I consider myself an automotive "engine guy," and know my way around automotive engines quite well, having rebuilt well over a dozen of them over the years (mostly Chevy big & small blocks, as well as a couple others). Aircraft engines, however, are completely new to me-- and the idea is not lost on me that the bar is set quite a bit higher with these engines than what I may be used to, especially when it comes to safety tolerances and redundancy. Still, for me, part of the attraction of building my own plane is to also build my own engine, and that is what I have set out to do.
On the back burner, I've been searching online for the "perfect" Lycoming IO-540 engine. I wanted it to have relatively low total time, and be in running condition but perhaps be close to overhaul time. I found an IO-540-J4A5 for sale in FL that came off an Aztec and seemed to meet the criteria I was looking for. A notable feature of the -J4A5 variant is that it is actually a turbo-normalized engine-- the only turbo model that Lycoming made (to my knowledge) that did not bear the TIO- prefix.
Before you go find the "flying high and fast" aka "tubos are bad for RV's" link and email it to me, I have no intentions of actually installing this engine on the aircraft with the turbo. In fact, this particular engine is unique in several ways. The crankshaft, rods, and pistons are all the exact same part numbers as for the non-turbo engines such as the Van's recommended -D4A5. In fact, the compression ratio is exactly the same as well. My plan is to run this engine normally-aspirated, and apart from a few minor differences it should be pretty close to parts-equivalent to the -D4A5. These are the only meaningful differences I am aware of at this time:
- The -J4A5 uses Bendix 1200-series magnetos instead of the Slick used in the -D4A5.
- The -J4A5 uses a gear-driven fuel pump instead of the more common pushrod drive
- The -J4A5 has piston-cooling oil jets-- something necessary for a turbo'ed engine but I believe will have significant benefits for NA as well. It may cause higher oil temperatures, I hear, but that can be mitigated with an improved oil cooler, if necessary.
- The -J4A5 has different mounting ears than the desired #70456 to mount to an RV-10. I'll be on the lookout to pick up a set of these at some point.
- The fuel injection servo is tuned differently to work with the turbo.
Most of these differences I consider to be unimportant, and additionally I should have a number of unused parts (turbo, servo, magnetos, etc) that I will be able to sell later on and hopefully recoup some of the purchase price of the engine. We'll play a lot of this by ear as time goes on, but the important part for me is that we have the engine now, and have plenty of time to deal with part-swapping as time goes on.
Anyway, here's the info on the engine itself: it has complete logs with 3046.7 hours total time, 1503 hours since major overhaul, and only 123.5 hours since a new top end (cylinders) had been installed. It did have a prop strike, but the seller was willing to guarantee the case, crank, and cam to be serviceable, as well as have an A&P/IA perform a "prop strike inspection" (more on this later), two fresh overhauled magnetos, and a sign-off for return to service. Basically, this engine could be bolted right back onto the front of an Aztec and fly away. Of course, my plans for it were a bit more involved.
The giant, heavy crate arrives that contains my 'new' engine! It was very well packed.
All removed from the crate and placed on the stand.
Side view of the engine prior to disassembly.
Over the next few weeks, I plan to tear it down and ship the parts off to the various overhaul shops around the country. I will be rebuilding it myself and returning everything to factory new tolerances, with a few experimental upgrades such as EFI and electronic ignition. Ideally, I'd love to home-brew that system but time, money, and comfort/safety may dictate otherwise. Plenty of time to figure this out... we'll see how this goes.
