Bulent Aliev wrote:

What about the new 2mm apex seals that Tracy demonstrated against

the

factory ones. Very impressive.
Bulent

-"Brian D. Cain" wrote:

We'll be building two engines using Tracy's new 2-piece 2mm apex seals
and springs pretty soon.  Both of them will be in a high powered

environment

so I'll
be anxious to see how they perform.  I expect good things from them.

One of

our friends
in Canada is using his stuff and, although he's satisfied, he's told me

that

they had an
extensively long break-in period of 1800 miles (automotive miles, that

is).

I'm assuming
the engine in question is using re-used rotor housings as well so that

may

be part of the reason behind it.

B

Brian D. Cain -/- Grand Prairie, TX -/- bdc196@comcast.net
BDC Motorsports - Performance Rx-7 13B Rebuilds, EFI tuning, etc.
MSN bdc196@hotmail.com, Yahoo! bdc196, AOL Symajhi, ICQ# 1733105
http://bdc.cyberosity.com -/-

http://groups.yahoo.com/group/HaltechSupport-

"Brian D. Cain" wrote:

I wish you'd chime in on this, Paul.  :)

Well as Jim Mederer pointed out in a recent magazine article on apex 
seals nobody can afford to do the extensive long term testing Mazda does. 
Apex seals are a complicated compromise of many conflicting requirements. 
Apex seal wear for an aircraft engine is probably the least of our problems.

I tend  towards 3 mm seals because the last thing you want in a turbo aircraft
engine is a fractured apex seal. That is a show stopper. We don't run 
9,000 RPM where a 3 mm seal might jump off the hump or chatter.

Also drilling the back of a 3 mm seal is a proven but expensive way
to make them lighter. Mazda successfully did that way back the late 60's.
It is probably not as expensive as ceramic apex seals and could
be less labor intensive today by the use of NC machines.

Also nobody has tried titanium nitride... the yellow stuff they put on cutting
tools to reduce friction and wear. That could be counter productive because
I suspect the friction between the slot and the seal tends to damp chatter.
I still think it is worth a try.

Paul Lamar
 
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