>
>
> >> Paul
> >> I don't want to be the source of discouragement to anyone so
feel free to
> >> post this or not.
> >>
> >> First up. Nice drawings. I was wondering how I was going to
model it. Yes I
> >> think we are pretty much in agreement now. A few differences
in terms and
> >> ID sizes. I happen to think a wee bit bigger ID is the way to go.
> >>
> >> A press fit in my thinking doesn't necessarily mean a
hydraulic press fit.
> >> Of course distortion is to be avoided. If the hole and insert
are round the
> >> you can do a slip press fit with a small tolerances (.002"?)
and a very cold
> >> insert. I suspect even a g ood fit may even move a thousand of
an inch
> >> during heating and cooling cycles. This is a good thing I
believe. Cary and
> >> a few others have already done press fit with a tap of hammer.
That is
> >> most likely because it is difficult to get it to go straight
in. A slight
> >> bevel on the front edge would help. As Scallawag says if you
get it cold
> >> enough you shouldn't need to heat the housing. He recommends
not to because
> >> of warpage potential. How to get it real cold? Dry ice in a
foam box, or
> >> liquid nitrogen. The later is not available at your
neighborhood supermarket
> >> I know.
> >>
> >> Yes all tubes and pipes are not completely round and so the
insert needs
> >> lathe work. I would machine a step on the end that holds the
flange as well
> >> to get a nice weld. The housing port will have to be finish ed
off, ground
> >> and polished in any case. It seems this is a given in P-ports.
There are
> >> ways to do this and precautions to take and the info is out
there.
> >>
> >> I do see where you are coming from design wise as it solves
the gap
> >> challenge and that you still have high regards for the JB Weld
to act as
> >> sealant. I don't think anyone can say how long it will hold up
in an
> >> airplane engine. That it works in auto racing engines is
proven without a
> >> doubt. These engines take a lot of short term abuse but don't
endure
> >> thousands of hours of hot cold cycles. I'm not trying to
discourage the
> >> P-port effort in any way. Au contraire. Safety is on my mind.
Who wants to
> >> rebuild engines even though they are easy to do so. I would
rather be
> >> flying with it. P-ports make a lot of sense for our air
planes. That and the
> >> adjustable length manifold are great innovations.
> >>
> >> Keeping the insert in place is not a design challenge. Finding
the best
> >> material to seal the inside housings but stay flexible is.
Machine a step on
> >> the insert to rest against the stubs and it won't be falling
into the
> >> engine. Counter sinking set screws drilled and installed in
the remaining
> >> two stubs on each side of the tube will hold it from coming
out as the steel
> >> bites into the soft aluminum. Look at how the exhaust port is
kept in place
> >> and you can see what I mean. Add to the holding force is the
sealant.
> >> You can pour the port full but why? Smeared around the insert
and hole
> >> before placement is adequate. Put some more around the pipe
perimeter after
> >> pipe insertion and then do a water test. Water leaks will be
easy to see
> >> where if indeed there are any with a tight fit. Is more
sealing better not
> >> necessarily. It is a mind set we do to make ourselves feel
better.
> >>
> >> O-rings are best for side sealing purposes but NG on our
desired straight in
> >> approach into a curved housing. I wonder what else is flexible
but a
> >> literal pain in the ass to remove from aluminum housings and
comes in two
> >> part liquid form as well with many hardness options to choose
from. Hint you
> >> use it to make molds for high temperature plastic forms with
undercut
> >> reliefs.
> >>
> >>
> >> No picture came through about the potential leak area. I would
be interested
> >> to see that as I must have missed it.
> >>
> >> I don't have access to the machine shop down the road now
because they are
> >> assembling some top secret industrial equipment for
Epsom/Seiko. It looks
> >> like a machine used in an assembly line plant for flat panel
displays.
> >> Seiko gets a little worried to see a non employee working in
the factory and
> >> threw their weight around. A-holes. Paranoid I might steal one
of their
> >> ideas. Actually they stole one of my research groups idea we
brought to
> >> them (our stupidity) to make 25 years ago. It was a wrist
watch that had a
> >> device in the band that sensed and displayed heart beat. They
patented it.
> >>
> >> Justice was done .... sort of. They spent a fortune trying to
market it and
> >> lost the fortune. Moral: Only let your rivals steal your bad
ideas:)
> >>
> >> That leaves me with a good drill press at the moment and a
chopper circuit
> >> to control the sp eed. The insert I will order out.
