It seemed their was a clearance issue when installing the Renesis rotors
 in a 13B engine.  Do you recall what it was?  I think the gears, and
 bearing may be different as well.

 Doug in Japan

 News to me.

 Paul Lamar



  Paul,

  I'm planning on using Renesis 10:1 rotors in my p-port 20B.  As I
  understand
  it, I will need to cut the apex grooves deeper to accept the 13b/20b apex
  seals, and use only one of the oil scraper rings.  And of course, have
 the
  assembly rebalanced.

  Mark S.
  Austin

  http://www.rotaryeng.net/history.html

  Why not run stock low height RX8 apex seals? They have less weight than
 13B
  seals so they will follow variations better. Also the RX8 corner seals
  have a very low friction Diamond Like Carbon coating. DLC should be
  applied to all the seals but I think Mazda choose only the corner
  seals to keep the cost down. Seal friction has a significant affect
  on engine efficiency. Particularly at the higher RPM ranges we run.

  Paul Lamar


  Paul,

 I was under the impression that there was a risk of the thinner apex seals
 catching when passing over the p-ports.  If this isn't the case, then I
 agree, go with the Renesis seals.

 Mark S.

 No the 2 mm seals have been used for years with peripheral exhaust ports
 with no problems. The peripheral exhaust port is far harder on the
 apex seal than a peripheral intake port. A little slot opens up and you
 have high pressure, very high temperature gases shooting out of
 there at supersonic velocities. That is the main reason you need apex
 seal oil. The apex seal oil cools the apex seal.

 By contrast there is no pressure difference across the apex seal
 as it passes over peripheral intake port and the apex seal is cooled
 by the incoming mixture.


 There is another subtle  advantage to our intake p-ports in that they are
 oval
 so the apex seal is introduced to the opening gradually compared to
 what happens in the rectangular exhaust port.

 Paul Lamar


 Mark,

 As it was explained to me by the guys at Arizona Rotary they use a 2mm
 wide apex seal but they cut it the slot deeper to accept the 13b/20b
 apex seals. The rational being the RENESIS apex seal weren't designed
 with P-ports in mind and as such wouldn't need the thickness- strength
 to bridge the open ports. Is it a true statement and does it matter?  I
 don't know but it would behove you to speak with several shops that
 have done similar conversions already.  I think Mazdatrix has done a
 few.  I knew about the need to rebalance but I thought there was an issue
 with apex seal length expansion that had to be dealt with during rebuilt.

 Doug Fir


 Absolute total nonsense. Pure uninformed and uneducated speculation.

 That does not make sense Doug.

 The load on the apex seal is a function
 of the volume of the apex seal times the density of the
 material (Cast Iron).

 Lets look at the worst case scenario. A 5 mm high seal.

 Let's say the rotor width is 80 mm and the slot is
 48 mm wide. The volume of the 5 mm seal is there fore 5 x 2 by 48
 mm or 480 cubic mm or .0293 cubic inch. Iron weighs about
 .3 pounds per cubic inch so that part of the apex seal exposed
 to the hole weighs .00879 pounds.

 This load is distributed along
 the 48 mm length of the apex seal. The centrifugal load is m X V^2/R.
 m is in slugs and V is in feet per second while R is in feet.
 See the attached formula.

 Lets say R is six inches. .5 foot. The rotor rotates at 1/3 engine RPM
 so that is about 2500 RPM. The seal velocity is therefore
 1 foot (dia) times 3.1416 x 2500 or 7854 feet per minute or
 131 feet per second. That is twice as high as Mazda claims.

 m (the mass) is weight divided by 32 or .00879/32
 or .000275 sligs.

 So the load on the apex seal evenly
 distributed along the 48 mm length is v^2 or 17,160 times
 .000275 / R is 9 pounds. The length is 1.875 or the load
 is 4.8 pounds per inch. Check my calculations.

 This mean you have a beam with a uniformly distributed load
 of 4.8 pounds per inch.

