will a 5.7 HEMI swap inplace of a 4.7 in 01 Jeep Grand Cherokee withought major changes ?

That job will require some major modifications to almost everything. Motor/ trans mounts, exhaust and fuel systems Wiring harness/computer. Trans compatibility issues. inner fender/ hood clearance issues. Tough but not impossible.

The 5.7 l hemi engine is absolutely compatible in the WJ Grand Cherokees. In fact you don't need a single modification, other than the exhaust y-pipe, which would come with a good used motor in the first place so you may not even need to do that modification. All exhaust components will clear, the engine mounts will bolt right up because they are in the same location and have the same pattern on both blocks, if you get the right year engine, you won't even need any harness modifications at all because all the sensors will be in a similar position and use the same plugs. The biggest concern would be that the hemi engine would starve greatly for fuel, and you would also have to use premium, to avoid pre-definition from a more advanced timing curve on the 4.7 l. But the operating range is the same on both engines, and the timing curve is very similar with some luck, the 5.7 l engine swapped out for the 4.7 l will run beautifully on premium fuel. One trick to avoid a tune, would be to install injectors that are 10 to 15 lb more per hour in flow. Sometimes that will help sometimes that won't. There are many different combinations through the years of both the 4.7 and the 5.7 Magnum and hemi engines respectively, but the engine's both have all the same or similar mounting points and bolt patterns and year to year they use the same sensors, they have the same firing order, and most use they use the same coils and if not you can still switch the coils over very easily. I have seen harness adapter kits for the coils to go from single to dual ignition with the Jeep harness. When attempting a swab like this, the easiest way to go is to find a 5.7 that is the same year as the Jeep you have or maybe even a year or two older, I don't exactly have a chart at the moment. But if you were to take a 2004 hemi engine and stuff it into a 2001 Jeep Grand Cherokee, it would be almost a direct Bolt in. My recommendations would be custom-made headers y-pipe and a full exhaust a k&n cold air located in the fender well bolt up a 6.2 or 6.4 intake manifold, and then go find a really good Dodge tuning shop with a dyno and you will see 430 to 440 wheel horsepower.