The B18B Has a low rod ratio, which makes it harder for it to go All motor. Because of this you really can't rev higher than 8,000rpm, and with these low displacement engines the best way to generate HP is very high reving. (when going all motor of cource)

It can be done, with good results though. I have seen a B18B setup that had room for improvement, run 13.5 on slicks. Not to shabby.