CMUCL's interpreter evaluated IR1 (the first intermediate representation of its compiler) IIRC, so it wasn't possible to have a truly compilerless CMUCL _and_ a functional EVAL. I believe this IR1 interpreter was dropped from SBCL very early on. When SBCL gained an interpreter again it was a simple metacircular evaluator a la SICP that was unrelated to anything inherited from CMUCL. (This is all as of 15 or so years ago, I'm sure things have evolved since then!)
SBCL has two evaluators now, sb-eval and sb-fasteval. I don't know how much structure they share. By default it builds with sb-eval, but this can be changed with options to make.sh. sb-ext:*evaluator-mode* is still :compile by default.