 The formula for the max deflection is attached.
 http://www.roymech.co.uk/Useful_Tables/Form/Stress_Strain.html

 E is modulus of elasticity for iron which is 14,000,000
 (14 million) L is 1.875 inches. w is the load per unit
 length or 4.8 pounds per inch.

 Where "I" is the moment of inertia of a rectangular beam 5 mm
 high by 2 mm wide.

 Lets just look at the major factors for a moment
 and ignore the beam moment of inertia ("I").
 L (1.875) to the fourth power is 12.36. 12.36 divided
 by 14,000,000 (14 million E) is .000000883!! Divide that by 584
 constant and you get .00000000151 inches deflection!!!!

 The other factors pale into insignificance compared to this number.

 So I am NOT going to calculate them as my brain is
 now tired :)

 I defy ANYBODY, let alone a bunch of shade tree mechanics in Arizona, :)
 to measure this apex seal deflection. Far more deflection probably comes
 from the temperature difference from top of the seal to the bottom.
 That is probably less on a 5 mm high seal than on an 8 mm high seal.

 Check all my arithmetic and find an online beam formula where
 you can just plug in the dimensions.

 You might try this one but it does not work on my computer.

 http://darkwing.uoregon.edu/~struct/resources/applets/beam.html

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

 As a check on my numbers page 57 Kenichi says the max inertia
 load on the seal is 2.6 Kg or 5.72 pounds or 3 pounds per inch.
 Less than the the 4.8 pounds per inch I calculated.
 That means the deflection would be even smaller.


 Paul Lamar

 Well OK then, I don't see any need to cut the rotors for 13b seals.  I
 just
 didn't want to start spitting out apex seals over the Gulf of Mexico.

 I've set a Renesis rotor onto a 20b side housing and they look to fit and
 mesh with no interference.  I didn't measure the gears for variations, but
 will do that before using them.

 Mark S.

 Everything about the RX8 (Renesis) engine is optimized for it's 9000 RPM
 red line so it is loafing at 7500 RPM takeoff RPM. With your variable
 pitch prop you may see a lot more HP on take off if you can buzz it
 to 8000 or 8500 RPM.

 What RPM are you seeing in fine pitch now?
 How many feet do you need to get off the runway in Austin?
 What is the maximum climb rate you have observed?

 Paul Lamar

 Paul,
 I'm running Tracy's EC-2 which is rev-limited at 7500.  So, I will run it
 up
 to 7200-7300 on initial takeoff, then dial it back to keep it under 7000.
 There's more adjustment on the prop controller, but it would push the
rpm's
 over the rev limit.  Under those conditions, I will see around 1300 fpm
 climb.  It is usually off the runway withhin 900-1000 ft.  I usually
cruise
 at around 5150-5200.

 Mark S.

 That is pretty good performance.

 Here are my C182 specs. Except I have the long range 88 gal tanks.

 Horsepower: 230 ....... Gross Weight: 2950 lbs
 Top Speed: 146 kts .....Empty Weight: 1640 lbs
 Cruise Speed: 139 kts.. Fuel Capacity: 65.00 gal
 Stall Speed (dirty): 50 kts.....Range: 550 nm

 Takeoff..............   Landing
 Ground Roll: 705 ft ....Ground Roll 590 ft
 Over 50 ft obstacle: 1350 ft..Over 50 ft obstacle: 1350 ft

 Rate Of Climb: 890 fpm......Ceiling: 17700 ft

 What is the empty weight of your Lancair ES aircraft?
 At 5150 to 5200 what is the airspeed?

 Paul Lamar


Paul,

At 5150-5200 rpm, cruise is 160 162 TAS.  Empty weight 2100 lbs.  Fuel
capacity is 94 gal.

Mark S.

That is a capable airplane.

Paul Lamar

Paul,
Yes, you won't get any argument out of me on that one.  ;-)

Mark S.