hooty301

Im looking for a Perfomance Speicalties Ultra Thrust muffler for my OS .61fx .Where could I find this ? Also what would be a better choice for max power, the Ultra Thrust ,Jett or a regular unmuffled tuned pipe? I was told to ask here about the ultra thrust.

mstam

My Feedback: (1)

This is YS support :-)

You didn't tell where you want the engine's power peak to be. Need it to be tuned for torque or max power?
For torque get yourself the shortest www.pspec.com muffler.
For max power use either the long Ultratrust muffler or a Macs (pre-tuned) pipe.
http://www.macspro.com/pretunedsystem.asp
or http://www.macspro.com/tunedpipes.asp if you like to tune yourself.

Props: Use low pitch (wide) props (APC) for torque. Use a higher pitch for power, depending on your application you want a 7 to 9 pitch. Start with 7.

For torque use a prop that lets the engine run between max torque and max power rpm, for power tune for max power rpm.

You already own the 61? If not, get yourself the 91.

Attached WAS an OS50-SX incl. Ultratrust muffler and Perry pump, tuned for max everything. It only lasted 6 months and is not worth repairing anymore.

Turk1

Do you mean OS or plane died?

proptop

My Feedback: (8)

Go here: http://www.rcuniverse.com/forum/forumid_197/tt.htm

Ask Dave Shadel...I know it sez YS Support, but he's the guy you'd get an U-T from.
They also make them for engines other that YS's

Maybe point him towards the thread of yours in the Extreme Speed forum so he can see what you are trying to do?

Edit: Added link http://www.pspec.com/results.asp?category=8

hooty301

Thanks for your help I appriciate it.

mstam

My Feedback: (1)

OS
piece of piston broken, piston ring eaten, grooves in cilinder and I already replaced the bearings earlier.

speedster 1919

My Feedback: (3)

I'll bet you got less than 10 hours total flying time when the first set of bearing went bye bye on that 50.

Build-n-flyer-RCU

My Feedback: (4)

Ultrathrust mufflers work really good. I run a pair on my Twin Air. I started with 46FX engines and they lasted a year or two before they were flat worn out, and then I replaced them with the newer 46AX engines.

The idle and transition has always been perfect which is important for a twin, and I get around 1000 RPM more with an Ultrathrust than with a regular muffer. But power does come at a cost. My experience is that running at peak or leaner with a tuned exhaust is really tough on engines. I ran 15% coolpower in the FX engines. I switched to 10% Omega for the AX engines and tune a little richer than I would using regular mufflers.

Walt

vwitte

My Feedback: (1)

where can I purchase an ultraThrust muffler?
thanks. OS 40 46 and 91FX

1QwkSport2.5r

They aren’t made anymore, so the only place you will find them is on the secondary market. What IS still available is the Jett Jettstream muffler from Dub Jett engines. Dubjett.com

The red mufflers are right on par with the ultra thrust in terms of power and tractability.