Here's why:
* Different bore sizes: The 3.4L has a larger bore diameter than the 2.8L. This means the cylinder heads are designed for a different cylinder size, and the valve locations will not align properly with the bores in the 2.8L block.
* Different valve sizes and angles: The 3.4L heads have larger valves and a different valve angle than the 2.8L heads. This is due to the larger displacement and different combustion chamber design.
* Intake and exhaust manifold compatibility: The 3.4L and 2.8L have different intake and exhaust manifolds, which will not be compatible with the other engine's cylinder heads.
* Possible interference: The 3.4L cylinder heads may physically interfere with other components on the 2.8L engine, such as the camshaft or rocker arms.
Possible alternatives:
* Head porting and machining: You could potentially have the 3.4L cylinder heads ported and machined to fit the 2.8L block, but this is a complex and expensive process.
* Use 2.8L heads: The most practical solution is to use cylinder heads specifically designed for the 2.8L engine. These heads are readily available and will be compatible with the engine's other components.
Conclusion:
Swapping cylinder heads between a 3.4L and a 2.8L is not possible without significant modifications. It's generally not recommended due to the complexities and potential problems involved.
