No doubt Lynn is correct. But while power is everything to a racer, it rarely is everything to the rest of us. Look at how temps in cars have been inching upward for decades. If metallurgy & lubricants would allow it, they'd be running 500 degree engines because it's more efficient (Lower delta-T; less energy lost to the coolant/outside world, where it's not doing any work).

On Mon, Jan 29, 2018 at 4:49 PM, Kelly Troyer keltro@gmail.com <flyrotary@lancaironline.net> wrote:

Guys,

   None other than our Rotary Guru Lynn Hanover has stated in the past that coolant temps over 160F hurt power........Perhaps

he will Chime in here again and enlighten us !!............<:)

Best,

Kelly Troyer

On Mon, Jan 29, 2018 at 4:14 PM, Neil Unger 12348ung@gmail.com <flyrotary@lancaironline.net> wrote:

Jeff,   I also installed a thermostat after trying all the other options, cowl flaps, cardboard over the rad,  and could not get it constant with the 180 degrees.  I have operated much machinery here all fitted with thermostats and have never had a failure for 40 years.  I am more than happy with a thermostat in my renesis -- would do it again every time.  Failures in thermostats are extremely rare, about as common as a prop coming loose.  My thermostat is permanently in place summer and winter.  If worried change it every 500 hours.

On 1/30/2018 7:51 AM, Jeff Whaley jwhaley@datacast.com wrote:

Hello All:
Up until this past weekend I have purposefully avoided using a thermostat in my 13B aircraft engine - reason being is that many years ago I had one stick open and another stick closed in my GMC truck.  Encouraged by reading Steve Boese's flight report from last fall, I decided to give one a try.  Operation up here in the frozen north requires some method of maintaining engine temperature when power is reduced or when it's really cold.  Cowl flaps, louvers and mechanical controls are okay but they add a lot of weight and complication VS a simple thermostat.

I opened up the top of my water pump housing, extracted the bypass plug, removed my 0.75" restrictor plate and inserted a 180F thermostat from Racing Beat.  On Saturday I refilled the coolant system, pressurized it and ran the engine up to temperature.  On Sunday I bled off the remaining pressure, rechecked the system, pressurized it to 8 PSI and went flying.  At first I felt a bit uneasy as the engine warmed up to 185F-indicated while still on the ground - but I assured myself that is what it's supposed to do !  Other than my gauge reading 185F and the device being advertised as 180F it worked flawlessly; temperature never varied at all and there was a good source of cabin heat.  OAT was about 3C or 36F at the time.

My plan is to leave the thermostat in place for now and keep a close watch on engine temps as the OAT rises next spring/summer.  I expect it will be removed for summer operations and re-installed again around October 2018 ... we'll see.

Jeff
13B, RD1C, 130 hrs TT.