In the post muscle car era, cars have to be more than just fast: they have to be street legal. Back when the muscle car was born, the name of the game was run, run, run, and hope you run enough. The door was wide open for manufacturers to do just about anything they wanted to make a car go faster. But in the early 70s, high performance gave way to the need for lower exhaust emissions. Getting these mega powered engines to meet federal emissions standards was difficult and expensive. So most auto makers just stopped making fast cars. Even after market hot rod parts had to be certified emissions friendly. This was the new reality and it brought with it the end of America’s first muscle car era.
Street Legal Performance
That’s the way thing were for nearly 20 years until a company called SLP engineering re-invented the process of making horsepower. SLP stands for Street Legal Performance. And putting muscle back into GM’s cars was their objective. But in this new high tech world, this required a high tech solution. Fortunately for muscle car fans, SLP is all about high tech solutions. Keith Maney remarks: “There are always people who want more. That’s pretty much the American way and SLP stepped up, just like the early guys did. SLP is the new tradition of after market performance.” SLP engineering launched into the high performance arena in the mid 80s with a new design induction and exhaust system for the GM 305 cubic inch small block engine.
Made especially for the Firebird and Camaro, these street legal bolt on parts increased the 305′s horsepower and torque by over 10%. This was the first ray of high performance sunshine for F body owners since the glory days of the early 70s. Most importantly, SLP’s close relationship with GM took much of the guess work out of building a faster Firebird. SLP parts were available through GM’s service departments. They could be dealer installed and the cost of the modifications could be financed in with the cost of the car purchase. In this new high tech world, this was the way to go hot roddin’.
“One of the scary things about fuel injection and computer control is that the average enthusiast thought they couldn’t modify them at all,” Says Keith Maney, “The engines respond to the same things that the early engines do, you just have to go about in a slightly different way. SLP showed everyone it could be done.” SLP evolved into a super car builder, making turn key hot rods for people who wanted that old muscle car punch to go along with the looks and the handling of modern cars. In their contemporary high tech manufacturing facilities, Camaros became SLP Camaro Super Sports and Firebirds became SLP Firehawks, in a process that upgrades every part of the car. Says Reg Harris, marketing director of SLP Engineering, “What we were trying to do is provide high performance, reliability, unique styling, performance and handling that the average enthusiast could afford.” Along with the drive train and suspension enhancements, aerodyamic body parts and free flowing and exhaust completed the SLP treatment, turning GM’s hot F body cars into thrill machines that actually out performed the legendary 60s muscle cars.
In addition to the Camaro SS and the Firehawk, SLP created the special versions of the Pontiac Gran Prix, a V6 powered Camaro RS and two sports trucks based on the GMC Express and the Chevy Seeker. To those who said you couldn’t get performance out of emissions legal engines, the cars from SLP were a revelation. And for those who never experienced a real 60s ground pounder, the new millennium muscle car cars provided a chance to have the kind of horsepower under their foot they’d only heard about in bench racing sessions. All of this happened because a group of people, led by an old hot rodder named Ed Hamburger, believed the muscle car era wasn’t dead. “Ed’s got a long tradition in motor sports. He was a racer back in the 60s, 70s and in the late 80s they had some ideas about what to do to provide more performance and better fuel economy and lower emissions,” says Reg Harris, “In 1987 he formed SLP Engineering and the whole goal behind SLP Engineering was to provide emissions legal products that added performance and also had the level of durability that the Oldie would respect.”
Breathing New Life Into the Power Plant
The third generation Camaro and Firebird were long awaited technological breakthrough cars. After several years of engines strangled by emissions controls, the new technology of computer controlled two port fuel injection was breathing new life into these power plants. Keith Maney explains: “It really turned the corner when they started using electronic fuel injection. In 1985, GM introduced the tune port induction engine. That was a really big step forward as far as performance is concerned. They finally learned how to balance a performance with emissions. As a side benefit, driveabilty was improved, cold starting was improved. Electronic fuel injection and computer controls have transformed the internal combustion engine.”
TPI engines were tuned for maximum torque and horsepower at lower RPMs. This made for fun launches and good stoplight to stoplight performance but they ran out of breath at about 4500 RPM. A super car needed an engine that would pull hard. This is where the SLP engineers started work. Keith Maney goes on: “So SLP came out with new runners, came out with exhaust systems, cam shaft design, things like that that really made the TPI engine a lot happier throughout the rev range.” Not all of the 305′s performance improvements came from the good old days, though. A major part of SLP’s tweaking was pure 21st century computer magic. SLP was one of the first companies to analyze their modifications for maximum engine performance in every gear. These new parts, along with a free flowing three inch exhaust system, and a new cold air intake system, which improved air flow to the engine as much as 30% immediately upped the 305s output by 50 horsepower. Best of all, where the stock TPI motors fell off at 4500, SLP modified engines pulled strongly all the way to the red line.
