I'm trying to decide which bore size to run on my GEM sleeved b18c1. I plan to run 24-27psi and make 500-550whp. I ordered a 84.5mm headgasket and it just looks so small between the cylinders. I know alot of people are running a 84.5mm bore without problems . I want to run CP pistons so my choices are 81.5 or 84mm. Will the tq or whp be a big noticeable differance between the two or could I just run a 81.5 bore and run a extra psi or 2 and end up with the same power.

 

the 84's are fine as long as you are careful getting the head on and the blocks built right. its thin, but it'll last if its done right. you won't need anywhere near 27 lbs of boost for 500-550 unless that turbo is small.

 

The sleeves do get a bit thin, but you should have nothing to worry about assuming the tuning is on point. The gains from a 2.0 vs 1.8 displacement is more than 2psi worth, probably closer to 3-4 psi. With a decent sized t3/t4 you'll be able to make 400whp on pump gas, and easily over 500whp on race gas.

BTW, 400whp in a eg hatchback will get you into the high 10's with a good sized slick.


[Modified by boosted hybrid, 1:49 AM 4/6/2003]