Long considered one of the most efficient and well-built engines in JDM history, Toyota’s 1JZ-GTE engine is a performance enthusiast’s dream. Though it’s not quite as revered as its larger 2JZ-GTE brother, the 2.5 liter 1JZ was one of the best performance engines of the 1990s. Just like the 2JZ, the 1JZ is easy to mod and tune for big power. It’s possible to make big horsepower with relatively few mods, and the 1JZ-GTE has bulletproof reliability when it comes to turning up the wick. Now that the 1JZ is legal for import stateside, American builders and tuners are finally getting their shot with an engine only released in the Asian and Australian domestic markets. Read on to find out the best 1JZ-GTE mods to make the most horsepower and torque.
Toyota 1JZ-GTE Upgrade Basics
Toyota produced the 1JZ-GTE inline or straight-6 engine for just under two decades from 1990–2007. While Toyota put it in several cars, its most popular use was inside the Toyota Supra Mark III from 1990–1993. While the engine was a hit for Toyota in the Australian and Japanese domestic markets, they never made it available stateside — to the disappointment of many Americans.
However, since 2015, it has been legal to import the 1JZ to the U.S. inside 1990 model year vehicles. So the 1JZ finally made its way to America eventually. As of 2023, any 1JZ from 1998 or earlier is eligible for import due to the 25-year import law for non-U.S. market vehicles.
Like its larger 3.0 liter 2JZ-GTE brother, the 2.5 liter 1JZ-GTE is one of the most capable JDM motors ever built. Not only is it relatively easy to make lots of horsepower, but the engine is also extremely reliable. For many people, a 550 wheel-horsepower 1JZ can be daily driven for long periods without issue. This makes them very popular for more budget and moderate builds.
From 1990–1996, the 1JZ-GTE used twin-turbochargers to make 276 horsepower and 268 lb-ft of torque. These were CT12A turbochargers and used either side or front-mounted, air-to-air intercoolers. Beginning in 1996–1997, Toyota ditched the twin-turbo setup for a more reliable larger single-turbocharger, a CT15B. In addition, the single-turbo versions also had variable valve timing for the intake camshaft (VVT-i).
Power increased to 276 horsepower and 280 lb-ft of torque on the single-turbo VVT-i engines. In addition, the original 1JZ made peak torque at 4,800 RPM. But the newer versions made it much earlier at 2,400 RPM, largely due to the VVT-i.
1JZ-GTE Power Limits With Mods
Over the decades, the 1JZ-GTE engine has proven itself to be capable of reliably and able to make some pretty staggering horsepower numbers with a completely stock engine. Generally, the bottom end is considered reliable through 600 wheel-horsepower. That’s pretty exceptional for a 2.5 liter straight-six engine, but the 1JZ is a thing of engineering beauty.
There are some people who claim to be running close to 1,000 wheel-horsepower on stock internals. It’s worth remembering, though, that at these power levels the block and internals are much less reliable. Generally, if you are considering a daily driver, you will want to be at a maximum of 500 wheel-horsepower. Anything more you will be sacrificing reliability for longevity.
Top 1JZ-GTE Mods
Now let’s talk about how to build the 1JZ with the best 1JZ-GTE mods. The stock 1JZ-GTE makes around 250 wheel-horsepower without any modifications. The biggest bottlenecks for improving performance are going to the fueling, exhaust, and turbocharger(s).
Unfortunately, the stock turbos are not very reliable, especially if you start increasing boost. Toyota used ceramic blades for the compressor wheel. Often, they will break and implode over time running higher boost pressure than stock. This is true of both the stock twin and single-turbo setups for the 1JZ. Generally, you don’t want to run more than 1 bar (14.5 PSI) of boost on the stock turbos.
To make 300 wheel-horsepower, you’ll need the so-called “Basic Performance Upgrades” (BPU). These basically upgrade the exhaust, fueling, and boost pressure. From there, to make more power you’ll basically add more boost and fuel until you reach a desired horsepower. Below, we’ll go over exactly what you need at every power level from 300-500+ wheel-horsepower.
