I'm buying a new motor for my EF hatch in a couple weeks when my income tax return shows up. I want to go with bolt-on's and a 55 shot zex set-up my dude has laying around. I'm torn between the DOHC ZC or the D15B vtec. I thought about keeping my D15B2 and doing the MPFI conversion with bolt-on's and a 55 shot, but I have my doubts. I also want to get a motor I can go through and do all new gaskets, water pump, oil pump, etc. while I still drive around with my underdog, slow, basically pointless dual point D15. At this point i'm leaning toward the ZC due to the fact it seems like an easier swap into my car, its only rated at 1 less horsepower than the D15b vtec, the wiring sounds like it would be easier, and i've heard myths that the DOHC ZC handles nitrous better (most likely not true at all, i doubt it is anyway). Someone enlighten me, which would be better/quicker with a 55 shot?

 

The ZC rods are stonger, but the D15 rods are longer and the RS ratio can take a little more stress. Its also .1L smaller, but has vtec which is better for a street car. Both are relatively high CR for what you're going to do to them (given the strength of their internals), so it really comes to which one is in better condition. I'd go D15B since you can get parts easier, or just go with a D16 block if **** goes south. THe DOHC ZC head requires mods if you plan to use a non-DOHC ZC block under it.