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New C4 Exhaust System - More Bark With Your Bite, Part 1New C4 Exhaust System Adds Power And PRRRRR From the September, 2008 issue of Corvette Fever By Dick Moritz Photography by Dick Moritz
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Here's our header system from... Here's our header system from Stainless Works, complete with A.I.R. plumbing, an EGR port, and a bung for the O2 sensor, along with nifty band-type clamps that are attractive, effective, and don't crimp the pipes being clamped, making any future disassembly a hassle-free experience. You know how some things you do on your Corvette are quick and easy? Like bolting on a performance air cleaner, adding graphics decals, or laying in a set of custom floor mats? These are things that take little time and, usually, not a lot of bucks, plus add an air of distinction and maybe a modest boost to performance or handling. Well, this story is about installing a complete performance exhaust system on an '87, and frankly, it is none of the above. It's not quick, it's not easy, and it's not inexpensive. In fact, it's a real pain in the butt to do. But if you've got the budget, a little creativity, and lots of patience, it's well worth the trouble. Removal of the rear half of... Removal of the rear half of the original exhaust system is as simple as removing three bolts at the flange of the catalytic converter and two hangers at the rear of the mufflers. It all comes down in one piece, which we'll keep for the lucky guy who will end up restoring this car twenty or thirty years from now. Before removing the cat converter, we marked the underside of the car at the rear edge of the catalytic converter flange. This would allow us to be sure the new system was in the proper fore-and-aft position to ensure proper alignment and positioning. Here's the deal: we sought out the best combination of exhaust system parts we could find-street performance headers from Stainless Works with their beautiful thermal coat finish and a high-performance catalytic converter from the folks at Random Technologies, who know a lot more about performance tuning than we ever suspected. For the cat-back pieces, we asked for advice from the tech people at Mid America Motorworks, who recommended a Corsa muffler package that they felt gives the best blend of sound and substance for our somewhat-modified C4. Removing the factory exhaust system was straightforward, even though it was twenty years old. The real challenge was fitting the headers in amongst all the parts that attach to, or pass near, or are in the way of them. And we don't fault the header design for that. Stainless Works has done a masterful job of designing equal-length headers to fit in a space where most folks would say headers would never fit. And they've constructed them to accept all the factory emissions system pieces in order to keep the Feds happy. There are an awful lot of heat shields, brackets, and other parts in the vicinity of the headers, and they all must be dealt with in a limited working area. We did the job on a lift, and it's fair to say that this job would be virtually impossible without one. By our estimate, with no exaggeration, we probably raised and lowered the lift at least fifty times in the course of doing this job, finding things in the way, moving or modifying them as we went, until we were able to get the headers bolted into place. Once the headers were mated up to the cylinder heads, the rest of the job was pretty straightforward. The air feed tube to the catalytic... The air feed tube to the catalytic converter is a multipiece affair. We used a cut-off wheel to surgically remove the clamp, being careful not to nick the tubing since we knew we'd be re-using it with the new system. Along the way, we had to fabricate a couple of brackets, bend a few tubes (not the header tubes, obviously), add a couple of spacers, and trim a number of heat shields to make everything fit. We even had to fabricate a special tool to tighten two of the spark plugs that were inaccessible once the headers were bolted up. in the interest of appearance, since our Project '87 is a Show 'n Go car, before we started the installation we sent the cat-back pipes to the artists at Classic Coatings, whose chrome-like finish was nothing short of breathtaking. OK, so the job was a huge hassle. Was it worth the time, trouble, and expense? We think so. The finished job is just gorgeous, rattle-free, and provides an exhaust tone that's just perfect-a pleasant burble at idle, a proper growl when you're hard on it, and virtually as quiet as the factory system during cruise. We don't know how they were able to make the system work this way, but we're sure glad they did. Since C4s span many model years, there's no way to show every step for every year. But we will share with you the highlights and lowlights of the installation on our '87, cautioning, as they say, "Your results may vary." Because getting the headers up into place was, by far, the most time-consuming part of this job, we've divided the story into two parts. This first installment will cover removal of the stock exhaust and installing the left-side header; next time we'll cover the more involved task of installing the right-side header and the remainder of the new system.  Here's the complete original...  Here's the complete original exhaust system in surprisingly good condition considering it's twenty years old. the car has always been garaged and has just 35,000 miles on it (some a quarter-mile at a time, of course), which has helped preserve this system that could be re-used if desired.  This clamp secures the metal...  This clamp secures the metal A.I.R. tube to the front pipe to prevent noise, vibration, and possible metal fatigue.  This bracket is essential...  