Or another way to put it, how much, if any, does the belt system for the Helcat blower stick out farther than a belt system for an early 5.7 setup? Are the belts the same number of ribs?

Should be able to get you measurements over the weekend.

Not sure about the belts. You'll need Hellcat heads and a whole bunch of other stuff as well.

I have Apache heads, and would build it with the 5.7 block most likly. I won't need as much reliability built into it for the car it would go in. It would never see more than 10 seconds of full throttle, if that. Another option is a helcat shortblock assembly is $4,000 which might make more sense if my rods and stroker crank aren't good enough for 800hp.

Without knowing, I would assume I will need a Helcat crank damper, and may have to space everything out a certain amount?

A hellcat blower has a different intake bolt pattern than any other Gen III. Apache heads might be able to work, but it will require modification and milling.

The new Edelbrock heads that are coming out have both bolt patterns.

The early 5.7 motors have a different pulley depth than later (2011+ ish) 5.7s and all 6.4s which I would assume to be the same for 6.2s as well but could be completely different altogether. Honestly, the path of least resistance for what you're doing would be one of the aftermarket blowers of your choice.

I already have the blower, although it does need a front bearing. I also have the Apache heads, A Molner 3.888 crank, and some H beam rods out of a Dragpak motor, and an older 5.7 motor to work with.
I see the Helcat uses a double belt system, and maybe an eight rib belt for the blower? Since I don't plan on AC or power steering, I have some options like a custom belt route for two belts, and spacers.

The Hellcat blower is specific to the Hellcat heads, the bolt pattern is not the same as you Apache heads. You will have to look and see if they can be modified to work.

Get the new eddy G3 heads and it should fit. They have dual bolt patterns

I would probably be cheaper to drill the proper holes, if possible. If some of the bolts line up, the blower could be used to locate the rest of the bolt holes?

No. Not possible.
The Hellcat supercharger has a unique straight 10 bolt pattern along the far-most driver and passenger sides.
Let's not forget that the Apache heads are made out of a different material (319 alloy) than the hellcat and eddy heads (356-T6). 319 alloy can and has been known to flex under boost and can cause a head gasket leak that will drive you nuts. There's a reason FCA went to the 356-T6 material. It's definitely not cheaper.

According to another post, 6.4 heads are made of the better aluminum alloy like the Hellcat heads. I have a set, so when I gat a chance i could test fit the blower and see.

I think the 6.2 heads are stronger aluminum.
As for the difference in blocks.

1

2

6.4 TRUCK heads only. Car 6.4 heads are 319 alloy vs hellcat and truck 6.4 356 aluminum alloy with T6 heat treat & age.

Also, you can't test fit much of anything with any set of 6.4 heads and a hellcat supercharger. The bolt pattern is completely different, as I stated above.

Are you sure it's not 319? 318 is an unusual grade.
319-T6 has similar strength to 356-T6 in sand castings.
Perm or semi perm mold will be a little higher.
Check out Matweb.com
Numbers will vary depending on the source
I believe 319 is less expensive.

6.4 car heads will be fine, PLENTY of SRT cars running boost with pass car heads. As far as ?redrilling them, unless your going to get into a water passage or something like that I can't see why not

Yeah that's my fault it's 319. I changed my post, don't want any misinformation. As for the issues guys were having with putting boost to these cylinder heads, there have been several on other forums that have had heads permanently deform under boost and not seal right. They would pull the heads, get them nice and flat again, run them for a short period of time, and have the same issue. It was a vicious cycle and some guys even went to.....(fighting vomit).......an LS