Paul,
Because I do not know how to add dimension lines to a photo I
have enclosed a picture of my practice firewall. The dimensions are:
A) 22.50" between upper engine mounts
B) 20.25" between lower engine mounts
C) 17.25" between upper / lower engine mounts
D) 9.75" from upper mounts to top of firewall
E) 4.75" from lower mounts to bottom of firewall
F) 12.00"
G) 5.00"
H) 28.25" top of firewall to corner
I) 30.25" firewall at widest point inline with top mounts
For a Lyc. 0-360 180 hp the plans call for an 11" long engine mount.
I have measured two installations:
A) an 0-360 that is 33" from firewall to prop flange and
B) an 0-320 that is 33.75" from firewall to prop flange
You will just have to make your best guess at mount length. I will
probably build a "corrected" 2nd mount after weight and balance.
This is a n/a engine with a dry sump oil system using a 2.85:1
redrive and approx. 220 hp.
Shoehorn what you can in front of this firewall. If I have to modify
the firewall dimensions some what that is not a problem. I will be
building a custom cowl so put radiator and engine air inlets where
you think best along with exhaust louvers if possible.
Did you consider doing a part 1 and part 11 cooling seminar at
Oshkosh? If I am going to have any problems with this installation I
think cooling will be it, I need to learn all I can about the
possibilities.
Thank you very much,
Randy
Here are a few 3D's and a side view. Apparently the dwg background
is rotated slightly so I assumed the firewall was vertical
and the fuse was aligned to match.
The bare engine weight is 190 pounds. Tracy's PSRU is 45
pounds. The starter is 8 pounds and the alternator is 10.5 pounds.
The motor mount is probably less than ten pounds.
Take a guess on the CG position of the various parts and
calculate the weight and balance
Ops forgot the pics.
Paul Lamar ...No rotor no motor.
Paul,
The firewall picture was taken slightly off center to keep the
camera flash from washing out my dimension lines. With the weights
and dimensions you provided I am getting a rough CG of 57" aft of the
prop flange. The prototype 180 hp Acrosport was 57.1" aft so its
looking pretty good. This is with bare rotary weight so the nose is
only going to get heavier but I have battery location to play with
when the time comes.
I am really surprised at the room under the engine. Maybe fitting
radiators, louvers, ducting, won't be as difficult as I anticipated.
What I really need to know right now is where do I need to make the
firewall grow to encompass intakes, exhaust, radiators, etc. A couple
dimension lines and tubing sizes on the engine mount picture and I
can get a lot of work done including mounting the engine before I
bother you again for cowling templates.
Thank you very much for your time,
Randy
You don't need to wrap the intake up and over the
top of the engine. You can come straight out to the side
All tubing shown is 3/4 .049. If you want to be a bit more
conservative for aerobatic use you can go up to .065 wall for the
for the four diagonals coming down from the firewall
to the Schertz beam. The X under the engine is overkill anyway.
Jerry Hey probably still has some Schertz beams in stock.
I suggest welding the rear motor mount to a custom oil pan.
Are you going with a dry sump system? Stock RX8 oil pan
perhaps?
You need to make a build or buy decision on
the Schertz beam. If you have access to press brake it is no
problem to build. I need the exact length before I can
calculate the tubing sizes and end cut patterns.
If you want to build I'll send some dwgs.
Yes I was amazed there is so much room under the engine.
I'll fool with the rad under there. Here is one suggestion.
Paul Lamar ...No rotor no motor.
Here are some dwgs and tube patterns if you want to
make your own Schertz beam.
Take these patterns to Kinko's and blow them up
until the dimensions are to scale on the paper.
Then cut them out, wrap around a tube and cut the end patterns
to fit. I guarantee they will fit together when it
comes time to weld. Will save a lot of cut and fit time.
Paul Lamar
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