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O-320 150hp to 160hp?

Radioflyer

Well Known Member
I know many have converted their Lycoming 150hp O-320 to 160hp by changing their Pistons to create a higher compression ratio. I also know that Lycoming documents that this is not condoned by them. I forget exactly the reasons, but recall that one factor given was that the 150hp engines had a smaller front crank bearing.
Nevertheless, it seems many conversions have endured the test of time. Is this true? Would you do it again?
 
I’ve done that mod several times and highly recommend it , it will limit you to only run 100 LL though , the first one I did now has 2000 hrs and is ready for a OH ,
The best insight might be to look up the Ram STC the certified world pays $250 for !
 
Cylinder temp

Be prepared that you may get higher ChT’s on climb.
Jetting out the carb or getting a higher flow carb may be in order.

I converted from 150 -160 with higher compression cylinders and have been fighting high CHt’s. I finally upgraded my carb to a higher flow model. Problem solved.
 
I know many have converted their Lycoming 150hp O-320 to 160hp by changing their Pistons to create a higher compression ratio. I also know that Lycoming documents that this is not condoned by them. I forget exactly the reasons, but recall that one factor given was that the 150hp engines had a smaller front crank bearing.
Nevertheless, it seems many conversions have endured the test of time. Is this true? Would you do it again?

Only some of the engines have smaller front bearings, you'd have to look you see what bearing yours has.
 
Also note that the 160 HP variants all use the thicker piston pin and you will need to upgrade to those if not already there.

Larry
 
Pistons

The 0 235 front main bearings(some E series engines) are ok for 160 hp but higher compression than standard 160 is a question mark.
 
160 HP Mod

I’ve done that mod several times and highly recommend it , it will limit you to only run 100 LL though , the first one I did now has 2000 hrs and is ready for a OH ,
The best insight might be to look up the Ram STC the certified world pays $250 for !

I’m doing my second Certified 172 upgrade with the aforementioned RAM STC......wait for it Try $1000 bucks !! Certified guys get screwed in so many ways. The RAM STC does call for a carburetor change to the #10-5019 if I recall correctly. I prefer to use the 10-5217 carb on the pumped up 320’s I build that use carburetors as it flows more fuel.
As for the experimentals with a wide deck engine just order #75089 Piston and thick walled piston pin and “ Forget About It “. The 0235 front main bearing in the “ E “ series is no factor in the upgrade. The RAM STC does not require it to be changed so not worried about it in a experimental. One of my earlier builds of an 0320-E2D ( 0235 front main bearing ) has over 1500 hrs and it has LyCon 10:1 compression ratio pistons. ( The 160 hp uses 8.5:1 compression ratio pistons for reference ).
 
The engine I'm considering for the horsepower upgrade is an O-320-E2D, wide deck. So, it has the O 235 bearing? All the above comments are so specific and positive that it almost feels silly not to do.
 
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