The B23 is seriously built - forged crank (in most), thick rods, bigger bearings, pistons with large skirts...

The B230 is more reasonably constructed for the type of load it sees - shorter piston skirts, thinner rods, smaller bearings, cast crank, higher wrist pin location...

I would surmise the following:

1) B230 has lower rotational mass, resulting in greater response, maybe a bit easier to move off the line.

2) B230 geometry biased oh-so-slightly more toward low-end torque than B23 - again, more oomph off the line.

However, there are many other factors involved which can affect an engine's feel in a given car. For instance, the B23, when backed with a manual, uses the lighter flat flywheel, whereas the B230 typically used the heavy stepped flywheel, which would tend to dull it's responsiveness. Likewise, the final drive ratio can heavily influence the feel of the car. It's a big difference between the 3.31 and 3.91, or even 4.10.


--
Speed Racer, '83 240 R, '93 940 OL1 (East Hartford, CT)