1JZ-GTE Engine Swap

Why a 1JZ Engine Swap | 1JZ Background | Good Things | Bad Things
The Plan | My 1JZ | 1JZ Pictures | Relevant Links

Why a 1JZ Engine Swap

For a while I have been toying with the idea of various mods to make more power. I considered building a 7M with a big turbo, fuel system, etc. I considered trying to get more power out of my current engine with more bolt on mods. I also considered a 1JZ-GTE swap. January of 2002 I sent a friend (Orin, the Texas expert in JZA70 Supras) an email asking if he had a line on a 1JZ I could import. About a month later he emailed me (quite to my surprise) to tell me he had an engine, ECU, wiring harness, and automatic transmission I could buy! This was a surprise because most of the people I have talked to have had to wait several months for their engine to arrive after they found one (which can also take months). I am very lucky.

My engine is from a 1993 Japanese spec Soarer (Lexus SC300). The only piece missing from the engine was the engine mounts (what makes the use of a JZ series engine in a A70 Supra possible) and the correct sump assembly (at this point I think the sump I have will work). Chip Springall is having engine mounts milled using Orin's engine mounts as an example. Orin will be selling these with his JZ engine swap kits. Neither the engine mounts nor the swap kits are available at the moment but they will be shortly. In all likely hood my car will provide the test and some of the instructions for the kit.

1JZ Background

The 1JZ was developed in 1989 to replace Toyota's aging "Truck Engine" the 7M. The 1JZ has a short stroke and high rev limit (7500 rpm). It displaces 2.5 liters and has a compression ratio of 8.5:1. In stock form, the 1JZ-GTE is rated at 280 hp at 8.5 psi of boost. In contrast, the 7M produced 232 hp with 7psi of boost. The C12A turbos have a reputation for failing at high boost (>20psi) in unmodified form. They present the first true limit to the power the engine can produce.

Good Things

• Speed density air metering from the factory (instead of a vortex type air flow meter).
• 7500 RPM redline.
• Bullet proof bottom end.
• Excellent Engine Management.
• Lots of 2JZ bolt on mods available that will work with the 1JZ.

Bad Things

• 380cc injectors (the 7M-GTE has 440cc stock).
• Frankinsteined wiring harness (Toyota changed the wiring harness in the JZA70 Supras).
• Replacement parts are hard, or impossible to get (especially quickly).
• 1JZ specific performance parts, while plentiful, were never sold in the US so they are hard to get.
• 122mph rev speed limiter.
• 12-14psi boost fuel cut (the 7M-GTE and the 2JZ-GTE both have this as well).

The Plan

Currently I am selling all my 7M specific mods (HKS F-Con/FCD, HKS Intercooler, Modified Turbo, Level 10 Tranny, 3" down pipe, K&N FIPK). The cash from this will fund the engine swap and the stage 1 items below. 

Stage 1

The idea of stage 1 is to get the engine in the car and running at a basic level. 

• Install the engine and get it running. This will involve frankensteining the wiring harness into the gauges and EFI accessories, such as the fuse box. 

• Install a HKS Type S front mount intercooler for the MKIV Supra. It is large enough to support substantial horse power, but not so large that it causes undo lag.
• Custom 3" down pipe.
• Hard pipe intake.
• Performance intake filter.

Stage 2

The idea of stage 2 is to take the car to the limit of the factory, unmodified C12A turbo chargers, which should be around 400 rwhp.

• HKS SCD - get rid of that pesky 122mph speed limiter ($150);
• HKS FCD - 14 psi will never be enough ($125).
• MKIV 550cc injectors.
• HKS Super AFR - compensate for the additional fuel from the injectors and tune the fuel curve ($350).

If necessary I will also add a Walbro fuel pump and adjustable fuel pressure regulator. The 550cc injectors should support the power I want to produce without upping the fuel pressure. If they will not flow the fuel this will allow me to up their fuel flow.

Stage 3

The idea of stage 3 is to take the car into truly scary territory. My goal will be >650 rwph. My plans for this stage are vague at best. I do not foresee any of this work occurring for at least 2 years. I will convert the engine to a largish single turbo and will probably add at least a 100 shot of NOS. I will also upgrade the intercooler to a thicker core, probably an HKS Type R for the MKIV Supra.

One advantage the 1JZ has over the 7M is that it can use all the 2JZ exhaust parts including the tuned manifolds that are available. I expect to use a 68 or 72 trim turbo. I have not given the exhaust a/r any thought at this point. The upgrades will also include a fuel system and the Apexi programable drop in computer.

My 1JZ

Pictures

A 1JZ-GTE with CT-26 turbo (i.e. it is the single turbo version) in the Tokyo childrens museum.

A very clean 1JZ-GTE engine.

A 1JZ-GE engine.

A scrap 1JZ waiting for a new home.

A 1JZ-GTE equipped MKII Supra.

Relevant Links

Orin Bevins - The Texas expert on 1JZ swaps. Orin sells a swap kit (including engine mounts) for the JZ series engines.

1JZ-GTE, The Forgotten Hero - A good history of the 1JZ-GTE engine.

MKIV 550cc Injector Upgrade - The Japanese market cars used high impedance injectors. This page explains the steps required to convert a Jap spec 4th gen Supra (same injector issues as the 1jz) to the larger, low impedance, US/UK injectors.