Matt Birnie’s goal is to hot rod his beautiful pro touring 1987 IROC-Z Camaro for autocrossing and road racing – while still keeping it fun to drive on the street.
Matt’s been involved in autocross for over eight years. “I got into it because I really enjoy using cars to their full potential,” he told me. “Being able to go full throttle, to use their full handling, their full braking. Autocross is a way to do that that’s relatively inexpensive, and it’s relatively easy on the car.”
In 2017 he set out to find a car that he could build for his racing and street goals. That’s when he found the IROC. He drove it for a little while, and even raced a few autocross events with it, but Matt wanted more. He went to work in his garage to make the Chevy what he wanted it to be. Two and a half years later, he’s got the Camaro pretty close.
Talking with Matt gave me a fascinating look at hot rodding a car for road racing. “In autocross, or on a road course,” Matt told me, “when the car is taking a corner at high speed, all that force has to be counteracted by the chassis and the suspension. There could be things that bend, like steering components, or frame mounts. As you upgrade certain things, like the engines or the tires, you have to make sure the rest of the components can handle it.”
When you increase a car’s cornering power, the suspension and the frame and all the pickup points have to be able to handle greatly increased loads. So it makes sense that the chassis, suspension, and brakes are Matt’s main focus in this build.
The Camaro already had a set of subframe connectors welded underneath it when Matt bought it. To further tie the front of the chassis together, he installed bracing to connect the steering pick up points – the drag link and steering box – to the frame. He’s also planning on installing a set of strut tower braces, but Matt hasn’t found any yet that fit his engine set up.
Third generation Camaros have coil springs on all four corners. Matt has installed new UMI springs with spring rates that are just one step down from full race springs. The springs have weight jacks that allow Matt to adjust the ride height to where he wants it. There are Koni Yellow shock absorbers on all four wheels.
The suspension is further stiffened by a complete set of Delrin bushings. “The Delrin bushings are a super hard plastic,” Matt said, “that acts almost like a rod end, but prevents all the squeaking and knocking you get with a rod end.”
In the front, Matt’s installed caster / camber plates, which firm up the suspension a little more, and give him a wider range of adjustment. He’s got them set to strike a balance between being mild enough for the street but also aggressive enough for the track.
Matt also put in upgraded ball joints that are 1″ taller to help the front suspension geometry. When the Camaro was lowered, the lower control arm went past horizontal to an angle that was slightly tilted up. The new ball joints corrected that geometry by pushing the control arm back to being parallel to the ground. Matt’s also upgraded the steering box to a 10:1 ratio, a bit quicker than the stock 12:1.
The solid axle rear end is located with a torque arm rear. The arm connects to the transmission crossmember to help prevent the rear end from rotating. There was an aftermarket torque arm on the IROC which ended up breaking when Matt took his refurbished Camaro to the track for the first time in July.
As Matt recalled, “There was one particular corner where you were coming off a banking, then onto flat ground, and then you immediately have to turn. The suspension has to compress one way, while the body is going the other way. I think that was the straw that broke the camel’s back. It ended my weekend.”
He just finished installing a replacement arm from UMI. He has taken the Camaro for a test drive and reports that everything is good to go. Matt’s been impressed with the folks at UMI. “They’re a great company and good guys to work with,” he said.
One of the build aspects that Matt relies on frequently, and it comes from him actually being an automotive engineer, is to use OEM products wherever possible. “I’ve worked for a couple of auto companies,” he told me, “and I really appreciate all the testing we have to go through on parts for them to be validated. I’m a big fan of using OEM GM products because I know how much testing they’ve gone through. I also like the ability to run into a dealership or any auto parts store and grab a part.”
On the Camaro, Matt put that philosophy to use on the brakes. While there are several really good aftermarket brake kits out there, Matt installed brakes from a Z51 C6 Corvette. They are a big upgrade in terms of braking power and rotor size, but it’s still a stock GM part – and if he ever needs a replacement, it’s as close as the nearest AutoZone store. He used a kit from bigbrakeupgrade.com to adapt the Corvette calipers to his Camaro. Matt said they were a great company to work with and the kit made the upgrade very easy.
Additional brake system upgrades include the power booster and master cylinder from a newer 4th generation Camaro to take advantage of the newer technology.
Matt has also installed a Wilwood proportioning valve to fine tune how much braking power goes to the front and rear brakes. This was another area where Matt explained the road racing aspect of it to me.
“You don’t want your back brakes locking up before your front brakes,” he said. “You can lose control pretty quickly. It especially comes into play during maximum braking, such as when you’re on a road course at the end of the straightaway doing 100 mph, and you have to hit the brakes as hard as you can entering the turn.”
Matt’s got the proportioning set up the way he likes it for the race track and leaves it that way for the street. But he said he would adjust it on a rainy day at the track. Unlike drag racing, road racing and autocross still goes on when it’s raining. Matt says that’s actually a fun aspect of the sport because you learn to control the car when it’s sliding, but at a slower speed, so it’s a little safer. “You reach the limit of the car a lot sooner,” he said, “and your car has to handle that – including the wipers and defroster.”
Of course, tires are critical to good handling, and Matt’s IROC relies on a set of BFGoodrich Extreme Performance tires which are one step down from a full race tire. The P315/30ZR18 size is the biggest he could fit under the car.
