Building the Naturally Aspirated Honda K Engine Part 3, Assembling the Engine


The engine’s bed plate is lowered down. We like that the K24 has a bed plate instead of the traditional main caps. In the past, the bed plate was something that bespoke racing engines had. That is now trickling down to production engines.

Bed plates really stiffen up the engine’s bottom end, which greatly helps structural integrity at high power levels and high revs. The most obvious benefit is longer bearing life, but block stiffness helps everything from crank life to improving ring seal and even head gasket seal.

Howard Watanabe installs the main bolts. There are 2 large main bolts per journal and two or more smaller bolts – more than twice as many that typical with standard main caps.

It is very obvious how this is going to radically stiffen things over the conventional, discreet main caps with two bolts and an oil pan. There are many other bolts attaching the bed plate to the block around the perimeter as well.

One of the things a bed plate also accomplishes is to partition the crankcase, which reduces windage and pumping losses as well. This helps power and fuel economy, and it works well with a dry-sump system.

Howard points to some oil passages that went to the K24’s balance shafts. The balance shafts have been removed, as it is difficult to keep them alive at high rpm because they spin at 2x crank speed.

Removing the balance shafts is good for at least 5 more horsepower and reduces oil temperatures. Balance shafts are there to damp out an inline, 4-cylinders engine’s natural up and down shaking moment. They are there for NVH reasons, not to dynamically balance the engine. Removing them won’t hurt component life.

Howard torques the main bolts to initial torque in three steps using a cross pattern. He then finally torques the bolt by angle, since the OEM bolts are torque-to-yield.

We used new OEM bolts instead of studs, as we felt that this NA engine would not put such a load on the bottom end. Running studs with higher torque often distorts the main bores, which mean the engine has to be aligned bored. If this is done excessively, it can cause problems with the oil pump and even the timing chain.

So if the engine doesn’t need it, it is sometimes, in our opinion, best to stick with stock.

We used King XP bearings for the connecting rods as well.

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