IROC-Z History
Total Production: 21,177
The IROC (International
Race Of Champions) began using the Camaro as the official vehicle.
To commemorate this, Chevy made an IROC model for the Camaro. The
IROC-Z was option B4Z on the option sheet and could only be ordered with
the Z28 option package. The ride height was 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.
This new performance icon boasted skidpad numbers within the range of .90
g. The top offering under the hood was the brand new TPI 305 which
boasted 215 horsepower and 275 ft/lbs of torque. This was the most
powerful 305 automatic ever offered in the IROC. The 190 horsepower
HO 4bbl 305 and the standard output 155 horse LG4 were the other available
motors.
The IROC also
came with a redesigned front fascia with a more rounded appearance and
a deeper chin spoiler with lower ground effects. The new fake hood
louvers were introduced on the Z28 and IROC. The IROC was available
in Yellow, Bright Blue Metallic, Black, Silver Metalic and Red.
Total Production: 49,585
In 1986, the
IROC received slightly different engine packages. The 86 IROC is
the armpit of the entire run. The 305 block in 1986 now had a one
piece rear main seal. The TPI 305 was the lucky recepient of the
LG4 camshaft, and the result was a drop of 25 horses and almost a half
second longer run to 60mph. Chevrolet did allow 50 IROCs out the
door with the 220hp L98 350. Beware when somebody sells an 86 as
a stock 350. CHECK THE VIN for accuracy. Chevy also let an
undisclosed number of these cars out with the T5 five speed transmission
as part of the 1LE racing option that also included air conditioning delete,
radio delete, as well as the deletion of all power accessories. The
1LE option was not available with T-tops, but did come with specially calibrated
springs, shocks and sway bars.
Visually, not
too much changed on the 86 IROC. The government mandated 3rd brake
light found its way to the top of the rear hatch near the roof line.
Curiously, rear window louvers became a factory option this year.
Some of the 86 IROCS came with the new 140mph speedometer. 86 was
also the first year for the base coat/clear coat paint system as standard
equiptment.
Total Production: 38,889
1987 brought
about only minor changes to the IROC. The motors now had the new
centerbolt style heads and manifolds had a revised bolt hole angle to accomodate
the different heads. The motors also made the switch to hydraulic
roller camshafts. This gave a 3.5% increase in gas milage, and an
extra 5 horsepower. The TPI 350 was now widely available, but only
with the 700R4 automatic.
Visually, the
87 is identical to the 86 model, except that the third brake light moved
from up on the rear hatch, to down in the rear spoiler.
Total Production: 27,811
1988 brought
about some welcome changes in the horsepower department, as well as a somewhat
revised exterior scheme. The Z28 was discontinued, and the
IROC was now its own model. For the first time in the history of
the camaro, no carburated camaros were available. All motors offered
fuel injection of some sort. The base IROC motor had the TBI injection
that was very similar to what was found on the trucks. A new camshaft
finally found its way into the 305 TPI and boosted horsepower to 195 horse
in the auto, and a stout 220 horse when backed with the T5. The 350
also got a small horsepower boost to 225 horse. All of the V8s starting
in 88 had "guided rocker arms" that featured a stamped-in lip on each side
of the pad that contacts the valve stem.
The exterior
of the IROCs received a mild update for 88. The most noticable difference
is that the wheels have been slightly changed. Instead of one line
through the center of each spoke, there were now two lines, and the center
area was a little different. Here's an interesting tidbit: for the
first time, the 16" wheel was an option on the IROC. The car came
standard with a 15" version. Along with that, the IROC-Z decal was
a little smaller and moved to the rear of the door instead of the front.
The stripe along the ground effects line now had the black line above the
silver. The silver Z-28 badges on the exterior have been replaced
with orange IROC-Z logos.
Total Production: 24,007
1989 brought
about some nice horsepower increases. The TPI 305 5 speed jumped
to 230 horse if the dual catalytic converters were ordered, and with dual
cats, the L98 350 jumped to 240 horse, with a staggering 345 ft/lbs of
torque! The TPI systems changed slightly. For the first time,
the 9th cold start injector was no longer used.
Visually, nothing
changed from the 1988 model.
Total Production: 5,517
This is the
first year the 1LE high performance option became widely known. The
1LE featured 4 wheel disk brakes, a 3.42 posi rear end, an aluminum drive
shaft, large 12" front rotors, aluminum calipers, engine oil cooler, larger
anti-roll bars and gas tank baffles. There were also numerous spring
rates available. The package could only be ordered without air conditioning
or fog lamps. 1990 also marked the year the the TPI systems changed
from the Mass airflow system to the Speed density system. These differences
are explained in the TPI tech section. The Speed density system allowed
an extra 5 horsepower from the 350, upping the ante to 245.
Visually, the
exterior of the 90 IROCs once again did not change, but looking through
the windows will show that they now had a driver side air bag as well as
revised instrument cluster.
Most of this information came from
either the Camaro Performance Handbook, written by David Shelby, or from
a special Camaro Performers magazine put out by the editors of Super Chevy.
The rest of the information came from Jim Irace and his vast knowledge
of seemingly useless facts.
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