TORQUE: USEFUL CONCEPT or AUTOMOTIVE RED HERRING ?
By Bob Palmer
VIN:
March 4, 2000
Overview:
 Time was when the performance of engines was discussed in terms of horsepower. These days it seems more savvy to talk about torque. So, is torque really a better concept than horsepower for evaluating and comparing the performance of automotive engines in various applications, and in particular with respect to Tigers? To answer this question, we will start with some very basic concepts and develop these ideas into some specific recommendations for building engines and gearing them appropriately to suit your individual goals.
Discussion:
Seems like it just gets harder and harder to keep up with this fast-paced, high-tech world we’re living in. Just about the time you think you’ve become an expert at something, they go and introduce a radical new technology and you’re back to square one. One of the things I like most about my Tiger is its inherent simplicity; no fancy electronics or computers. The good part of this is that if something goes wrong, I can probably quickly diagnose and repair it. But, in spite of all the electronic controls and gadgets on modern engines, they are still basically the same as they always were. After almost thirty-five years in production, the venerable Ford Windsor small block is a case in point. With all of this experience with internal combustion engines, you would think we would already have learned pretty much everything that’s worth knowing. However, there’s always more to be learned and even the old lessons need to be retaught to a new and eager audience. Unfortunately, all too often the wisdom of the past has been abandoned in favor of trendy rheotoric inspired by a combination of ignorance and the profit motive. Now, there’s nothing new about this problem. Since even before the time of the chariots it’s been caveat emptor - let the buyer beware. Most of the bogus information is just hype for the purpose of getting a leg up in competition for your hard-earned bucks. Sometimes, however, the errors are of a more fundamental nature and reflect a basic misunderstanding of the issues. While it would be foolish to try and correct all of the misleading and bogus information being purveyed by even so-called experts, some of the more important issues should be confronted from time to time. A case in point are the concepts of torque and horsepower, their relationship to each other and to the performance of your car. Time was when the performance of engines was discussed in terms of horsepower. These days it seems more savvy to talk about torque. So, is torque really a better concept than horsepower for evaluating and comparing the performance of automotive engines in various applications, and in particular with respect to Tigers? To answer this question, we will start with some very basic concepts and develop these ideas into some specific recommendations for building engines and gearing them appropriately to suit your individual goals.
Being a physicist by training as well as by nature, I like to start with the basics and build a good fundamental understanding of a subject. The advantage of this approach is that (1) it has a much better chance of getting the correct answer, and (2) it allows you to apply what you learn to a variety of similar situations, rather than just having specific answers to specific questions. With this philosophy in mind, let’s start at a very fundamental level with the concepts of torque and horsepower and their relation to the performance of automotive engines and then go on to present some rather simple guidelines for building and gearing engines for optimum performance. First of all, what do we really mean when we talk about engine performance? While for some people performance might mean gas mileage, miles between overhauls, or the ability to turn really high rpms, the measure of performance that relates to how quick you can turn a 1/4 mile or how fast you can run an oval or road track is most directly related to acceleration. That good old feeling of acceleration you get on your backside when you push on the accelerator (appropriately named), regardless of how much sturm and drang accompany it, is really the bottom line.
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