Tracy is dealing with water coolant plumbing problems as we speak.
It is still running hot. I just got off the phone.

He is also disappointed in his cool air duct to the intake system
with several inches of water drop. Also his HP is down compared to his
old engine. Some of that is no doubt related to the pressure drop.
Some pressure drop is due to a long SCAT hose but some is due
to the NACA duct used instead of a ram air scoop. During the Sun 100
race he was reporting 32 inches of Hg in the intake system.
His last engine used the large third gen intake ports while this
engine uses the low power auto TX version of the RX8 engine with

smaller

ports. It is too early to say for sure that this version of the
RX8 engine will generate less HP than a 3rd gen engine but that
is my humble opinion. Note the small size of the intake ports in the

pic

below.
Here too is a picture of the high power RX8 intake ports for

comparison.

Every time you make what appears to be a simple change new problems

occur.

His new intake system looks like this currently.
The plywood box will be replaced by a metal box eventually.

One thing about Tracy. He enjoys going against and ignoring

conventional

wisdom :)
It will be interesting to see what he eventually winds up with :)

Paul Lamar

If I might suggest a pair of Jerry's PP inserts will fix Tracy's HP
problems!!!  (along with new intake and exhaust systems - Tracy, ain't
it great to be on the leading edge!).

Ken Powell

I warned him about the low power RX8 engine but he would not listen :)
We shall see if it is ever as fast as his old engine. Bruce Turrentine
has him hung up on intake velocity :)

Paul Lamar

The other thing that Tracy is being stubborn about IMHO is the use of evap
cores for cooling. I was hoping he would start with a clean sheet of paper
on the RX8 eng installation and use a real water radiator under the engine.
IMHO evap core are too thick to work well in our speed ranges. He tried
to take a short cut here and use as much of the old installation as possible.
When Tracy did the original installation over eight or nine years ago there was 
little to go on other than what Everett Hatch and Allan Tolle did. Their system
was not cooling all that great either.

He got part of it right by using the K&M bell shaped curve but he missed the part
about the duct length required to be 2.5 times the rad dimension. These ducts 
are too short according to K&M. There is just not enough room in an aircraft cowl for 
a proper K&M duct. The only hope is to go with the Kays & London wedge shaped
diffuser. You can still get K&M ducts to work (sort of) if you open up the hole 
to 50% or so of the area of the evap core. That is about what he had before however 
that never really cooled well under all conditions either. He had to resort to water
dribbling over the surface of the evap core.

If it sounds like I am picking on Tracy I am not. We learn from our mistakes.
We have been all over this many times in the past and Tracy is a busy man
so he may have missed some of it. Don't read me wrong. I highly appreciate
all the things Tracy has accomplished and I am especially grateful for the
engine computer and the gear box. The last thing I want him to do is take
the time away from shipping computers and gear boxes to do it right :)

Paul Lamar
 
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