The LT Wet Sump Engine Oil Pump Issue


As we continue to push the LT engine platform to greater RPM and power levels, we have identified a common issue with the OE-style oil pump struggling to maintain adequate oil flow at high RPMs, particularly under hard acceleration with G Force opposing oil intake to the pump.

This is due to a combination of factors, including the large pick-up tube volume and the pump not being designed to be efficient above the factory redline. In this article, we will discuss the problem in more detail and share our solution for addressing it.

The Issue:

The OE-style oil pump in the LT wet sump engines is not designed to be efficient above the factory redline. This is partially due to the relatively large pick-up tube volume as well as the pump simply not being designed to be efficient above the factory redline. The aftermarket modified versions of the OE Pump have more robust internal components and work well at lower RPMs; however, in our experience, they do not improve the high RPM condition.

As the oil pump becomes inefficient at pulling the oil through the inlet, it will aerate the oil, deteriorating the performance of the hydraulic lifters, not to mention the loss of protection for the other engine components relying on it for survival. This issue is exacerbated when attempting to add a crankcase vacuum pump.

The Solution:

To address this issue, we have developed the GPI – Gen 5 LT Oil & Vacuum Pump Combo. Our solution involved designing a robust mount to accommodate a Moroso Tri-lobe Single Stage Oil Pump with an Enhanced Design 4-Vane Vacuum Pump. The Vacuum pump is driven off the back of the oil pump, while the oil pump itself is driven off the front of the balancer. This assembly replaces the AC compressor, considering that most vehicles operating at the level necessitating this system would likely benefit from removing this component.

We modify the oil pan by installing an AN 16 feed for the oil pump inlet. We then include an oil filter adapter so we can retain the OE integrated filter (yes, no remote filter required). This kit comes with an oil cooler delete component to shave off a bit more weight and all plumbing and mounting hardware you will need for the conversion.


The LT wet sump engine oil pump issue is a common problem that can be addressed with the right solution. The GPI – Gen 5 LT Oil & Vacuum Pump Combo is a proven solution for improving oil flow and power at high RPMs.

Additionally, the kit includes an oil filter adapter, an oil cooler delete component, and all the necessary plumbing and mounting hardware for the conversion. With this solution, you can push your LT engine to greater RPM and power levels without fear of inadequate oil flow!

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