How to Make 300 Wheel-Horsepower With 1JZ-GTE Mods
This first stage of mods are known as the “Basic Performance Upgrades” (BPU). For an entry level, stock-turbo build, 300 wheel-horsepower is a solid goal for the 1JZ-GTE. The stock turbo(s) are maxed at around 300 wheel-horsepower, as they will be running around 1 bar of boost. Your first step for 300 wheel-horsepower is to upgrade both the intake and exhaust. This means replacing the stock intake with a cold air intake. This will allow your turbo(s) to suck in as much air as they need without any restriction.
After the intake, you’ll want a full 3 inch downpipe(s) for the turbo(s). This will allow for a reduction in back pressure and restriction, and 3 inches will flow enough for more than 500 wheel-horsepower. In addition to the downpipe(s), you’ll also want a full 3 inch catback exhaust through the mufflers.
At this point, you’ll need to increase the boost pressure, which means you’ll want a manual or electronic boost controller (M/EBC). Opening up the exhaust will cause your stock turbos to run around 12-13 PSI, but not steadily. A M/EBC will allow your turbo to consistently make boost without fluctuation, and allows you to control boost levels yourself and raise them to 14.5 PSI max (for turbo longevity).
Now, you’ll want to improve cooling with a larger front-mounted intercooler. This will help your turbos last for much longer and will help improve power. You will also reduce potential detonation with a bigger intercooler, and help your engine stand up to repeated runs.
The BPU should run you around 300 wheel-horsepower altogether. With the stock turbos, 300 wheel-horsepower is going to be your reliable limit at around 14.5 PSI.
At this point, you will want to make sure you have gauges to monitor the health of your engine to verify everything is running optimally. At a minimum, this usually means an air-to-fuel ratio gauge, boost pressure gauge, and an oil pressure gauge. Using these you can make sure your engine is not running lean, not underboosting, and that the oil pressure is not dropping.
How to Make 300-400 Wheel-Horsepower With the 1JZ
With 300 wheel-horsepower being the limits of the stock turbos, to make more power you’ll need a larger turbo(s). For most 1996 engines, this means ditching the twins and going with a single-turbo setup. A single-turbo will be more reliable and be capable of making more power than twins most of the time. This will require a new single-turbo manifold, which should bolt-up from the later gen 1JZs.
For these power levels (300-400 wheel-horsepower), the Garrett GT3076R with a T3 0.82 A/R housing would be ideal. These max out around 400 wheel-horsepower at 20+ PSI, and have good mid-range to give them a great street-powerband. The Holset HX35 is another popular option.
With the larger turbo, you’ll need to upgrade the fueling. This means a fuel pressure regulator and larger fuel injectors for 400 wheel-horsepower. Injectors will range from 400-600 cc, depending on your power levels, to support enough fuel at less than 90% duty cycle. You may also consider an upgraded clutch at this point, to support the increased power.
Additionally, you will now need an ECU solution. The stock ECU is going to cut fuel at 14.5 PSI, meaning you won’t be able to run more boost until you replace it. There are countless options, including from AEM, Haltech, Apexi, ECU Master, and several others.
With the upgraded ECU, you will also need a tuner to dial it in with all of your mods. Make sure you buy your ECU in conjunction with your tuner so it’s something they are familiar and comfortable with.
With GT3076R and the BPU, you should be at 400 wheel-horsepower max.
How to Make 400-500 Wheel-Horsepower With the 1JZ
For those looking to step up to the 400-500 wheel-horsepower mark with 1JZ-GTE mods, you’ll want to turn up the boost even higher. Two of the most popular turbos at this point are the Precision Turbos PT5858 or PT5862 with an A/R of 0.81-0.83.
These are going to put you on the higher end of the scale, closer to 500 wheel-horsepower, and you will definitely notice more lag than the GT3076R. You will however see more top-end and peak numbers. Another option is the Garrett GT04R. The GT04R will net around 450 wheel-horsepower and will have less lag than either of the Precision Turbos options. It will however not make as much peak horsepower.