SLP performance packages were available as dealer installed options on new Firebirds or over the counter from GM service parts system. Says Scott Settlemire : “When you can get a relationship with someone like an SLP and you can utilize their engineers and then have our engineers verify the data and share with them that we know about the car, that’s when you get some really incredible things done.” With GM’s stamp of approval, SLP’s cars were politically correct in every sense of the word. They worked with and not against the car’s pollution control equipment. They made GM’s two port engines more efficient and efficiency means more power. And SLP’s equipment didn’t even void the cars warranty.
Reg Harris goes on: “For many years in the after market, parts were stamped for off highway use only and that was kind of a wink wink. Person bought the parts and you knew what he was doing but if the parts broke or if they caused, more importantly, some other parts in the drive line in front of it or behind it to break, you were on your own and Ed Hamburger our owner and founder, to his credit, as a business strategy said ‘Our parts are going to be street legal and they’re going to be emissions compliant. And they’re going to provide better performance.”
Back to High Performance Fun and Games
SLP had the new smog legal engines scienced out and was now among the forefront of speed equipment manufacturers. But by the early 90s, America’s auto makers were back to their old high performance fun and games. Detroit technology had caught up with the rest of the world and the new fun machines from GM were starting to have that old muscle car feel. Even the #1 litmus test for muscle cars, straight line acceleration was coming back. muscle car fans from the good old days and a whole new crop of high tech road warriors were taking American iron back to the streets again. For SLP’s engineers, these new cars were a great place to start making their kind of horsepower. But once again, SLP had a bigger vision. They wanted to build a car that would offer all world performance at a reasonable cost.
The ZR1 Corvette had been Detroit’s cutting edge car since it first rolled out in 1990. Its double overhead cam, four valve per cylinder aluminum block 350 was the be all and end all in American performance. This engine cranked out 375 horsepower in street trim. And the ‘Vette’s handling was race ready. Duplicating the performance of the ZR1 in an automobile costing half of much would be a nice trick if they could pull it off. But SLP’s high tech hot rodders were up to the task. As a base line for their modifications, they chose the 1992 Firebird. This car already offered blurred vision handling and Bonsai straight line acceleration. But when it rolled out as the new SLP Firehawk, it was a steel bodied Corvette.
Keith Maney describes: “Those cars were very special for showroom stock racing. They had highly modified L98 TPI engines that made 350 HX. You could get competition brakes, roll bars, new back seat, a ton of chassis modifications. That was really the most hard edged F body you’ve ever been able to buy. It was reflected in the price, of course. But if you look back in the history of F body performance, the ’92 Firehawk has to be at the top.” To create the Firehawk, the Firebird’s factory drive train was removed and in its place went a special high strain four bolt main 5.7 liter block, a forged crank, the high “pink” rods, and LT-1 pistons and a custom ground SLP roller cam. On top of the short block, SLP added a set of ported cylinder heads with 2″ intake and 1.56″ exhaust valves. A special T-ram port injection intake manifold with tuned intake runners and a larger throttle body fed the charge into the cylinders and a set of stainless steel headers fed the SLP exhaust system. This engine made 350 horsepower at 5500 RPM and 390 foot pounds of torque at 4400. And what pulled strongly all the way to the 6000 RPM red line. Getting all this new power to the ground required another upgrade. The ZF six speed gear box from the Corvette, a rear end with 354 gears, and wheels with P 275 40 ZR17 rubber made sure this car would hook up on a launch and stick in the turns.
All this performance came with a hefty price tag, though. Nearly $40,000. The former Firebird’s base price was around $19,000 and the Firehawk conversion ran it up another $20,000, pricing it out of the range of most Firebird buyers. This first Firehawk was exactly what SLP had promised: a car that offered Corvette style performance costing thousands of dollars left. But even though the ’92 Firehawk was a technological breakthrough and an awesome first effort, unfortunately the marketplace wasn’t ready for a $40,000 formula Firebird no matter how quick it was. As a result, only 25 ’92 Firehawks were ever built. But SLP’s original concept of all world muscle at showroom prices was still a good one. They just needed a little help from GM. That help came in the form of the 1993 Firebird. The fourth generation F bodies were beautifully styled and more importantly, Pontiac now offered the car with a LT1 engine and a six speed transmission. This meant SLP didn’t have to replace the entire drive train. So the cost to convert a Firebird into a Firehawk headed south in a hurry. This was the big bang for the buck SLP had been looking for.
SLP had graduated from making a conversion package for the Firebird to, in essence, making a street legal race car in just a few years. But their original vision of making a car that outperformed the 60s muscle cars in every way without costing an arm and a leg was still out there. But finally, the prize was in sight, thanks to the fourth generation Firebirds and Camaros. Reg Harris details: “The ’93 with all new body style, GM had raised the bar to 275 horsepower in a base V8 Firebird. So by adding a ram air package to it, we got it up to the magic number: 300 horsepower.” Building around the 275 horsepower LT1 and a six speed transmission, SLP replaced the stock formula hood with a new unit made of composite material featuring a cold air induction system which upped the horsepower to 300. 17″ wheels and ZR-rated rubber were part of the standard package as was a new rear spoiler, the Firehawk graphic treatment, and megaphone-style tail pipes. This basic Firehawk conversion added a much more reasonable $5995 to the Firebird’s base price.
