Tuning the Chrysler 6.1 Hemi

"Comprehensive guide to tuning and performance parts on the Chrysler 6.1 Hemi engine!"

We are regularly seeing threads requesting info on the best tips on 6.1 Hemi power upgrades. So let us look into Chrysler 6.1 Hemi upgrades and outline the best modifications on this great engine and point out some potential pitfalls along the way.

We shall review 6.1 Hemi tuning and outline the ultimate modifications. Chrysler 6.1 Hemi are popular engines and with carefully chosen sports upgrades like ECU maps, turbo improvements and camshafts you will maximise your driving fun.

Just because particular tuning mods are appear in lots of 6.1 Hemi projects it doesn't mean its worth having, we will optimum tuning mods that will give your 6.1 Hemi the best power gain for you money.

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.

NB: Fast road cams normally bump the torque across the rpm range, you might lose a little low end power but the higher rpm power will be higher.

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

On a road car must carefully try to match your power band to your cars usage.

I'd never have found a 6.1 Hemi Competition camshaft is a pleasure to live with when in heavy traffic.

Different 6.1 Hemi engines respond better to more aggressive camshaft durations so view each engine as unique.

The engine timing and fuel pump and injectors also have a large bearing on the bhp gains you'll hit.

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.

6.1 Hemi Best Tuning Mods & Upgrades

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Guide to the best tuning mods & Upgrades

  1. ECU Map Tuning & Remaps

    Some cars may require a piggyback ECU's or aftermarket ECU's to change the OEM map, but remapping is the most vital step of your tuning project to fully maximise your mods. Expect 10-20% on NASP engines and 30-40% on turbocharged units.

  2. Strengthen Your Engine

    Tuned cars will show up weaknesses, typically in the turbochargers, clutch and internal engine components. Whilst most engines can cope with mild tuning mods, TorqueCars recommend that you upgrade the internal components before these weak spots manifest themselves.

  3. Mods that Remove a Restriction

    A restricted intake or exhaust will have an impact on your performance, so use a better flowing air filter/induction kit and better flowing exhaust (sports cats where legal are a good option) whenever your tuning creates a flow restriction. Turbo engines also benefit from intercooler upgrades as these resist heat soak for longer periods of time.

  4. Mods that Improve Fuelling

    Every tuning project will aim to increase the air supply, but fuel supply is just as vital and will need to match the air the engine can utilise,  a fuel pump and injector upgrade are usual mods, but also in many cases the fuel regulator will need improvement.

  5. Mods to Provide better Airflow

    Increasing the air supply is just as essential as improving fuelling, we suggest you look at head mods (flowing and porting, 5 angle valve jobs), fit bigger valves, fast road cams and forced induction upgrades (adding a better flowing turbo) to improve air intake.

Tuning Stages

Stage 1 6.1 Hemi modifications: Sports exhaust manifold, Fast road camshaft, Intake headers, Remaps/piggy back ECU, Panel air filters, Drilled & smoothed airbox.

Stage 2 6.1 Hemi modifications: Ported and polished head, fuel pump upgrades, Fast road cam, Sports catalyst & performance exhaust, high flow fuel injectors, induction kit.

Stage 3 6.1 Hemi modifications: Competition cam, Crank and Piston upgrades to alter compression, Internal engine upgrades (head flowing porting/bigger valves), Twin charging conversions, Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting.

The 6.1 Hemi engines respond well to mods and we see that there is a lot of modifications and tuning parts around.

ECU mapping helps fully realize the full potential of all the tuning parts you've done to your 6.1 Hemi.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results may differs on the tuning parts you've applied and the condition of your engine.

It is the whole point to any tuning project to feed more air and fuel into the 6.1 Hemi engine

Headers take the air from the air filter and allow it to be sucked into the engine cylinders.

Shape and rate of flow of the Intake headers can make a substantial difference to to fuel mixing and power on the 6.1 Hemi.

Many mass produced engine air intake manifolds are crying out for performance upgrades, although some makers provide fairly well optimized air intake manifolds.

Fitting big valve kits, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also raise performance, and as an added benefit will give you an improved performance increase on other parts.

Turbo upgrades for the 6.1 Hemi

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 6.1 Hemi

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.

When your motor has a turbo already fitted parts are going to make more power and we find turbo charged engines are made with many forged and stronger components.

There are reliable limits for every engine, with some being over specified and some only just able to handle stock power

Research these restrictions and upgrade to better quality components to utilize the power.

We've seen people spending a lot of money on turbo upgrades on the 6.1 Hemi only to see the car explode soon after it's been completed.

Bigger upgraded turbos commonly suffer a bottom end lag, and small turbos spool up much more quickly but won't have the peak end bhp gains.

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

Twin scroll turbo units divert the exhaust gases into a couple of channels and flow these at differently angled vanes in the turbo. They also boost the scavenging effect of the engine.

It is common that there is a restriction in the air flow sensor MAF/MAP on the 6.1 Hemi when a lot more air is being drawn into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped performance at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although harder to configure. We have this feature on twinchargers if you want to read more.

Uprating 6.1 Hemi fuel injectors

Don't forget to improve the fuel system when you are increasing the bhp and torque - it makes the car more thirsty. Don't forget to be generous with your injector capacity.

The accepted safe increase is to add 20% to the flow rate when specifying an injector, this allows for injector deterioration and gives you some 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.

Best 6.1 Hemi performance exhausts

You should look to boost your exhaust if your current exhaust is actually causing a restriction.

On most factory exhausts you'll see the exhaust flow rate is fine 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 can usually air flow through the engine but do not go too large or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.

Typically exhaust restrictions come around the catalyst and filters installed, so adding a higher flowing race alternative will help avoid this restriction.

BHP lbft and applications of the 6.1 Hemi Engine

425 bhp (317 kW; 431 PS) at 6,200 rpm and 420 lbft (569 Nm) of torque at 4,800 rpm

  • 2005–2010 Chrysler 300C SRT-8
  • 2006–2008 Dodge Magnum SRT-8
  • 2006–2010 Dodge Charger SRT-8
  • 2006–2010 Jeep Grand Cherokee SRT-8
  • 2008–2010 Dodge Challenger SRT-8

Problems and issues to look out for on the 6.1 Hemi

The 6.1 Hemi engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the 6.1 Hemi, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your 6.1 Hemi engine please join us in our friendly forum where you can discuss tuning options in more detail with our 6.1 Hemi 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 to complete and improve this page, so do give us your feedback in the comments box below.

We really like hearing from our readers, and hearing about which modifications were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our 6.1 Hemi guides and tips are kept up to date.

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