Oil Filters Revealed

Description

This is a quick look at a few HP1 racing filters.  This filter is used in many racing applications where a filter compatible to the Chrysler/Ford reference would be used.  The mounting configuration is the same, but the main differences are: higher burst pressure (300-500psi), higher bypass pressure (20psi instead of 8psi), and a longer case and cartridge (hopefully).  The additional case length varies slightly, but only amounts to between 1/8"-1/4".  The higher bypass pressure is meant to prevent the filter from going into bypass as much during high RPM use.  The assumption is that a racing engine will use a high pressure oil pump, so the 20psi drop across the filter is less of a problem.

The other parts of this project:

• Project Overview - high-level view of this project.
• Reference Filter - original, most complete reference for the common Chrysler/Ford filter.
• Mopar Choices - filters of varying dimensions that are also compatible with the Chrysler 2.2L/2.5L engines
• German Filter - a common filter for German vehicles in order to get a look at some unique brands.
• Toyota Filter - a filter for many L4, V6, and V8 Toyota engines.

Brands

The analysis is sorted by brand name in alphabetical order.  Only some brands and manufacturers actually sell a true HP1 filter.  Often it cross-references to it's more common Chrysler/Ford sibling filter (the reference filter), but they are not the same filter.  Detailed sections of some of the models follow.  Filters tested only in 1999 have the vintage specified as such.  If they have been verified as unchanged since then, they are labeled 1999-2008.  If this filter has never been acquired, the vintage is marked as N/A.  Note that even though the surface area is listed for comparison, the values don't correspond exactly to the filters' holding capacity.  This is a function of the media's composition as well as the surface area, which is not something I am equipped to compare.

Fram

These filters are manufactured by Honeywell (formerly Allied Signal).  See this 1999 email from an Allied Signal production engineer.  Also see episode 41 of the TV show "How It's Made" for a look at the production line for these filters.

Fram Extra Guard HP1

This filter cartridge has a small outside diameter with a rather low filter element surface area (193 sqin), and features cardboard end caps that are bonded in place using a thermal adhesive.  The rubber anti-drainback valve seals the rough metal backplate to the cardboard end cap and easily leaks, causing dirty oil to drain back into the pan.  If you have a noisy valve train at startup, this filter is likely the cause.  The bypass valves are plastic and are sometimes not molded correctly, which allows them to leak.  The backplate has smaller and fewer oil inlet holes, which may restrict flow.

The telltale signs for a Fram Extra Guard are:  It has 8 small holes for the oil inlet and a thin, cheap looking backplate, and is currently stamped with a "2Y".  There are 5 very small crimps holding the gasket in place.  If you look into the center hole all the way to the top of the filter, you will see a kind of "button" in the end cap of the cartridge (which looks like it's made of metal from there).  This is the plastic bypass valve.

Exploded view and backplate:

Purolator

Premium Plus HP1/L30001

Exploded view and backplate:

Conclusions

For modified engines running high oil pressures in race-only applications, the HP1 filter is worth considering.  It does provide some additional surface area relative to filters from the same manufacturer, but not any more than a few other alternative reference filters.  The additional bypass pressure may add some extra protection, but at the expense of some oil pressure when the filter element cannot flow all of the oil (high RPM, low temperature).  On the other hand, the 20psi drop could be used as an indication that the filter has become plugged and that the engine may be on the verge of failure due to a wear item.

If you want to hear my opinion take a look at the Oil Filters Revealed: Opinions and Recommendations page.  Which filter is the best?  There is no easy answer to that one.  It depends on what kind of oil you use and how much you are willing to spend.

Return to Oil Filters Revealed

Updated 02/19/2008.

Copyright © 1996-2008 Russ W. Knize.