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God (And His Horsepower) Live In The Details: A Primer on Advanced Engine TuningJul 16 '00 (Updated Jul 18 '00) Write an essay on this topic.The days of cheap, shadetree horsepower increases are receding into history. Automotive engines have become so dependant on electronic controls the old fixes-a new manifold and a bigger carb-no longer apply. Sport motorcycle engines are still carbureted and relatively straight forward. But with stock horsepower outputs closing in on 200hp per liter-the realm of Formula One racing engines just a few years ago-the factory engineers aren't leaving many stones unturned. So it's ironic that the EPA and the fight among billion-dollar motorcycle companies for magazine praise has revitalized a mechanical art nearly killed by bolt-on parts in the hot rod era. Engine tuners are in a renaissance. In gearhead circles the names of the best-Lingenfelter, Roush, Muzzy and Ferracci-are mentioned with a reverence art aficionados reserve for Van Gogh and Gauguin. For fans of both the mechanical and visual arts there is little difference between the disiplines, as insane as it might sound. At the highest levels engine tuning is about expressing and understanding what no one can see-the movement of a molecule of air through an intake passage at hundreds of miles per hour, the tides of sonic waves and pressure fronts that resonate through the machine like air through an instrument, all to create a perfect, swirling flame of combustion in each cylinder up to 60 times per second. The difference between masterpiece and failure is measured by a thousand tiny deliberate actions-brushstrokes on metal-that combine to create a single whole when it goes right. Most of all, like art it is a skill and a trade you can practice for your entire life and never fully understand. At its most basic, engine tuning is removing the mistakes and shortcuts made when the factory sent the engine down the assembly line. Flip through a repair manual and you will notice that there is no one precise value for any part of your engine. Even when the parts are all brand new the factory will say the diameter of a crankshaft journal can range between 1.500 and 1.504 inches, or the weight of one piston compared to the others can vary by 20 grams, and meet the factory requirements. Removing these variances is called balancing and blueprinting and it's at the heart of any proper engine tuning. The margins are reduced from thousandths of an inch and whole grams to ten-thousandths of an inch (0.0001"-also called "tens") and fractions of a gram on parts that sometimes weigh almost two pounds. It's the kind of precision associated with Swiss watches, only its not that simple. On any part there are a number of often conflicting standards to bring together. The valve springs-deceptively simple looking coiled metal wire-will need to agree on weight, height and measured compression rate. Pistons need to agree on weight, measurement across the top (the crown), the bottom (the skirt), and the clearance between the piston and the tool steel wrist pin that keeps it attached to the connecting rod when forces greater than three tons are placed on it. And one measurement is hardly ever enough. Part "A" is this wide in diameter at this point, but what is it 45 and 90 degrees from your first measurement? You have better odds of winning the lottery than getting the exact same reading three times on four pistons. A couple of tens of ovality is inevitable, but how much is too much-and how much will any correction affect the other critical specifications? Multiply this by the dozens of parts that need to be massaged and brought together for everything to work in symphony. And when you begin to feel like you could do this in your sleep it is past time to start searching for other hidden secrets you might have missed because someone else already is. When it's done right, the difference between a balanced and blueprinted engine and a production piece is startling. The first thing you notice is an incredible smoothness. When all the internal parts aren't fighting each other the great majority of vibration and harshness is eliminated, some engines feel almost turbine-like. The second thing you notice is power. Even without added compression or any other typical high-performance modifications a balanced and blueprinted engine will routinely generate 25% more power. It will also last longer, and should you decide to treat the engine to some "serious" work it will be more receptive to the tweaks than any shadetree wrench ever dreamed of. Tuning is a mix of current technology and art as old as the automobile. The best tuners today are implementing NASA developed permanent engine coatings that achieve everything Slick 50 promises, cutting internal friction losses by 20% and adding another dimension to the engine performance. At the other extreme, the all-important intake path is massaged and reshaped to create the most efficient path for the air and fuel to reach its final destination. There are machines to measure the results but the work is still done by the hand of a person grinding away a little metal here, adding a little filler there, reshaping it as he tries to see the molecule of air making its journey. (And for what it's worth, no bolt on part short of a supercharger or turbocharger will increase the power output of your engine more than good cylinder head tuning.) None of this comes cheaply. If you can get their personal work the best tuners charge as much as a Park Avenue therapist. The work done by their staff is only slightly less dear-the 475hp engine package for the Chevrolet Corvette from John Lingenfelter starts at $18,000-nearly half the cost of the complete car. Strangely enough, professional tuning for a $10,000 motorcycle can cost as much as the $40,000 Vette. (With professional-caliber racing suspension, brake and bodywork to compliment the engine the "bargain" sportbike's price can push amazingly close to-gulp- $100,000.) If all you care about is how big the peak horsepower numbers are, there is no way to justify the expense of a professionally tuned engine. Turbo and supercharger packages are available for cars and bike at a fraction of the price, many can be installed by an owner with a little mechanical ability over a long weekend. Nitrous oxide injection is cheaper yet. But the feel couldn't be more different. If a tuned engine has a massive power hit as the top end of the powerband it will be because someone designed it to be there, not because that's when the turbo finally comes online. Speed builds much more effortlessly in a tuned car than in a blown or nitroused machine, more smoothly, and it makes the car or bike much easier to transition through corners. Like the focus on synergy with the parts of the engine, a car or bike with a tuned engine has an excellent start on feeling like one united piece where a forced induction machine has a handicap to overcome feeling like a collection of parts. Or maybe I'm an anal-retentive, elitist, a-hole. I have strong feelings about fly fishing and single-malt scotch, too, so there might be a pattern emerging. Don't rush into this. If you are planning to make a large investment in your sports car or motorcycle, beg a ride in a Lingenfelter Corvette or a quick spin on a Rob Muzzy Raptor. Then tell me if you don't think two similar numbers on a dyno chart can tell very different stories. -Brian Igo  |
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