Hi Sharon,
My preference would be the A50 14L for 8S. The I-90 instructions call for an A50 16L (but I looked closely and the instructions also call for 10S). So, I was incorrect in advising the A50 16L for your 8S setup. I have experience with an E-Flite power 110 in this airframe on 8S. Performance is very good indeed with that setup. That motor (the Power 110) is almost identical to the A50 14L in KV and weight. The 14L = 310 KV and weighs 470 grams, The 110 = 295 KV and weighs 490 grams.
Hope that clarifies things a bit.
Ed

PS .... I've corrected the post above to 14L