This section exists
to help give back to the community by explaining some of the technical
challenges we've faced along with their solutions.
Oil Filter Losses
A relatively unknown aspect of the 4g63 and probably most other
engines is just how much oil pressure is lost over the oil filter.
This is something I didn't investigate until 2011 and; consequently,
had no idea how significant it was. All 4g63 oil filters have
bypass valves in them. Most of those valves are set at around
20psi. Beyond about 5000rpm, this bypass valve is wide open
and free-flowing unfiltered oil to the entire engine. The drop
across the filter at this point is this 20psi. All the OEM pressure
taps are pre-filter, so what your engine is actually seeing
is about 20psi lower than this. This can become a big concern
at high rpm if 80psi pre-filter and demand to push oil to the
center of the crank for rod oiling starts to get near 60psi.
Theoretical requirements to oil the rods start getting up around
50psi around 10k, and there could also be some losses in the
passageways post-filter. The main lesson is we're better off
being better-informed. Here is a datalog from my car showing
pressure pre and post-filter. The pre-filter tap is on my MIVEC
feed line before its filter, so that pressure reading does jump
around whenever there is a big cam timing change, like just
after the launch.
©2011 Kiggly Racing, LLC
