The more common difference between the Toyota 1UZ-FE and 2UZ-FE engines simply comes down to size. The 1UZ features a bore and stroke of 3.44 in. by 3.25 in., making for a 4.0L engine displacement. In terms of power, it was quite satisfactory, generating up to 256 hp and 245.4 lb-ft of torque. For someone looking to get a luxury sedan like the Lexus LS 400 or the Lexus SC 400 grand tourer, these V8 engines could give you a blend of good power and comfort.
On the other hand, the 2UZ engine bored it out to 3.7 in. and increased the stroke to 3.31 in., bumping up the displacement to 4.7L. This gave the engine a moderate jump in power, upping things to 271 hp, but in terms of torque, there was a massive increase, generating up to 315 lb-ft. This is why this engine was used more in the SUV and pickup truck models from Toyota and Lexus, like the Lexus LX 470 and the Toyota Tundra.
The other major difference between the two was the material used for the engine block. The 1UZ was a pretty standard aluminum block, but Toyota opted to use a cast iron block for the 2UZ instead. Because it was being used with heavier duty vehicles, the cast iron decision gave the engine a bit more reliability to handle that extra power and torque. The reason it is especially odd is that the 3UZ-FE engine went back to having an aluminum engine block. Beyond these things, the Toyota 1UZ and 2UZ work quite similarly.
[Image by Ypy31 via Wikimedia Commons | Cropped and scaled | Public Domain]
