>> This was done by Matt who is the race car chassis builder
        >> at Mazdatrix. It had some aluminum removed around the
        >> steel liner where it was welded to the 304 SS .065 wall tube.
        >> As Mark Steitle discovered this is totally unnecessary.
        >>
        >> Removing aluminum is difficult to do and labor intensive as
   compared
        >> to just welding it in.
        >>
        >> It took Matt about five minutes to weld this and I paid him $22
       bucks.
        >>
        >> Welding them in is not completely necessary but it gives
   another
        >> level of security against coolant leaks.
        >>
        >> Sure is quick and easy to do. I am going to do it on
        >> the RX8 P-port engine.
        >>
        >> Paul Lamar ...No rotor no motor.
        >>
        >
        > Paul,
        >
        >
        > Great and timely picture. I was speaking to the factory owner up
       the road
        > from me on this very topic yesterday and mentioned our
   experience of
        > cracking TIG joints due to vibration in the water pumping
       applications. He
        > has extensive experience as you have seen in supplying all
   sorts of
        > equipment for high tech IC Board manufacturing plants. In brief
       he says in
        > your P-port welding application which is hardened steel welded to
       SUS 304,
        > shouldn't have a problem with vibration. The key he said was
       providing
        > proper support for the pipe as their is thermal expansion of
   three
        > different alloys. I guess that is where your JB weld comes
   into play.
        >
        > The larger factor of concern he said would be the different
   thermal
        > coefficient characteristics, with I suppose the SUS-304 pipe
       expanding
        > faster than the liner steel material. He did say that those
   events
        > happening on start-up and cool down are few over the life of the
       engine so
        > all in all its maybe a good idea. 'Maybe' as you have heard
   is as
       close to
        > 'Yes' as you get over here:)
        >
        >
        > Doug Fir
        >
        > The temperature differences on that side of the engine are
   minimal.
        > I am not worried. A crack probably would not hurt anything
   anyway
        > because the JB Weld is still in there.
        >
        > Hey the liner is steel and the housing is aluminum. Nobody
   has seen
        > them crack apart in two million engines for the last 40 years.
        > The combustion chamber side is 500 F.
        >
        > BTW that rotor housing
        > I used was from Dave Leonard's turbo rotary powered air plane and
       he melted
        > the aluminum from around the lower spark plug treads while he
   was
       in the air
        > flying without coolant :) In other words the lower spark plug
   hole
        > and combustion chamber now communicate with the water jacket
       passages :)
        >
        > Here is an idea for Mazda. Weld a steel spark plug boss to the
        > the steel liner to make the engine even more cannon proof
   than it is
        > already.
        >
        > Paul Lamar ...No rotor no motor.


       Paul

       Hey that sounds good in principle but wouldn't be so pretty in
       application.
       By the time you cleaned up the weld area there would be a slight
       depression
       around the hole. Psssst The sound of lost compression.:)

       Doug Fir

       Just the lower spark plug hole. The pressure difference there is
       minimal.

       This is the same reason my p-port trap door will work on the
       stock RX8 engine.

       Paul Lamar ...No rotor no motor.

       Paul,

       What about aluminum brazing?

       http://www.aluminumrepair.com/

       I've used this for fixing stuff around the farm and it works very
       well. I've also used JB Weld, with mixed results. To tell the truth
       I am not too keen on using JB weld to glue engine parts together.

       Aluminum brazing uses low heat -- propane, mapp, acetylene. It flows
       nicely into nooks and crannies so I think it should seal well
       against pressure.

       The website claims it's actually stronger than tig welding (I don't
       know about that), but it has proven to be plenty strong. It could
       also be used for making aluminum gas tanks.


       Regards,

       Gordon.


       JB Weld is no problem gluing these engine parts together as there
       is plenty of bonding area. Proper preparation is essential.
       You need to etch the aluminum surfaces. JB Weld is 4000 psi shear
       strength and some of my test prove it. That is 100 times more
       than what is need to keep this tube in the rotor housing.

       I think tig welding the steel liner to the steel tube results
       in less heating of the aluminum. Mark Steitle reports 130 degrees
       F. That is way lower than what you would have to do to aluminum
       braze it together. Tig welding is a very localized heating
       system indeed.

       All this is not about strength anyway. It is about sealing the
       water jacket.

       -----------------------------------------------------

       I measure the rotor housing with the welded in 304 SS tube today
       and it came out right on the money. No shrinkage or expansion.
       3.149" or 80 mm

       Paul Lamar ...No rotor no motor.

       What about distortion of the wear surface, Paul?

       Even a small amount could affect the apex sealing.

       -- Gordon.


   I have not polished mine out yet but I think Mark Steitle checked
   his with
   a straight edge and found none. Is that correct Mark?

   BTW due to the low pressure difference in this part of the housings
   apex seal sealing is not critical.  You did see this chart recently
   did you not? I thought I uploaded it. Perhaps I was mistaken and it
   did not go out.

   Paul Lamar ...No rotor no motor.

Paul,

I checked and it and couldn't detect any warpage.  As we discussed
earlier, I welded small sections at a time, then moved half-way around
and welded another small section, then moved again until it was
completely welded.  A different technique may provide different results.

Mark Steitle.

I don't think Matt bothered. I think  he welded the top half and
then the bottom half from the looks of it.