Hi All,

The ongoing saga of setting up my Oriental I believe is nearing an end.  I originally was running an LA 46 with the stock muffler, stock needle valve and a BYO 11-4 prop on a uniflow setup w/o muffler pressure.  I could easily complete the pattern on 3 1/2 oz of Sig 5% nitro 20% caster fuel.  The other day I replaced the stock muffler with a tongue muffler and on a lark went to a Bolly 12.5 x 5.5 carbon fiber prop.  I assumed the prop would be too much for this engine.  Not so.  It took off like a shot and was giving lap times of 5.20 seconds on 62 foot lines.  It went wherever I pointed it without any loss of line tension.  My first flight was on four oz of fuel.  The plane ran out of fuel in the middle of the overhead eight.  On the next flight I filled the tank to its 4.5 oz capacity and ran out of fuel in the cloverleaf.

I do not have room to put in a 5 oz tank unless I can get a custom made tank.  My tank size is 1 inch tall, 4 1/2 inches long, 2 inches wide.  I have excess space to add 3/8 inch to the height of the tank.  I am willing to purchase such a tank if anyone can make a recommendation to someone who can make one. 

If anyone has any other suggestions to solve this problem I certainly would appreciate hearing from you.

Thanks

Peter Mick 

Hi Peter Mick

I run LA 46's too. I use an OS 762 muffler, LA 25 Venturi, stock NV, two head shims, 11X4 Vess, 10-22, 50/50 and use about 3-1/2 oz's for the pattern.
This is with a Vector 40 (ARF) size ship running a rich 2,2,2 stroke and I have NO problem with power.

I'd suggest going back to your first set up and getting rid of that @#%$*&@#$ tongue muffler. ( I don't like TM's) But that is just my HO...........well maybe not so H.

Jerry

More load increases fuel consumption, as does more nitro, more air flow (i.e., bigger venturi or muffler outlet) or higher oil %.  While the Bolly might well work better than the BY&0 11-4, I think you should keep looking for a more suitable propeller. Perhaps a TT 11-4.5, an APC 11.5 x 4 or 12.25 x 3.75? Remember, it's not about how it looks or how heavy it is, but how well it works,  how likely you are to break it, and can you replace it if/when you do break it.    Steve

On my Fronkensteen 4, I use an OS LA 46 and a Tower 40 Muffler with an XOAR 12 X 4 prop. It uses 3.75 oz of fuel, 5% nitro, 15% castor, 5% Klotz.

Interesting timing on your problem.  I just finished a scratch built "Green Box" Nobler and put an LA46 in it.  For the sake of heavy front end I put a Randy Smith LA 46 CNC tube muffler on it.  It weighs 1 oz.  A great savings over the 2+ oz. stock muffler.  

I ran out of fuel on the overhead 8.  Next filled my 6 oz tank with 5.5 oz.  Was barely able to complete the Clover leaf but not the 2 laps after.  This engine had been in a profile Pathfinder and I always used 5 oz with a very comfortable margin for the pattern.  After a lot of "horsing around" with set up, I went back to the stock, albeit heavy, muffler.  I am now back to a full pattern with plenty of comfort for completion on 5 oz fuel.  Guess I need to learn a lot more about exhaust systems.

Your putting out more power with my muffler, are you running high nitro ?, you can do several things, first drop to 5% nitro, that engine with my muffler setup make huge power for a Nobler, you could also add 1 head shim ,you should check to see what size venturie is in the motor, and what NVAs is in it, if it is the stock size it will use more fuel ,as it is a 20 size Spraybar and about .30 thou smaller diameter than the normal size bar , you should be able to do a pattern with 5 or so ounces

Randy

Randy, guess my answer did not really answer your questions.  So I'll try to do better.

I started out with Sig 10% Nitro and 20% (half Castor and half synthetic) fuel which is my typical.  I have only the one stock head shim, running an oversize venturi (.297) which I changed out with a stock venturi (.282 or thereabouts), with both your NVA and an ST51 NVA.  As you can gather, I was trying different variables to try to get at the problem.  Once I get through the contests I will try your suggestions with your muffler once again.

Thanks again.

Mike