I tried a .46 Jett muffler (red) on my G51 and lost power compared to the ST silent muffler on normal props. They're tuned for a top rpm of about 17,500-18,000 I think (the red Jett). Maybe a tad less. The red Jett mufflers are said to be about 500-800rpm below a full pipe without the "Pipey-ness". If you're after all out power, then obviously the long pipe is the way to go. OR try the gold Jett muffler which is like 17,000-20,000. I think the Q40 black one is good for 22k+... airraptor knows for sure though.

Felt like making some noise. Tried my AX with the 10-6 on my Twist with no muffler. 15,750. With the muffler was 15,300. Maybe the baffle was not in. Not sure, seemed kind of loud. It seems like the FX, AX, SF and most of the similar ones all run about the same. The AX is maybe a bit under the FX, but the newer Powerbox muffler makes that up. Same sh-- different pile. My Royal one was up there too. I have sold it since then.

I have found the Super Tigres respond well to porting. I had a tired old Italian S .40 and after porting and a new ring it turned a 10X6 MA on 5% at 15,000 rpm with the first version of the swing muffler. I made an adapter to use the .60 size swing muffler on it and it turned 15,400 rpm. The Super Tigres are one of my favorites. I have also gotten great results porting the ST S .61.s as well.

Regards, Bill

Just about any engine will benefit from porting. I haven't done any aircraft engines yet, but I did a Picco .28 buggy engine recently. The biggest changes I made were boring the crank out .75mm and increasing the induction port probably 15 degrees or so. It is a stout engine in stock form, but it gets to be quite the beast when modified. I look forward to doing the SuperTigres. I will probably do one of my GS 45s first. I have an S45 ring that does 14,700-14,900 on a 10x6 APC and silent muffler. The smaller swing mufflers are loud and rob some power. I like the idea of using a larger muffler - I've found substantial gains by using larger mufflers on smaller engines. My little Enya .30 gained almost 1800rpm by using a .46 sized muffler on it - and it only has about 150 degrees of exhaust timing.

Most of the Enya stuff was designed in the 1970s when mufflers were not used much. There have been a lot of improvements since then. Even the newer Supertiger mufflers are a good change. I don't have one to test, but know they are quieter. That style, as well as the OS tend to tear off the lugs of the exhaust in a crash though. Headers are kind of nice that way.

I have a G51 Italian ST that I rebuilt awhile back. It came with a silent muffler that I ran it on for some power tests and later tried a .46 sized Jettstream muffler and actually lost power with it compared to the silent muffler. The silent muffler is heavier though.

The Enya 30 I spoke of is the SS series with twin ball races. I'm not sure when they were designed, but they succeeded the X series by some time anyway. The new SS 30 is ABC, but still comes with a lapped piston like mine.

Well after working with my buddy Ron we got one of the old Italy ST 45s to turn a APC 9x8 at 17,400 with a tower muffler on 10% nitro and 18,100 on a red Jett muffler with 5% but needs a bigger chamber with the pipe. Runs really well with the Tower muffler. It has the lowest ports of all the Italy engines too it seems they were changing port sizes and heights over time.

That's 145 mph with a clean plane on the red Jett pipe. Pretty good for a $100 motor. High pitch props make things fun.

The Tower muffler is shorter and smaller in volume than the Jett muffler, isn't it? I haven't had a Tower muffler (same as the GMS .47 muffler I think?), so I'm not familiar with it. My running ST .45 has been run as a diesel since I got it - as a diesel with a thin spraybar, it turns a 13x6 APC at close to 11,000. With the round spraybar it originally came with it turned the 13x6 at 9,900rpm. I have a new Italian .45 in the box I paid $40 for that I might setup as a hot rod.

Have you been able to get a .45-.55 engine to match what a Jett 56LX can do on a 10x6?

Yes I think so. the 9x8 is a good benchmark prop for me. I will have to go look and run a few engines on the 10x6 APC and get back with you. may tack some time as I am working on race planes for Muncie in July. Going to the NATS to race.

Picked up an Evolution .40 still with the flywheel ring. It surprised me a bit with a run of 16,900 with no muffler, and 15,000 with the stock pretty muffler. I took it apart and noticed that the crank is blended on the bore. I think that is a good detail for a cheap motor to have. I radiused the top sharp corner with the little grinder. I can not remember if that was done before or after the test. I ran another Supertiger that I got that day that said G.40, and it did 15,000 with the muffler. It was an odd muffler, not the new one or the one that pivots.