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peterc005

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Hi,

I have a O-320-E1A engine that needs three new cylinders (cracked) and am thinking about replacing them with the higher compression equivalents to convert the engine to a O-320-D1A.

The higher compression cylinders are P/NO5K21100

The would take the engine from 150hp to 160hp and I hope to pick up maybe 5kt in the cruise.

Can anyone comment on whether this is a practical thing to do?

Is there a STC for this conversion?
 
stc

The only STC I find listed is for the E3D and E2A engines. If you search on groups.yahoo.com/group/lycoming you will find lots of info from Mahlon on this subject. The issue for certified aircraft is the 0 235 front main bearing used on many of the E series. The STC does not appear to be available for these engines. For experimental it doesn't matter. The STC that I found is RAM.
 
Thanks for the reply, I'll check the Yahoo forum.

My 320-E1A engine is a later model and has the bigger main bearing.

Who/what is RAM?
 
RAM

I think it is the RAM in Waco TX that does mostly Continental/twin Cessna work. Very well regarded in the Twin Cessna community.
 
Thanks for the tips.

The STC on the RAM site is a good start, but for a slightly different model (E2B?).

I'll keep reading the Lycoming forum so see what I can dig up.
 
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All you really need are 4 good cylinders and equip them with the 8.5:1 pistons and then you've got a 160hp O-320. You'll need to run at least 91 octane fuel. The STC'd conversions usually change out the carburetor too, since I think the 160hp carb is jetted a little richer.
 
The existing cylinders have 3,100 hours on them, and Lycoming say they are good for 3,000 hours. Unexpected pain having to replace them, but not unusual.

The cylinder kits cost about $1,100 each and are brand new from Lycoming. They include new cylinders, pistons, rings, valves etc. Bit of a pain, but the top end will be all new and not really worth messing around with used parts.

I think the STC says new carb jetting because it relates to different grades of fuel, rather than the compression.

I don't think the mixture would change with different compression, but am open to suggestions.

The low and high compression cylinder kits cost almost the same, so I figure I can pick up an extra 10ho + 5knt cruise for no extra cost or weight.
 
IIRC the issues relate to the cylinder hold down stud length and the thickness of the cylinder flange. If the current cylinders have a thick flange or spacers you should be fine - otherwise you may need to replace the studs.

Do check with someone who really does know before committing.
 
The only physical difference between the different cylinders is the bore.

I'll check to see if new studs are included in the kit, but expect that they are.

Thanks for the heads up.
 
The O-320-E1A can be converted to an O-320-D2A using an FAA-337 form as a major alteration, if the installation is a certified one. So no STC is necessary to get the engine converted. The bores are the same size it is only a piston compression ration difference that gets the extra 10 HP. You may or may not need an STC to get it on the airplane depending on if the TCDS has an approval for the D2A for your aircraft. I am assuming you are in a PA-28-140 and if so there is an STC to get the D2A on it from New England Propeller. If you are experimental then no STC is necessary to get it on the aircraft.
Hope this helps.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
Gudgeon Pins

I have done this conversion on my engine which I will start rebuilding in the next few days. I plan to put photos on my blog.

Mahlon as usual was a great help!!!!

When you fit the new pistons don't forget to fit heavy walled gudgeon pins (wrist pins in American). Mahlon supplied the parts for mine.
 
I'm not sure what the experimental aircraft engine modification & repair rules are is Australia, but here in the US you could also consider aftermarket cylinder kits such as the ECI Titan series of cylinder kits... ECI makes both certificated FAA-PMA'd and also experimental non-cert versions, at different prices of course.

Though nothing is wrong with Lycoming factory nitrided steel cylinders, those are very good. My old Cherokee had 4 new factory Lycs installed when its engine was overhauled before I bought it and now with over 1000 hours on it, the fellow who I sold it to reported compression readings in the mid-upper 70's at last annual inspection and it's running as strong as ever. My RV-6 has a factory Lyc O-320-D1A with the nitrided steel cylinders too.

A few years ago, I researched the costs of upgrading the Cherokee's O-320-E2A to 160hp and found the cheapest way was to use Art Mattson's STC and to buy the ECI brand pistons (FAA-PMA equivalents to the Lyc part#'s). I never did that upgrade however, and started flying RVs instead.

And to answer one of your original questions:
peterc005 said:
Hi,
Can anyone comment on whether this is a practical thing to do?
Click to expand...

Definitely!

10 more horsepower is 10 more horsepower!!! And it's a very cheap extra 10 horsepower if you're already having to do a top-end overhaul anyway due to 3 cracked cyls. I know in the Piper Cherokee, the extra 10hp makes a very noticeable difference in take-off and climb power. And for some weird reasons that I don't completely understand myself, an 8.5:1 compression O-320 is sometimes reported to run a little cooler cylinder head temps than the 7.0:1 compression, 150hp version of the otherwise exact same engine.
 
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mod

I don't think any one addressed to post about cylinder struds. This applies to narrow deck engines only and only the few that were built without the cylinder holdown plates that go under the cylinder nuts.
 
If the serial number of the engine ends in "A" it's supposed to be a wide deck. I don't think I've ever seen an O-320-E1A or -E2A whose serial number didn't end in "A".
 
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