This bracket is essential for supporting the alternator. Word on the street is that leaving it off will result in a broken mounting ear on the front of the alternator. As you'll see later, we had to fabricate a new bracket since the original would not clear the header tube. The left-side exhaust manifold... The left-side exhaust manifold lifted out easily without the need to remove the alternator, just the bracket mentioned previously. We were even able to leave the spark plug wires installed while removing the left-side manifold, but we did have to remove them and the spark plugs, on both sides of the engine, in order to position the new headers. | DIFFICULTY INDEX ::: IIII | | ANYONE'S PROJECT | no tools required | I | | BEGINNER | basic tools | II | | EXPERIENCED | special tools | III | | ACCOMPLISHED | special tools and outside help | IIII | | PROFESSIONALS ONLY | send this work out | IIIII | The high-performance catalytic... The high-performance catalytic converter from Random Technologies is more than just another replacement converter. In our discussions with the folks at Random, we were impressed with the depth of their knowledge in overall engine management and how it must be carefully integrated with various performance parts so everything works in harmony. Parts ListStainless WorksC48591 '85-'91 Corvette headers plus Y-pipe/ThermalcoatNBC250 (4) accuseal high torque band clampEBC250 (2) accuseal wide high torque band clampRandom Technology191-30001 high-performance catalytic converter w/accy'sMid America Motorworks628-096 Corsa exhaust system cat-back603-930 catalytic converter hose kit614-559 (2) muffler insulatorsLocal speed shopARP header bolt kitHeader gasket setLocal Chevy dealerDipstick tube Tools Of The TradeIn addition to everyday hand tools, such as screwdrivers, wrenches, and sockets, you'll also need:5/16-inch, 12-point, 1/4-inch drive socket for header bolts1/4-inch open end or box wrench for hose clamps for A.I.R. hoseTorx T-20 socketCut-off wheelImprovised spark plug wrench  Since our headers and mufflers...  Since our headers and mufflers are so pretty, we decided to send the extension and "Y" pipes to Classic Coatings for their chrome-like ceramic coating. The finish was spectacular and will inspire us to place mirrors under the car at shows to display the gorgeous finish on the entire exhaust system. We did notice some small balls of material in some of the inner nooks and crannies of the pipes, which seem to be leftover from the plating process. While they appeared harmless, we did take the time to remove them using a dentist's pick.  Since our '87 is equipped...  Since our '87 is equipped with aluminum cylinder heads, we cleaned off the old gasket material by pulling rather than pushing on a razor blade in order to prevent gouging the metal. The gasket surface needs to be perfectly clean to prevent leaks. We cleaned the last of the gasket material off with an abrasive pad, but we left the spark plugs in and also plugged the exhaust ports in order to keep abrasive particles out of the engine.  In anticipation of a snug...  In anticipation of a snug fit and to ensure the entire job was done with quality parts, we picked up a set of ARP header bolts from our local speed shop.  The flange on the Random Technologies...  The flange on the Random Technologies cat converter has extra bolt holes to allow it to fit multiple applications. It also includes ports on both sides for connection of the A.I.R. tube on different applications. this is no "will-fit" universal part-it's designed for alternative mountings and was a simple and direct bolt-in.  Here's the Corsa cat-back...  Here's the Corsa cat-back system that was recommended by Mid America Motorworks. It's made to mount to the factory hangers, making installation a snap after the headers are in place.  Installing the left-side header...  Installing the left-side header wasn't too difficult. There was adequate room to lift it up into place from below. We tried dropping it down from above, but there was simply not enough room to snake it into place.  The new headers didn't come...  The new headers didn't come with gaskets, so we bought a set locally. Note that the bolt holes on the front and back of the gasket are not full circles, but rather are slotted. This allows us to install the header with the end bolts first to hold it in place, and then slide the gasket down into position before installing the remaining bolts.  Here you can see how easily...  Here you can see how easily the new gasket slides into place with the two end bolts holding the header in place. This is far easier than struggling with trying to start the bolts while juggling the header and the gasket at the same time.  As it turns out, all four...  As it turns out, all four of these brackets (two on each side) interfered with the header flange.  Fortunately, we didn't have...  Fortunately, we didn't have to cut any material off these brackets. we only needed to bend each tang 90 degrees to prevent interference with the header flange.  The original alternator rear...  The original alternator rear support bracket bolted to the rear bolt of the front tube on the driver-side exhaust manifold. The new header tube does not leave clearance for the stock bracket, so we decided to make a new bracket and mount it to the next bolt back.  We used the original long...  We used the original long shouldered stud and made a "stand-off" tube to move the hex head out where we'd be able to attach a bracket without contacting the header tube.  Even with the stand-off tube,...  Even with the stand-off tube, the fit was so snug that we had to grind off the integral washer until it was even with the hex.  As long as we were changing...  As long as we were changing out the whole exhaust system, we chose to install a new Bosch oxygen sensor. While these sensors are usually thought of as being expensive, ours was only $21!  It's no surprise that twenty-year-old...  It's no surprise that twenty-year-old plastic that's been heat-cycled a zillion times is brittle. The lock tab broke off this O2 sensor wire connector when we disassembled it, so we used a plastic tie to hold the connection together to prevent future problems.  You can see that the hose...  You can see that the hose from the oil filter is just too close to the header tube on the driver side. We ended up using several 90-degree adapters and hose clamps to position the hose away from the header tube until we decide on a more professional-looking solution.  In the course of our work,...  In the course of our work, we found the speedometer sensor at the rear of the transmission was leaking. With the exhaust system removed, this was the logical time to repair this simple problem.  Just one bolt holds the clamp...  Just one bolt holds the clamp on the speedo sensor. With the clamp out of the way, the sensor pulls right out.  The fix was as simple as replacing...  The fix was as simple as replacing the O-ring on the sensor. Three cautions here: lube the new O-ring so it slides into the transmission more easily; be careful not to nick the O-ring; and be careful when removing the unit so the speedometer gear does not fall off inside the transmission.  We found we had to bend this...  We found we had to bend this lower heat shield on the passenger side in order to keep it from vibrating against the header.  This is the functional, but...  This is the functional, but not very pretty, temporary solution to the interference problem with the hose on the driver side that carries coolant from the engine block to the oil cooler, which is part of the oil filter adapter. A more sanitary solution is in the works.
 | Our Project '87 Gets A New Set Of Vocal Cords |
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