Comprehensive tuning guide

"We look at the best tuning mods for the 1JZ engine."

The 1JZ engine was fitted to many models of Toyota and Lexus, from family oriented models to the more sporty models such as the Supra.

The 1JZ engine was a naturally aspirated 6 cylinder 2.5 liter engine with a variable valve timing system introduced in 1996 along with a revised cylinder head, making this the ideal base for your tuning project. A later turbo charged model was introduced with a GTE suffix and this makes an interesting proposition for the tuner.

Plan your 1JZ upgrades carefully, and don't be tempted to try and turbo a NASP block.

It was replaced in 2007 with the 4GR-FSE engine, to help meet ever tightening emissions regulations and requirements.

We are often asked if you can turbocharge a NASP 1JZ engine from people looking at the 2JZ setup and the 1JZ-GTE engine.

Whilst it is possible it is not really cost effective, especially when you can source a 2JZ or 1JZ-GTE engine with a turbo installed and drop this straight in.

If you insist on turbocharging you need to reduce the compression ratio, modify the head slightly and add an aftermarket ECU to control the fuelling and turbo. Essentially you will commit to a costly strip down and rebuild of the engine.

The 2JZ engine is pretty much a drop in replacement and there are many around, or you could source the 1JZ GTE block as a replacement. So it makes economic sense to do an engine swap if you are looking for forced induction rather than converting your existing engine.

Best 1JZ tuning mods

When talking about the best and most optimal modifications for your 1JZ engine, we are going to tuning mods that give the biggest return for your cash.

Significant gains can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

Fast road cams usually push up the torque across the rpm range, you may lose a little low end power but your high end rpm power will be lifted.

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 car driven daily you need to optimize your torque band to your typical driving style.

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

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

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

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

The 1JZ engines respond well to mods and we're finding that there are plenty of upgrades and performance parts about.

ECU mapping will help release the full potential of all the parts you've fitted to your 1JZ.

(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 15% on NA (naturally aspirated) engines, but you mileage will vary depending on the parts you've done and the condition of your engine.

Pulling more air into the 1JZ engine is the aim to any engine modification project.

Intake take the air during the suck phase from the air filter and allow it to be drawn into the engine cylinders.

Structure and rate of flow of the Intake can make a noticeable difference to fuel atomisation and engine efficiency on the 1JZ.

We often see manifolds are begging for aftermarket tuning parts, although a few OEM provide reasonably good headers.

Fitting big valve kits, carrying out port matching and head flowing will also improve torque, the fantastic side effect is it will raise potential for a better torque increase on other tuning mods.

Fitting lower compression pistons, rods and sorting out the oil flow to the turbo are essential considerations, ideally you should also fit forged parts for added strength and resilience.

There is still plenty of potential to tune the 1JZ engine in it’s NASP form.

1JZ engine specs

Let’s look at the engine options in the 1JZ range and differences between them.

  • 1JZ-GE 1990-1996 lower compression ratio putting out 180bhp
  • 1JZ-GE 1996- revisions to the ignition system, higher compression ratio the VVTi variable valve timing and made around 200bhp.
  • 1JZ-FSE from 2000-2007 has a higher compression ratio thanks to the direct injection of fuelling
  • 1JZ-GTE this was a turbo charged engine based around a twin turbo setup until 1996 when it was replaced with a single turbo. Both revisions of the engine made around 280bhp but the latter benefited from a slightly higher torque output and much wider power band.

Weak spots, problems and issues on the 1JZ

Thankfully these engines are very robust and reliable but there are a few things to look out for. The VVT System can be problematic if not properly maintained and serviced, this usually causes a rough idle at first and later misfires and non starting issues. High oil consumption on older engines is usually down to worn valves and pistons, replace this if there is excessive smoke.

Spark plugs tend to foul up but it’s worth checking the ignition coils if there are misfires and other electrical issues.

