In the past, we’ve explained high pressure vs high volume when it comes to oil pumps, and Melling has done a great job trying to educate the consumer on similar performance issues. However, Melling has a real-time source of feedback on what its customers do and don’t understand in its tech line.
One call that has been coming into the tech line quite a bit lately has to do with the oil pressure springs in the LS lineup of oil pumps. As Melling’s Technical Director Cale Risinger explains, the industry-wide rule of thumb for oil pressure relief valve settings is 10psi of oil pressure for every 1,000 rpm of engine speed. If the engine has a 6,000 rpm redline, then the rule of thumb is that the 60psi spring should be installed.
That said, each pump in Melling’s high-performance LS lineup has a different factory-installed spring, and optional spring set included. Risinger explains in the video, what springs come with what pumps, for what final pressures.
The M365HV pump comes with an orange, 70psi spring installed and includes a yellow spring which will decrease the pressure relief setting to 60psi, as well as a green spring, which will increase pressure to 80psi.
The 10294 pump comes with blue, 60psi spring factory installed and includes both a red spring to bring the relief valve up to 70psi and the Copo spring, which will bring the pressure bypass up to 75psi.
The 10295 pump comes with a red, 70psi spring installed from the factory and a blue, 60psi spring as well as a gray 75psi Copo spring.
The 10296 comes with a red, 70psi spring installed, and has the optional blue 60psi spring included.
The 10355 comes with an orange, 70psi spring installed along with both a yellow spring to drop the bypass pressure to 60psi and a green spring to increase pressure to 80psi.
The 10355HV high-volume option comes with the exact same spring lineup as the 10355 pump (orange 70psi installed, optional 60psi yellow, and 80psi green).
While all the numbers and letters can make for a confusing array of options, hopefully, this breakdown can at least help you understand the pressure options for the different families of LS oil pumps, be it a standard or high-volume variant of Melling’s performance pump lineup.