01. Ceramic-coated headers are from Street & Performance.
02. Header collector with O2 and exhaust temperature units installed.
03. Ken Kleitz of Patten Cycles taking system measurements.
04. Driver-side exhaust pipe.
05. Exhaust hanger at transmission crossmember.
In our project series thus far, we've covered project planning, chassis, suspension, drivetrain, braking, and installing C5 seats in a midyear. In this installment, we'll address three aspects that will consume quite a bit of your time. These are the various engine-related systems, such as engine electronics, exhaust, fuel, and cooling. In this installment, we'll cover the first three of these and address the cooling system in a future article. Over the course of this project series, we'll cover each one in enough detail to give you a good idea of what's involved and the sources we used. Since each project is unique, and you'll have your own ideas on the approach to take and components to use, we'll just describe the approach we've taken, and what has worked for us.
Exhaust System-Key Design FactorsThe key factors to consider in the design of your exhaust system are clearance, performance, and routing.
Clearance: Adequate space for clearing the body and other components and allowing enough room for the heat generated are key aspects to consider in your design and choice of components. In some instances, it may be possible to use stock exhaust components; however, in many cases you'll be faced with having your exhaust pipes custom bent or, at least, modifying some of the system. For our project, we decided to build a complete system in stainless with custom headers, exhaust pipes, mufflers, hangers, and exhaust tips. We'll describe the design and show the system's design a little later.
PerformanceHeaders: Depending on your objectives, and whether you want to achieve maximum engine output, you may decide to use headers in either the short- or long-tube design versus stock manifolds. The size of the primary tubes is also a factor and should be matched to your particular engine. There are many sources today for LS headers, such as Street & Performance, Sanderson, Stainless Works, and so on that should have headers which will fit most of the custom Vette-Rod chassis. Quite often stock manifolds will also fit and can have the advantage of being quieter. For our project, we worked with Street & Performance to develop headers to match the unique exhaust port shape of the LS7, have the right sized primaries, and clear the engine and framerails. We also chose to use Stage 8 header and collector bolts that have a lock to keep them tight (Photo 01).
Coating: Ceramic-coated headers are a good choice as they retain their appearance, as well as keep the underhood temperature down. Typically, the claims for heat reduction are in the range of 60 percent on the header surface as well as increased exhaust scavenging. Many companies coat both the outside and the inside of the header.
Exhaust & Tailpipes Material: We like to use 304 stainless for our systems as it lasts forever, retains its appearance, and can be polished if you want to take things that far. We also use stainless collectors for the headers and weld the exhaust pipe directly to them. Photo 02 shows the collector thathouses the O2 sensor. The second bung you'll see is for the probe to measure exhaust temperature for a gauge mounted in the dash.
06. Exhaust hanger at differential carrier.
07. Exhaust hanger at rear chassis crossmember.
08. "V Band" exhaust clamp.
09. Installed mufflers from Random Technology.
10. Rear exhaust exit and Corsa tips.
Pipe Bending: We prefer to have the bends made by a mandrel bender because it retains the same diameter throughout. Places that have this equipment can be hard to find in some areas. We were lucky enough to find one company in our area (Patten Cycles in Manchester, Connecticut) that had the equipment and would work with us on the design. Photo 03 shows Ken Kleitz of Patten Cycles taking measurements to be used in the CAD design for routing the pipes. Another method often used would be to buy a kit with premandrel bent sections of pipe that can be cut and welded into the design you need.
Size: Most systems are made in either 21/2-inch or 3-inch diameter. The size you use depends on your performance goal, but also which will fit best. For our project, we went with 21/2-inch diameter pipes. Photo 04 shows the driver-side exhaust pipe.
Hangers: If you are using a converted stock chassis it may be possible to use stock-style hangers at their original locations. In many instances, however, with a custom chassis you may need to identify the best locations and make custom hangers. For our project, we designed custom hangers at three locations and had them machined from billet aluminum. The first hanger is mounted just behind the transmission crossmember, the second is mounted under the differential, and the third mounts to the rear chassis crossmember using the original captured nuts for the spare tire well. Rubber insulators were used to give some room for movement and to insulate against vibration. Photo 05 shows the hanger at the transmission crossmember mounted to the frame. Photo 06 is the hanger under the differential and also shows the Split Personality emblem made by Austin Barnett. Photo 07 is the hanger at the rear chassis crossmember. The pipes are held in place by a connecting-rod-style mount for the first two hangers. On the third hanger, a machined holder holds the pipes from the underside. You can also see the much modified Corsa Pro-style tips in Photo 07.
Clamps: For a custom system, there are several choices in addition to the old guillotine-style clamp. One popular choice is the stainless band clamp that conforms to the mating pipes without crushing them. For this project, we found a unique clamp from Verocious Motorsports called a "V Band" clamp. It's made in 304 stainless and has two machined sealing flanges as part of the kit. The flanges are welded to each pipe, and we chose to weld them from the inside. The clamp itself fits over the male and female flanges, drawing them together. The part number for the 21/2-inch clamps we used is VBKS 250. Photo 08 shows the clamp in place.
