Quote:
Originally Posted by lvporschepilot
Wow. What are you doing to those heads! Love these builds. I have a very similar 2.8L build with ITB EFI (AEM Infinity), same compression as you (JE pistons), Carillo rods, twin plug, 39mm/38mm ports, and am running a DC65 cam. Idle is a bit lumpy at 1100-1200 (with 4-5 degrees timing), but it is otherwise very tame just driving around and revs very well to 8k. I may try a DC40 cam as I feel a DC60 or 65 wants a perhaps bit more static compression to work really well. I think a DC40 will have very close to the same rev range with all the light internal components and head flow anyway. DC40 duration is very close to DC60-65 and I feel like my heads may not be flowing way at the top end what optimizes a DC60-65. It's like I hit a wall for fuel requirements at around 7300-7400, as after that my EFI mapping requires to maintain the a/f ratio I'm going for at WOT that I back off fuel a touch to 8k. I really don't know for sure but will undoubtedly give this a shot to satisfy my curiosity and report back.
DC40 @ 1mm 266/249 .490 lift
DC60 271/255 .485 lift
DC65 272/258 .508 lift
stock 'S' cam 268/240 .455 lift
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That's great info, thank you for sharing. We haven't settled exactly on the cams and this is one of those areas that experience and experimentation is really important based on the target engine performance...
The headwork is basically building up the material to reshape the chamber for the right CC needed based on the piston design... in addition to some reshape, and changing the spark plug sizing, dual plugs, port and polish to spec, and larger valves. Xtreme is doing the work and it's not cheap.... but sill about 1/2 the price a set of their full spec heads!!!???!!!