guys chasing big power from B's are using 92mm and 95mm cranks... with 85+ bores...

but with "tall deck blocks" and long rod combos... so mitigating (somewhat) the extra stress of big stroke cranks...

a 85 x 89 block is pretty good compromise, particulary considering the 'high-revving' B18C7 has a stroke that is only 1.8mm shorter...

i note the B20B has a better "piston to bore" ratio than the B18C engine... whislt the B18C has a marginally better rod/stroke ratio of 1.58 vs 1.54...

the "worst" thing about a B20B is the cylinder insert being one-piece, compared to multi-piece...

IMO - this is not a problem at all, provided you are clever and dont try to detonate the engien by bad tuning...

see here for info about the unique B20B sleeves:

http://dwolsten.tripod.com/articles/jan96a.html

(i use this article to explain to people who ask: "why didnt Honda just make a 84mm bore B-series in the first palce? that would have kicked ass?")