Tuning the GM LS9

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

The GM LS9 offer good returns when tuned and with carefully picked sports parts like a remap, turbo improvements and camshafts you will certainly improve your driving enjoyment.

This pages aim is to examine the world of LS9 tuning and outline the best modifications.

History 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 mods

When talking about the best and most optimal modifications for your LS9 engine, we are going to concentrate on the tuning parts that give the biggest return for your cash.

The cam profile plays a big part in the engines power output so cam upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen cam profile, so large power band gains are on offer for cam upgrades.

Fast road camshafts usually push up the torque through the rev range, you may sacrifice a little bottom end torque but top end will be lifted.

Competition camshafts, push up the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a typical daily driver must carefully try to optimize your bhp range to your typical driving style.

I'd be shocked if you have found a LS9 Motorsport and race cam is a pleasure to live with when driving in heavy traffic.

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

The engine timing and fuelling also have an effect on the bhp gains you'll get.

A longer valve duration 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.

Stage 1 modifications: Remaps/piggy back ECU, Drilled & smoothed airbox, Intake headers, Fast road camshaft, Sports exhaust manifold, Panel air filters.

Stage 2 modifications: Fast road cam, fuel pump upgrades, high flow fuel injectors, Sports catalyst & performance exhaust, Ported and polished head, induction kit.

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

Carefully think through your options and then source your tuning parts and set yourself a power target to avoid costly mistakes.

A remap should help to release the full potential of all the mods you've fitted to your LS9.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the end result will rely on the mods you've fitted and the condition of your engine.

It is vital to any car tuning project to pull air into each cylinder

The intake plenum take the air from the intake filter and allow it to be drawn into the engine and mixed with fuel.

The shape and rate of flow of the Intake manifold can make a noticeable change to fuel atomisation on the LS9.

It's not uncommon that intake are ripe for a performance upgrade, although a few car makers provide well optimised intake.

Larger LS9 valves, carrying out port matching and head flowing will also lift performance, & importantly will raise potential for a better performance increase on other tuning parts.

Turbo upgrades

NASP 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 impressive power gains.

When a car has forced induction upgrades are relatively easy and you'll see that turbo engines already contain stronger components.

However you will find an engines have weakspots

We recommend you find these limits and upgrade to more solid crank and pistons to cope with the power.

It's not unheard of mechanics spending a lot of money on turbocharger upgrades on the LS9 only to have the whole thing literally blow up soon after it's been completed.

Larger capacity turbo units tend to suffer low end lag, and smaller turbo units spool up quickly but do not have the peak end engines power gains.

Thankfully the range of turbochargers is always increasing and we are seeing variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust flow into two channels and flow these at differently profiled vanes in the turbo. They also help the scavenging effect of the engine.

You'll commonly see there's a limitation in the air flow sensor (AFM/MAF/MAP) on the LS9 when loads more air is being drawn into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting power at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although more difficult to get working. We have this guide to twinchargers if you want to read more.

Fuelling

You will need to ensure that the engine is not starved of fuel so should pay attention to the fuelling when you start exceeding 20% of a power increase.We strongly recommend you to be generous with your flow rate on the injectors.

The rule of thumb is to add 20% capacity when specifying an injector, which takes into account injector deterioration and gives 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.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

Exhaust

Only look to boost your exhaust if your current exhaust is actually creating a restriction.

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

Sports exhausts equal out the flow of air through the engine.

But if your exhaust pipe is too big, ie: over 2.5 inches bore, you will lose much of your flow rate and end up sapping power and torque.

Usual exhaust restrictions are in the catalysts installed, so adding a higher flowing performance alternative will help avoid this restriction.

Weak spots, Issues & problem areas on the LS9

The LS9 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the LS9, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information 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.

We need your help improving this article, so please send us your feedback in the comments box below and pass on any tips, points or facts we have wrong or have not covered.

We really like hearing from our readers, and hearing about which mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our LS9 guides and tips are kept up to date.

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