determining compression ratio- NEW GUY

wadem · #1 09-08-2012, 07:27 AM

Hi guys,pulled the trigger and bought a 4! very excited and have a million questions....this is what I'm trying to figure out today!
Is it possible to determine what compression pistons are in an engine,i.e.,formula,compression check etc? engine is a O-320 E2D, which was only 150 hp (low compression) but seems to have a lot more.
Previous owner (who was not the rebuilder) has supplied a bunch of receipts of engine parts and the piston numbers are 73851. This makes no sense to me as all the research i have done says these are O-235 pistons (low compression)
would these work in an O-320? I also have piston ring number and other part numbers if it may help.
I want the ability to run regular octane mo-gas, thats why the enquiry, if i can't its no big deal, just trying to find out.
This plane is great! runs awesome. Serial number is 1537, originally built by Ralph Dye, and then I believe Dave Lathum of Washington state. If anyone has any track history or info on this plane please pass it along!
From what I can tell most parts were ordered from Superior Air Parts Inc. From there it looks like Ralph had the engine built by Pointer Aviation. (Good place??)
Any help here guys would be greatly appreciated, again awesome site and am happy to be aboard!

woodmanrog · #2 09-09-2012, 05:55 AM

There should be a complete history of the aircraft in the airframe, engine and prop logbooks. There should also be compression readings of all of the cylinders in the last conditional inspection report. Welcome to the club. I flew a "6" for 8 years with a 150 HP engine and loved it. I'm sure you will learn a lot and have many enjoyable hours.

FlyingArcher · #3 09-09-2012, 06:48 AM

Hello Wade,

Looked up in my O-320 PC and no reference to your piston p/n in here.

Here is the cross-reference for cylinders and pistons so you might find some help with it.

Good luck

TomVal · #4 09-09-2012, 07:23 AM

Quote:

Originally Posted by wadem

...From what I can tell most parts were ordered from Superior Air Parts Inc. From there it looks like Ralph had the engine built by Pointer Aviation. (Good place??)...

Since you have the name of the engine shop that built your engine, they could best answer your questions. What would help them in locating your engine build sheet is giving them the work order number on your engine overhaul invoice.

Regards,