GM LEA Tuning

"All you need to know about tuning and performance parts on the GM LEA engine!"

We were asked for more information about tuning and building a modified LEA, specifically which turbo improvements work best, so we put together this feature that covers our go-to changes for this engine as well as what we believe are the greatest value modifications you can do.

The GM LEA is a good project engine, and with the right tuning changes such as ECU maps, turbo upgrades, and camshafts, you can truly optimize your driving potential.

TorqueCars will look at LEA tuning and report on the best mods that work.

History of the LEA Engine

General Motors' LEA engine is designed for a wide range of small & medium automobiles.

The Ecotec engine family includes the LEA, which has a displacement of 2.4 litres in an inline-four layout.

It has direct injection, variable valve timing, and it can work with E85 fuel.

• Buick Verano CX and CXL 182hp 172lbft
  Buick Regal (fleet only) 182hp 172lbft
  MH8-6T40
• Chevrolet Captiva Sport (fleet only) 182hp 172lbft
  MH7-6T45
• Chevrolet Equinox 182hp 172lbft
  GMC Terrain 180hp 171lbft
  MH7-6T45 or MH7-6T45-AWD

Tuning the GM LEA and best LEA performance parts.

Best LEA upgrades

The best LEA parts on an engine are usually the ones that provide the most powerful improvement for the money spent.

Popular LEA components will not sway us; they must be cost effective.

Fast road cams perform best at higher RPM power, making it a good mod for NASP and turbo petrol engines, but not so great for diesel.
On most engines, we've always observed peak power gains with performance camshafts.

As a result, changing your LEA camshaft will affect the engine power band.

Choosing a higher performance camshaft profile expands the power range typically higher up the rpm range.

Fast road cams tend to increase the bhp throughout the rpm range, you could sacrifice a little low down torque but the top end will be lifted.

Race cams, increase the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a car used daily you should ideally try to match your bhp range to your preferences.

I'd be surprised if you find an LEA Motorsport camshaft is a pleasure to live with when driving around busy urban areas.This is because the lumpy idle will make the car more likely to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

LEA Camshaft Upgrades

Some LEA engines respond differently primarily due to the airflow when camshafts are fitted depending on the camshaft being more aggressive camshaft durations and cam duration as unique due to manufacturing tolerances and quality variations|so set your engine up on a rolling road|check your engine on a rolling road.

The ecu map and fuel pump and injectors also will make differences on the power gains you'll achieve.

Longer valve durations can adjust the power band, and on most engines there are some advantages to extending the intake or exhaust durations and valve lift.

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

Best Engine Mods for your Car

1. 1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
   2. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
   3. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
   4. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

   So we will break these usual recommendations down and see if these 'best mods' are appropriate for your car and we shall look in detail at the mods that will work for you and your needs.

Typical stage 1 mods often include: Remaps/piggy back ECU, Fast road camshaft, Drilled & smoothed airbox, Panel air filters, Sports exhaust header/manifold, Intake manifolds.

Typical stage 2 mods often include: Fast road cam, Sports catalyst & performance exhaust, Ported and polished head, high flow fuel injectors, fuel pump upgrades, induction kit.

Typical stage 3 mods often include: Crank and Piston upgrades to alter compression, Engine balancing & blueprinting, Competition cam, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves).

ECU Mapping Improvements for the LEA

ECU mapping enables a tuner to unlock the full potential of all the modifications you've made to your LEA.

(Sometimes, chip tuning the ECU is not an option, so an aftermarket ECU is the way to go; most of them outperform the specs and performance of your factory ECUs, but make sure it has knock protection and is properly installed.)

It will often provide roughly 30% more power on turbocharged vehicles and around 15% more power on NA (naturally aspirated) engines, although your results will vary greatly depending on the parts you've installed and the state of your engine.

Air Flow improvements on the LEA

Feeding more air and fuel into the LEA engine is the whole point to any engine upgrade project.

Air Intake manifolds flow the air during the suck phase from the filter and allow it to be drawn into the engine and mixed with fuel.

The bore size, shape and rate of flow of the Intake manifold can make a substantial effect on to fuel mixing and power on the LEA.

We often see intake are improved through an upgrade, although a few car makers provide reasonably well designed intake.

Larger LEA valves, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also improve bhp, and importantly will allow you to get a greater bhp increase on other tuning parts.

LEA Turbo upgrades

NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your LEA

The more air that can enter an engine, the more fuel that can be burned, thus improving induction with a turbocharger upgrade results in considerable power gains.

Every engine has weak points, with some being tremendously powerful and others barely able to handle stock power.

Determine these limits and add stronger pistons, crankshafts, and engine components to withstand the force.

Many tuners have spent a lot of money on turbocharger improvements for the LEA, only to be humiliated by the engine exploding soon after they've done.

Larger turbo chargers frequently have low end lag, whereas compact turbo chargers spool up much faster but do not have the peak-end horsepower benefits.

Fortunately, the field of turbochargers is continually evolving and we commonly find variable vane turbochargers, allowing the vane profile is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust gases into a couple of channels and push these at differently profiled vanes in the turbo. They also increase the scavenging effect of the engine.

You'll commonly see there is a limit in the air flow sensor MAP/MAF/AFM on the LEA when a lot more air is being sucked into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped torque at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more complex to configure. We have this in depth look at twinchargers if you want to read more.

LEA Fuelling Upgrades

When you lift the bhp and torque you will need to look at the fuel delivery.

More bhp and torque needs more fuel. Boosting the fuel pressure provides a more snappy the acceleration responsiveness.It makes sense to be generous with your injectors flow rate.

The accepted safe increase is to add 20% when fitting an injector, this accounts for injector deterioration and allows a bit of spare capacity should the engine need more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

LEA Performance Exhausts

You only need to to boost your exhaust if your current exhaust is actually causing a restriction.

On most factory exhausts you'll find your flow rate is good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Note that with the widest exhaust you can find this will reduce the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

For road going cars mods such as a sports catalyst pretty much removes this restriction, thanks to its larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed.

This keeps the car road legal and will allow the full exhaust flow due to its higher internal surface area and design. The alternative catless mod or catalyst removal should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars (and in some, you can't even replace a working catalyst).

Weak spots, Issues & problem areas on the LEA

The LEA engines are pretty solid and give little trouble as long as they are regularly serviced and maintained.

Frequent oil changes are vital on the LEA, and more so when the car is modified and will help prolong the life of the engine.

If you want to know more, or just get some friendly advice on Tuning your LEA engine please join us in our friendly forum where you can discuss LEA tuning options in more detail with our LEA owners. It would also be worth reading our unbiased GM tuning articles to get insights into each modification and how effective they will be.

Please help us improve these tips by sending us your feedback in the comments box below.

We love hearing what our readers have got up to and which tuning mods work best for them on each model of car. We use your comments and feedback to improve the accuracy of these LEA tuning guides which get regular updates and revisions.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Buick, Cadillac, Chevrolet, GM. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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