>> 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.
So is the next step to make a composite steel/aluminum p port tube. Thread
the two together in the center and tig both ends.
John Gibbons
?????? :) I have no idea what you are talking about John :)
The aluminum runner on the out side of the slide throttle is tig welded to
the aluminum outer plate of the slide throttle as in these jpg's.
The inner steel tube is welded to a steel flange that is then bolted to
the
inner side of the slide throttle. It must be that way or you would never
get the engine apart.
Paul Lamar ...No rotor no motor.
In one of the pictures you posted you could see the outer side of the rotor
housing. If it could be tig welded there then you would have great seals on
both sides. Of course you can't weld the steel to aluminum but if you made
the insert steel on the inner end and aluminum on the outer you could weld
both ends. You could weld an aluminum flange to the end for connection to
the slide throttle. A snug slide together fit between the two halves of the
insert would be fine as there is the JB Weld in that area. Should be
impossible to leak.
John Gibbons
The JB Weld is working great. I don't want to add to the time or expense
of building a p-port. Right now it is probably cheaper and quicker to build a port
than it is an effective six port manifold.
Paul Lamar ...No rotor no motor.
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