REFLECTOR:High Taxi And Hold Temps.

[Ronnie Brown]

Sid and Jim:

Here's a note I wrote a year ago.  My engine cools very nicely.  I have the GRT EIS with bayonet thermocouples on each cylinder.  I only have the single oil cooler up front.  If you can get the engine to cool normally, then you shouldn't need the 2nd oil cooler.

Ronnie Brown
N713MR - 160 hours
http://home.sprintmail.com/~romott/page10.html   
  ----- Original Message ----- 
  From: Ronnie Brown 
  To: reflector at tvbf.org 
  Sent: Monday, January 12, 2004 1:46 PM
  Subject: Re: REFLECTOR:High Taxi And Hold Temps.


  Like Scott mentioned yesterday, a key consideration for cooling this pusher is to make sure the engine cylinder baffles are correctly installed - no gaps at the crankcase.  Also, make sure the wraps go around the bottom of the cylinder and only leave about 1.5 to 2" gaps at the bottom of he cylinders and heads for the air to exit from the cylinders.  This sounds restrictive, but IT WORKS.  It keeps the air flowing THROUGH the fins with good velocity.  Also make certain that there is a wrap on the back of #4 (right, forward cylinder), because the Velocity supplied plenum leaves this area very open.

  My NACA top inlets on my 173 Elite RG with Lycoming IO360 C1C (angle valve engine), will stay under 320-330 CHT's while taxiing, holding, etc.  

  On climb out, the hottest I have ever seen is 370-380 CHT and all I have to do is add airspeed, i.e., instead of 100 knot climb, reduce climb to 120-130 knots, and the temps go back down.  I did not have to seal my plenums with RTV but I did lay up 2 BID from the plenum onto duct taped cylinder block to close up the gaps.

  My cruise CHT's are 320 - 360 degrees depending on RPM's and leaning.  My oil temps stay under 210 on hot days, and runs 180-190 on cool days.  I have good heat coming from my oil cooler too.  I haven't flown below 40 degrees, but I have to just about close off the heater to keep from getting too warm in the cabin.  I have taken care to close up the gaps around the elevator torque tubes and closing up the space between the top of the canard and the canard cover. 

  I am very pleased with my Velocity engine cooling.  I expected troubles from talking to other Velocity builders, but I have really been very pleasantly surprised with how well it works.  Mark Machado had similar success with his 173 (now the standard factory trainer) when he changed from arm pit to top NACA scoops.  I also noted that Mark had built BID wraps for the bottom of his plenums.  Mine are Stainless Steel, but it doesn't matter what they are made of (aluminum will work too), make sure you have wraps on the bottom of the cylinders.

  Incidentally, I have noticed that my front cylinders (3&4) run warm at higher speeds and the rear ones (1&2) run warmer at lower speeds.  So I have not done anything to balance flows.  Works good like it is.

  Ronnie Brown
  N713MR 110 hours
  http://home.sprintmail.com/~rolandbrown/page10.html
    ----- Original Message ----- 
    From: MikeWatsonSpg at cs.com 
    To: reflector at tvbf.org 
    Sent: Monday, January 12, 2004 1:04 PM
    Subject: REFLECTOR:High Taxi And Hold Temps.


    Does anyone else have any theories to alleviate the long taxi and hold heat situation?

    Mike



    Hi Mike
    I confess to having those chimney hopes as well. I expanded the oil door opening to about a 1 foot by 1.5 foot opening, so I could do a better pre-flight check and occasionally wonder about running a cable back there to pop it open while I'm sitting on the ground as the cowling sure traps in the heat. I am pulling some ideas together to put in two small scoops on the belly to run air directly at the fins of cylinders 5 &6. as they just get too hot in climbing out, but I don't think that will do anything much to aid cooling when I'm sitting on the ground... but who knows.

    Rodney Brim, Ph.D.
    CEO, Performance Solutions Technology, LLC
    Delivering goal+plan based technology/processes for highly coordinated and accountable management teams
    www.performancesolutionstech.com or www.managepro.com
    Ph. (562) 799-1267


      -----Original Message-----
      From: reflector-admin at tvbf.org [mailto:reflector-admin at tvbf.org]On Behalf Of MikeWatsonSpg at cs.com
      Sent: Sunday, January 11, 2004 3:48 PM
      To: reflector at tvbf.org
      Subject: Re: REFLECTOR: Frankliln/IVO High Temps


      Thanks Rodney,

      I also have 10.5:1 ratio. If I have to hold for more than 15 minutes on a 85 degree
      day, my CHT's approach 385 F. Usually I have to pull off at the run up area, shut
      down for at lease 15 minutes.

      I thought the heat would escape up through the ducks and out the nacca while
      idling, like a chimney draft. I guess I was wrong.

      Mike Watson 

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