RE: Rossi 53 questions
 

CNCswiss, IT gets on the pipe on a good down line, but not level flight. Dub Jett recommended putting a smaller prop on the motor. He told me that it should stay on the pipe, when I richen it up. And to richen it up 800-1000 RPM.

I just switched the Jett Pylon muffler for a Nelson ultra thrust sport. The motor now comes on the pipe around 10.5k and jumps to 12.5-13k. I then lean it out to 16.2k. I can richen it down to 15k and it does not fall off the pipe.

This is what leads me to believe that the pipe is too short! I can put the Jett pylon muffler back on it, and try a smaller prop. I just dont think that the rossi likes to turn more than 17k.

This is off of the rossi page

RE: Rossi 53 questions
 

Its about 6 1/2 inches long.

RE: Rossi 53 questions
 

What Dub told you is correct. I has less to do with the engine porting.... more to do with the prop selection to hit the rpm tune point on the muffler. If you have the black muffler you have to find rpm by reducing prop size. (what is what the racing muffler is for... high rpm, small props)

What prop are you running.... ???

The racing muffler has to spin upwards of 17.5K rpm and higher.

(the sport muffler boosts from 13K upward, just like the sport ultra-thrust - "racing" ultrathrust is 16.5K and up )

If you are seeing the engine hit 16K, but is more comfortable around 14-15K(wit the UT muffler) ...... you either have a lot of prop on there, or something is wrong.

8.75x8W or 8.8x8.5 ---- try one of those.. or a stock APC 9x7

RE: Rossi 53 questions
 

Bob,

I am now running an 8.75x 9 on the motor with the UT sport pipe. and I am getting 16.2k out of it. This is a lot of prop.
If I want to run the Jett Pylon pipe, I need to put a smaller prop on the motor, so I can get on the pipe.
Is there a limiting RPM that the motor is capable of? if not, can I put a 7x8 on it and spin 20k on the short Jett pylon pipe.

RE: Rossi 53 questions
 

Well, from what I understand, the engine is rpm capable. I wouldn't worry about breaking it.

If you have the "real" Q-500 muffler (black one) that muffler is designed to turn up - so yes, you would want to target somewhere around 18K or better for ground rpm. A little experimenting is in order.

With the regular Jett-stream (red) muffler yes, 16K would be the right number.

The 8.8x9 and 8.75x9W are a lot of prop, but they only fly well at airspeeds that easily get up over 150 mph.
(for reference, the Q-500 .40 engines turn these two props 19K on the ground and 21K in the air)