Really, Nicholas Otto should have known. When the 18th Century inventor/engineer/designer/builder/deep-thinker was finally able to take French engineer Alphonse Beau de Rochas' 1862 internal combustion engine theory and put it to practical use with the building of the first internal combustion engine, he should have recognized that men would soon attempt to improve on his engine, making changes and modifications with the focus on more power, more reliability, and more overall performance. Thus was born the first high-performance enthusiasts. And the performance aftermarket industry has never looked back, continually developing and improving the internal combustion powerplant, taking the four-cycle engine to a level of sophistication that would make Rochas and Otto proud -- we hope.
Today, the fundamental concept of an Otto-cycle engine (named for its creator) is no different than in past decades -- we just have better parts to play with. What follows is a basic review of the internal combustion process, followed by a technical showcase of the best power-producing parts currently available.
Four-Stroke Engine Function:
The Foundation of Power
A four-cycle engine's operation is complex, to be sure, but a description of the internal combustion process can be reduced to fundamentals. Air and fuel are drawn into an engine through a fuel-mixing device and an intake manifold (the intake stroke); the fuel and air is compressed inside a chamber by the upward travel of a piston (the compression stroke), after which the compressed mixture is ignited by the spark of a spark plug, and the heat of the explosion pushes the piston downward, which in turn, forcefully rotates the crankshaft (the ignition/power stroke). Then the spent exhaust gases are routed out through the exhaust valve (the exhaust stroke). That's the basic operational theory of the four-stroke internal combustion process, although the nuances and details of engine function -- and how best to increase power -- are extremely complex.
The Principals of Power: Increasing an Engine's OutputMaximizing the power output of any engine is fairly basic in theory. Since an engine is fundamentally an air pump, taking in air (and a small dose of fuel), compressing and burning that air, and exhausting the leftover air, it stands to reason that any engine modifications that increase the amount of air flowing through an engine will increase power, and that's the basic theory behind most of today's engine performance parts: Move air into the engine, burn it completely, and move air out. With the basic theory of internal combustion examined, let's get to the good stuff -- bring on the high-performance parts!
The Intake Cycle:
For an engine to function properly, it must be fed a precise mixture of air and fuel, normally in a 14:1 (air/fuel) ratio. The primary air/fuel management device is the carburetor or Electronic Fuel Injection system. With either a carburetor, a multiport EFI, or a throttle-body EFI, a small amount of fuel is introduced into the air stream flowing into the engine. The intake manifold plays an important part in managing the airflow on the engine's intake side. Basically, an intake manifold is a series of channels (runners) that take the air/fuel mix (from a carburetor or throttle-body EFI) or the air (multipoint EFI) and efficiently route it to the intake ports of the cylinder heads.
Superchargers open an entirely new concept in performance since a blower stuffs the intake manifold and the combustion chambers full of a larger volume of air than is possible in a normally aspirated intake tract. With the increased amount of air, more fuel gets in the combustion chambers and more power is produced.
When you're looking to upgrade engine performance, induction mods should be at the top of your list. Intake manifolds that flow a large volume of well-managed air, carbs, and EFI systems are designed to not only precisely meter fuel, but also provide the least possible restriction to airflow. Superchargers that force-feed an engine all the air it can use are components with a proven -- and well-deserved -- reputation for performance.
The Road Demon carburetor is a far cry from OE and most aftermarket fuel-mixers because of its state-of-the-art design. Rated at 625 cfm, the four-barrel, vacuum secondary Road Demon is ideally sized for a small-block V-8 application, and boasts such features as an electric choke, a dual-feed fuel inlet, streamlined throttle bores and a choke tower for enhanced airflow, adjustable fuel metering jets, four adjustable idle circuits, and large-capacity fuel bowls. For more information, contact: Demon Carburetion, Dept. OR, 1450 McDonald Rd., Dahlonega, GA 30533, (706) 864-8544, www.demoncarbs.com.
Turbo City's Rock-It Hi-Flow Throttle Body is a bolt-on EFI system for Jeep TJs and YJs that boosts throttle response, fuel efficiency, and performance, but doesn't cost a fortune. Built from an OE casting, Turbo City's TBI is 50-state-legal, installs with basic handtools, and fits the Jeep 2.5L four-cylinder engine as well as the 4.0L inline-six powerplant. For more information, contact: Turbo City, Dept. OR, 1137 W. Katella Ave., Orange, CA 92867, (714) 639-4933, www.turbocity.com.
Edelbrock's Performer intake manifold is a standout among performance intake manifolds. The dual-plane design is ideal for 4x4s because it enhances bottom-end power and throttle response. The cast-aluminum Performer is compatible with all OE components, including AC brackets, a carburetor choke heater, a water neck, an alternator bracket, an EGR system, and a distributor. The Performer is 50-state legal, features a carburetor pad that's drilled to accept either an OE carb or an aftermarket fuel mixer, and is available for a wide variety of V-8 engines.For more information, contact: Edelbrock Corp., Dept. OR, 2700 California St., Torrance, CA 90503, (310) 782-2222, www.edelbrock.com.
