MOTOR RB26 OPTIONS

k20a2/ k20a3 blocks Is there any big dif. amongst these two. I'm talking just the blocks. As in would a K20a2 block certainly be a better choice in sleeving in excess of the A3? The A3 are so inexpensive to come back by so I just wished to know.Did any ever get imported here, or are these all engine imports only? Supra turbo is a great deal a proba