You should be able to lift power to around 250bhp on most 1JZ engines, with the right modifications. Get a gas flowed cylinder head and port and polish the intake and exhaust to maximize flow through the engine. Fast road cams will give more peak power but if the profile is too aggressive you will suffer from a lumpy idle and the car will be hard to drive in traffic.

Power upgrades

A sports exhaust and high flow catalyst will also help the engine to make more power. If you balance the engine you can raise the red line and being an inline 6 this engine revs really freely and is silky smooth offering a lot of top end power.

The standard fuelling system on the 1JZ is usually good for fairly substantial power gains and, unless you are adding a turbo should be able to cope with substantial power figures from the NA (naturally aspirated) engine.

A lighter flywheel will help the engine to rev more freely and we recommend fitting an uprated clutch when you start increasing the engines power beyond 250bhp.

A fast road cam is probably the single most effective mod for the 1JZ, adding around 20% more power. We have heard of people fitting the 2JZ cams to this engine, but you'll need to hone the journals to get them to fit. Porting and gas flowing the head, and adding larger valves also prove to offer a good return of power for your investment.

Most standard 1JZ airboxes flow quite well so we wouldn't recommend an air filter upgrade until you are pushing power levels around 30% more than standard.

Tuning the 1JZ GTE

The turbo version of the engine is quite a different beast from the NA (naturally aspirated) engine and is a great engine to work on. 17psi seems to be the safe limit for these engines, the standard ECU will be happy to around 15psi boost.

If you want to go higher then you need a standalone ECU replacement or high quality piggyback ECU, we quite like the Greddy E manage Blue setup, thanks to it's flexibility and processing power and makes adding an aftermarket air flow sensor quite easy.

There are many people spending a loads on turbo upgrades on the 1JZ only to suffer the humiliation of seeing the 1JZ go up in smoke when it's been completed.

Larger turbo chargers tend to suffer low end lag, and little turbo chargers spool up more quickly but won't have the peak end engines power gains.

Thankfully the choice of turbo chargers is always moving on and we commonly find variable vane turbo chargers, where the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo chargers divert the exhaust flow into 2 channels and feed these at differently angled vanes in the turbo charger. They also increase the scavenging effect of the engine.

You'll commonly see there is a limitation in the air flow sensor AFM/MAP on these engines when loads more air is being pulled into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting bhp at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although more difficult to get working. We have this adding a twincharger setup guide if you want to read more.

Adding a bigger turbo and good quality boost controller will take you to around 365bhp for 1.2 bars, around this point the air flow sensor starts to struggle and needs to be uprated. Most 1JZ GTE owners upgrade to a map sensor at this point.

A favourite turbo to upgrade to is the HKS2835 giving a little over 400bhp with the right setup and very little lag. The GT35R and 255 liters per hour pump, 650cc injectors will be good for 550bhp with the right engine management setup.

Many of our members mods on the 1JZ engine include parts from the 2JZ version, injectors, cams and fuel pumps are popular swaps.

A word of warning, the Decat option does seem to cause premature turbo seal failure. Many owners are reporting issues with the seals after a decat but no direct cause has been found.

Please help us complete this article, add your tips suggestions and corrections via the feedback form below, we do rely on user submissions to help keep our tuning tips at the cutting edge.

Our forum is also a great place to go if you want more specific tips or are having trouble with your 1JZ engine tuning project.


Only look to upgrade your exhaust if your current exhaust is creating a restriction.

On most factory exhausts you'll find 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 do not go too large or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to around 2.5 inches to maximise flow rates, and this should take into account the amount of air your engine is moving.

Typically exhaust restrictions are traced to the filters installed, so adding a faster 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

The 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 , 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 engine please join us in our friendly forum where you can discuss tuning options in more detail with our 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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One Response to “Tuning the 1JZ engine”

  1. Lungile says:

    In my 1jzvvti I want to upgrade turbo from t61 to gt3582
    Do you think is a good idea?

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