ACCEL's SuperRam is a retrofit tuned-port injection system for small-block Chevy engines. Designed by legendary engine-builder John Lingenfelter, the SuperRam replaces the carburetor or the throttle body and provides tunable, driveable, and powerful air/fuel management in a high-tech, stand-alone, multiport-injection package. A 1,000-cfm throttle valve, a high-flow plenum, large-diameter intake runners, and a special manifold base designed to enhance throttle response are trick features of the SuperRam.For more information, contact: ACCEL/Mr. Gasket Performance Group, Dept. OR, 10601 Memphis Ave., Ste. 12, Brooklyn, OH 44144, (216) 688-8300, www.mrgasket.com.
Kenne Bell's Twin Screw Supercharger is a unique and highly efficient twin-screw blower that takes incoming air and accelerates (pressurizes) it by forcing it through the length of its dual, screw-shaped rotors. Because of this design, the Twin Screw Supercharger is capable of producing maximum boost at 2,000 rpm, and that boost continues at max up to the peak of the engine's powerband. Plus, there's virtually no blower lag, and throttle response is crisp. The Twin Screw Supercharger is internally lubricated with its separate oil supply and enjoys 50-state-legal status. All Kenne Bell Twin Screw Supercharger systems are completely bolt-on applications, with no fabrication required. For more information, contact: Kenne Bell Hi-Tech Performance Products, Dept. OR, 10743 Bell Ct., Rancho Cucamonga, CA 91730, (941) 909-6646.
World Products' Motown 220 cylinder heads are designed for small-block Chevy engines. Because the 220cc intake ports flow plenty of air, the Motown heads are best suited to engines that are moderately modified with a performance camshaft and induction upgrades, or are more than 383 ci in displacement. The Motown heads are cast iron, using World Products' RightCast technology, which ensures that the intake, the exhaust ports, and the combustion chambers retain their designed shape during the casting process. The heads are available with either 64cc or 72cc combustion chambers, as well as straight or angle-plug configurations. The Motown heads are available as complete assemblies, including Manley stainless steel valves, valve springs, and screw-in rocker arm studs, or as bare castings with screw-in rocker arm studs. For more information, contact: World Products, Dept. OR, 35330 Stanley, Sterling Heights, MI 48312, (810) 939-9628, www.worldcastings.com.
Airflow Research designed its Small-Block Ford Street Heads to be high-performance components -- of course -- but there was also a focus on making the new aluminum cylinder heads 50-state-legal, and they are. The SBF Street Heads, intended for 351ci Ford V-8s, use 185cc intake runners for excellent low-speed power, 2.02-inch intake valves, 1.60-inch exhaust valves, and 58cc or 64cc combustion chambers. The AFR SBF heads are loaded with neat stuff: The deck is a full 3/4-inch thick, which keeps the head gaskets intact under severe use and the combustion chambers and the intake and exhaust ports are CNC-machined so that their shape is true to the original design. The Airflow Research heads are ready to run with screw-in rocker arm studs, a three-angle valve job, valves and valve springs, hardened valve seats, and bronze valve guides. For more information, contact: Airflow Research, Dept. OR, 10490 Ilex Ave., Pacoima, CA 91331, (818) 890-0616, www.airflowresearch.com.
Trick Flow's 23-Degree Aluminum Cylinder Heads are true high-performance cylinder heads designed with a focus on useable torque, which is just what a small-block-powered 4x4 or heavy truck needs during off-road romps. The Trick Flow heads use 195cc intake runners that are smaller-than-typical in cross-section. This small inside diameter really wakes up low- and midrange performance since airflow is accelerated. Don't worry; the 23-Degree heads still have ample capacity to flow a lot of air at higher rpm. The alloy heads use 64cc combustion chambers, and the 23-degree valve angle makes for maximum airflow and a fast-burn combustion chamber. For more information, contact: Trick Flow Specialties, Dept. OR, 1248 Southeast Ave., Tallmadge, OH 44278, (330) 630-1555, www.trickflow.com.
Federal Mogul's Sealed Power Hypereutectic pistons are one of the best ways to add power and reliability to an engine. The forged pistons are flat-top in design with reliefs machined into their top for valve clearance, and will increase the compression ratio when installed on older engines that originally used dished-top pistons. Typically, expect a two-point increase in compression ratio just with the installation of the Sealed Power pistons. The Sealed Power pistons' skirts are graphite-coated to minimize heat buildup and reduce wear. For more information, contact: Federal Mogul, Dept. OR, P.O. Box 1966, Detroit, MI 48235, (248) 354-7700.
ACCEL's Performance Ford Distributor is an all-new, direct-replacement performance distributor for Blue Oval V-8s. The ACCEL distributor uses true performance-bred electronics, a center-less ground shaft, a high-dielectric strength cap, and a balanced rotor. The Performance Ford Distributor's integral wiring harness is plug-in compatible with the OE Ford harness, and the distributor is 50-state-legal. Depending on just how weak an engine's OE distributor is, installing the ACCEL distributor can yield an increase of as much as 30 horsepower, thanks to more efficient management of the ignition process. For more information, contact: ACCEL/Mr. Gasket Performance Group, Dept. OR, 10601 Memphis Ave., Ste. 12, Brooklyn, OH 44144, (216) 688-8300, www.mrgasket.com.
