The factory 7.3 Powerstroke exhaust manifolds are now discontinued from Ford, making good OEM replacements increasingly difficult to find. New old stock still surfaces occasionally, but the original Ford left- and right-side manifolds, F81Z-9431-AA and F81Z-9430-AA, are no longer being produced.

Plus the years of abuse have taken their toll. Original 7.3 manifolds have now seen decades of heat cycles, towing loads, corrosion, and exhaust pressure. Warped sealing surfaces, cracked castings, broken bolts, and leaks at the manifold or up-pipe connection can cause exhaust ticking, soot buildup, slower turbo response, and lost drive pressure. Luckily, there's a fix, and it's so much better than just going with a set of OE manifolds. 

KC Turbos' Upgraded Exhaust Manifolds give 7.3 owners a new replacement instead of hunting for used or discontinued OEM castings. Separate kits cover 1994-1997 OBS and 1999-2003 Super Duty trucks.

What KC changed

These are not reproduction stock manifolds. KC redesigned the areas most likely to give trouble on an aging 7.3, plus, they added a few welcome improvements on the performance side (because why build something if you can't improve every part of it!):

• Thicker High SiMo castings
• Increased flange thickness
• Larger sealing surfaces
• Port-matched runner entries
• Enlarged and optimized internal passages
• Improved exhaust-flow geometry
• Redesigned up-pipe mounting surfaces
• Integrated EGT probe port
• Retains the factory EBP tube port
• Stainless steel manifold gaskets included
• OEM-style interference-thread manifold bolts included

Which kit do you need?

1994-1997 OBS 7.3L

KC Turbo 302873 is designed specifically for OBS F-Series trucks.

https://www.riffraffdiesel.com/kc-turbo-upgraded-exhaust-manifolds-set-94-97-7-3l/

1999-2003 Super Duty 7.3L

KC Turbo 302874 fits Early 1999 and Late 1999-2003 F-Series applications.

https://www.riffraffdiesel.com/kc-turbo-upgraded-exhaust-manifolds-set-99-03-7-3l/

Note: Neither kit is designed for Econoline vans. At this point, there’s no news from KC Turbos on when or if Vans will be covered. 

Why the up-pipe flange matters

A manifold can seal correctly against the cylinder head and still leak where it meets the up-pipe. KC redesigned this connection to improve alignment and clamping, especially useful on trucks with upgraded turbos, higher EGT, or up-pipes that have already been apart several times.

Installation (with a slight difference from OEM)

Remove the factory manifolds and up-pipe connections, clean the cylinder-head sealing surfaces, chase the bolt holes with a tap or thread chaser (the latter is preferred), install the stainless gaskets and new manifolds, then align the up-pipes before final tightening.

Note (the important part): KC supplies OEM-style interference-thread manifold bolts, so they will feel tighter going into the head than a standard bolt. The manifold-to-up-pipe bolts are not included.

Bottom line: With the original Ford 7.3 exhaust manifolds discontinued, simply buying new OEM replacements is no longer the easy option it once was. The KC Turbo manifolds give OBS and Super Duty owners a new, heavier-duty replacement with stronger High SiMo castings, thicker flanges, improved sealing, better flow, and a redesigned up-pipe connection.