Chrysler 392 6.4 Apache Hemi Tuning

"All you need to know about tuning the Chrysler 392 Apache Hemi engine!"

The Chrysler 392 Apache Hemi are fantastic project engines and with a few sensible uprated tuning mods like remapping, turbo kits and camshafts you will certainly maximise your driving fun.

We shall detail the best approach to 392 Apache Hemi tuning and show the best modifications.

History, Power & Specs of the Engine

• 470 hp (350 kW) and 470 lbft (637 Nm)
• 485 hp (362 kW) and 475 lbft (644 Nm) from 2015

The 392 Apache crate was fitted to the following models, with some variation in specs and setup. Truck versions were optimised for low end torque.

• 2011 Dodge Challenger SRT8
• SRT8 Dodge Charger
• Chrysler 300
• Jeep Grand Cherokee
• 2500 and 3500 Pickup
• 3500 SRW Cab Chassis with RFE transmission: 410 hp (306 kW), 429 lbft (582 Nm)
• 3500 Mega Cab, 3500 DRW Cab Chassis
• 3500 SRW/DRW 370 hp (276 kW), 429 lbft (582 Nm)
• 4500 and 5500 Cab Chassis: 366 hp (273 kW), 429 lbft (582 Nm)

Tuning the Chrysler 392 Apache Hemi and best 392 Apache Hemi performance parts.

Best 392 Apache mods

When talking about the best modifications for your 392 Apache engine, we are going to focus on the tuning mods that give the biggest return for your cash.

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

Fast road camshafts normally increase the power throughout the rev band, you could sacrifice a little low end power but the top end will be lifted.

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

A Motorsport and race cam won't do well if driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

You should ideally match your torque band to your typical driving style so for a road car stick with a shorter duration 392 Apache cam

Each engine responds better to different camshaft durations than others.

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

Longer valve durations can alter the power 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.

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

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

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

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

ECU mapping will help fully realize the full potential of all the parts you've done to your 392 Apache.

(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 the end result will vary depending on the parts you've fitted and the condition of your engine.

It is vital to any engine performance tuning task to force fuel and air into the 392 Apache engine

Intake flow the air from the air filter and allow it to be sucked into the engine cylinders.

Shape and rate of flow of the Intake can make a noticeable improvement to fuel atomisation and engine efficiency on the 392 Apache.

Many mass produced engine intake manifold are needing a performance upgrade, although a few makers provide well optimised intake manifold.

Larger 392 Apache valves, getting port work and head flowing will also boost bhp, & importantly will permit a greater bhp 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 392 Apache

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 your car is turbo charged tuning mods are going to make more power and you will discover turbo engines are made with strengthened components.

However most engines will have power limits

See where you'll find these limitations and upgrade to more solid crank and pistons to cope with the power.

We've seen guys spending a lots of money on turbocharger upgrades on the 392 Apache only to see the whole thing throw a rod soon after it's been enthusiastically driven.

Larger capacity turbos will usually suffer a bottom end lag, and small turbos spool up quickly but don't have the high rpm power band gains.

Thankfully the world of turbos is always improving and we commonly find variable vane turbos, permitting the vane profile is altered according to speed to lower lag and increase top end bhp.

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

It is not unusual that there is a limit in the air flow sensor AFM/MAP on the 392 Apache when considerably more air is being sucked into the engine.

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

Adding a supercharger or additional turbo will make large bhp and torque gains, although more complex to configure. We have this article covering twinchargers if you want to read more.

Fuelling

When you increase the bhp you will need to ramp up to the fuel delivery.

More bhp needs more fuel. It is important to over specify your injector capacity.

The accepted safe increase is to add 20% to the flow rate when buying an injector, which takes into account injector deterioration and allows a little spare capacity should the engine require 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 may need to boost your exhaust if the current exhaust is actually causing a flow problem.

On most factory exhausts you'll see the exhaust 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.

Sports exhausts generally help improve air flow through the engine but do not go too big or you could very well end up with a reduced flow rate. So generally speaking, keep to 1.5 to 2.5 inches for best results.

Usual exhaust restrictions come around the catalyst installed, so adding a better 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 392 Apache

The 392 Apache 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 392 Apache, 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 392 Apache engine please join us in our friendly forum where you can discuss tuning options in more detail with our 392 Apache 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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We love to hear what our visitors have got up to and which tuning mods 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 392 Apache tuning guides which get regular updates and revisions.

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