Subject: Mazda Service doesn't do engines
From: Rotary Engine
Date: 4/10/2009, 7:51 AM
To: AAA Put this in the To box


  I called a local mazda dealer's service department, seeking a second
opinion
  on
  my used rotors. I was told by the service writer that dealer service depts
  do
  not take down engines, they don't even know what things inside look like,
  they
  just get a new engine form Mazda. Hmmmm.
  Does anyone out there who has the experience of rebuilding a rotary make
  inspection measurements as called for in the shop manual? During cleaning
I
  found some "minor" dings and dents, and some burrs along the edges (not
  seals)
  that I carefully stoned out in a 2 step process, med-fine, then very fine.
  the
  rotor housing clearence passes minimum of .1mm. but there are still some
  cosmetic issues where some knuckle head used a brass hammer, and a couple
  other
  dings. Would anyone here care to see pictures and offer comment?
  Will be posting turbo manifold this evening, along with other picuters if
  there
  is an interest.
  C. Smith

  Sure send the pictures.
  Paul Lamar

  Here are some images. I didn't want to compress them too much, and loose
all
  the detail.
  If there is a particular size you prefer to the group, please let me know.
  C. Smith

  Those are some strange marks but I don't see anything that is a show
stopper.
  As long as the holes for the end seals are not too oversize you should be
  OK. The pict size is fine. Perhaps a few too many but OK for this once.

  Paul Lamar

Yep 9:1 cr rotors

Skip

Still learning, what is the marking, or clue that identifies the rotor as
the NA 9:1 rotor?
Thanks, C. Smith

Old message.

Paul Lamar

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 Hi Paul,
 I'm enjoying following along with your current threads!!
 Hope you don't mind me chiming in here again to ask another newbie
 question:

 I've been slowly acquiring S5 NT (9.7 : 1) rotors for my 20B NA
project  (much cheaper that RX8 rotors).  I had 2, and just received the
3rd one  today.  I've been trying to be careful to make sure I get 
 rotors with  matching weight code stamps, but the one I got today is
different.  Can  you help here?  I hope you don't mind me including pictures!!  I
tried  to make the files small.  The first 2 pics are the rotors I
already had,  and they show a "C" along side another weird symbol (kinda looks
like  a 7).

 The next pic is the rotor I got today.  It shows a "C" along 
 side an  "E" :  My question is.......Is it OK to use all these rotors 
 together?  Are  these all S5 (9.7 : 1) rotors?  Is this last rotor a weight code
"C" or  "E" ?  What's the other symbol of Letter mean?

 Thanks again for all your help and knowledge!!
 Don

 From what I gather you can't mix and match weight codes.
 I think you need to have it balanced by an experienced
 rotary engine balancer. The rotors must be balanced
 about their center point and matched with all the other rotors
 for weight and then the counter weights adjusted
 for the exact weight of the rotors. There is a guy here in
 So Cal that does it.

 Rotor weight codes.
 The only thing I can find is this.
 http://www.rx7club.com/showthread.php?p=1309602#post1309602-

 I'll forward this to Jim Mederer. Hopefully he will have time
 to help as he gets the really hard questions :)

 Paul Lamar ...No rotor no motor.


Hi Don;

These all appear to "C" weight rotors.  For a 2-rotor, letter 
 codes must be adjacent,
e.g. B/C, D/E, C/D are OK  (A/C, B/D are NOT)
The rotors themselves are balanced about their centers at the 
 factory.
I am not sure what the balance requirements are for a 3-rotor.
I believe the backwards "E" and other characters are Japanese - don't
know what they mean.
Theoretically, the S5 rotors weigh the same as the 20B rotors, and 
 you "should"? be able to use the 20B front and rear counterweight without 
 rebalancing.

I posted some rotor/balance info a few weeks ago.
The S5 rotor faces are machined, the S4 have a rough cast appearance.
You could also measure the depth of the combustion area.
See attached file
- might be worth adding to the website.   I don't have any turbo 
 stuff. A couple of housing comparisons might be useful as well, I'll see 
 what I can scare up...

When mixing and matching parts for higher than stock rpm, a custom
balance is not a bad idea.

Cheers
Cary


 Thanks Cary,
 This is what I have:

 All are machined faces.
 Thanks,
 Don

Hi Don;
The S5 NA rotors are at a bit of a premium for racing and higher 
activities :)
Worth a quick depth check on the rotor recesses to ensure they are all 
the same. Personally, I would run the stock 9.0? 20b rotors in NA mode for the 
5-8% HP loss. If you have the room under the cowl - you could re-add a turbo later.
Just curious, what is your project? 
(Sorry if I've missed it, I don't read all the emails)

Cheers
Cary