Great as a stock replacement, the BD 1045947 exhaust manifolds were designed with expansion joints and heavy webbing to prevent cracking. The exhaust runner design maintains exhaust velocity to drive the turbine wheel. Runner size does not go beyond the size of the exhaust ports on the head because when the runners are larger, the velocity to drive the turbo is lost due to the expansion and temperature in the exhaust manifold which reduces the turbine drive pressure needed for turbocharger response.
On engines with enhanced fuel flow and larger turbochargers, the principal remains the same. Velocity and temperatures are needed to drive the turbine wheel which turns the larger compressor wheel that supplies the extra volume to attain proper air-to-fuel ratios. Optional manifold gaskets (part# 1045986) sold separately. This Product also comes with BD Diesel’s 3 Year / 75,000 Miles Parts Warranty.
Note: BD 1045985 can be used as a direct replacement for Cummins part number 3946036 used on pick-up engines.