Having learned a lesson with their first cars, SLP now created a new way of buying the Firehawk. Instead of offering a once price hot rod with all the bells and whistles like in 1992, now you could order from an a la carte menu of performance options according to your go fast desires and your budget. Going down the menu, a performance exhaust system was available for $995, which was good for an additional 15 horsepower. And to go with your upgraded tires and wheels, you could order the full on suspension package for another 1495. 201 Firehawks sold in 1993, 500 were sold in 1994, and 671 hit the streets in 1995, including 102 Convertibles. Performance from this new Firehawk was right in line with the muscle cars of the 60s: 13 second quarter miles and a top speed of almost 150 mph meant Firehawk owners didn’t have to back down from anything on the street, no matter how big and bad or nostalgic it was. Finally, the SLP mission had been fulfilled, They had created a car with Bonsai acceleration that went around corners with the best of the world’s sports cars for a few bucks more than a showroom Firebird and it was street legal in all 50 states.
Now that their vision had been achieved, the SLP team set about widening their lineup. In mid 1995, SLP created the Copta, a special car based on the Trans Am made to commemorate the 25th anniversary of the BF Goodrich TA radial tire. After their success with Pontiac, in 1996, SLP introduced the Super Sport Camaro with its retro hood scoop and hugger orange paint scheme, it was a throw back to the legendary SS 396 cars of the 60s with enough punch to make you think there was a good ol’ big block rat motor under the hood.
Scott Settlemire explains: “Because of SLP we were able to take their engineering expertise, take a Z28 and bump the horsepower on that LT1 engine to come out with this great car in 1996 called the Camaro SS which took us right back to the first generation muscle car, the muscle cars of the past.”
By now, the trust level between GM and SLP was so well established that SLP was given a task of building Pontiac’s 1996 and 1997 ram air Trans Ams. This is big time stuff for a company that started out tuning up GM’s F bodies! But when you’re good, you’re good. And on the horizon were even more super cars made for a more diverse audience. After the Firehawk’s success, SLP set their sights on the Sports Sedan and the Sports Truck markets with the Gran Prix GPX and the Seeker and Express Ford trucks. But, by far, the big news was the massive popularity of the Super Sport Camaro. There was a risk in resurrecting one of the most beloved names in muscle car history. SLP knew that anything named Super Sport would have a lot to live up to. Their version of the SS Camaro met this challenge head on. Explains Scott Settlemire : “The SS has always been the ultimate in terms of horsepower. One of the beauties of the Camaro SS is, let’s face it, it is performance American style. What do I mean by that? I mean it has a muscular V8 engine, it has rear wheel drive, solid axle, it’s what we always knew as the American performance muscle car. In recent years, we’ve built the fastest Camaros and most powerful Camaros we’ve ever built and you can run the air conditioner while you’re doing it!”
The V6 Revolution
For 2001, a V6 revolution went on. With a new version of an old favorite, the Rally Sport Camaro. All the go fast tricks learned from the Super Sport were folded into this car, along with some special tuning to create a V6 powered street machine that beat V8 cars’ insurance premiums by a mile. Modern Firehawks and SS Camaros were created in SLP’s new facilities located 20 minutes away from GM’s F body assembly lines. Under one roof, SLP’s 250 car builders handled the complete transformation from great car to super car. Stock rear axles were changed to high strength Auburn units. Shocks, springs, and sleigh bars were upgraded and bigger brakes were installed. SLP’s own design fiberglass hood with its more efficient horsepower making air box and heat extractors were manufactured on site and taken straight from finishing to installation. This step ensured the highest quality control for these parts. 17 by 9 wheels and Firestone 275 40/17 ZR tires were mated perfectly to the car’s needs and capabilities. And each car got it’s own special cosmetic treatment as a warning that this car packed a little more heat than ordinary Camaros and Firebirds. This heat came from the modern version of America’s favorite engine: the 350 cubic inch LS1 small block.
Keith Maney says: “The LS1 V8 debuted in the F car in 1998 and a lot of people questioned the wisdom of putting a push rod two valve engine in a modern car. I’ll tell you what, those cars really knew what they were doing, you don’t get the flat broad torque curve with the V8 with an overhead cam engine. It may be traditional architecture but it was a state of the art power plant.”
The 327 horsepower LS1 engine provided low 13 second quarter mile times and the car corners like a slot car. The bark from the cat back exhaust system was guaranteed 60s cool. The SLP graphics were genuine traffic stoppers. Firehawks and SS Camaros were extreme low production automobiles and they generated enough excitement from collectors to make them overnight classics. But these were cars that were meant to be driven and driven hard. And that’s how a car gets to be a classic. SLP has done all this their way using the highest tech methods to achieve the same old result: kick in the pants performance in a car that’s drop dead gorgeous for a price everyone can afford. Hey, isn’t that the same way the muscle car thing started?
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