OS40FP

I know this question has been asked before , but I don't know how to find the information.
What do I need to do to make this thing stunt friendly????? Venturi size? I think some one said to block off the boost port??
Compression ???
Anyone out there that can help me?? Thanks. Bill

LAST EDITED ON May-05-06 AT 10:04 PM (CST)
 
Bill,
Use three head gaskets. A 5/8 tall venturi,with a .280 hole size.
And a good tube type muffler.

Gordy

283 venturi, large OS FP venturi, available from Tower. At least two head gaskets. Drill out stock muffler or use a tongue muffler that is free flowing. 101/2x41/2 apc. Powermaster %5 22% (50/50). Sometimes a third head gasket helps. It should run a fat 2-cycle. Straight muffler pressure, no uniflow. Lots of power. A nasty break when airplane needs an extra pull. Good parameters for a start.

These engines respond well to running lots of fuel through them. Reason for the large venturi and low back pressure exhaust. Small venturis and a stock exhaust can drive you crazy with run run runaway. If you're getting ridiculous long runs on 3 ounces of fuel, open the venturi up and put some holes in the muffler. When tamed these engine are addictive beasts. Presently I'm running five or six of them. (Depending on what's recently crashed and under repair.) The ones in stunt planes haul and are controllable. The ones in sport planes sing a siren song of speed and power. My Buster and Galaxy are a blast. Tune me up.

Anyway, the above is what we do in Philly. Opinions will vary.

Best,

> I know this question has been asked before , but I don't
>know how to find the information.
> What do I need to do to make this thing stunt
>friendly????? Venturi size? I think some one said to block
>off the boost port??
>Compression ???
> Anyone out there that can help me?? Thanks. Bill

Bill;

A thread concerning the FP40 was commented on very recently:

http://www.clstunt.com/htdocs/dcforum/DCForumID1/19246.html

V/r

LAST EDITED ON May-06-06 AT 10:28 AM (CST)
 
Check this post I threw out there last year, it really helped me.
http://www.clstunt.com/cgi-bin/dcforum/dcboard.cgi?az=read_count&om=14640&forum=DCForumID1

BTW, I use the smaller OS 35-40FP-S venturi (not the really small 20-25), stock NVA for FP20-FP40 and the stock muffler with no other mods and love the way it runs.

Parts:
Muffler is the E-3030
NVA is #22311000
Venturi is #23312100

Chris Sterner

Lots of "guaranteed to work" formulas are around. My considerable explerience with this engine says "your experience may vary".
Differernt FP40's seem to require different solutions. More head shims are a place to start, Our host has .010 shims very reasonably(cheaper than OS).
Prop loading is important. Underproped engine will drive you nuts. An 11-4 or 11.5-4 APC is a good start.
Try different venturis .250-.280 to see what works best.
Use 5/22 or 10/22 half castor fuels. Too little oil=runaway.
Chunk the factory muffler.
Jim