GM LS9 Tuning

"All you need to know about tuning the GM LS9 engine!"

The GM LS9 great bases for a tuning project and with carefully picked tuning parts like ECU maps, turbo upgrades and camshafts you will definitely enhance your driving enjoyment.

This pages aim is detail the best approach to LS9 tuning and point out the premier upgrades.

History, Power & Specs of the Engine

The LS9 was based on the stronger LS3 block, it had a supercharger fitted and put out 639bhp.

  • 2009–2013 Chevrolet Corvette ZR1
  • 2017 HSV GTSR W1
  • Equus Bass 770

Tuning the GM LS9 and best LS9 performance parts.

Best LS9 tuning parts

When talking about the best best for your LS9 engine, we are going to concentrate on the tuning parts that give the best power gain for you spend.

Significant gains on the LS9 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

Fast road cams usually raise the power throughout the rpm band, you may sacrifice a little low end bhp but higher rpm power will be lifted.

Motorsport and race cams, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a car used daily, really you should, ideally aim to match your engines power to your preferences.

You will never have ever thought or claimed that a LS9 Motorsport and race cam is a pleasure to live with when in heavy traffic because low end power will be very lumpy. Competition cams are designed for maximum power at the top end of the RPM range, a place that most daily commutes will not permit!

Some LS9 engines respond better to more aggressive cam durations so set your engine up on a rolling road.

The map and fuelling also will make differences on the bhp gains you'll achieve.

Longer valve durations can alter the bhp band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

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Best Engine Mods for your car

  1. Mapping - remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. 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.
  4. 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.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

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

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

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

The LS9 units respond well to mods and thankfully there are quite a few choices of mods and performance parts out there.

A remap helps unlock the full potential of all the upgrades you've fitted to your LS9.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but your results may differs on the upgrades you've carried out and the condition of your engine.

Forcing air into each cylinder is the aim to any performance tuning task.

Air Intake manifolds carry the air from the filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

Shape and flow rate of the Intake manifolds can make a noticeable change to fuel engine efficiency on the LS9.

It's not uncommon that intake are in desperate need of an upgrade, although a few makers provide well optimised intake.

Big valve conversions on the LS9, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also raise power, and as an added benefit will give you raising the power increase on other upgrades.

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 LS9

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes excellent power gains.

If a car has a turbo already fitted parts are simpler to install and turbo engines are made with harder and stronger components.

There are common areas of failure for every engine, with some being over specified and some only able to handle stock power

See where you'll find these restrictions and fit forged components to cope with the power.

We see many people spending a fortune on turbocharger upgrades on the LS9 only to experience the engine block explode when it's used in anger.

Big capacity turbochargers will usually experience a bottom end lag, and little turbochargers spool up quickly but won't have the peak rpm power band gains.

We are pleased that the range of turbochargers is always improving and we now see variable vane turbochargers, allowing the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbochargers divert the exhaust flow into 2 channels and feed these at differently angled vanes in the turbocharger. They also improve the scavenging effect of the engine.

It is common that there is a limit in the air flow sensor (AFM/MAF/MAP) on the LS9 when a lot more air is being drawn into the engine.

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

Adding a supercharger or additional turbo will make large bhp and torque gains, although more difficult to install. We have this article on twincharging if you want to read more.

Fuelling

Don't overlook the need to improve the fuel system when you are increasing the power - it makes the car more thirsty. We would recommend you to over specify your injector capacity.

As a rule of thumb add 20% when buying an injector, this accounts for injector deterioration and provides a little 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.

Exhaust

You should look to replace your exhaust if your current exhaust is creating a restriction.

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

Don't go with the widest exhaust you can buy this will slow up 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.

Usual exhaust restrictions can be located the filters installed, so adding a freer flowing performance catalyst removes the restriction. We note that performance cats perform similarly to decats and have the added benefit of keeping your car street legal, as decats or catalyst removal is illegal in most territories for road going cars.

Weak spots, Issues & problem areas on the LS9

The LS9 engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Regular oil changes are vital on the LS9, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your LS9 engine please join us in our friendly forum where you can discuss tuning options in more detail with our LS9 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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

We love to hear what our visitors have got up to and which tuning parts work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these LS9 tuning guides which get regular updates and revisions.

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