Mark Langford wrote: >I'm still looking for ideas on "what works" in various VW aircraft installations, because what I have isn't working. I took off in 95 degree temp yesterday, and after idling to the runway and a quick runup, it was at 400F as I turned crosswind, and I wasn't even at pattern altitude yet!<
I spent some time looking through my engine log book for my first KR and the CHTs were always in the 400 to 425 degree range on climb out and then around 375-400 in cruise. The last set of heads on that engine were CBP 044s. I purchased then 1990, and had 150 hours on them when I crashed in 2009. When I tore them down the exhaust valves had a lot of wear in the seating area and all the valve spring retainer groves were really worn, along with the valve guides. I had done many different things to get them to run cooler including installing adjustable cowl flaps. I gained the most by smoothing out the cowling exits and changing to full synthetic oil. I remember reading some people reporting a higher CHT using synthetic, but I did get a consistent 25 degree drop in CHT. Of course, the oil temp went up from 170 to 190 in cruise. Not enough to worry me. I have rebuilt the old 044 heads with new valve guides and new 214NSS stainless valves from CBP and recut the valve seats with a Neway cutter. I currently have about 75 hours on them. I Flew on a 100F degree day over the weekend and here are the temps I got. Climb: 330F, taken under a cylinder head stud and 410F under a spark plug. (I think I got hotter than that). Cruise at 6500 ft. 3200 RPM, 145 MPHI: 300F under the stud, and 350F under the spark plug. The engine is a 2180 with the compression ratio set at 7.2:1 I always pull the prop through four blades to make sure the valves have not developed a leak. I have 75 hours on the heads and the engine is still running strong and smooth, but now after shut down and pulling the prop through I have a slight hiss coming from one cylinder out the exhaust pipe. If I let the engine cool for 10 minutes or more the leak goes away. Maybe a sticky valve guide? It will be interesting to see how your DPD heads hold up. Roger Bulla rbulla2 at wic.net -----Original Message----- From: Mark Langford via KRnet Sent: Tuesday, July 19, 2016 7:15 AM To: KRnet Cc: ml at n56ml.com Subject: Re: KR> Cylinder Heads Again
