EA81 engine has oil delivery issues to that rear main. There is more info on
the web on this for a fix..
On Wednesday, December 25, 2019, 09:45:42 PM MST, Max Power via KRnet
<krnet@list.krnet.org> wrote:
EA81 Subaru thrust bearing wear https://imgur.com/gallery/DooQjEm
Image gallery link above.
Story: New to me kr2 acquired 4 years ago, had 18 hrs on the clock all
ground run. I've flown for almost 4 and brought total to 26 with a little
bit of crank endplay I assumed was normal but one day I was getting what
seemed like a misfire and when looking thru the prop in the air I could see
it's actual shape for a split second when it would skip or misfire which I
chalked up to the endplay as it moves in and out upon rotation of the prop.
I've grounded it since sept '16
So now 3 years later and a plan to vastly improve many aspects of the craft
I split the case of the Subaru EA81 to examine the thrust bearings and what
I found was the opposite of what was expected. The prop is on what would be
the rear of the engine in a car. I don't know the history of if it had been
rebuilt prior to conversion but the wear isn't what I would expect to find
in a car either.
These are worn down to nothing on the wrong side, the prop was pulling away
from the worn side and technically I could've just left it alone.
I don't know if any of this is useful info, It's been so long since I've
run it I don't remember any data from gauges but I know it was very slow
and I had to keep it at WOT nearly the entire flight time. I had a crazy
long rollout, well more then half a 3000ft runway, this has hydraulic
retractable tri-gear that I never raised and I know that was most of my
speed issue.
It is set up as direct drive and the prop should be putting pressure on the
thrust bearing, I'll measure the new ones to determine how much was
actually worn off that face that still is good.
I can only imagine this if it was involved in a front end collision while
in a car still to have actually put any significant force in that direction
but it would've pushed the drive pulley back first hard enough to score the
engine case and there's no evidence of anything like that.
Just wondering if anyone else has seen wear like this on any engine really?
It's going to a machine shop to get bored, shaved, and a cam regrind to
bump hp for a shorter rollout.
I'm reengineering some pieces from steel to aluminum. Dropping the radiator
and it's draggy "in the breeze" mount to a double or triple stack of
motorcycle sized radiators with a naca duct and a 2 speed fan or something
similar after extended testing, reengineering some aluminum parts like
coolant reservoir to plastic. Will be lighter and more powerful when
complete.
A 3-D printer is extremely helpful in building a better aircraft, I'm
building a complete intake system to bypass the coolant passages in the
original intake manifold that cost me some HP that will eventually be
rebuilt in machined aluminum parts but it's great for dryfitting things to
see how they would fit.
Thanks in advance for any and all information. I'm so glad to be a part of
this group.
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