did a lil more research irocs have 145mph speedos seen only 130 or highest 140 with z28 but only on first glances don't know that to be concrete..

 

Here is a extract from the white book. From what I can tell its the most informative and thoroughly researched book for our hobby.

the new option the IROC sport equipment package (RPO B4Z) debuted in 1985....... the IROCfeatured lower trim height and center of gravity, special front struts, springs and jounce bumpers (I dont know what a jounce bumper is), Delco Bistein rear shocks, special rear springs and stabalizer bar, higher effort steering, increased caster, front fraimrail reinforcement, Goodyear eagle P245/50VR blackwall tires on 16x8 aluminum wheels, fog lamps, numerous chassis tweaks, and uniquegraphics. The IROC was not a separateCamaro model; rather it was an option available with Z28 models. this car was capable of .92g's in skidpad tests and 7 second 0-60 all in showroom package.....
in 85 there were 21, 177.

eventually GM dropped the name Z28 altogether, among other changes, and at one point there was only an RS or IROC-Z option. Basically the difference was that an IROC was an option for the Z28 - so every IROC was a Z28.

there were other changes along the way, as mentioned, but that is the basic gist of it.

 

You guys are correct. The an IROC was essentially a trim package with different suspension settings and different wheels. When they debuted in 1985 they came with the same 5.0 litre that you could get in the Z28. Sometime in 1986 they started offering the 5.7 litre but it was hard to get. By 1987 50% of all IROC's were coming with the 5.7 BUT you could also order a Z28 with one as well (but very few would step up and pay the extra $$ to upgrade the engine and then not want the IROC package). 1988 and 1989 the Z28 was dropped and only the IROC was available (most came with the 5.7 litre by this time).
Most people consider the IROC a "badass" because it looks alot sportier and because most IROC's on the road have the 5.7 litre (compared to the very few Z28's that have them).

 

Also correct as of 88-89 Irocs did become there own models for z28 being dropped but the big difference was the sport performance of the parts combos that have been all listed by now no z28 will out handle a iroc not just looks but literal drive the main way on the streets u can tell a iroc from a clone at first glance look at the ride height the way wheels sit in the wells will be ur fastest determination of real or not z28's are in the air not just bottom trim but space in wheel wells then next is rear disc brakes and axle my stock iroc is practically inches from the ground stock no z28's had g80 rears till after iroc died and still the next step up from irocs were 1le's that were stripped irocs with better brakes and oil coolers dual cats thats about it..

 

so what im getting here is i should junk my 83 z28 and find me an iroc to rebuild? too bad my 83 tranny had to give out on me at 300,000 miles and be my first car. So im gonna make it badder than any stock iroc out there.

 

but didnt the irocs have a borg warner rear end as well as the 350

 

I believe that the irocs have stiffer suspension, heavier swaybars, and faster steering. I believe the engine could be gotten in the Z-28 as an option. The irocs also came with a lower rearend ratio with limited slip differential standard. This could also be secured on the Z-28 via the option list. As far as the decals on the side go you can buy them, or remove them if you don't like them.
James V

 

the IROC was like the generals version of the SS for the third gen camaro.

 

iroc has high performance nitrogen delco shocks it sets lower has 16 inch aluminum wheels and some other styling differences but the main difference is the suspension

 

I like how people keep posting up random garbage without really knowing anything at all.

If the OP is still interested, how the hell is he going to know who's making **** up and who actually knows what they're talking about?

Give this a look over; I'm sure it's not perfect but it'll be a bit more informative.
http://www.iroczone.com/history.asp