Originally Posted by
juiced2ndgenteg
The pr3's came in usdm b16's and first gen jdm b16's. The p30's only came in second gen jdm b16's. The reason that the b16 pistons give you a higher comp ratio is because the b16's have a lower compression height compared to the b18 blocks. When you put them in a b18, the higher comp height bumps the compression up higher than you'd get in a b16 block. The pr3's will put you at around 11.5:1 and the p30's will get you up in the 12:1-12.5:1 range. You can run 12.5:1 compression on 93oct without and problems. It will give you the most HP/TRQ on 93oct. I ran 12.5:1 on a lsV about 5yrs ago and made 214whp with CTR cams and a P&P b16 head. It was a sweet NA setup. Pegged rev limit from a roll in 1st once vtak cracked at 4400, with 205/50/15's. Also, running the highest comp that you can still run 93oct allows you to get a race gas tune and get another 10-15whp whenever you put race gas in your tank and just swap the pump gas chip with the race gas chip.
dude i dont know where you crunched your numbers at but, p30 pistons will not put you at 12:1 + compression with gsr stroke and head etc... anyway, ppl are forgetting to mention the differnece in the heads. a type r head is ported/polished/etc from the factory and is of the same CASTING as the b16, so its got larger combustion chambers. the gsr head will give higher compression than an itr head. thus, if you install jdm itr pistons in your gsr block, youll end up with higher than jdm itr compression bc the head has smaller combustion chambers, while the block remains geometrically identical. pct pistons will probably put you close to 12:1 compression. check out c-speedracing.com for a compression ratio calc. your ideal compression for the street is probably not much higher than 11.5:1. any more than that, and you have to detune to run on pump gas depending on how large your cams are and how much compression they can bleed off. in any event, on a street tune you wont make any more power running over 12:1 compression than you would running low 11:1 compression range. you can tune the lower amount of compression more aggressively and make the same power.
bcIII is a mean cam designed for road course use. broad useable power its its goal, hence your vtec crossover is not very noticeable bc the primaries are similar to the secondary lobes (much like an h22). thus, you get more area under the curve and a slight upgrade over itr cams. skunk2 stage 2 cams are a great street cam, but it sacrifices some midrange to the itr bc of its larger profile. the beauty of itr cams is their broad area of power. they may not make the same peak numbers, but they will make more power at a lower rpm before the s2stg2 cams pass them up. just my thoughts.
and by the way, its hard to believe that an lsv with 12.5:1 compression on p30 pistons and ctr cams made 214 at the wheels. its hard enough to get a 2l setup to make 200 n/a hp on ctr cams with that compression, let alone 14 more whp.