I have a 1986 Z28 5.0L TPI.....I was just wondering exactly what the difference in a Z28 and an IROC is? After doing as much research as I could find, the only difference I can see is the emblems. Most IROC's came with the 5.0L motor, with an optional 5.7 upgrade.

Are the emblems the only REAL difference?

 

The IROC package(RPO-B4Z option on the Z28)was more than just decals.You would get larger anti-sway bars,stiffer springs,chassis braces("wonderbar" -steering brace)and most years 16" wheels were included(this is above what was standard on the Z28).For '86 the LB9 TPI 305 was the top motor.The B2L/L98 TPI 350 started as an option in '87.

 

The ride height is lower than a standard Z28, and featured performance-calibrated front struts and springs, Bilstein rear shocks and 16 inch aluminum wheels with Goodyear Eagle 245/50/16 tires...

 

The '86 Z28's also outnumbered the Iroc-Z's by almost 2 to 1. 88,132 vs 49,585 respectively.
The foglights (RPO T96) were also standard on the Iroc-Z but optional on the Z28.

PS; the Iroc-Z also had increased wheel caster (related to the suspension changes and ride height) and higher effort steering.

 

Actually both TPI motors were options... TBI was the standard motor... look under the resto forum if you don't believe me.

 

V10viper04 you're partially correct.For '86 the LG4 Carb 305 was still the base motor with the LB9 TPI 305 optional.The LO3 TBI 305 wasn't available until '88(possibly mid '87?)and then it was the standard motor for the IROC with the TPI motors optional.