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Hi all, I'm pretty new to all this stuff but I'm learning as I go. I'm trying to create a pretty decent NA build overtime but I'm not 100% sure on some things. I just purchased skunk2 stage 3 cams along with titanium retainers and new springs. I plan on buying a new chain and tensioner as well. People have been saying these cams like a higher compression ratio around 12.5 to 1. Should I send the head off to get ported and buy higher compression valves? Also what should I be looking for injector and TB wise?

Build: 2007 civic si, k20z3, full skunk2 exhaust + headers. Skunk2 cai, hondata, stage 2 clutch + flywheel
 

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Arouse the DAMPFHAMMER!
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Welcome 0260in15mins to K20a.org! That's a very nice first post. I love NA engines...

...skunk2 stage 3 cams along with titanium retainers and new springs....saying these cams like a higher compression ratio around 12.5 to 1. Should I send the head off to get ported and buy higher compression valves? Also what should I be looking for injector and TB wise?
Which series did you buy? The S2 Tuner Series 3 or the S2 Ultra Series 3? Beside that, the stage 3 cams are both crazy high engine speed supporters. With a duration of 282°@1 mm or 277°@1 mm you will see a peak power around 9000+ rpm (depending on displacement). On a 86x86 engine you may look for a piston dome volume of 16+ ccm (never saw a piston with that 🧐) to get a valuable dynamic compression ratio. My recommendation for you would be, search for the highest possible CR piston, look for very light pistons and rods, make your engine safe for 9500 rpm at least to gain what these cams are designed for (1/4 mile, high speed circuit racing).

As those cams will kill ponies down low due to their looooong opening duration and the only 500 ccm/cylinder displacement. On the other side the huge CR you need to get these cams working on high speed cam your engine will suffer knock on low speed cam. Depending on the application a compromise has to be found, for race at least 13.5:1 for DD at least 12.5:1. So between these extremes I would see the CR compromise.

Build: 2007 civic si, k20z3, full skunk2 exhaust + headers. Skunk2 cai, hondata, stage 2 clutch + flywheel
The stock clutch can handle up to 260 ftlb's, I think that money you can safe if you not keen on the different clutch sweet spot behavior.
The flywheel need to be lighter, definitely. You should balance the crank, idler pulley, flywheel with respect to the rotating and oscillating weights of the rod and piston assembly to make them keeping up with the necessary engine speed for these cams.

Regarding the IM, I would use ITB's and tune the length to cams via Bell Mouth length. If you go with a plenum IM you won't find something on the market really feeding this cams, but S2 Ultra Race would be a candidate of those which are available. The stock Honda stuff won't support the cams.

Regarding cylinder head port, you will need about 330+ [email protected]" valve lift at intake to feed those cams right. Exhaust I would keep stock (valves and port).

These cams came with a lot of consequences, if built right to a good level of output, as those are real monster cams. But finally this engine will be a blast, if done right 260 whp should be possible at around 9200 rpm.
 
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