Thorp Air Command - T18.net

How are these pistons going to me made?
Any room for custom comp. ratio?
900 for titanium pins and total seal rings?

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http://www.dixiefriedfabrication.com/

The pistons will be CNC'd from forgings. What compression ratio you looking for? 9310 pins per the suggestion of my piston guy and Deves rings. Deves are more user friendly in our air cooled engines. Let me know what you are looking for. I'm also going to have the pistons and pins match up to standard O-290 parts weight wise so if you just want to top your engine balance won't be an issue. If you really want Ti pins we can do that but they are more $$, I didn't even price them.
I just ask for your patience and tolerance here as we are in the middle of horse show season and I do crop hay all summer.

Code name "Lizard Man"
The Possum Works

Oh, just to be clear, $900, may be slightly more or less for everything, pistons, pins, buttons and rings.

Parts Department
The Possum Works

My compression numbers are getting lower so the AP wants to hone and do rings although we can't find rings. Can I get your source on rings in order to price them? I'll need 3 chrome and 1 non-chrome (I have 1 chrome cylinder). Depending what we find I might just take up that $900 package and just refresh the hole thing if there is piston wear.

Guys,

What about the strength of the cylinder bases when you increase the compression ratio? I have a wide deck IO-320 and from what i remember about the O-290 is that the flanges on the cylinders are thinner than what is on my engine.

Jim

O-290 are all Narrow Deck engines. Narrow Deck O-320 high compression and O-360 engines came with cylinder flange plates to add strength to the flange. They use special Barrel Nuts because the larger cylinder bore (than the O-290) causes the cylinder exterior to be closer to the cylinder studs, so a typical cylinder wrench won't fit over standard nuts.
The force applied to damage the flange would be 10.5% greater on an O-320 (5.125" bore) because the bore is greater than an O-290 (4.875"). An O-360 has the same bore as an O-320, with 1/2" longer stroke.
The question is: Do O-435 high performance engines, like GSO-435 (300 HP!) from an Aero Commander or a helicopter use cylinder base plates and barrel nuts? If so, get some. These engines use angle valve heads, which would require different pistons, so I'm just referring to the cylinder base.
http://canadianflight.org/content/lycoming-go-435-0

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Scott Emery
EAA Chapter 326
T-18 N18TE