I've been following the post on 150 to 160 hp upgrade. For a point of reference, my '66 Cherokee 140 (150 hp) was featured in the July CPA rag, so rather than buy a 180 - I've decided to march on with improvements and enhancements...
What I know so far is it just takes higher compression pistons, piston pins and the appropiate STC to bump up my O-320 E2A to a 160 hp mill. My questions are:
1. Parts cost to do this - minus the STC?
2. Best prices and who did you buy from for the above? I'm thinking Art's STC without the rpm restriction...
3. Anyone do the parts without buying new cylinders? If you did, after honing for the new rings - did they seal?
4. Probably better to buy new cylinders (and the correct higher compression pistons and related) - what would the Lycoming cylinder assembly part number be or what engine would it apply to?
My engine is about 254 hrs into a field overhaul, no problems, no oil leaks, no fouling, etc ("knock on a wooden propeller..."), so if I could do this with the right pistons, rings, and piston plugs without buying new cylinders, that would be a plus. I DO NOT want to hone the old cylinders and then find out they did not seal, so I need "been there - done that advice" on how you did your upgrade. If I had 1000 hrs or more on the cylinders, then it would make sense to do all new cylinders, pistons, valves, etc...
Looking forward to the replies...
Thanks.
Mike
aka "LTC V"
BTW: I bought Tom Lansden's plans for the baggage door mod (installed it) and installed Isham's 3rd window STC - wow, what a difference! No more climbing on the wing to load my 140 and it really opened up my interior - feels like I driving a 2/3 scale Cherokee 6...
Edited 1 time(s). Last edit at 07/16/2008 09:42PM by LTC V.
I can't address most of your upgrade questions as my O-320-E2A was upgraded to 160hp (O-320-D2A) at overhaul time. I got new Millenium cylinders and there was basically no additional cost for the upgrade other than to buy Art's STCs. Recently installed the Power Flow Exhaust when the old system developed issues, and the combination of the upgrade and the Power Flow are impressive. I took off the other day at about 3000' DA and got 1100 fpm initial climb rate moderately loaded. Temp was about 100df. I did a static runup on the runway and got 2340 RPM at this temp. Used to struggle to get 2285 RPM in the summer. Prop is pitched to the max and has Art's mod. Can't wait for cooler weather. If you upgrade, think about both mods.
Your baggage door project sounds very interesting. I often wish I had one too, as we travel with baggage a lot. I'd like to hear more about the project, like where you got parts, how long it took, what surprises you found, the hardest part, etc.
You should be able to install new pistons and rings in this engine without any problems, just treat it like any other TOH. You didn't say whose cylinders you used so I would advise to go with your cylinder mfg. recommendation relative to the honing procedure. Best of luck!
Before you make the decision to upgrade have your mechanic perform s.b. 505A on your crankshaft. If pitting is found this would limit the crankshafts service life. In simple words, the 150hp crank can be run indefinitly with internal pitting, the 160hp can not. Good luck!
With 250 hours you should have no trouble with your cylinders. All the 8.5 pistons do is ride about 1/8" higher because of the piston pin hole being lower on the piston.
If you have great compressions now, I have heard of folks even using the same rings on the new pistons and then you don't even have to break it in. The rings and cylinder walls do not care about the new piston.
If your engine had more time, you would want to be certain there is no wear that would have created a ridge. A ridge could break the rings, as they would ride 1/8" higher into the bore than the original lower comp ones did.
LTC - I have a 1967 Cherokee 140. I am really interested in your baggage door upgrade. I have been thinking about adding to mine. I hate climbing the wing to put baggage in.
I got Art's STC and upgraded during total overhaul. One of the important things to me was to make sure the cylinders were air flowed.
It isnt expensive and to me it is really worth it. You might check it out.
I too installed the Power Flow exhaust and increased my prop to 61 pitch. I did not have Art repitch. If you do something with your prop and the plane will be down for a while I would also suggest you look into having your ring gear balanced as well. Mine was out of balance.
