[1]
Back in the day, the “Tri-Y” or 4-2-1 header design, which pairs non-adjacent cylinders together to create an enhanced scavenging effect, found its way under the hood of many a musclecar. But, you don’t see a lot of them these days; “shorty” headers are easier to build and install, and long tube 4-into-1 designs are pretty easy to get right, at least when it comes to sizing the primaries for peak power.
Pfadt has done their homework, though, and as a result their new 4-2-1 headers [2], which will be available for all the different C6 Corvette variants, from base to ZR1, can take full advantage of the strengths of this design. One of the basics of header science is that whenever exhaust flow meets a change in cross-section, like going into a collector or meeting a “step” in tube size, it reflects positive and negative pressure waves back to the exhaust port at the speed of sound. By adjusting the length of the tube, and therefore the timing of that pulse, headers can actually be tuned to create a scavenging effect that helps pull more fresh intake charge into the cylinder.
[3]
With long-tube headers, this scavenging effect is most prominent at a single point in the RPM range, because there’s only one transition to work with. Tri-Y headers, on the other hand, can be tuned to broaden both the mid-range and top end of the curve, and that’s just what Pfadt has done with this new design.
[4]Features:
- TRI-Y Design, 4-2-1 tube merging
- Makes much more torque under the curve, while still increasing top end HP
- 1.75/2″ tube diameter
- CNC flanges with OEM locating features
- Fully hand-TIG welded on-site
- T-304 16 Gauge Stainless Steel
- Fully Brushed Stainless Steel Finish
- V-Band Clamp connections
- Equal length long tubes
- 1-piece X-Pipe available w/ and w/o Cats
- Full 3″ collector and X-pipe
- Comes with bullet-nosed flange bolts for installation
- Available with 2 or 4 O2 Sensor extenders
- Available with Cometic Multi-Layer Steel gasket upgrades
- Exhaust system with Cats is 24lbs lighter than factory
- Exhaust system without Cats is 27lbs lighter than factory.
- Made in Salt Lake City, Utah
For more information, and to see Pfadt’s 5-part series on the development of these headers, and their accompanying crossover mid pipes, visit their website at pfadtracing.com [2]