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Many engines have become legendary among enthusiast motorists, sometimes for their longevity, sometimes for their performance and sometimes even their character. In the case of Toyota’s 1JZ and 2JZ, all three of those boxes are unequivocally ticked.
So what are we dealing with exactly? Well, the 1JZ and 2JZ are both from the Toyota JZ engine family which was first seen in production cars in 1990 and effectively replaced the ageing M family of passenger-car engines.
Early cars with 1JZ engines included the Toyota Crown Athlete, while the 2JZ motor arrived in 1991 in the Toyota Aristo. Other cars with 2JZ engines include the Toyota Crown and Cresta and the Lexus IS 300.
The ZJ family members are inline six-cylinders with a cast-iron block, alloy cylinder head, belt-driven overhead camshaft(s) and four valves per cylinder. All family members were designed for rear-wheel drive applications and were mounted north-south.
The main difference between 1JZ and 2JZ units is the displacement, but it’s not as simple as it sounds. The 1JZ engine has a bore-stoke relationship of 86.0mm x 71.5mm respectively.
That gives it a capacity of 2.5 litres, while the 3.0-litre capacity of the 2JZ is achieved by using a longer stroke of 86.0mm (making the latter engine square; where bore and stroke are equal).
But as well as the longer crankshaft throw, the 2JZ engine specs also include the fact that it got a taller block and longer connecting rods, so, the 1JZ vs 2JZ comparison is not as straightforward as some engine families with varying capacities.
The A80 Supra made the 2JZ king.
The major variations of the JZ theme over the years have been the fitment of Toyota’s variable valve timing system (VVTi) and whether or not the engine in question used turbocharging.
That’s the basis for the nomenclature, too; the 2.5-litre version with variable valve timing is a 1JZ VVTi and a 3.0-litre engine with turbocharging is a 2JZ-GTE.
In its most basic form, the early 1JZ non-VVTi was a non-turbo unit which made 125kW of power and 235Nm of torque.
The 1JZ turbo soon emerged with twin ceramic turbo units, but this proved to be a bit problematic for some owners with the turbos dying early thanks to oil contamination in the exhaust reaching the turbos.
The 1JZ is 500cc smaller than the 2JZ.
This remains one of the few relatively common 1JZ twin-turbo problems and it was fixed with the later development of the 1JZ-GTE which was effectively, a 1JZ single-turbo and adopted the latest version of VVTi.
Toyota claimed 206kW of power for this engine, but may have been understating the true performance as Japanese laws at the time effectively limited production-car power to this figure.
The 2JZ kicked off in non VVTi form but for MY98, this tech had been added, lifting power to 169kW in its most powerful non-turbo form. In that case, the engine used sequential fuel-injection and Toyota’s take on coil-on-plug ignition.
The a modified 2JZ can easily make 700hp. (image credit: LSB/Twitter.com)
The one everybody remembers, of course, is the 2JZ-GTE which was fitted with a pair of sequential turbochargers, an air-to-air intercooler and VVTi.
Under those same Japanese rules, Toyota was still claiming the same 206kW for the engine, but export-market brochures told a different story with 239kW being quoted. Even that might have been a bit conservative on Toyota’s part.
For this version of the 2JZ pistons were switched to a dished design to reduce the compression ratio to a more turbo-friendly level and oil jets were added to cool the pistons from underneath.
A change to con-rod specification saw some of the later 2JZ-GTEs criticised for a weaker bottom end, but overall, the 2JZ’s reputation for being bulletproof is standing up well.
A proper screamer and designed partly as an answer to Nissan’s equally-revered RB26TT inline six, the 2JZ-GTE was found in all sorts of Toyotas and Lexuses, including the Aristo, Altezza and, most famously of all, the JZA80 Supra RZ, a car that has since gone on to immortality among collectors. In fact, a 2JZ Supra in any form is hot property.
A naturally aspirated 2JZ can be found in the is300.
So why are the JZ engines so darn good? It’s a simple answer, really; they’re bordering on bullet-proof. The cast iron block is part of the secret and allows for great bottom-end rigidity which is what you need when you’re blowing huge boost into the thing as those running an aftermarket 2JZ turbo kit have discovered.
That block material bumps the 2JZ weight a little, but most tuners will happily trade off a few kilos for that bomb-proof build. Other details include the closed-deck design of the crankcase and those oil squirters for the pistons.
Making bulk, safe 2JZ horsepower is also possible because the crankshaft is a forged item (rather than cast) and it rides in huge bearing journals.
Frankly, it’s almost like Toyota was thinking of tuners when it sketched up the JZ engine, and many workshops have cobbled up high-output engines with more than 520kW (700 horsepower) on the stock bottom end.
A70 Supra could be had with a twin-turbo 1JZ engine.
The secret is in the engine’s ability to handle boost and while the odd tuner has built a supercharged 2JZ, the vast majority of modifiers stick with turbocharging.
But even details like the standard 2JZ oil pump, cooling system and timing belt arrangement will support up to 750kW (1000 horsepower).
What goes wrong with them? Not a whole lot, although those sequential-turbo models we mentioned do seem to destroy turbocharger units with some ease.
Again, most tuners switch to a bigger, single turbo which can still provide the boost and flow required for big power.
Beyond that, it’s small beer. The timing-belt tensioner bracket can fail, the engine can destroy its own crank pulley and there have been cases of the oil-pump seals failing.
There are aftermarket solutions for these things, of course, and, thanks to the popularity of the engine, you can buy a whole 2JZ crate engine as well as an alloy billet 2JZ cylinder block. Longer stroke crankshafts are also available to increase cubic capacity.
Finding a second-hand 2JZ engine for sale is not too difficult, as the unit wound up in so many Toyota and Lexus models.
Some people have already begun swapping 2JZs into the new A90 Supra. (image credit: Daigo Saito)
Specialist importers of used engines are a good place to start. A 1JZ will be cheaper to buy, but even the average 2JZ price seems like pretty good value for such an iconic powerplant.
A 2JZ-GE which had no turbocharger can also be found cheaply, but will need low-compression pistons fitted before you add boost. Don’t rule out the engine from a wrecked Lexus IS300 2JZ, either.
An imported Soarer 1JZ is another option, but beware those twin turbos and check them carefully before handing over the money. In fact, plenty of 1JZ Soarers were privately imported to Australia, so they’re more common than you might imagine.
In Australia, the Ford Barra vs 2JZ debate continues to rage. Both engines have their strong points, but it remains that they have a lot in common.
They’re both good solid bases to start modifying, they both have good inherent strength from the factory and there’s a huge aftermarket just waiting to supply modifiers with anything they need.
Done right, either engine can be a world beater, but the Toyota unit will always have the global appeal.
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