Mufflers: There are many choices of mufflers in various lengths, widths, and shapes to fit most projects. For our project, we wanted a custom length and diameter muffler to fit under the rear of the car and work with the exit location we had chosen. Random Technology manufactured the mufflers to our design needs and did a super job. Photo 09 shows the mufflers installed.
11. CAD drawing of exhaust system from Patten Cycles.
12. Unpolished versus polished rear pipes.
13. Polishing exhaust and making a mess of the workshop.
14. Full exhaust system view.
15. Gas tank vent and overflow hoses.
16. Fuel pressure sending unit.
17. Main fuel line along rear of frame.
RoutingChoices: The first choice you will make is whether you want an undercar or side-exhaust system. The latter avoids much of the clearance issues and can be simpler to connect to the exhaust header or manifold. If going under the car, you'll have to find the straightest route that will clear the major components and allow for enough space to avoid exhaust heat in the transmission tunnel, under the floor, and the gas tank.For our project, since the '63 didn't have side exhaust as an option, we wanted to retain the undercar location. We also, however, wanted to include a C5/C6 styling element, as we had with our '62, by routing the exhaust tips through a cutout in the center of the rear valance. The valance had to be cut to the height and width needed to clear the four Corsa exhaust tips, which are shown in Photo 10.
Design: We went a little further than usual for our project by having our initial design converted into a CAD program. We worked with Ken Kleitz of Patten Cycles on the design, and they bent the system on their mandrel bender equipment. This was quite an involved process because it required taking precise measurements to attain the angles needed to mate with the collectors, clear the transmission, hit the center of the transmission crossmember openings, clear the floor and differential, and end up with the exhaust tips exiting where we wanted. Photo 11 shows the CAD drawing made by Patten Cycles, which was used as the guide for bending the pipes.
Polishing: As with everything else on this project, there were many hours spent in grinding welds, smoothing all the components, and polishing. While the smaller pieces can be done using a stationary buffer, we found the longer pipes had to be prepared by hand. After removing any marks left from the bending equipment, we began by using the Dynafile with a Trizact belt and then a random orbit sander with finer and finer grits of sandpaper. Then it was into the hand work, using strips of sandpaper from a 220 through 2,000 grit to remove any scratches and prepare for polishing. Next, we used the Porta-Cable random orbit buffer and various polishing compounds for the final finish. Photo 12 shows a comparison of the pipes before and after polishing. Photo 13 shows the polishing by hand, and the small mountain of used sandpaper and grime on the floor. Polishing the mufflers was a bit easier as they are round, and we were able to make a jig to hold them in our wood lathe. That allowed us to turn the mufflers to grind the welds and smooth the surface to prepare for polishing.
Finished System: Photo 14 shows what our finished system looks like from a rear overhead shot. Since we don't have the car ready to run yet, we don't know what it will sound like, but it should be great.
Fuel System-Key Design Factors:The key components in the fuel system are the fuel tank, fuel pump, fuel supply and return lines, fuel pressure regulating, fuel filtering, and fuel level monitoring.Fuel Tank: For the LS engine, most folks use a fuel tank with an in-tank pump. We used the stainless tank from Rock Valley. We did make a few design changes, such as having the outlet and return lines located at the top of the tank rather than at the bottom. This kept the bottom of the tank clean and also made it easier to route the supply and return lines. The tank has an in-tank LS fuel pump. Photo 15 shows a rear view of the tank, the vent, and overflow lines.Tank venting can use an original vented-style gas cap or use the vent/check valve setup supplied with the tank. Either one should work fine, but we went with the supplied check valve and used a locking nonvented gas cap. Rather than running the vent hose over the tank, we chose to run it into the filler boot that you can see in the photo. You can see the drain line from the boot, which also uses a braided hose. To retain its shape, a 5?16-inch fuel line was inserted into the braided hose and then bent to shape. It's held in place by a fitting bolted to the rear crossmember.
18. Main fuel line along framerail.
Fuel Level and Pressure Monitoring: Sending units for fuel level are available from many aftermarket suppliers. Ours came from Classic Instruments, which made our gauges, and is a straight-forward installation following their instructions. Basically, you have to cut the length of the unit to work with the depth of the tank, cut the float arm to length, and make the electrical connections for power and ground.We also like to monitor the fuel pressure, so we mounted a fuel-pressure gauge in the dash. Since you can't run a fuel line into the passenger compartment, this one uses an electric sending unit that we installed at the end of the hard fuel supply line. Photo 16 shows the location of the sending unit.
