Hi,

I have purchased two new G51 Super Tigers from Tower Hobbies to run in a Topflite Cessna 310. I mounted up both engines and have set them up identically down to the linkages.
I started both engines today, and out of the box, one runs exactly as it should, and the other runs like a pig. It surges, doesn't burn very much fuel (leaves a big mess) and idles terribly. Mid range gets a little more like it, but low end is not very good.

Now both engines regardless have had the same amount of fuel put through them (about half an hour of running), and while the good one has fine compression, the poor one has noticeably lower compression. I lifted off the head to check the seating on the cylinder, retorqued the head down and checked the rest of the engine as well. I did notice fairly uneven wear on the cylinder wall from the still bedding in ring. I noticed what appears to be a small hole in the cylinder head to perhaps locate the ring in it's land. I also noted the poor alignment of the maching jig for the head has caused the holes drilled for the head bolts to erode through to the sidewall into the relieve machined for the cylinder liner. I don't believe this causes a compression loss however as it is not a machined sealing surface.

also on further inspection (and strangely enough) the compression is better in the reverse direction than the forward direction.....any explanation for this??

Now my question is, should I persevere with this engine or send it back for warranty work? With a twin I'm concerned that the performance may never match the other engine, and that if the performance disparity is apparent now, it must have a poor machining tolerance somewhere in the manufacturing process.