The regular old plain-jane 2.3 at it's best had 109hp... in 1974, and it went downhill from there, though fuel economy eventualy went up a little bit (heck, in 1974, a 2.3 Mustang II or Pinto could do 30mpg plus... and it still had a points-triggered distributor and a 2-stage 2-bbl. Holley!)
The 2.3 Turbo is both the same and different, the displacement is the same, but the pistons are forged in the turbo motor, the connecting rods are a slight variant on the old Boss and 289 hipo designs, the block is modified for oil feed and return, and the intake and exhaust manifolds for each are unique, as is the cam.
An N/A 2.3 can be built to scream... for some big money... but only with either a full aftermarket EFI (I'm still contemplating a Holley 4-bbl. TBI on an Offy 4-bbl. 2.3 intake... lol...) or a carburetor (You'd be surprised how big a carburetor a stock '70s vintage 2.3 can run with just an adapter plate, I drove mine for a few days with a 600cfm Holley 4-bbl., it idled at 1500rpm, but it took off like a shot from a cannon! The factory EFI systems for the EFI 2.3s, while based on the same basic principles and architecture as the 5.0 EFI systems, aren't really all that upgradeable.
Hey Dawrr? When you say "late 80s" T-bird, do you mean the 1983-1988 Thunderbird "Turbocoupes" or the 1989-1991 Thunderbird "Supercoupes"?
Two different animals, the "Turbocoupes" are 2.3 turbo cars, while the "Supercoupes" are 3.8 Supercharged cars.. Both were awesome in their own right, but I'd take an '87 or '88 Turbocoupe any day... over almost any other Ford. (The four exceptions would be a 1978 Mustang II King Cobra, a '71-76 Thunderbird with a 429 or 460, a 71-73 Mustang convertible, or a 1963-1968 Thunderbird.)