I don't think an oil cooler will be necessary. ?One of the things I did during this round of modifications was to significantly reduce the cowl outlet area, primarily because the engine ran too cold, and secondly to reduce cooling drag. ?I probably got it about right, but with the additional timing advance available in the P-mags, it creates quite a bit more heat during cruise flight, so now the oil temps are running a few degrees warmer than I would like to see. ?However, I don't think it's going to take much more than a little bit of redirecting of available air to the oil tank to address the additional heat. ?Hopefully, I'll get a chance to do something with it in the next week or two.
-Jeff Scott Los Alamos, NM > ----- Original Message ----- > From: Randy Powell > Sent: 07/01/13 06:44 PM > To: KRnet > Subject: Re: KR> Additional testing data with P-mag timing > > I believe an oil cooler can be added to the o200 if you should choose to do > so. > > Sent from my Ipad > Randy Powell > Wachapreague Va 23480 > > > On Jul 1, 2013, at 12:54 PM, "Jeff Scott" <jscott.planes at gmx.com> wrote: > > > > > I dialed in the aggressive timing on the P-mags for testing this weekend. I > > really don't expect better performance from the additional timing advance. > > It should have a some additional timing advance with lower manifold > > pressures at higher altitudes or partial throttle operations (cruise > > flight) to help with fuel savings. Bear in mind that I operate from a high > > altitude airport, so can not pull more than 23.5 inches of MP, so expect > > some timing advance even during full throttle climb operations. I found > > that during climb out, my hottest CHT bumped up from 390 to 405. That is > > still acceptable, although on the cusp of what I am comfortable with > > running. As soon as I start dialing the throttle back a little, the CHT > > immediately drops as the throttle plate disturbs the air flow and the fuel > > mixes and distributes a bit better across the intake spider. #2 cyl has > > always been the hottest CHT under full throttle conditions due to an uneven > > fuel distribution at full throttle, so has become my measuring stick during > > climb operations. As soon as the throttle is reduced, the temperature drops > > into line with the other cylinders. During today's flight, under cruise > > conditions the CHTs ranged from 300 - 340*F across all 4, with only #2 > > (back left) running a bit warm during climb out. > > > > The biggest issue was the oil temp during cruise flight. I was cruising > > with the cowl flap closed and 18.5" MP at 11,500'. Under those conditions, > > the timing curve should be fully advanced to 39*. My oil temp topped out at > > 220*F and stayed there under those (summertime) conditions. I was able to > > drop the oil temp back to 210* by opening the cowl flap, but that also > > induces a significant amount of drag, which is less than ideal for cruise > > flight. This is about 15 degrees warmer than the oil temp was running with > > the timing curve topped out at 34* under similar conditions. I am going to > > leave the timing dialed up while I explore ways to get a bit more cooling > > air directed at the oil tank (the O-200 does not have an oil cooler). If I > > can't get a little better results with the oil temps, I may have to > > restrict my timing advance to 34* during the summer months and dial up the > > timing for the fall and winter months. > > > > This and other write ups are located on my web site at > > <http://jeffsplanes.com> > > > > Jeff Scott > > Los Alamos, NM > >
