Chrysler 6.2 Hellcat Hemi Tuning

"All you need to know about performance parts and tuning the Chrysler 6.2 Hellcat Hemi engine!"

The Hellcat is one of the most powerful engines to come out of Chrysler, and it's solid design allows the tuner to make some very impressive power figures.

TorqueCars will examine 6.2 Hellcat Hemi tuning and highlight the best mods that work. Chrysler 6.2 Hellcat Hemi make awesome project engines and with the best modified mods like a remap, turbo kits and camshafts you will substantially improve your driving opportunities.

History, Power & Specs of the Engine

This was a twin screw supercharged Hemi and shares much with the 5.7 Hemi it is based on.

• 707 bhp (717 PS) @6,000 rpm 650 lbft (881 Nm) @4,000 rpm

The Hellcat 6.2 was used in...

• 2015–Present Dodge Challenger SRT Hellcat
• 2015–Present Dodge Charger SRT Hellcat
• 2018–present Jeep Grand Cherokee Trackhawk
• 2018–present Hellcat Crate Engine
• 2021 Dodge Durango SRT Hellcat
• 2021 Ram 1500 TRX

Demon 6.2

In 2018 we saw the arrival of the Demon 6.2 with new cam profile, larger 2.7 litre twin-screw supercharger, and valvetrain improvements.

• Dodge Challenger SRT Demon 808 hp

Tuning the Chrysler 6.2 Hellcat Hemi and best 6.2 Hellcat Hemi performance parts.

Best 6.2 Hellcat Hemi parts

The ultimate 6.2 Hellcat Hemi upgrades on an engine are as we have found the ones that give the best value for money.

We won't be swayed by popular 6.2 Hellcat Hemi upgrades, they need to be cost effective.

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

Fast road cams commonly push up the torque across the rev band, you may sacrifice a little low end torque but high end rpm power will be better.

Motorsport cams, push up the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a road car you need to optimize your engines power to your usage of the car.

I would be surprised if you have ever thought or claimed that a 6.2 Hellcat Hemi 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!

Each engine responds better to more or less aggressive camshaft durations so view each engine as unique.

The engine timing and injectors and fuel pump also have an effect on the torque gains you'll make.

Extending exhaust or intake 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.

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Best Engine Mods for your car

1. Engine Tunes - engine tuning/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:
Intake manifolds, Remaps/piggy back ECU, Sports exhaust header/manifold, Fast road camshaft, Panel air filters, drilled & smoothed airbox.

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

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

 

 

ECU mapping should help to release the full potential of all the upgrades you've done to your 6.2 Hellcat Hemi.

(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 figures achieved often depend much on the upgrades you've fitted and the condition of your engine.

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

Intake flow the air from the filter and allow it to be fed into the engine and mixed with fuel.

The size of bore and shape and rate of flow of the Intake manifold can make a big improvement to fuel mixing and power on the 6.2 Hellcat Hemi.

On popular production engines intake manifold are ripe for performance upgrades, although some manufacturers provide well optimised intake manifold.

Larger 6.2 Hellcat Hemi valves, doing some 3 or 5 angle valve jobs and porting and head flowing will also raise performance, & more importantly will afford you an improved performance increase on other mods.

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 6.2 Hellcat 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 significant power gains.

When a car has a turbo already fitted modifications are more reliable and you'll see that turbo charged engines will have many forged and stronger components.

However you will find an engines have limits

It is important to find these restrictions and fit more solid crank and pistons to handle the power.

We see many mechanics spending a lots of money on turbo upgrades on the 6.2 Hellcat Hemi only to suffer the indignity of watching the motor catastrophically fail just after it's been finished.

Larger upgraded turbo units will usually experience no power at low rpm, and low capacity turbo units spool up really quickly but won't have the high rpm engines power gains.

Thankfully the range of turbochargers is always developing and we commonly find variable vane turbochargers, where the vane angle is altered according to speed to lower lag and increase top end bhp.

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

You'll commonly see there's a limit in the air flow sensor AFM/MAF on the 6.2 Hellcat Hemi when considerably more air is being sucked into the engine.

We see 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 power gains, although harder to setup. We have this feature on twinchargers if you want to read more.

Fuelling

You will need to ensure that the engine is not starved of fuel so need to uprate the fuelling when you start exceeding 20% of a bhp increase.We strongly recommend you to over specify your injectors flow rate.

 

The rule of thumb is to add 20% when specifying an injector, this accounts for injector deterioration and provides 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.

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

4 Cylinder turbocharged engines

• 58 PSI 340cc/min 200hp
• 58 PSI 511cc/min 300hp
• 58 PSI 682cc/min 400hp
• 58 PSI 1022cc/min 600hp

5 Cylinder turbocharged engines

• 58 PSI 273cc/min 200hp
• 58 PSI 409cc/min 300hp
• 58 PSI 545cc/min 400hp
• 58 PSI 818cc/min 600hp

4 Cylinder NA (naturally aspirated) engines

• 58 PSI 285cc/min 200hp
• 58 PSI 426cc/min 300hp
• 58 PSI 568cc/min 400hp
• 58 PSI 853cc/min 600hp

4 Cylinder supercharged engines

• 58 PSI 312cc/min 200hp
• 58 PSI 468cc/min 300hp
• 58 PSI 625cc/min 400hp
• 58 PSI 937cc/min 600hp

Exhaust

Only look to improve your exhaust if the current exhaust is actually causing a flow problem.

On most factory exhausts you should find that your 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.

Note that with the biggest exhaust you can source this will reduce the exhaust flow rate - the best exhausts 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 come around the catalyst and filters installed, so adding a higher flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

Weak spots, Issues & problem areas on the 6.2 Hellcat Hemi

The 6.2 Hellcat Hemi 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 6.2 Hellcat Hemi, 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 6.2 Hellcat Hemi engine please join us in our friendly forum where you can discuss tuning options in more detail with our 6.2 Hellcat 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.

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