Ultimate Chevy 6.2 EcoTec3 Mods Guide

The 6.2 EcoTec3 is the biggest and most powerful engine offered in half-ton trucks. While it’s got a good amount of power, what’s not fun about adding some more? With just a few basic bolt-on modifications you can get the 6.2 EcoTec3 up to around 500whp, at which points aggressive cams or forced induction will be the route to take.

In this guide we’re going to teach you how to build a 500whp engine with just an intake, headers, tuning, and E85 fueling. Additionally, we’ll cover camshafts, supercharging, and displacement on demand even though these aren’t quite needed to hit these power levels.

Best Chevy 6.2 EcoTec3 Mods

• Cold Air Intake
• Long-Tube Headers
• ECU Tuning & Flex-Fuel
• Camshaft
• Supercharger

1) Cold Air Intakes

By using a larger, lighter, and less restrictive air filter and tubing, your engine will be able to suck in more air at a higher velocity. This is one of the best ways to increase horsepower and torque on the engine, by allowing it to essentially breathe easier. In addition, usually aftermarket intakes are made of heat resistant and lightweight material. This helps shed unwanted weight and keeps temperatures down. In addition, they also spruce up the engine bay and you can really hear the induction sounds much more, too.

2) Long-Tube Headers

Not only will an exhaust increase performance, but it will also add a noticeable volume to your engine. Just like with an intake, a larger and less restrictive exhaust helps the engine breathe better and suck-in more air at a faster rate. Less restriction and less back pressure means more horsepower and torque, and also a considerable amount more volume out of your exhaust, too. 

The most important part of the exhaust to upgrade on a naturally aspirated V8 like the 6.2 EcoTec3 are the headers or exhaust manifold. The headers connect directly to the cylinder heads. They help direct the flow of the exhaust gasses into the cat-back and out the tailpipe. By upgrading the headers, you’re reducing restriction as close to the engine as possible. That allows the effects to be as substantial as possible. 

There are two main types of header upgrades: either long-tube and short-tube headers. Long-tube headers will offer more performance than short-tube headers, because they replace more of the exhaust manifold. These either remove or replace the catalytic converters with high-flow versions, which is where a lot of the restriction in the exhaust comes from. Long-tubes will usually add 15-25 horsepower and torque, while short-tubes will be closer to 5-15 horsepower and torque. 

3) ECM Tuning & E85 Fueling

Combining ECU tuning with flex-fuel takes the gains to a whole new level. Flex-fuel, or E85 ethanol, is much better for performance than traditional pump gasoline. Full E85 has an octane rating of around ~105, which is substantially higher than your normal 87-91 octane from pump gas. Additionally, ethanol also has superior cooling properties and combusts at a lower temperature, which also helps to reduce detonation and pre-ignition. 

By installing a new tune to your engine, things like the ignition timing, camshaft timing, fuel pressure, and variable valve timing can be optimized to increase the engine’s horsepower and torque output. In addition, if you have other mods — like an upgraded intake or headers — flash tuning will allow you to get even more gains. Usually, with tuning, you can expect to add 5-20% horsepower and torque over stock. 

4) Performance Camshafts

Camshafts are responsible for actuating how long and how much the valves open. This plays a crucial role in how much air the engine can take in and how much power it can make. The most important things to look at are the camshaft’s duration and lift.

A camshaft that has a longer duration will allow the valves to stay open for longer, letting them suck-in more air. Camshafts that have a larger lift will open the valves more, allowing for more air to be ingested into the engine. These contribute a significant amount of airflow and air velocity for the engine, which really increases horsepower and torque. Depending on the size of your cam specs, you can easily add more than 50+ horsepower with the right cam. 

The OEM camshaft specs are: Duration 200°/207° (intake/exhaust), Lift 0.551 in./0.524 in., and LSA 116.5°. That makes them fairly mild in terms of duration, but relatively high-lift, too. 

5) Supercharger Kits

While the other bolt-ons above will net around or a little over 500 horsepower crank, forced induction is really the only way to crack 500 horsepower at the wheels. Without forced induction, you’ll need to look at upgrading the cylinder heads, intake manifold, as well as getting a high-lift cam that will really change how the engine handles. 

Going with a supercharger is the quickest and easiest way to gain lots horsepower and torque. The purpose of a supercharger is to induct compressed air into the engine, which massively increases horsepower and torque output. Depending on the size of your blower, you can easily add anywhere from 50-150+ horsepower in just a few hours. The 6.2 is a great candidate for supercharging because it already has very stout internals, and its large displacement means it will make some serious power. 

Bonus: Disabling AFM / DoD Delete Kits

While it won’t add any horsepower, a very popular modification to make to the EcoTec3 is a DoD delete kit. DoD means “Displacement on Demand.” It refers to the Active Fuel Management (AFM) system the engine uses to boost fuel economy and reduce emissions. 

Many people do not like the feeling of AFM/DoD when driving. It sucks power and can make the truck/SUV feel very sluggish from a stop. In addition, the DoD also limits the lift of potential camshaft upgrades. This makes it a necessary modification depending on how big of cam you are going with (see recommendations below). 

We recommend disabling AFM & DFM with the BOOST AFM Disabler.

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