Upgrading O-320-E1A to O-320-D1A?

[peterc005]

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?

[jrs14855]

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.

[peterc005]

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?

[mosquito]

Originally Posted by peterc005

Who/what is RAM?

http://www.ramaircraft.com/aircraft-...72-upgrade.htm

-jon

[jrs14855]

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

[peterc005]

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.

[Neal@F14]

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.

[peterc005]

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.

[Doug]

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.

[peterc005]

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.