How to Increase Horsepower in Your Car

Going as fast as possible for the least amount of money is every gearhead's holy grail.

All motors are different by design, but they all basically work the same way. An engine is like a furnace, working to combust fuel in the presence of oxygen to produce heat and gases. More air going in allows you to burn more fuel, and an optimized ignition and fueling system makes sure that the fuel gets burned and a good exhaust system gets rid of gases to make room for more air and fuel. Making horsepower is all about eliminating waste and moving more air and fuel.

Instructions

1. Replace the intake tube with a cold-air intake and high-flow filter to get more air in, and replace the entire exhaust system from the catalytic converter back (known as a "cat-back") to get exhaust gases out. You may also consider replacing the exhaust manifolds with tubular headers to complete the exhaust upgrade. An aftermarket intake manifold is a good idea for most engines, particularly carbureted ones. These basic modifications are worth a bit of power, and set the stage for upgrades to come.

2. Eliminate any of the accessory drive items that you can, and install underdrive pulleys to slow the rest of them down. Power steering pumps, A/C compressors, smog pumps and mechanical cooling fans are horsepower leeches, and you don't need them. Replace the mechanical fan with an electric unit mounted directly to the radiator. Change your oil, flush the oiling system and switch to a full synthetic racing oil to reduce heat and parasitic drag.

3. Upgrade your ignition system with a set of platinum or iridium-tipped spark plugs, larger-diameter plug wires, a more powerful ignition coil (or coils) and a high performance distributor cap and rotor, where applicable. If you have a distributor, set the initial timing advance so that the engine just starts to knock under full throttle, then back the timing off by 2 to 3 degrees.

4. Reprogram your stock computer with a pre-programmed "power tuner." These devices simply plug into your onboard diagnostic port, and require only that you press a few buttons to upload a program optimized for horsepower. You could use a laptop or a more advanced tuner to manually alter the engine variables, but you do so at your own risk. The slightest error could result in engine meltdown, so it's safest to leave the programming to professionals.

5. Install a nitrous system. There are two routes you can take here, either "dry-flow" or "wet-flow." Dry-flow systems inject nitrous oxide into the engine at the throttle body; the engine's computer automatically adds more fuel through the injectors. Wet-flow systems inject both nitrous and fuel, and are the only option for carbureted engines. A nitrous system will add as much horsepower as the engine will physically take, but don't get too ambitious. About 15 horsepower worth of nitrous per cylinder is a safe amount for most engines, but do your research first.

References

• "How to Rebuild Small-Block Chevy LT1/LT4 Engines"; Mike Mavrigan; 2002
• "Maximum Boost: Designing, Testing, and Installing Turbocharger Systems"; Corky Bell; 2003
• "Underdrive Pulley Upgrades"; Terry McGean; Hot Rod Magazine; August, 1998
• "Nitrous Basics"; Jeff Smith; Hot Rod Magazine; February, 2009
• "Is Synthetic Worth It?"; Steve Magnante; Hot Rod Magazine; Februaray, 2009