K-Series Oil System Upgrades

Rethinking the k's oil pump
The K-series is going on six years now and parts development for the platform has arguably surpassed most everyone's expectations. Compare it to the B-series, which six years after its introduction had nowhere near the amount of support the K does. It isn't the new kid anymore; its strengths and weaknesses are well known. One such weakness lies with the oiling system. It's a minor one though, which means the solution is best suited for competition-bound, race engines-not necessarily your average street-built K20A-although the mod certainly won't hurt. The flaw? The oil pump, specifically its drive gear. Few people understand the inner workings of the K-series better than HyTech Exhaust's John Grudynski, the brains behind all of this. So that's who we went to.

The Problem
Honda has earned a reputation for manufacturing parts with leftover potential. That's why its engines are so tunable. Who else makes a stock forged crank that can handle 700 hp? It can be argued that certain things have been dictated by budgets not power potential over at Honda as of late though. One such result is the K-series oil pump that tends to cavitate past that 8,700rpm mark. The problem doesn't sound so serious, especially since even the high-revving K20 Type R valvetrain is limited to 8,600 rpm, but for those building serious drag or road race engines, even street setups with high-end rebuilds, the right mods will tempt even the best of us to fool around in that upper powerband.

Most Honda oil pumps operate at one-to-one ratio crankshaft speeds. Take the B-series oil pump for example-it is, after all, driven directly off the crankshaft. Not the K's though-it operates at 1.6 times the crankshaft's speed. That's extremely fast, so fast that when that K20 spins at 8,000 rpm, that little pump is turning at an astonishing 12,800 rpm! It's no wonder it can't keep up, which is what leads to cavitation. So why would Honda do such a thing? The answer is both simple and smart. You see i-VTEC incorporates VTEC as well as variable cam timing. Both systems rely on oil pressure, and lots of it. Since the majority of camshaft movement happens at lower and middle engine speeds, driving an oil pump at such speeds might not provide enough pressure-especially if you're a Honda engineer and you want to keep the pump small. Overdriving the pump takes care of all of this, which is exactly what Honda did.

The Pump Fix
The HyTech fix begins with blueprinting the stock pump. The side clearance of the pump's gears is reduced from 0.0012 of an inch to 0.0008 of an inch. This helps better seal the gears against the housing, thus reducing leakage. The exit port where oil transitions from the pump to the block is fairly rough. Its corners create flow eddies, or turbulence, which restrict oil volume made available to the block. HyTech employs a hand-finished procedure that puts a uniform radius on the entrance, allowing for more oil to be fed through.

Not satisfied? Further oil pump fixes involve fitting the S2000's pump to the K, which features a different internal design with a larger gear and bigger ports. This isn't such an easy mod though, and you can't run the stock K-series aluminum pan with it. Not a good deal if you've got a new Si with the oil pan-placed motor mount. Enough with the S2000 pump then.

After cleaning up the K pump, HyTech goes one step further by reducing pump speed by 10 percent. Now engine speeds can reach 9,500 rpm before cavitation begins. That's high enough for just about any street or road race engine. HyTech also cuts a new gear from an OEM piece using a method accurate within 0.0002 of an inch. The process also leaves a superior finish on the surface of the newly cut gear.