BigBadJon

is it better to go with a ultra thrust sport muffler or a ultra thrust plyon muffler on a rossi 53 thats going into a prop jet?

plyon http://shop.vendio.com/RossiEnginesU...897/index.html

sport http://shop.vendio.com/RossiEnginesU...895/index.html

daven

My Feedback: (1)

John,

You would want the sport muffler. The pylon one is only effective at higher rpms than would be practical on your Rossi.

Also, go to www.pspec.com and save some money over the site you listed.

Kmot

My Feedback: (24)

Don't beat me up for asking the following question!

The Tower Hobbies muffler looks very similar in design to the UT muffler. How similar is the performance?

Razor-RCU

My Feedback: (50)

Geesh, what a stupid question Tom!

I like the Tower muffler myself but the Ultrathrust does yield better performance, about 800 rpm's in my book. Not sure why... Bob?

daven

My Feedback: (1)

The Ultrathrust is tuned, the tower muffer is not.

Many have said that the Tower muffler does tend to increase rpm over stock mufflers, but not nearly as much as the ultrathrust.

Mike Connor

My Feedback: (5)

We did some testing of the Tower vs UT on a TT 46 Pro a couple of years ago. The Tower did give close to 1000 rpm increase but the UT gave almost 1500 rpm increase. The Tower is cheap but it was not uncommon to lose the back half in flight.

proptop

My Feedback: (8)

The way I understand it, or at least I think I understand it is...

The U-T is a tube within a tube, right? The exh. pulses go back, then bounce fwd. then back again and out, correct? It's kind of like a compact version of a tuned pipe. (what is it, a half wave, or ???)

The Tower is an empty chamber that just happens to be the correct size and configuration to provide a tuned effect on engines of around the .40-.50 displacment.

Ed_Moorman

My Feedback: (1)

You are correct about the Ultra Thrust. Here is a photo of one I cut apart after I broke the mounting ear in a crash.

The Tower muffler is a large, expansion chamber that gives a good bit of tuning. I have gained 800-1000 rpm on .46-.52 siezed engines. You can gain 1500 rpm or more with an Ultra Thrust provided you use the correct size prop. The Ultra Thrust, and the Jett, which is similar, are cut to length for a fairly high rpm range. You need to use a prop that lets your engine run at that rpm. Generally, they need to turn a minimum of 13,500-14,000. You can definitely hear when they stage on the pipe.

BigBadJon

Already have a plyon muffler for it, but will order a sports muffler if needed. i just got the engine. but anyone got any ideas for a plane and a prop size to run the rossi 53 with plyon UT muffler?

KC36330

8.8x8.75 APC Pylon would get you into the RPM range to benefit with the pylon muff and will give some impressive speed on the right airframe.

kc

EDIT: make sure you get the APC is a 'D' hub (thicker for the higher RPM), the Pylon series are.

Rudeboy

Wow... the Tower sounds good... you can gain 1000 rpm with this thing on a seized engine...

Julian537

My Feedback: (9)

Make sure you do not use more than 5% nitro in that rossi, or you will have all kinds of tuning problems!!

proptop

My Feedback: (8)

Thanks for the pics Ed [sm=thumbup.gif]

Hey...about how thick is the casting? Specifically the area where, oh, let's say a Q40 typically grinds down when it noses over on landing? My guess would be about .060 or so or maybe a frog hair more?

bob27s

My Feedback: (19)

The ultra-thrust and jett-stream mufflers are very similar. These are both tuned exhaust systems, and include porting and internal geometry that basically make them a 1/4 wave tuned pipe. Part of the design consideration is the gas velocity and backpressure - which is why these mufflers have carefully sized exhaust outlets, and great consideration is given to the muffler/tank pressure fitting location. Most importantly, they are assembled as a one-piece unit, and neither of them is going to come apart.

Both the Jett-Stream and Ultra-thrust mufflers are available for different rpm ranges (different applications) and of course various sizes and types of engines. As example, the standard Jett-Stream .46 size muffler will boost a TT40, 46 or OS 46FX by and easy 1300-1700 rpm on a 10x6 prop. Target range for this muffler is 14,500 up to 17,500 - with the best boost in power noted over 16,000 rpm. Jett also offers a similar muffler, tuned for about 1000 rpm lower for slightly bigger props, and the SS or LX muffler tuned for 1500 rpm higher for smaller props. (from my test notes, the OS46FX ran between 14,100 and 14,300 with a 10x6 and stock setup - with the jett-stream it ran from 15,800 to 16,000)


The tower muffler is similar in external appearance, but does not have the same internal design consideration or gas flow path. However, it does has demonstrated an 'inadvertant' tuning effect none the less, and aside from the through bolt it is a fairly well designed muffler. Boost of around 800 rpm is common. A bit more on smaller props. The tuning effect for this tends to be right around 15,500 rpm - and can boost up to around 16,000. So if you use this muffler for the Tower 46, or other engines, and prop for something 15K or higher, the muffler does kick in and can give you a few hundered rpm boost (as opposed to a shell and baffle type muffler).

Bob

Kmot

My Feedback: (24)

Thanks for the excellent info about the differences in these mufflers.

Razor-RCU

My Feedback: (50)

I was gonna post that but I don't have time since I am at work- [X(]

bob27s

My Feedback: (19)

it took most of my lunch time

daven

My Feedback: (1)

9am lunch

DHG

My Feedback: (7)

Well, would you look at that -- it's lunch time AGAIN!

Bob,

I'm curious about how critical the placement of the pressure tap is. On a double-tapered ( "full" ) pipe I put it at the widest point, or sometimes right on the exhaust stack next to the engine. Either way seems to work, although I've always assumed the wide point gives the highest & most stable pressure. Do things get spookier with a folded pipe? For example, are there places on the exhaust stack that work better than others?

Mr. Part-Time Resonant

Happy Feet

If you take a flight from the east coast to the west, you could have a 4 hour lunch!

bob27s

My Feedback: (19)

Duane,

the pressure placement is not super critical, but there are a few places where the pressure is "higher". Mainly the pressure location has to do with the structure - where you can tap for the fitting. Turns out that is a higher pressure, lower velocity area anyway.

DHG

My Feedback: (7)

Bob,

Thanks, that's reassuring.

Duane