what's the differences between a 305 RS and a 305 Z28? are there any power differences, or is it just the appearance and available options?

 

there are some huge differences but they only exist in the top half of the engine. im sure you know one has tuned port injection and one has throttle body injection, another big differences are the head ports, the ones for the tbi (rs) are much more restrictive the last and probably biggest is the cam, the 305 in the rs models got a peanut cam with very low profiles and not real good for making power but the z28 got the same cam as the l98 350 tpi which is a decent cam capable of making moderate power. other than that the only difference is a few sensors.

 

eehhhh wrong... in 85, 305's got the 350 cam.. but in 86-90 305's autos came with the "peanut" cam. 5spd came with the 350 cam. There are some strange things that happend in 91 that some most, if not all 305's got the 350 cam... im not 100% sure on that.. but the 305 always got the peanut cam. TBI isnt really for performance, but for trucks. TPI is what your looking for if you want some type of factory performance. no RS's got TPI.. but some Z's did get the TBI L03's. TBI would look like a carb set up where tpi has an elaborate set up of intake plenum and runners... this is a pic of tpi

 

ok, that helps explain some....so i should definitely go with a Z28 if i want any performance (without doing an engine swap).