The Davis Unified Distributor for Chrysler small-block V-8s is a true high-performance distributor that's void of external or add-on components (it's unified, like the name says). Built on the foundation of a GM HEI distributor, the DUI unit uses a Dyna Module ignition module for longer-than-stock ignition dwell time, an ignition curve specific to each of the small-block Mopars it's available for, and a 50,000-volt internal coil that's efficient as high as 7,000 rpm. Installation is a bolt-on; a single 12-volt wire powers the coil, and the distributor drops into place once the troublesome OE distributor is removed. Expect improved throttle response with the DUI distributor, and as much as 45 additional horsepower. For more information, contact: DUI Performance Distributors, Dept. OR, 2699 Barris Dr., Memphis, TN 38132, (901) 396-5782, wwwperformancedistributors.com.
MSD's 6AL Ignition Control unit is a common sight on modified engines in every category of the off-road world -- rockcrawlers, prerunners, boggers, and everyday 'wheelers can all benefit from the computer-controlled sparks that the MSD 6AL produces. The key to the 6AL's performance lies in its ability to produce multiple sparks during each cylinder's ignition cycle. The multiple sparks -- delivered during the initial 20 degrees of each cylinder's ignition cycle -- ensures that the combustion process is complete, which is a notable aid to engine efficiency, power, and smoothness. The MSD 6AL is easily adaptable to four-, six- or eight-cylinder engines, features an adjustable Soft-Touch Rev Control, and is 50-state-legal.For more information, contact: MSD Ignition, Dept. OR, 1490 Henry Brennan Dr., El Paso, TX 79936, (915) 857-5200, www.msdignition.com.
ACCEL's 10.8 Ferro-Spiral spark plug wires aren't just cool looking, they're true performance components. The ACCEL wires feature thick brass terminals, a fiber inner core for strength, a spiral-wrapped stainless electrical wire, a thick, primary insulating jacket made of silicone, a second braided jacket, and a second silicone on the exterior for protection against heat, oil, moisture, and chafing. The plug boots are 100 percent silicone and are available in straight, 45-degree angle, or 90-degree angle configurations. For more information, contact: ACCEL/Mr. Gasket Performance Group, Dept. OR, 10601 Memphis Ave., Ste. 12, Brooklyn, OH 44144, (216) 688-8300, www.mrgasket.com.
Edelbrock's Stainless Steel headers deliver excellent gains in exhaust flow, and they look good to boot. Edelbrock headers feature a nickel- or chrome-plated finish for durability, and the primary tubes are mandrel-bent for wrinkle-free corners. The tube material is 17-gauge stainless steel, the cylinder head flanges are laser-cut for an accurate fit, and the headers are 50-state legal. Edelbrock's Stainless Steel headers are available for a wide variety of early and late-model GM trucks and SUVs.For more information, contact: Edelbrock Corp., Dept. OR, 2700 California St., Torrance, CA 90503, (310) 782-2222, www.edelbrock.com.
Hooker's Super Competition Headers for 258ci Jeep I-6 engines are fabricated from 18-gauge mild steel tubing, and use equal-length primary tubes to enhance exhaust flow. Hooker Super Competition Headers feature a long collector, which smoothes and blends together the exhaust flow of the primary tubes, and a 5/16-inch-thick cylinder head mounting flange with integral metal O-ring seals around the exhaust ports for leak-free performance. The headers can be ordered with Hooker's Metallic Ceramic Thermal Barrier Coating, which is rust-resistant and provides a high-luster finish that's heat-resistant to 1,600 degrees.For more information, contact: Hooker Headers, Dept. OR, 1024 W. Brooks St., Ontario, CA 91762, (909) 983-5871, www.holley.com.
Stan's Headers manufactures one of the few headers for big-block-powered Ford 4x4s. The Tri-Y headers are unique in their primary tube design. One header (four tubes) pairs two primary exhaust tubes together in a small collector. The remaining two primary tubes are paired in a separate collector. Then the two collectors are paired together in a large collector, which is the source of the Tri-Y name. This intricate design reduces exhaust gas reversion and smoothes, scavenges, and accelerates exhaust flow for increased performance. The cylinder head flanges are machined flat, making for a precise, no-leak fit.For more information, contact: Stan's Headers, Dept. OR, 4715 Auburn Wy. N., Auburn, WA 98002, (253) 854-5310, www.stans-headers.com.
The Other Guys' headers feature all the good stuff: 1/2-inch-thick cylinder head flanges, 14-gauge tubing, and electroless nickel plating on the exterior and interior of the entire header. The Other Guys' headers carry an unlimited lifetime warranty, and the company claims its headers will boost a late-model Chevy small-block's rear-wheel output by 20 horsepower. All installation pars are supplied, including the components required to integrate the headers with the OE exhaust system. For more information, contact: The Other Guys, Dept. OR, 2937 Cherry Ave., Long Beach, CA 90806, (562) 989-1570, www.theotherguysproducts.com.