Tuning guide "5.7 Hemi Modifications"

5.7 Hemi Modifications Guide

How to modify and upgrade the Chrysler 5.7 Hemi

"Comprehensive guide to tuning the Chrysler 5.7 Hemi engine!"

Sites like TorqueCars are frequently getting emails requesting information on how to improve the 5.7 Hemi from people inquiring about getting more power from the 5.7 Hemi and wanting to know what are the things tuners are recommending when it comes to 5.7 Hemi mods that work. So let us look into Chrysler 5.7 Hemi upgrades and outline the best upgrades on this great engine and point out some problems along the way.

The Chrysler 5.7 Hemi great bases for a tuning project and with the right motorsport mods like a remap, turbo kits and camshafts you will certainly maximize your driving fun.

In this article we look at 5.7 Hemi tuning and summarise the greatest mods that work.

Just because particular mods are are common on 5.7 Hemi it doesn't mean it is good, instead we will concentrate on the best mods that will give your 5.7 Hemi the best power gain for you spend.

Without us subscribing to the common myth of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

5.7 Hemi induction kits

Improving air intake on the 5.7 Hemi

You need air matched to fuel for an engine to work. If there is insufficient fuel then it will run lean, if there is insufficient air it runs rich sapping power which risks damage to the 5.7 Hemi. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the primary aim to any engine performance tuning job to force more air into your 5.7 Hemi but this has a knock on effect with the air flow sensor.

It is common that there is a restriction in the air flow sensor MAP/MAF/AFM on the 5.7 Hemi when considerably more air is being pulled into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope with quite large power gains, whereas the OEM air sensor limited bhp and torque at a much lower level.

Intake take the air during the suck phase from the filter and allow it to be fed into the engine cylinders with fuel for the squish phase.

The shape and rate of flow of the Intake headers can make a substantial change to fuel engine efficiency on the 5.7 Hemi.

I usually find intake headers are in dire need of motorsport parts, although some manufacturers provide well optimised intake headers.

Fitting big valve kits, getting 3 or 5 angle valve jobs and porting and head flowing will also boost bhp and torque, & more importantly will permit an improved bhp and torque increase on other parts.

5.7 Hemi performance cam tips.

Some 5.7 Hemi engines respond better to different cam durations check your engine on a rolling road.

The ecu map and fuelling 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.

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 bhp gains are on offer for cam upgrades.

NB: Fast road camshafts commonly increase the bhp and torque over the rpm range, you may sacrifice a little low end power but top end will be better.

Competition 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 camshaft is not great on the daily commute.

You should ideally match your engines power to your driving style so for a daily driver stick with a shorter duration 5.7 Hemi camshaft

Stage 1, 2 and 3 mods for the 5.7 Hemi

Stage 1 5.7 Hemi parts:

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

Stage 2 5.7 Hemi parts:

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

Stage 3 5.7 Hemi parts:

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

The 5.7 Hemi engine blocks respond well to upgrades and we're finding that there are increasing numbers of modifications and tuning parts around.
Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

A remap will help to establish the full potential of all the parts you've done to your 5.7 Hemi.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the outcome usually depend much on the parts you've applied and the condition of your engine.

Turbo modifications on the 5.7 Hemi

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the 5.7 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 superb power gains.

If the engine is fitted with a turbocharger upgrades are giving better power gains and most 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 able to handle stock power

It is important to find these limits and fit forged components to handle the power.

It's not unheard of mechanics spending a lot of money on turbocharger upgrades on the 5.7 Hemi only to suffer the humiliation of seeing the engine literally blow up soon after it's used on the roads.

Big turbo chargers tend to experience low end lag, and smaller turbo chargers spool up much more quickly but won't have the peak rpm bhp gains.

Thankfully the selection of turbos is always increasing 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 direct these at differently designed vanes in the turbo. They also increase the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although harder to install. We have this article on twincharging if you want to read more.

Tips about fuel supply on the 5.7 Hemi

When you improve the performance you will need to look at to the fuel delivery.

More performance needs more fuel. We strongly recommend you to be generous with your flow rate on the injectors.

The accepted safe increase is to add another 20% when fitting an injector, helps cope with injector deterioration and allows you some spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended 5.7 Hemi performance exhaust upgrades

You should look to upgrade your exhaust system with an upgraded one is if the existing exhaust is actually causing a flow problem.

On most factory exhausts you'll find the exhaust flow rate is fine even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts will certainly help air flow through the engine but do not go too large or you could will reduce the flow rate. Stick to one and a half to two and half inches for best results.

Usual exhaust restrictions can be located the emissions filters installed, so adding a freer flowing high performance alternative will help avoid this restriction.

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the 5.7 Hemi

Like most engines an 5.7 Hemi, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the 5.7 Hemi, failure to do this will exacerbate engine wear, on a tuned 5.7 Hemi this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your 5.7 Hemi why not pop over to the forums at TorqueCars where you can chat about 5.7 Hemi tuning options and read about others projects who may be planning to do similar modifications on their 5.7 Hemi.

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