You gots to swap on the hellcat heads or possibly drill the bolt holes in the apaches, dont know if theres enough meat and the alloy is not as good at conducting away the extra heat. Different front cover arangement also.
You will have more compression so you will neeed more octane. The apache cam has a tiny bit more lift and a lot less exhaust duration.
If you just bolt it on you could have similar power maybe even a tad more TQ, but you WILL need more octane, probably 100 octane. Even so your cast pistons will be living on borrowed time. Also the block will probably be just fine BUT the BGE block used on the hellcat and truck 6.4 does have slightly revised coolant flow for better cooling with all the extra heat as well as the cylinders are siamesed about 1/2 way up to make them more stable as well as the ribs on the outside.
Wow I learn something new all the time about Gen III Hemis. I did not know the Hellcat cylinder head had a completely different bolt pattern and I did not know the front of the Hellcat block had a diffrent front plate front cover as well.
Sounds like Hellcat is its own engine and has barely anything to do with the regular 5.7,6.2 or 6.4 Hemis.
I was going to try and build a "Hellcat engine"starting with regular 6.2 or 6.4 engine. Sounds like they are way too different.
That is good info and thanks.
