Discover "LS9 Modifications"

How to modify and upgrade the GM LS9

"Comprehensive guide to tuning the GM LS9 engine!"

Popular tuning sites like TorqueCars often are getting emails asking how to improve the LS9 from people wanting to know what are the best LS9 modifications. So let us look into GM LS9 mods and outline the best modifications on this great engine and point out some problems along the way.

Now we will provide a guide to LS9 tuning and outline the greatest mods that work. GM LS9 really good project engines and with carefully chosen modified parts like remapping, turbo upgrades and camshafts you will really enhance your driving opportunities.

The top LS9 modifications on an engine are usually the ones that give the best gains for your money.

We won't be swayed by popular LS9 modifications, they need to be cost effective.

Improving air intake on the LS9

You need air matched to fuel for an engine to work. If there is not enough fuel then it will run lean, if there is a lack of air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Forcing more fuel and air into the LS9 engine is the primary aim to any tuning task.

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

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited performance at a much lower level.

Intake take the during the engines suck phase from the filter and allow it to be fed into the engine cylinders with fuel for the squish phase.

Structure and flow rate of the air Intake manifold can make a big difference to to fuel engine efficiency on the LS9.

On popular production engines air intake manifolds are in dire need of aftermarket tuning parts, although a few car makers provide well optimised air intake manifolds.

Fitting big valve kits, doing a bit of port work and head flowing will also raise torque, & more importantly will make space for an improved torque increase on other upgrades.

LS9 performance cam tips.

Each engine responds better to more or less aggressive camshaft durations than others.

The ECU mapping and fuel pump and injectors also have a large bearing on the torque gains you'll make.

Longer valve durations can alter the torque 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.

Altering your LS9 camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

NB: Fast road camshafts normally bump the power through the rpm range, you may lose a little low end power but higher rpm power will be better.

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

For a daily driver you must carefully try to match your power band to your typical driving style.

You will never find a LS9 Race camshaft is a pleasure to live with when driving around busy urban areas.

Stage 1, 2 and 3 mods for the LS9

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

1. Suspension Upgrades - always improve your cars handling
2. Brake Upgrades - Even before adding power improve those brakes
3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
6. Fuelling - when you've increased power you'll need to match this with more fuel
7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 LS9 parts:

Intake headers, Sports exhaust manifold, Remaps/piggy back ECU, Drilled & smoothed airbox, Panel air filters, Fast road camshaft.

Stage 2 LS9 parts:

induction kit, high flow fuel injectors, Sports catalyst & performance exhaust, Ported and polished head, Fast road cam, fuel pump upgrades.

Stage 3 LS9 parts:

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

A remap allows a tuner to fully realize the full potential of all the modifications you've done to your LS9.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results usually rely on the modifications you've fitted and the condition of your engine.

Turbo modifications on the LS9

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the 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 massive power gains.

If your motor has a turbo already fitted tuning mods are going to make more power and you will discover turbocharged engines are built using stronger components.

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

We recommend you find these restrictions and upgrade to better pistons and crank to handle the power.

It's not unheard of people spending a fortune on turbo upgrades on the LS9 only to experience the whole thing explode when it's used on the roads.

Bigger capacity turbos commonly suffer no power at low rpm, and low capacity turbos spool up much more quickly but do not have the peak rpm power band gains.

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

Twin scroll turbos divert the exhaust gases into 2 channels and feed these at differently profiled vanes in the turbocharger. They also help the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large torque gains, although more complex to setup. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the LS9

Don't miss you'll need to boost the fuel delivery when you are increasing the power - it makes the car more thirsty. We would recommend you to over specify your flow rate on the injectors.

The accepted safe increase is to add 20% to the flow rate when fitting an injector, this takes into account injector deterioration and gives a little spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended LS9 performance exhaust upgrades

You should look to increase your exhaust system with an upgraded one is if the existing exhaust is creating a restriction in flow.

On most factory exhausts you'll see the exhaust flow rate is still fine even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts can usually air flow out of the engine but do not go too large or you could will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Usual exhaust restrictions can be located the emissions filters installed, so adding a higher flowing performance alternative will help avoid this restriction.

Decatting (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the LS9

Like most engines an LS9, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the LS9, failure to do this will exacerbate engine wear, on a tuned LS9 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your LS9 why not pop over to the forums at TorqueCars where you can chat about LS9 tuning options and read about others projects who may be planning to do similar modifications on their LS9.

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This entry was posted under Makes and Models. Tags: engine, GM
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