cgmg
Senior Member
- Joined
- Oct 30, 2003
- Messages
- 1,149
- Location
- El Paso, IL.
- Aircraft
- Empty hangar right now, have owned and flown Air Command & RAF
- Total Flight Time
- 375
Latest update on my Subaru issues:
Once I got everything back together, and did my first runup on the ground, I discovered the engine would only achieve 4400 rpms, not the 5300 I had been achieving previously. Called the sub guy, and he suggested I put the original throttle body back on, as the engine may not be compatible with the 2.5 one(they look identical, don't know how anyone knows the difference).
Finally got back up there, and spent a couple of hours switching out the throttle bodies. Jim had worked me through how to set the TPS sensor, which took me a while to get good readings there.
Took the gyro outside, did my trial runup, no change in maximum rpms!!!!!! I then took a degree of pitch out of the prop, and tried again. Same result! And, to add insult to injury, discovered the alternator had failed. Had to jump start the gyro to pull it back inside.
When I was discussing my problems with my NAPA buddy, who said the alternator was covered under warranty(yahoo!!!) he suggested my problem sounded like a plugged exhaust.
I really hated to break open my Supertrapp, since I had no experience doing so, but today was really warm here, so the deed got done. Guess what???
Yep, it was plugged almost solid with fiberglass fluff!!!! Not sure how it ran at all, since I could hardly see any open slits in the baffles. There's really nothing to the Supertrapps, construction-wise, and they're easy to remove, disassemble, and put back together. I removed all the fiberglass before reassembly.
Did a trial run with the exhaust wide open, and as soon as the rpms hit 5300, shut it down. Let it cool a little, then re-installed the baffles. Wire-tied everything, and did another runup. It was headed for 5700 rpms when I shut it down. Not sure how far away from full throttle I was, but didn't want to find out how much more rpms it would gain.
Added two degrees of pitch to the prop, and tested again. Seeing about 5400rpm max now, which may still be too much in the air. But, daylight was almost gone, so called it a day.
Now I have to wait for the alternator to arrive, and for decent weather again, for the next tests. This time of year, good days for working on the gyro, and testing things, are few and far between. We're scheduled for snow and much colder weather for the rest of this week.
The bad thing is, I wasted a lot of time and effort avoiding messing with that Supertrapp, for being afraid of working on it. The good news is, my engine is now ready for flight, and I didn't have to pay for another mechanic trip, or to replace a bad alternator. Gotta love those NAPA guys for their lifetime warranty on their alternators.
One other note: If you're using a Supertrapp, take it apart and pull that fiberglass out of it! To my amateur eye, it appears the only reason the fiberglass is in those things is to keep the exhaust heat from frying the exposed ends of the little socket head bolts that hold the baffles in place. I'd much rather buy a new baffle set every two years or so than deal with the frustration of lack of engine rpms. Just my two cent's worth.
Once I got everything back together, and did my first runup on the ground, I discovered the engine would only achieve 4400 rpms, not the 5300 I had been achieving previously. Called the sub guy, and he suggested I put the original throttle body back on, as the engine may not be compatible with the 2.5 one(they look identical, don't know how anyone knows the difference).
Finally got back up there, and spent a couple of hours switching out the throttle bodies. Jim had worked me through how to set the TPS sensor, which took me a while to get good readings there.
Took the gyro outside, did my trial runup, no change in maximum rpms!!!!!! I then took a degree of pitch out of the prop, and tried again. Same result! And, to add insult to injury, discovered the alternator had failed. Had to jump start the gyro to pull it back inside.
When I was discussing my problems with my NAPA buddy, who said the alternator was covered under warranty(yahoo!!!) he suggested my problem sounded like a plugged exhaust.
I really hated to break open my Supertrapp, since I had no experience doing so, but today was really warm here, so the deed got done. Guess what???
Yep, it was plugged almost solid with fiberglass fluff!!!! Not sure how it ran at all, since I could hardly see any open slits in the baffles. There's really nothing to the Supertrapps, construction-wise, and they're easy to remove, disassemble, and put back together. I removed all the fiberglass before reassembly.
Did a trial run with the exhaust wide open, and as soon as the rpms hit 5300, shut it down. Let it cool a little, then re-installed the baffles. Wire-tied everything, and did another runup. It was headed for 5700 rpms when I shut it down. Not sure how far away from full throttle I was, but didn't want to find out how much more rpms it would gain.
Added two degrees of pitch to the prop, and tested again. Seeing about 5400rpm max now, which may still be too much in the air. But, daylight was almost gone, so called it a day.
Now I have to wait for the alternator to arrive, and for decent weather again, for the next tests. This time of year, good days for working on the gyro, and testing things, are few and far between. We're scheduled for snow and much colder weather for the rest of this week.
The bad thing is, I wasted a lot of time and effort avoiding messing with that Supertrapp, for being afraid of working on it. The good news is, my engine is now ready for flight, and I didn't have to pay for another mechanic trip, or to replace a bad alternator. Gotta love those NAPA guys for their lifetime warranty on their alternators.
One other note: If you're using a Supertrapp, take it apart and pull that fiberglass out of it! To my amateur eye, it appears the only reason the fiberglass is in those things is to keep the exhaust heat from frying the exposed ends of the little socket head bolts that hold the baffles in place. I'd much rather buy a new baffle set every two years or so than deal with the frustration of lack of engine rpms. Just my two cent's worth.