How to Rewire Your Engine for More Horsepower Without Paying a Mechanic

Adding horsepower to your engine can give your car a significant boost in performance and acceleration. But paying a mechanic to do it can be expensive. With some basic mechanical skills and knowledge, you can rewire your engine yourself for extra horsepower on the cheap.

Assessing Your Vehicle

Before diving into an engine rewire, you'll want to assess your vehicle to make sure it's a good candidate. Here are some things to consider:

• Engine type - Certain engines like V8s or turbocharged engines respond better to rewiring than naturally aspirated 4-cylinders. Rewiring works best on engines with some built-in performance headroom.

• Overall condition - Make sure your engine is in good working order before trying to extract more power from it. Trying to rewire a worn out engine usually just results in problems.

• Computerized engine management - Newer computer-controlled engines are harder to rewire than older distributor-based ignition systems. And you risk throwing error codes by altering computer-controlled systems.

• Power goals - Be realistic about how much extra power you're hoping to gain. Massive horsepower jumps require internal engine mods, not just rewiring.

If your vehicle checks the right boxes, a rewire can potentially give it 50-100 more horsepower safely.

Understanding Ignition Timing

The core concept behind an engine rewire is optimizing ignition timing. Here's a quick primer:

• Ignition timing refers to when the spark plug fires relative to the piston's position.

• Optimal timing gives the air/fuel mixture maximum time to fully ignite but also allows peak combustion pressure to act directly on the downward moving piston.

• Advanced timing improves power but risks detonation. Retarded timing prevents detonation but reduces power.

• Most stock engines have conservative ignition timing to prevent engine damage.

The goal of a rewire is to safely dial-in more advanced timing without risking detonation. This is done by altering or adding new ignition system components.

Rewiring Basics

Here are the main components that can be altered to change ignition timing:

• Coil - A higher output coil can allow more timing advance.

• Spark plugs - Non-resistor plugs and hotter heat range plugs support more advance.

• Wires - Low resistance mag core wires prevent voltage loss to the plugs.

• Distributor - Adding an adjustable timing gear or replacing the advance curve springs can optimize timing.

• ECU - Getting an ECU tune will maximize timing on a computer-controlled engine.

And here are some other rewiring mods that can help optimize ignition:

• Installing an ignition amplifier

• Adding an MSD ignition box

• Switching from a stock distributor to coil-on-plug

• Converting to a crank trigger ignition setup

Avoiding Pre-Ignition Issues

Too much timing advance risks pre-ignition, also called detonation or knock. Here are some tips for avoiding it:

• Use higher octane fuel - The higher the octane rating, the more resistant fuel is to premature ignition.

• Lower compression - Engines with over 10:1 compression often need race fuel to support big timing jumps.

• Improve cooling - Pre-ignition happens easiest in hot combustion chambers. Improving cooling reduces the risk.

• ** Advance slowly** - Work your way up to higher advance levels safely by making gradual timing changes.

• Tune for optimum AFR - Detonation is most likely to occur near 13:1 air/fuel ratios. Tuning for 12:1-12.5:1 gives a safety margin.

• Add ethanol - Ethanol has a very high octane rating and makes fuel much more detonation resistant when blended.

Getting Professional Help if Needed

The best method for dialing in maximum ignition timing will depend heavily on your specific engine setup. If you are unsure about how aggressive you can get with the timing, it can't hurt to get the advice of a professional performance shop. They can ensure the timing and other parameters are optimized safely.

While a professional tune is an added expense, it gives you the peace of mind that your engine rewire will deliver power gains reliably. And it still beats paying a shop to handle the full rewire job.

With the right assessment of your engine, intelligent component selection, and some mechanical skills, rewiring your engine's ignition system can potentially give it a healthy horsepower kick while saving you money compared to paying a mechanic. Just be sure to take precautions against pre-ignition as you search for those extra ponies.