Five changes made it much easier to fit the engine in the cowl-

1) I put the prop flange at 44" forward of the firewall, instead
of 39". I put the heat
exchangers under the main spar to put some weight back a bit to
even out the CG. I will do
the weight and balance soon, and change the battery position if
needed. I don't think it
will be.

2) I used a 16" dia spinner, which allows a slightly wider and
taller cowl, especially in
the forward part of the cowl. It looks really nice, too.

3) I raised the firewall 1" by making a new portion that goes
from the top of the engine
mount up. This gives a little more room up top.

4) The cowl goes two inches deeper- lower on the bottom. That
allows me space to put a
muffler under the fuselage, and run the oil and coolant lines
under the fuselage. I put a
lot of heat sheilding and protection for the coolant lines under
there because of the
muffler. The muffler and lines are completely enclosed under the
fuselage for
streamlining. There are provisions for venting- three NACA ducts
on the forward part of
the cowl, spaced 120 degrees apart, one on the top, two on the
sides. The top one provides
a blast tube for the alternator, the left side feeds into a
plenum that surrounds the
exhaust system, and the right side provides a blast tube that
blows over the coils that
are mounted next to the engine. I am going to put a reverse
scoop at the exhaust outlet to
pull air through the cowl and over the muffler.

5) I chose to make an aluminum cowl so that I wouldn't worry
about burning a fiberglass
cowl. Material costs for the cowl were under $300, not counting
the purchase of an english
wheel ~ $350, and the several previous practice attempts at a cowl.

I'm really happy with the results, it gets a lot of positive
comments.

I'm waiting for my registration application to come back from
Oklahoma, then will be
looking at an inspection.

I was running the engine up yesterday, doing a little taxiing
around. Tracy's EM2 shows
151 HP at 4550 RPM static, I didn't give it any more throttle,
there was a bit more left.
I have the 2.85/1 redrive, so would expect around 6800 at
cruise. The prop is a Catto 74"
dia x 88 pitch. Compression is 9.1/1 I think, this was a turbo
engine, but is now N/A If
the torque curve was completely linear, and the EM2 reflects a
true HP value, then I
should get around 225 HP at 6800 rpm. If this is the case, then
I will have exceeded my
expectations by around 35 HP. It's probably too good to be true.
In any case, I'm not
disappointed with this engine.


Brian Trubee

Hi Brian.  I have an atkins 13b still in cosmoline.  I
have his wrap over intake and the Atkins iconel exhaust.  I plan
to run it full throttle at 7500 rpm's.  Any thoughts ?  I am
using two Ellison TBI's.  I hope to get 180hp at full throttle
from it, sound realistic ?
Lionel madore


 You should be able to get 180 out of it at 7500, depending on how
the intake, exhaust and porting are configured. What I mean is, I
think you'd have to have some sort of problem NOT to get at least
that much out of it.

 My intake runners are 18 inches long, the outers are 1 1/2 inside
dia, inners are 1 3/8's, if I recall correctly, and the exhaust
pipes are 2" id and 32 inches long before they join and run into a
hushpower muffler. The engine is a freshly rebuilt 93 13BREW
Japanese domestic  market engine. It originally made 270 HP with
it's twin turbos, which I sold to buy the rebuild parts. It's
normally aspirated, but the four intakes are big compared to older
13bs, and when I build the intakes, I matched the ports and polished
them.
 So, yes, I think you can reasonable expect 180 hp at 7500RPM.
 Brian Trubee

Check the spark plugs for the proper kind and number. Atkins has been
known to put the wrong plugs in there resulting in a failed
engine when the plugs came apart and destroyed the apex seals.


BTW there is a weird bug or virus out there that affects Thunder Bird.
Something is attached to the header file that supposedly "Tracks Abuse"
One must delete the message from the inbox and the inbox index file.
Thunder Bird will regenerate the index file automatically when
it is executed. At least I think that is what happened. I am not sure
who I get it from.

Send yourself a message and look at the complete header.

Paul Lamar