Chrome Coating:
Protects the header surfaces from initial rust or corrosion, but not for extended life. It is not intended to be "show chrome," as it will discolor upon initial fire-ups, and this is normal. Chrome headers are still guaranteed against manufacturer's defects and workmanship.
Ceramic Coating:
Doug Thorley ceramic-thermal coating protects the header against the elements and can take temperatures as much as 1,400-degrees Fahrenheit. This coating keeps heat inside the tubing, thus promoting velocity while absorbing up to 40 percent of the engine's temperatures. This keeps the engine running cooler and helps in all areas where heat is the issue. A ceramic coating of 3 mm is applied inside the header tubes.
Tri-Y Headers Theory:
The Tri-Y header gets its name from having three total collectors, instead of just one. In this design, the primary tubes are welded to the flange, then two of the primary tubes go into a collector, and the other primary tubes go into another collector. From these two collectors, a single tube emerges from each collector, then these secondary tubes go into the end or final collector. Each Tri-Y header is designed to match the synchronization of the engine's firing order, thereby maximizing exhaust scavenging. This design creates the best torque and horsepower gains.
After the prototype headers were made, a CAD program was created, which allowed all of the pieces to be automatically cut and bent. | 
Pieces were randomly checked for proper angle and joint fitment. Here, we see the final collector being fitted to the two single tubes that are extruded from the two primary collectors. |
Each of the tubes making up the header were locked into the fixture. | 
After the header pieces were locked into the fixture, they were welded 360 degrees. |
To check for leaks, the header flange was C-clamped into place on a neoprene sealing board, then submerged under water. The header was then pressurized to 110 psi. | 
The header was examined for air bubbles detecting leak. |
After passing the leak test, the headers were sent to be polished, then nickel-plated. | 
The highly polished nickel-plated Doug Thorley Tri-Y headers perform as good as they look. |
What makes Doug Thorley Tri-Y headers unique is the three-in-one collector design. The four flanged primary tubes that retrieve the exhausted gasses from the engine's cylinder head exhaust ports are paired off and merge into two separate primary collectors. A single tube emerges from each of the two separate primary collectors, which merge into the third collector. The four primary header tubes conform and flow into the three collectors, which forms the Tri-Y header design. | 
Doug Thorley Tri-Y headers are legal in all 50 states. The EO, or carb number certification tag, is welded onto each header. |
The thermo-seal gasket was dropped into place, then the header bolts were secured. | 
The Doug Thorley Tri-Y headers now exhaust gasses from the cylinder ports, thereby increasing horsepower and torque. |
From the Driver Seat:
The exposure to Doug Thorley Headers Tri-Y design, manufacturing procedure, and testing was very informative. Since '67 Nightmare was not finished, we were not able to perform any dyno pulls. But, we did get some numbers that were presented to us: 30 horsepower at 35 lb-ft of torque.
Doug Thorley LS1 5.7L V-8 for a '67 Chevy C10 pickup.
Parts Used:
| PARTS USED: |
| Doug Thorley Tri-Y Ceramic, PN 324Y-C | $580.00 |