Tuning Feature: Nissan VQ38HR Modified

"Comprehensive guide to tuning the Nissan VQ38HR engine!"

We are frequently getting messages inquiring about getting more power from the VQ38HR and wanting to know what are the greatest VQ38HR mods that work. So let us look into Nissan VQ38HR parts and outline the best upgrades on this great engine and point out some frequent tuning mistakes along the way.

This Nissan V6 evolved considerably over it's production run and cc ranged from two to four litres. Nissan produced a motorsport version badged as the VQ30DETT showing what this platform is capable of. Some of the 3.5 liter engines have pretty strong internals and can withstand up to 1000hp in ideal conditions, and parts from these high spec engines are often sourced and fitted into others accross the range.

The Nissan VQ38HR have loads of potential and with the ultimate motorsport mods like ECU maps, turbo improvements and camshafts you will positively maximise your driving fun.

Our aim here is to examine the options for your VQ38HR tuning and summarise the optimum mods that work.

The top VQ38HR upgrades on an engine are usually the ones that give the best power gain for you spend.

We won't be swayed by popular VQ38HR upgrades, they need to be cost effective.

Altering your VQ38HR cam should make a dramatic difference to your engines torque. Choosing a higher performance cam profile raises the torque accordingly

NB: Fast road cams tend to raise the power through the rpm band, you may lose a little low down bhp but top end will be higher.

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

For a typical daily driver one, ideally, need to optimize your power band to your typical driving style.

I'd be surprised if you have found a VQ38HR Race camshaft is a pleasure to live with when on the daily commute.

Each engine responds better to more or less aggressive camshaft durations than others.

The map and fuelling also have a large bearing on the bhp gains you'll achieve.

Extending exhaust or intake durations 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.

VQ38HR Tuning Stages

Stage 1 VQ38HR modifications: Remaps/piggy back ECU, Intake headers, Drilled & smoothed airbox, Panel air filters, Fast road camshaft, Sports exhaust manifold.

Stage 2 VQ38HR modifications: fuel pump upgrades, induction kit, high flow fuel injectors, Sports catalyst & performance exhaust, Fast road cam, Ported and polished head.

Stage 3 VQ38HR modifications: Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Competition cam, Engine balancing & blueprinting, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves).

Mapping will help release the full potential of all the parts you've done to your VQ38HR.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the outcome will vary depending on the parts you've carried out and the condition of your engine.

It is the whole point to any engine modification job to force fuel and air into your VQ38HR

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

Design and flow rate of the Intake headers can make a substantial difference to to fuel engine efficiency on the VQ38HR.

It's not uncommon that headers are begging for motorsport parts, although a few makers provide fairly well optimized headers.

Larger VQ38HR valves, getting 3 or 5 angle valve jobs and porting and head flowing will also improve performance, and as an added benefit will permit a better performance increase on other upgrades.

Turbo upgrades for the VQ38HR

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 VQ38HR

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes major power gains.

When your motor is fitted with a turbocharger parts are giving better power gains and you will discover turbocharged engines are made using strengthened components.

There are reliable limits for every engine, with some being extremely strong and some only able to handle stock power

Research these restrictions and upgrade to better pistons and crank to utilize the power.

We see many people spending a loads of money on turbocharger upgrades on the VQ38HR only to see the car catastrophically fail soon after it's been completed.

Large upgraded turbo units will usually experience a bottom end lag, and smaller turbo units spool up really quickly but do not have the peak rpm power band gains.

Thanks to new tech the market of turbos is always developing and we are seeing variable vane turbos, where the vane profile is altered according to speed to lower lag and increase top end bhp.

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

You'll commonly see there's a limitation in the air flow sensor AFM/MAP on the VQ38HR when considerably more air is being fed into the engine.

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

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

Uprating VQ38HR fuel injectors

When you improve the power you will need to look at to the fuelling.

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

The rule of thumb is to add another 20% when buying an injector, this accounts for injector deterioration and affords 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 VQ38HR performance exhausts

You may need to boost your exhaust if the current exhaust is actually causing a flow problem.

On most factory exhausts you should find that the exhaust 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.

Do not go with the widest exhaust you can get you'll 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.

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

Problems and issues to look out for on the VQ38HR

The VQ38HR engines, if regularly serviced and maintained, are generally very reliable and have few issues. {But if neglected they can cost a small fortune|When neglected they get very expensive to run|They can however be quite expensive if neglected| }

Regular oil changes are vital on the VQ38HR, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your VQ38HR engine please join us in our friendly forum where you can discuss tuning options in more detail with our VQ38HR 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 really like hearing from our readers, and hearing about which tuning 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 VQ38HR guides and tips are kept up to date.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Nissan. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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