The Goodrichs are mounted on Weld S71 wheels. Matt used the same 18 x 10.5 size for all four wheels. Depending on the track and how he’s racing, one set of tires can wear significantly more than the other. Keeping them all the same makes it easy for him to rotate the tires to even out the wear.
Of course, going fast on any race track requires some horsepower and Matt’s got that too.
The IROC came with a 350 cubic inch ZZ4 crate engine. It was running pretty strong so Matt just wanted to refresh it. He took it apart and put in new gaskets and seals, and painted the block.
The small block runs pretty strong because it’s got some pretty strong components, like Air Flow Research 195 aluminum heads with Crane roller rocker arms and roller lifters. Matt’s not sure what cam is in it but, he says, “it sounds pretty lopey at idle.”
The ZZ4 gets its fuel from a tuned port injection (TPI) system with a Holley throttle body mounted on a Lingenfelter Super Ram manifold. Matt considers the Super Ram the crown jewel of his engine compartment. “This intake was the top of the food change in the 90s,” Matt said. “It was the most sought after for the TPI motor.”
He loves having it, and it’s working well, but the Lingenfelter is kind of finicky because it has a lot of small pieces and fasteners that need to be fit together and sealed very intricately. He’s looking at an intake upgrade in the future – not only for a more modern fuel injection system, but also for a more versatile computer to control it.
The Lingenfelter still uses the stock engine control computer that originally came with the car. While the engine runs fine, that stock computer is very limited – and somewhat difficult – to work with. To make a change requires burning a custom chip. Not only would a new engine computer allow Matt to change the tune on the fly with just a laptop, it would also provide him with more information on how the engine is running.
A pair of Hooker shorty headers take care of the exhaust. Matt wrapped the headers with DEI Powersports exhaust wrap, partially to control the heat, but also because, he said, “It looks like a race car.”
Those headers feed a very unique exhaust system. Third generation Camaros like Matt’s have very little space underneath for a dual exhaust system. On Matt’s IROC, exhaust from the driver’s side header goes immediately underneath the engine and meets up with the header on the passenger side. That connects to a single 3” pipe that runs the length of the car. Matt says the single pipe set up works just fine for the amount of power the ZZ4 is currently making.
A perhaps unexpected complexity is that the oil pan has to be compatible with that unique exhaust system, while still having the appropriate baffling to keep oil around the pick up during racing. Matt went back and forth with a few different pans to find one that fit and that provided the reliability and dependability he needed on the track. A pan from Canton Racing Products, specifically made for this car and chassis, fit the bill perfectly.
A Cold-Case aluminum radiator with dual electric fans and shroud keep the small block at the right temperatures. Matt set up the fans so that one comes on at 195 degrees. The second fan comes on at 210 degrees, or when the AC is turned on. So far the system has worked well on the street, but a full road course race will provide the real test.
The V8 works through a T-56 six speed manual transmission from ‘93-’96 era LT1 Camaro. Matt says putting it in the IROC was a fairly easy swap, as the bellhousing bolts right up to a small block and there are several aftermarket crossmembers available. He freshened it up with new seals and he painted it. He controls the T-56 with an MGW racing shifter. Matt used to own a 1997 Corvette that had that same shifter and he really likes how tight it is and how close the shift gates are. That’s critical when he has to make quick upshifts and downshifts while racing.
Although the IROC had a lot of good components when Matt got it, overall the work on the car wasn’t done up to his standards. A lot of the time on the rebuild was spent on small details that are important to him.
He’s a big advocate of upgrading all the hardware and bolts on his cars. So Matt replaced all the hardware on the IROC, and made sure they were all torqued down properly. Then, after a shakedown drive, he rechecked them all again. “It’s cheap insurance,” he said, “and makes me feel better when i start to push the car.”
He also rewired everything. “I’m kind of neat freak,” he told me, “I like things nice and organized.” The way the car came from the factory, the wiring harness was on top of the brake booster. To hide it under the brake booster, Matt had to cut and extend a lot of wires. It was painstaking and slow moving work. “While I was doing it,” he said, “I was kind of kicking myself and asking myself why I keep doing this. But now that it’s done, I think it was worth the effort.”
For all his enthusiasm for autocrossing and road racing, having his IROC be street legal and enjoyable to drive was Matt’s main goal in this build. It’s been a challenge for him to combine the race and street aspects, especially with Massachusetts’ strict yearly inspection for street cars. But Matt wants to be able to drive the Camaro every day.
“My dream,” he said, “is to be able to hop in the car, drive an hour or two to the race track with the windows up and the AC on, drive it all day at the race track, and then drive it home. That’s a lot to ask of a 30 year old car.”
It looks like Matt, and his IROC, are up to the task.
Matt would like to thank Pat at Procision Industries, Nick at Accurate Automotive, and Ryan and Ramey at UMI Performance for all their help along the way – and especially his Dad, who helped throughout the entire project, from taking the car apart to putting it back together again.
Photos courtesy of Matt Birnie and Ron Francis Wiring
Click here to see more photos of Matt’s IROC Camaro
You can follow Matt’s build on Instagram via @garage_engineer