ORIGINAL: Hughie42
The beginner is me. I have a full pipe and header from circa 1999. I want to bolt it on to my ST G-51 which will subsequently go in to a Model Tech .36 Extra 300. I want a reasonably speedy model to thrash about on the weekends. Are pipes difficult to tune and mount, and if so am I better off just purchasing one of the newer items such as the Jett Stream pre-tuned pipe, which they claim will increase a ST RPM in the order of 2-3 thousand. What prop would you recommend swinging, with an emphasis on speed for the model and motor in question?
Can I also use these Jett pipes on an OS 55AX. This time in a 40 size F3A style aircraft, called the Shadow, forget who makes it, smaller version of the Power 3D. Again what size prop would you recommend?
Thanks all
They're not difficult per se, but you have to understand the procedure and know how to analyze what is going on. A tuned muffler system probably gives you a bit wider rpm range in which you'll see boost. To see that boost you need to operate the engine in the pretuned range of the system. For specifics on the possibilities with the Jett tuned muffler system, I would cross-post to the Jett support forum, Bob27 probably will toss you some sage advice in no time.
That said, an Extra 300 is not a speed model, but it can fly quickly with enough power. Since it is also an aerobatic model, and you're dropping a .51 into a .36 airframe, my first instinct is that for flexibility over the entire operating range of the engine a regular can muffler might be the most versatile choice, giving you the baseline power of the engine and the tractability of a can muffled engine. I'd take a stab that a 10-7 would be a good starting point, allowing the engine to spin up reasonably well and offering good disk area, possibly dropping to a 9-8 or so if it will pull that somewhat draggy airframe well about which I have some doubts.
IMHO next in line from the can muffler would be a tuned muffler system a la Jett, but I would run your idea by them in the support forum and get a recommendation. I'm not sure I see the point of a full pipe in an Extra, but that would be your call.
My $0.02 worth, your mileage may vary.
MJD