Hey Rotorheads;
This summer I bought the Fluidyne DB30618 but it
is only a single pass. I recently inquired about them
with Summit Racing and they say they will provide a
2-pass as a custom order. The stock oil cooler is a
2-pass but much more restrictive. The single pass
added a longer hose with a 180 swept fitting to make
it work.
I'm seeing higher temps than I'd like to despite
my improved duct work. Actually inlet duct was
improved, but outlet duct is new as I didn't have one
before and I do wonder if the outlet duct is
restrictive but I'm limited with space and old nose
gear mount being in the way (as much as I'd like to
remove the nose wheel mount it is integral to the
engine mount, so I'm stuck with it), so I wonder if it
would be better to remove the exit duct completely and
just leave the oil cooler exit air un-ducted?
But to the main question for tonight, I'm
thinking about converting my cooler to a 2-pass. I
have been experiencing higher oil temps than expected
at around 110C and considering the OAT has dropped
considerably, I would like to reduce these somewhat. I
suspect that the flow is not going through the entire
cooler evenly with a majority of flow channeling
through only a few of the tubes as it is not really
any different than the temps it used to see with the
Mazda cooler. The larger size and more efficient
design should produce better cooling if oil was
flowing evenly through all tubes and spending a longer
time in the cooler.
So I'm thinking it should be simple enough to
convert to a 2-pass cooler which should ensure a
better distribution of flow through all the tubes. But
is it really so simple?? See pic at
It would seem a simple matter to zip-cut a slot
where the red line is, slide in a baffle plate and
weld it up, re-sealing the end tank, drill a hole and
weld in the new AN10 fitting and at the other end, zip
off the old AN12 fitting and weld it up. This would
also simplify plumbing, as the oil in line would be
shorter and go straight in with no 180 bend.
But the thing is I can only weld on 3 sides of
the baffle plate that I would install. I can ensure
that it is tightly seated against the tube end plate
between the tube but it wouldn't be a sealed junction.
Do it right and an insignificant amount of oil may
bypass there and not go through the tubes. Do it wrong
and it could be a significant amount with a drastic
reduction in cooling.
Obviously I've already removed the cooler and
brought it home with the intent to do this mod, but
now I'm second guessing myself. I've considered that
if Summit Racing is modifying these as a custom order
then they likely are doing just what I plan to do.
Otherwise it would have to be done during manufacture
by Fluidyne.
It seems simple, but I lost sleep last night
considering all the various issues. Still didn't do it
today, so I figured I'd pose the question to the group
and go hunting with my kid tomorrow while I wait for
the opinions to arrive.
On another topic, during a take-off roll the
other day, the diaphragm in my old stock wastegate
actuator blew. I didn't catch it with the throttle
until I hit 16.5 psi of boost. No damage but I gotta
say that's a fun way to get off the ground in a hurry!
I usually limit myself to 6 psi of boost as that was
the spring pressure. I do have an electronic
controller (TurboSmart) which allows me to have higher
pressures above the spring pressure, but that is
intended for high altitude and mountain flying.
I've ordered a new adjustable piston type of
actuator that comes with a selection of 6 springs. I
intend to use the 3 psi spring as I usually use the
boost very conservatively and the TurboSmart
controller can give me more if I need it for short
mountain strips.
Anyways, I look forward to your opinions on the oil
cooler.
Todd Bartrim ....... 20.6 hours
on new RV9 version 2.0..... I had to cash in beer
cans for gas money....
C-FSTB
RV9 13Bturbo