Is it possible to replace the 3.1V6 engine in a 95 Beretta with 3.4 V6 without replacing transmission if they both use 4 speed automatic transmission?
It's not a direct replacement. The 3.4L V6 engine has a different bolt pattern than the 3.1L V6 engine, so you would need to modify the engine mounts and possibly the transmission mount. Additionally, the 3.4L V6 engine has a different electrical system than the 3.1L V6 engine, so you would need to modify the wiring harness. The 3.4L V6 engine may also require a different fuel pump and exhaust system. Therefore, it would not be practical to replace the 3.1L V6 engine with a 3.4L V6 engine in a 1995 Beretta.