Tuning the Chrysler 392 Hemi

"Comprehensive guide to tuning and performance parts on the Chrysler 392 Hemi engine!"

We are regularly getting posts about the ultimate 392 Hemi power upgrades. So let us look into Chrysler 392 Hemi parts and outline the best modifications on this great engine and point out some common pitfalls along the way.

Here we look into 392 Hemi tuning and provide tips on the optimum upgrades. Chrysler 392 Hemi are awesome to work on and with a few sensible motorsport enhancements like remaps, turbo improvements and camshafts you will substantially maximise your driving experience.

The top 392 Hemi upgrades on an engine are as we have found the ones that give the biggest return for your cash.

We won't be swayed by popular 392 Hemi upgrades, they need to be cost effective.

Altering your 392 Hemi camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

NB: Fast road cams tend to boost the performance over the rpm range, you could sacrifice a little low end torque but the higher rpm power will improve.

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

On a typical daily driver must carefully try to match your engines power to your typical driving style.

I'd be shocked if you have found a 392 Hemi Competition camshaft is a pleasure to live with when driving around busy urban areas.

Some 392 Hemi engines respond better to more or less aggressive cam durations than others.

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

Altering 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.

392 Hemi Tuning Stages

Stage 1 392 Hemi modifications: Sports exhaust manifold, Drilled & smoothed airbox, Intake headers, Fast road camshaft, Panel air filters, Remaps/piggy back ECU.

Stage 2 392 Hemi modifications: Ported and polished head, Fast road cam, Sports catalyst & performance exhaust, fuel pump upgrades, induction kit, high flow fuel injectors.

Stage 3 392 Hemi modifications: Competition cam, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Crank and Piston upgrades to alter compression.

Review your options and then buy your upgrades and set yourself a power target to save yourself from expensive mistakes.

Mapping will help unlock the full potential of all the tuning parts you've done to your 392 Hemi.

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 usually depend much on the tuning parts you've fitted and the condition of your engine.

It is the whole point to any engine tuning task to force fuel and air into each cylinder

The intake plenum take the air from the air filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

The size of bore and shape and flow characteristics of the Intake can make a large change to fuel delivery on the 392 Hemi.

We often see plenum chambers are needing aftermarket parts, although a few makers provide fairly well optimized plenum chambers.

Big valve conversions on the 392 Hemi, doing a bit of 392 Hemi port enlargement and head flowing will also lift performance, and as an added benefit will make space for a greater performance increase on other tuning parts.

Turbo upgrades for the 392 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 392 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 massive power gains.

If a car has a turbocharger modifications are going to make more power and turbo charged engines are built using harder and stronger components.

However every engines have weakspots

It is important to find these restrictions and install higher quality crank and pistons to utilize the power.

We see many people spending a lot of money on turbocharger upgrades on the 392 Hemi only to experience the whole thing literally blow up on it's first outing after it's first rolling road session.

Big upgraded turbos will usually suffer no power at low rpm, and low capacity turbos spool up much more quickly but won't have the peak end torque gains.

In recent times the world of turbos is always evolving and we now see variable vane turbos, allowing the vane profile is altered according to speed to lower lag and increase top end power.

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

You'll commonly see there is a limit in the air flow sensor MAP/MAF/AFM on the 392 Hemi when a lot more air is being drawn into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited bhp and torque at a much lower level.

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

Uprating 392 Hemi fuel injectors

When you boost the torque you will need to increase to the fuel system.

More torque needs more fuel. Most tuners we speak with say to be generous with your injectors flow rate.

As a rule of thumb add another 20% when buying an injector, this takes into account injector deterioration and gives you some 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.

Best 392 Hemi performance exhausts

You should look to replace your exhaust if the existing exhaust is actually causing a restriction.

On most factory exhausts you should find that the flow rate is 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 generally help improve air flow out of the engine but avoid an exhaust that is too big or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.

Typically exhaust restrictions can be traced to the catalyst and filters installed, so adding a faster flowing high performance alternative will help avoid this restriction.

Specs, applications and bhp lbft on the 392 Hemi

  • 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 Cheroke
  • 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.

Problems and issues to look out for on the 392 Hemi

The 392 Hemi engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the 392 Hemi, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your 392 Hemi engine please join us in our friendly forum where you can discuss tuning options in more detail with our 392 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 parts were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our 392 Hemi guides and tips are kept up to date.

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