CALLIES LS ULTRA BOOST CRANKSHAFT - 4.000" STROKE - 58X RELUCTOR - APO-31@-UB

Ultra Boost family of crankshafts represent the pinnacle of severe duty shafts. Designed specifically for the most harrowing, ultra-high output applications where no exceptions are to be made for reliability, years of experience and talent culminate to shape the industry’s most capable crankshaft. Each Ultra Boost crank is machined from Callies renowned 4330 bar stock, sourced from TimkenSteel right here in Ohio. Taking lessons from the Top Fuel world, where our crankshaft routinely outperforms the competition, we’ve implemented similar design language into the Ultra Boost line. Two of the most prominent changes include increased material found on the pin arms and pin tops. These changes, along with others, allow for the most reliable crankshaft that is offered today— helping make sure you spend more time at the track than in the shop.