The fundamentals of fabrication revolve heavily around time and patience. While some have the natural knack for fab work, for others it's a skill that takes years to develop and perfect. When tackling a project as big as our Viper-powered Durango, it was important to equip ourselves not only with the right tools but the right professionals too.
Working with the crew at National Speed in Wilmington, North Carolina, we spent last month fitting the 505ci engine into our Monster Mudder and began forming the custom dog-box firewall. Now it was time for the headers. Since space in both the engine bay and firewall is limited, we pulled the 8.3L out and headed to Momentum Performance to build the headers. We relied on Momentum's fabrication experience with performance headers to build us a set that will allow all 500-plus horses to exhale freely.
In addition to the headers, we used our time at Momentum to finish up the custom firewall. With the engine now resting nearly a foot past the original firewall location we needed a few access ports built into the dog box to service the back half of the engine. Though we looked at making the unit completely removable, we were concerned about how feasible it would be to take it out of the vehicle once the dash was in. The other issue was sealing the firewall to keep out the elements. In the end we opted to weld it in place.
Be sure to check us out next month as we continue to hammer away on our Durango and move forward with the remainder of our monster Mopar powertrain.
 1. A quality set of header...  1. A quality set of header flanges will save you serious time and fabrication work. To get started, we went with a set of Belanger flanges for our 8.3L. Belanger Headers is known for its high-performance Viper headers and exhaust and has parts available for models Gen I to current. |  2. Another time saver is to...  2. Another time saver is to round up a variety of J-bent tubing. Using an assortment of tight- and wide-radius 1 3/4-inch J-bends from Maganflow, Summit Racing, and Momentum, we were able to cut and fit the headers with precision and efficiency. |  3. Momentum Performance's...  3. Momentum Performance's chief fabricator, Bobby Downes, spent a healthy number of hours fitting and creating the header tubes for the Gen III Viper engine. Blue masking tape will be a big help when test-fitting the pieces, as it will aid in keeping the tubing in place while you tack things together. |
 4. Since building the headers...  4. Since building the headers required us to remove the engine from the Durango, we created a mock firewall using TIG wire to indicate how much room is available. Though the 505ci block is not much wider than the original 5.9L, pushing the engine as far back and over as we did created incredibly tight tolerances. |  5. Using Belanger collectors,...  5. Using Belanger collectors, we sent two of the header tubes into one collector, while the other three dumped into another. The two 2 1/4-inch collectors then merged to a final 3-inch on each side of the block. |  6. The final 3-inch back exhaust...  6. The final 3-inch back exhaust fitting will have to wait until we place the engine back into the Durango; but minus an O2 bung or two, the headers are practically complete. While building header tubes to equal lengths is the best way to achieve maximum performance, clearance issues made it a tough. |
 7. To finish up our new dog-box...  7. To finish up our new dog-box firewall, we added a few access ports to both sides and one in the middle. This should allow us to more easily bolt up the headers and access the back of the engine. |  8. After spraying the freshly...  8. After spraying the freshly built firewall black, we peeled off the taped edges and began the delicate process of welding it in place. Paul Murray chose to MIG the structure in, strategically welding small sections a little at a time to prevent the sheetmetal structure from warping. |  9. The Dodge Viper is notorious...  9. The Dodge Viper is notorious for cabin heat. And since the back few cylinders are sitting next to our legs and inside of the cab, we needed a little extra heat protection. Our high-temp defense came via a 48-inch cut-to-fit sheet from Design Engineering. Built to reflect up to 1,000 degrees, the DEI Reflect-A-Cool adhesive heat shield should keep our legs from melting. |
What's Cooking?
Talk about the ultimate manifold burrito access port! With our dog-box firewall set in place, we still have a laundry list of items to cover. Be sure to check back next month to see if we found a place for our accelerator pedal and to see us start on the bulletproof drivetrain that has to handle the V-10's grunt.