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A common swap if you can get all parts in the same place at the same time and if you have the money to do it a mixture of the two engines that are said to be toyota's best
he 1.5JZ is not a production engine but is created by combining a 1JZ head with a 2JZ bottom end. The 1JZ cylinder head will, with modifications to the oil gallery alignment, bolt on to the 2JZ bottom end.
It should be noted that the 2JZ-GE (Naturally Aspirated) bottom end has no oil squirters as found in the 2JZ-GTE (Twin Turbo) bottom end. Galleries and mounting bosses do exist in the GE block to allow the addition of oil squirters, however this requires machining.
* 1JZ = 2.5L Inline 6 (86.0mm bore x 71.5mm stroke)
* 2JZ = 3.0L Inline 6 (86.0mm bore x 86.0mm stroke)
Using a 2JZ bottom end with the 1JZ components allows an extra 500cc of displacement.
Reasons for this conversion is a matter of opinion and discussion. The 1jz has a larger Exhaust valve at 30.0mm yet a smaller intake valve of only 31.0mm whilst the 2JZ has a 33.6mm Intake valve and a 29.0mm exhaust valve. The debate is, that it was easier to go 1.5JZ instead of 2JZ due to electronics, and configurations for pre existing manifolds etc.
Reference http://www.supraforums.com/forum/showthread.php?t=329805
What is known is that the 2JZ head compared to the 1JZ head has more restriction in the 5th and 6th cylinder exhaust ports due to an S shaped casting. The 1JZ also has different shaped combustion chambers which, when directly placed on a 2JZ block, increases the compression slightly and leads to a power increase when using unworked heads. Once worked (ported and chambers reshaped, valves resized) the heads have been proven to flow much the same.
The most likely reason for the setup would be if the owner of a worked 1JZ engine suffered from bottom end failure or if they wanted the extra displacement and torque of the 2JZ bottom end, as the heads are interchangeable. Thus all the existing manifold, plumbing, fittings, turbo(s) could be retained making for a very cost effective power and torque upgrade.
he 1.5JZ is not a production engine but is created by combining a 1JZ head with a 2JZ bottom end. The 1JZ cylinder head will, with modifications to the oil gallery alignment, bolt on to the 2JZ bottom end.
It should be noted that the 2JZ-GE (Naturally Aspirated) bottom end has no oil squirters as found in the 2JZ-GTE (Twin Turbo) bottom end. Galleries and mounting bosses do exist in the GE block to allow the addition of oil squirters, however this requires machining.
* 1JZ = 2.5L Inline 6 (86.0mm bore x 71.5mm stroke)
* 2JZ = 3.0L Inline 6 (86.0mm bore x 86.0mm stroke)
Using a 2JZ bottom end with the 1JZ components allows an extra 500cc of displacement.
Reasons for this conversion is a matter of opinion and discussion. The 1jz has a larger Exhaust valve at 30.0mm yet a smaller intake valve of only 31.0mm whilst the 2JZ has a 33.6mm Intake valve and a 29.0mm exhaust valve. The debate is, that it was easier to go 1.5JZ instead of 2JZ due to electronics, and configurations for pre existing manifolds etc.
Reference http://www.supraforums.com/forum/showthread.php?t=329805
What is known is that the 2JZ head compared to the 1JZ head has more restriction in the 5th and 6th cylinder exhaust ports due to an S shaped casting. The 1JZ also has different shaped combustion chambers which, when directly placed on a 2JZ block, increases the compression slightly and leads to a power increase when using unworked heads. Once worked (ported and chambers reshaped, valves resized) the heads have been proven to flow much the same.
The most likely reason for the setup would be if the owner of a worked 1JZ engine suffered from bottom end failure or if they wanted the extra displacement and torque of the 2JZ bottom end, as the heads are interchangeable. Thus all the existing manifold, plumbing, fittings, turbo(s) could be retained making for a very cost effective power and torque upgrade.