be￾cause it is a significant competition engine today (it is not; its

sole claim to fame was as the powerplant for the Southern Cali￾fornia Timing Association's fastest "lakester" back in the late

194os) , but because it is representative of all 45° V16 engines￾a cylinder arrangement that could find a place on the racing

scene in the not-distant future.

This book is not a "how-to-do-it" book. It is better de￾scribed as a "how-to-know-what-you're-doing" book. That is,

there are many engine tuning methods and many design fea￾tures that the racing enthusiast recognizes as effective in com￾petition. Consequently, such a person, ill pn::paring an engine

for racing, may decide that forged aluminum connecting rods

are necessary-because he has seen forged aluminum connecting

rods in other competition engines. This book will help him to

make his decision more wisely by telling him when forged

aluminum rods are necessary and, for that matter, when they

are unnecessary or undesirable.

The Design and Tuning of Competition Engines is par￾ticularly helpful for aspiring speed tuners, who may be well

informed in matters of practical mechanics, but lack compre￾hensive engineering training. Many such people have gone on

to great accomplishments in racing, and it is our hope that

this book will be an important step for many others in their

quest for a sound theoretical foundation. Auto racing aside, we

need look no further than the Wright brothers for an historical

precedent that shows the manner in which the self-taught can

tread the path to success.

Contents

Preface Vll

Introduction/The Competition Engine in America xiii

PART I/THEORY

1. Heat Engine Operation 3

Theoretical Considerations 3

Indicated and Brake Horsepower 20

Factors Governing Expansion Pressure 23

2. The Production of Power 27

Bmep and Torque 27

Heat Loss 34

Valve Size and Gas Velocity 37

3. Problems of High-speed Operation 39

Valve Timing 39

Pulsating Pressure 49

Mechanical Stresses 55

4. Mechanical Construction of High-power

Engines 62

Basic Materials in Construction 62

Valve Operation 68

Camshafts and Drives 72

The Overhead Camshaft Engine 83

Crankshafts 96

IX

Bearings and Materials 100

Engine Block Materials 110

Pistons and Rings 117

Connecting Rods 123

The Cylinder Head 128

5. Crankshaft Design and Engine Balance 139

Bearing Location 139

Problems of Balancing 141

The Single Cylindel' Engine 145

Multiple Cylinder Engines 149

Engine Mounting 177

Bore/Stroke Ratio and Other Considerations 179

6. Planning for Performance 190

Performance Data 190

Cylinder Head Design 191

Port Shape 200

Special Exhaust Systems 206

The Combustion Chamber 207

T01'que Requirements 211

7. Efficient Combustion 215

Improving Performance 215

Spark Plug Position 223

Ignition CU1Tent 227

Timing 233

8. Mixture Production 241

Mixture Supply 241

Constant Depression Carburetors 246

Fixed Venturi Carburetors 250

Fuel Injection Systems 269

PART II/PRACTICE

9. The Cylinder Head 287

General Condition 287

Improving Volumetric Efficiency 288

Valves, Springs, and Retainers 303

Exhaust Pipe Layout 306

The Induction System 311

x

10. The Valve Gear 314

Valve Train Modifications 314

Valve Timing Modifications 323

1 I. Crankshaft, Cylinders, and Pistons 327

General Condition 327

Piston Rings 330

Piston Design 334

Connecting Rod Alignment 335

Balancing 337

Assembly Work 340

12. Compression Ratio 343

Selecting a Ratio 343

Obtaining the Ratio 347

13· The Engine in Operation 357

The Engine Installed 357

Mechanical Losses 362

14. Supercharging 368

Historical Background 368

Roots Blowers 371

Vane·type Blowers 373

Pressures 374

Turbocharging 376

PART III/ENGINES AND APPLICATIONS

15. The American V8 Engine 387

Expert Tuners 387

Standard Design 387

Cylinder Heads 391

Crankshaft, Connecting Rods, and Pistons 398

Cylinder Block 403

Tuning 406

16. Formula Ford 409

The Engine 409

Cylinder Head 414

Crankshaft, Connecting Rods, Cylinders,

and Pistons 419

Tuning and Maintenance 424

xi

17. Cosworth 426

Choice of Champions 426

Cylinder Head 432

Cylinder Block 436

Crankshaft, Connecting Rods, and Pistons 437

Tuning 441

18. Datsun 443

The Datsun Heritage 443

Cylinder Head 447

Cylinder Block 455

Crankshaft, Connecting Rods, and Pistons 457

Conclusion 459

19. Volkswagen Air-cooled 461

Competition Beginnings 461

State of the Art 462

Cylinder Heads 465

Crankcase 469

Crankshaft, Connecting Rods, Pistons,

and Cylinders 470

Formula Vee Ignitiun and CU1buTetiun 474

Supertuning and Supercharging 475

20. Volkswagen Water-cooled 478

New Force in Racing 478

Cylinder Head 480

Crankshaft, Connecting Rods, and Pistons 484

Cylinder Block 485

Ignition 486

21. Other Popular Competition Engines 487

Wankel Rotary 487

Toyota 490

Ford SOHC "Four" 492

Porsche 91 I 493

Amateur Racing 498

Appendix/Definitions, Constants, and Formulas 501

xii

Introduction / The Competition Engine

in America

The Competition Engine Defined

What exactly is a competition engine? It is not, as the

general public fancies, the same thing as a high-performance

or hot ' rod engine. A competition engine is first uf all one that

is competitive in a particular kind of racing or in a particular

racing class.

For example, the humble VW 1200 engine, offering at

best about 45 bhp per liter, would scarcely be competitive in

most kinds of racing. Yet, by virtue of its being the only engine

permitted by the rules of Fonnula Vee, it is a competition

engine. Consequently it is appropriate in a book of this kind

to talk about the VW 1200. On the other hand, it would be

inappropriate to waste space on the Rover 2000 or Mercedes

Benz 250C engines; they are unquestionably powerful and

sophisticated, but they are never used in American racing.

Yesterday's racing engine cannot be classified as a compe￾tition engine today either. In the previous edition of this book,

it seemed indispensable to discuss the Hillman Imp and the

260 cubic inch Ford V8, which were being campaigned, re￾spectively, in the SCCA's D Sports Racing and B Production

classes. Alas, how the mighty are fallen. The appearance of

either engine is rare in road racing these days.

xiii