Inside PPE’s New Cast-Iron Duramax Heads
Despite the fact that the Duramax’s OEM cast-aluminum cylinder heads hold up well in many applications, at the high-end of the performance spectrum several problems can surface. For starters, the different expansion rates between a cast-iron block and aluminum cylinder heads can lead to uneven clamp loads—which eventually means blown head gaskets. Then, in extreme heat environments the factory heads are prone to cracking. Over the years several companies have released cast-iron replacement cylinder heads for the iconic 6.6L GM V-8, but Pacific Performance Engineering’s latest product may just be the homerun everyone has been waiting for. The company has designed and manufactured high-quality cast-iron heads that should be on the market by the time you’re reading this.
For a bit of comprehensive, pre-market validating, PPE shipped a set of heads to LinCo Diesel Performance—a Troy, Missouri based company that’s not only a PPE dealer but that boasts a machine shop that rebuilds Duramax engines on a regular basis. After examining PPE’s new cast-iron heads in every way it knows how, LDP shared its findings with us at Diesel World. Guide clearance and valve recession specs on the heads were found to be ultra-consistent, and their profilometer-verified surface finish was found to be just about as close to perfect as it gets. In addition, they feature de-burred ports and smooth radius’s on the valves and valve pockets, upgraded and fully nitrided intake and exhaust valves, and come with 125-lb valve springs. If you’re searching for a one-and-done type of head package (heads that support horsepower and reliability), PPE’s cast-iron heads look to be solid performers right out of the box.
LinCo Diesel Performance
Pacific Performance Engineering (PPE)