With the larger turbos, you’ll again want to upgrade the fueling. This means larger injectors and potentially a second fuel pump. You’ll want injectors in the 500-650 cc range if you plan on running pump gas. However, a popular option at this point is to run either methanol injection or E85. Both of these will raise the octane rating of your fueling, allowing for more boost, more timing, and more power.
If you’re going with E85, you’ll need new fuel lines, 800-1000 cc injectors, dual Walbro 255 fuel pumps, and an Aeromotive Fuel Pressure Regulator. For a water/methanol setup, you’ll need a separate methanol injection kit — the most popular being from Snow Performance.
How to Make 500+ Wheel-Horsepower With the 1JZ
For those looking to make even more horsepower, in the 500+ wheel-horsepower area, you’ll once again need to turn up the boost and add more fuel. In addition, you’ll definitely want to consider alternative fueling like methanol injection or E85. Another popular mod for 500+ wheel-horsepower builds is lumpier camshafts. Upgrading the cams will aid spool and help with power in the mid-range and top-end.
Turbo-wise, popular options are the Garrett GT35-series, Garrett 67 mm, Precision PT 6466, PT 6266, and the Borg-Warner 88-75. These have been tried and tested on countless builds, and they are good for 500-600+ wheel-horsepower on the 1JZ. Keep in mind, the larger the turbo the worse your low-end response will be, so daily drivers should take caution before sticking on the largest turbo possible.
Toyota 1JZ-GTE Mods Summary
Toyota’s 1JZ-GTE engine is one of the most reliable and dependable inline-six engines in history. Since 2015, they have been legal for import into the United States, opening up a whole new world for JDM fanatics stateside. Nowadays, it’s not uncommon to see local 1JZ builds reaching more than 500-600+ wheel-horsepower, something that was just a dream barely a decade ago.
In terms of 1JZ-GTE mods, it doesn’t take much to truly make the 1JZ into a very formidable beast. By upgrading the exhaust, fueling, and boost pressure, it’s astounding how much power these 2.5 liter engines can make.
For those looking to make 300 wheel-horsepower with their 1JZ, the stock turbo(s) with a big exhaust and manual boost controller is the way to go. Builds looking to step up to the 300-400 wheel-horsepower level would be well served by a Garrett GT3076R turbo running ~20 PSI of boost. At the next level, for 400-500 wheel-horsepower, a Garrett GT04R, Precision PT5858, or Precision PT5862 are very popular options that will not leave you wanting for power.
Finally, for those looking at more than 500+ wheel-horsepower, the Garrett GT35-series, Garrett 67 mm, PT 6466, PT 6266, and the Borg-Warner 88-75 are all great options at 20+ PSI. The sky is truly the limit with 1JZ builds, and it’s almost scary what these small six-cylinder, 2.5 liter engines can accomplish.
Toyota 1JZ-GTE Mods FAQ
Stock, the 1JZ-GTE makes 276 horsepower and 268-280 lb-ft of torque. With a big enough turbo, the 1JZ is capable of making more than 600 wheel-horsepower while still using the stock internals.
For a 300 wheel-horsepower 1JZ-GTE build, the best turbos are the stock turbo or twin-turbos. At ~14 PSI, the stock setup will make around 300-wheel horsepower with an upgraded exhaust and front-mounted intercooler.
For a 300-400 wheel-horsepower 1JZ-GTE build, the top turbo options are the Garrett GT3076R or the Holset HX35. Both of these will produce around 400 wheel-horsepower at ~20 PSI with a quick spool.
For a 400-500 wheel-horsepower 1JZ-GTE build, the Garrett GT04R, Precision PT5858, or Precision PT5862 turbos are good options. They will be a bit laggier but will make north of 500 wheel-horsepower with the right supporting mods.
For those looking at more than 500+ wheel-horsepower 1JZ builds, the Garrett GT35-series, Garrett 67 mm, PT 6466, PT 6266, and the Borg-Warner 88-75 are all great options at ~20 PSI.