Line Routing/Fuel Filtering and Pressure Regulating: With the LS series engines, and any fuel-injected engine that we know of, you'll need both a supply and return line. Most systems we have seen have used a 3?8-inch supply line and a 5?16-inch return line. Some builders run both lines from the tank along the frame to the engine. Another popular approach, and the one we used, is to use the C5/C6-style fuel filter. This has two advantages: It has a built-in fuel pressure regulator, and it allows the use of a shorter return line to the tank if mounted toward the rear of the car. Finding a good location for the fuel filter needs to be done before routing the lines from the tank to the filter and from the filter to the main hard line running to the engine. We searched for a location that would be clear of heat sources, allow for a straightforward approach to route the lines to clear the body, and provide easy access for service. Well, achieving all three wasn't exactly as straightforward as we had hoped. While two of the three objectives were relatively easy, gaining easy access in the best location we could find wasn't as simple. We ended up locating the filter along the rear of the passenger-side inner framerail close to the tank. That made for a short distance for both the supply and return braided lines between the tank and the filter, and also provided a good route for running the supply line along the frame to the engine. Gaining easy access for servicing though wasn't as easy. We ended up making a small door in the rear compartment to get at the filter, and that solved the problem. Photo 17 shows the location of the fuel filter and the supply and return lines from the tank.
We used braided stainless lines and AN fittings for the lines between the tank and filter, and a hard stainless line for the run along the frame to the engine. Using a braided line for the supply line along the frame is not recommended as most hose manufacturers will warn against using lines over twelve feet in length. One tip that can help in bending the hard line to the shape you need is to first use a length of 3?8-inch copper tubing to make a template. Copper is easy to bend and should give you a good idea of the best route and bends you need to make. Bending stainless tubing is more difficult, but with a little practice first and a good tubing bender, it can be done well. We wanted one continuous line with no additional connectors, which made it a little more involved, but with a second pair of hands and eyes, it worked out well. We used billet aluminum clamps to mount the line along the frame and Swagelok compression fittings at the fuel filter. Photo 17 also shows the route we took for the hard line along the rear of the frame; photo 18 shows the line running along the main framerail toward the engine. From the end of the main fuel line, we used a braided stainless setup from Street & Performance, which connects to the fuel-rail fitting using a Swagelok fitting (Photo 19).
19. Main fuel line to engine fuel rail.
Engine Wiring Harness & Computer:What once seemed like a daunting task is now made relatively easy by using an aftermarket engine wiring harness along with a reprogrammed computer. These provide for all the necessary connections, as well as the reprogrammed ECU that eliminates all the unnecessary programs contained in the stock ECU program.Sources: There are many sources for the LS engine wiring harness these days. They come with the right plugs for making the connections, the ECU, and the programming needed. For this project, we used components from Speartech that did a super job on the harness. When ordering the harness, you should have a good idea of where you want to mount the ECU as that will determine the length of harness that will fit best. Some common locations for mounting are in the engine compartment, under the dash, or even in the trunk. Deciding on the placement and taking measurements of the length you will need at this point will make the installation neater and avoid unnecessary routing of any excess harness.
Components: The Speartech system comes with instructions for the connections to the engine plugs and sensors that include: fuel injectors, coils, knock, cam, crank position, oxygen, MAF, MAP, and coolant sensors. They can also provide a "fly-by-wire" throttle, which includes the throttle position and throttle pedal plugs, along with the computer program for that feature. Also included are the reprogrammed ECU, fuel pump relay, diagnostic port, check engine light, harness fuse block, and the lines for the vehicle speed sensor and reverse solenoid.
Installation: The first step recommended is to review the instructions provided, locate the components on the engine, and label each of the harness wires. Many of us don't like to take the time to read instructions, but these steps will make things easier. When you first open the engine harness package, it will look like a snake pit, so it's best to take the time now to become familiar with what you have to install.
The second step is to mount the ECU and find the best route for the wiring. You've already determined the location when ordering the harness, but mounting the computer at this point will help determine the best route to take. We start with the injector and coil wiring. Find the best route, keeping in mind the clearance of rotating parts and avoiding heat sources. It's also a good idea to use some type of holder for the wires, which will make the installation neater and keep things in place. We used stainless strap holders from Street & Performance, which can make them in any size you need. For the best fit you may find that some wiring may need to be shortened. We un-wrapped the harness in those locations, reinstalled the convoluted tubing, and re-taped things in place.
For our project, we decided to mount the ECU on the driver's side of the frame under our battery mount. This allowed a shorter harness length, easy access, and was next to the area of the firewall that we want to use for the wires, which will be routed into the passenger compartment. We made a plate and mounted the ECU to it and the plate to the chassis using neoprene isolators. Photo 20 shows how we mounted the ECU. Photo 21 shows the two connections at the transmission for the reverse lockout and the vehicle speed sensor. Photo 22 is a view of the rear of the harness, showing the lines running to the injectors and coils. Everything in the harness plugged right into place as it should.
20. ECU mounts to chassis on driver's side.
21. Transmission connections for reverse, solenoid and vehicle speed sensor.
22. Rear view of engine harness. Upper braided hoses are for dry sump tank vent lines, and
Next Up:In future installments, we'll cover the cooling and heat/A/C systems when we address the interior and exterior features of the car. At the time this was written, we were still cranking away at a very long list of things to do, but enjoying every minute (well, most of the time) of the project and looking forward to its completion. You can check our Web site at http://www.corvetteforum.net/c5/richs7/ for more information and updates.