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From what I've read the "bowl" area is usually the lowest hanging fruit (easiest to improve on) for most cylinder heads I've read about. also sometimes the chamber can be "unshrouded" to help flow (though on hemi combustion chambers I think this is a moot point). A kick butt valve job is usually well worth the money as well.
Part of the "magic" is that you can ruin the heads if you don't know what you are doing. If port size was the key then everything would be huge from the get go. But velocity and flow at a given valve lift is what is important, and typically a flow bench and velocity probe are used by head porters to measure their improvements.
In some cases epoxy or welding are used to radically change port shapes.
I'm betting that minor cleanup is all you'll want to do; hogging metal is a recipe for disaster unless you know where it needs to be coming from.
I ported a 2.2 dodge turbo head a long time ago (and spent hours and hours doing it). It made a huge difference - but I spent a bunch of time planning it out and researching it, and the 2.2 head design isn't as good out of the box as an xs11 head is, it's not a cross flow head (intake and exhaust ports are on the same side) and it uses a conventional wedge shape with 2 valves). The 1100 has a hemi shaped combustion chamber if I remember correctly.
Actually, it's a pretty cool looking combustion chamber. For kicks google the new hemi motor and read up on how efficient it's 2 valve design is - its pretty remarkable considering the hemi costs less to manufacture than the 360/318 did (http://www.allpar.com/mopar/new-mopar-hemi.html).
Dan
Part of the "magic" is that you can ruin the heads if you don't know what you are doing. If port size was the key then everything would be huge from the get go. But velocity and flow at a given valve lift is what is important, and typically a flow bench and velocity probe are used by head porters to measure their improvements.
In some cases epoxy or welding are used to radically change port shapes.
I'm betting that minor cleanup is all you'll want to do; hogging metal is a recipe for disaster unless you know where it needs to be coming from.
I ported a 2.2 dodge turbo head a long time ago (and spent hours and hours doing it). It made a huge difference - but I spent a bunch of time planning it out and researching it, and the 2.2 head design isn't as good out of the box as an xs11 head is, it's not a cross flow head (intake and exhaust ports are on the same side) and it uses a conventional wedge shape with 2 valves). The 1100 has a hemi shaped combustion chamber if I remember correctly.
Actually, it's a pretty cool looking combustion chamber. For kicks google the new hemi motor and read up on how efficient it's 2 valve design is - its pretty remarkable considering the hemi costs less to manufacture than the 360/318 did (http://www.allpar.com/mopar/new-mopar-hemi.html).
Dan
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