> >>
> >> DougFir
> >
> > Darn. Too bad! That machine shop was one hell of a resource for
you.
> > Is this the 1990's SAE paper you referred to above.
> >
> > Paul Lamar ...No rotor no motor.
>
>
> Paul
>
> About the SAE paper I think the one referred to is different. It
is best you
> refer to page 20 at the above mentioned RX-7 site. Posting the
data here
> will just confuse everyone. Again I concur racing ports shapes
and aircraft
> engine shapes have different design goals.
>
> One question. When boring through the housing how much of the lower
> bolt hole housing do you go through? None ? just graze it? Halfway?
>
> Here is a post from the same site I thought you would enjoy.
>
>
> "If you want to make a big precise hole in aluminum there is an
easy way if
> you have the tools.
> 1- center drill (no flexing in the tool that will determine the
placement of
> the port)
> 2- use your hole saw, a smaller one though, like 1/8" under what
the final
> hole should be.
> 3.1- I make my own boring tools, It's easy as hell, take a 1" or
greater
> steel round
> 3.2- turn one end down so it fits in the chuck or collet of your
machinery
> 3.3- cross drill a 3/8" hole in the other end of the 1" round
> 3.4- cross drill and tap another hole in the round that
intersects the 3/8"
> hole
> 3.5- take a broken 3/8" tap and walk to your bench grinder (it's
a hard
> metal and makes good cutters.
> 3.6- grind away until the thing is shorter than your hole dia
(plenty of
> clearance)
> 3.7- now grind a cutting edge into what's left of the tap (I know
kind of
> unclear)
> It should look similar to a cutter for a lathe
> 3.8- stick your cutter into the 3/8" hole you drilled earlier and
secure it
> with a set screw in
> the hole you tapped earlier.
> 3.9- chuck this boring bit into your machine and make a hole a
few thou
> under desired
> so the final pass just cleans it up and makes a nice surface.
> My dad is an old tool maker and he taught me this, we have a half
dozen
> different sizes lying around the shop.
> The end result should be way more precise than the hole saw
method and
> should hold the sleeve a lot better. I can't imagine the surface
is smooth
> with a hole saw, the more rough the less surface area and less
holding
> force.
> Making the tool might take an hour but it will make a perfect big
damn
> hole."
>
>
> Doug Fir
>
> That is funny. No mention of the required mill or lathe
> rigid enough to hold the cutting tool and the rotor housing
> in precise align ment due to the tremendous forces involved.
> You want to know why a good mill weighs 7000 pounds?
> It is because there is no substitute for lots of cast
> iron when it comes to rigidity.
>
> Heck if you own a mill or lathe you can afford a $60 Chinese
> boring head. You are not going to do this on a drill press.
> I should not say that as you might try and be successful :)
>
> "One question. When boring through the housing how much of the
> lower bolt hole housing do you go through?
> None ? just graze it? Halfway?"
>
> I am not sure I understand the question. OK I think I know
> what you are saying. You are talking about the lower TENSION bolt
> hole just below the p-port bore.
>
> We go through quite a bit of it but we don't break through
> the bolt hole. See the attached scale Mazda DWG.
> We split the difference at 8.640 inches up from the
& gt; bottom. The Lemans engine uses the same tension bolt
> pattern as the 13B and RX8 engines.
>
> You have hit precisely on the problem of using a tube greater
> than 2 inch OD. I think you just talked your way out of it:)
> The problem did not occur to me until you just found it :)
>
>
> Paul Lamar ...No rotor no motor.
>
> I have not read every silly page but as far as I know
> nobody has equaled the 172 HP per NA rotor Mazda got.
> These guys are talking 150 HP per NA rotor.
>
> Kenku may be Japanese but he lives in Wisconsin.
>
> Doug, you seem bent on the rest-of-your-life R&D program
> so why don't you try something like this :)
> I may have these lying around someplace.
> Ken Powell and I put our heads together on this.
> I drew them up and built them.
> You want a good idle with a p-port. Here it is.
>
> Paul L amar ...No rotor no motor.
Paul and Doug,
I shipped these to Jerry Hey for a future project when 'life' bogged
down my RV-4 project. I bet Jerry would be willing to part with
these if Doug wanted to give it a try. Jerry?????
Ken Powell
Bryant, Arkansas
501-847-4721
C150 / RV-4 under construction
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