Steel Forged Crankshaft
When it comes to the internal combustion engine, there is no component more important then the crankshaft. Crankshafts are the backbone of the rotating assembly and are responsible for much of the work of an internal combustion engine. When doing an engine rebuild, there are a variety of factors to consider.
Having discussed this with our local crankshaft machine shop, The Crankshaft Company, it was determined that the best course of action for our high performance turbo Buick application was a 3.8L steel forged crankshaft. The Crankshaft Company noted that this crankshaft offered added durability because of the improved radius in the connecting rod and main journals. Additionally, steel forged crankshafts are able to flex under extreme loads whereas a cast crankshaft would simply crack.Unfortunately for us, the only available steel forged crankshafts are from China. The Crankshaft Company did obtain one of these crankshafts for us and the tolerances of the journals left little to be desired. Therefore, the Crankshaft Company machined the journals down to a .010 undersize. Since we were doing the rebuild ourselves, I had the machine shop order us the bearings. We were advised to use a Sealed Power “H” bearing, which is designed for use in high performance applications. For us, it also meant we would not have to chamfer the bearings to make them fit.
With our crankshaft complete, we were able to use our pre-purchased K1 Technologies connecting rods. These were stock length connecting rods and required not block or crankshaft clearancing. But to make sure, we did a dry fit with our Diamond pistons already hung on the connecting rods. Once we determined we were in the clear, we were back to the machine shop to get the entire rotating assembly balanced. It is important to note that we used an internally balanced flexplate and harmonic balancer. This was an ideal choice to major drilling in the crankshaft. The last thing we wanted to do is have 3+ slugs of heavy metal in the crankshaft. With the cost of drilling and the heavy metal, each slug can easily run $80 a piece.
With our steel forged crankshaft rotating assembly completely balanced, we were able to fully assemble our short block. In a follow up post I will detail what we did to the upper end. Keep in mind this V6 engine is the powerplant behind a car that can do high 9′s and is driven on the street as well!
