MyWay

Supertigre 45 with Jett SS tuned muffler with exhaust timing raised so that tuned muffler would be effective ran as follows; 15% fuel and APC props, 9x8=18200,9x9=17000,9x10=16200. Had to increase the combustion chamber volume and cut the face of the exhaust port flush with crankcase to get these numbers. Just hope it stays together.

Duane-RCU

My Feedback: (5)

What were the before numbers with those props?

MyWay

Duane-RCU, With the 9/8 and stock muffler around 15200. With open exhaust 16000. With timing bumped up just a little, 16800 with open exhaust. With this configuration I tried the tuned muffler and it ran 17200. Can't tell you what this engine in stock condition will run with a tuned muffler. I already had it modified to run a tower muffler before I got the tuned muffler. The tower muffler ran the same rpm as the open exhaust.

bob27s

My Feedback: (19)

With the SS muffler, prop for 17K and over ground rpm. You can see how it falls off. Tune point is between 17,500 and 19,000 rpm.

Stout setup. nice job.

Is this an older S-45 or a newer engine ? Which carb ?

Bob

MyWay

Bob27s, This engine is the new one made in China. With this engine setup I tried the sport tuned muffler and rpm went down 500 rpm for the 8,9,and 10 pitch props. The carb is the one that came with the engine but the throat size was increased to .360". The spray bar in this carb is quite restrictive even after thinning it down a little. I also tried this setup with the Supertigre 51 and got identical results. I just hope they stay together.

derferic

My Feedback: (32)

MyWay,

I have not tried these pprocedures, so I want to understand them better.

I presume "exhaust timing raised" means removing material from the top of the port. Approximately how much material?

Could you explain a little more about "increase the combustion chamber volume and cut the face of the exhaust port flush with crankcase"?

MyWay

derferic, First of all, I do not recommend this modification until I put more time on the engine. I have a feeling it won't take the extra stress. Second, the steel sleeve on the .51 is very hard and on the .45 the chrome plating was a challenge to cut. Third, You risk cutting thu the crankcase when elongating the holes to match the hole spacing of the tower muffler.
As far as timing goes it all depends on what you want to use for a muffler. The worst for power is the stock muffler. The tower muffler is better, a tuned muffler even better, full tuned pipe best. Each situation has different exhaust timing numbers.

DarZeelon

MyWay,


If you are talking of the new, Chinese GS-.45, it is an ABC engine.

By cutting away at the sleeve's exhaust port, you are risking a peeled sleeve.
It would not be an immediate, imminent event, like with an ABN's nickel coating, as the electro-plated chromium sticks much better to the sleeve's brass, but there is a risk involved nonetheless.

If it was a ringed engine with a non-plated steel sleeve, it would be much safer to do.


These RPM numbers are VERY impressive?

A 9x8 (sport) APC offers about the same power absorption, as an APC 10x6 and the RPM is over 1,000 higher than a Jett .50...

Bob?

buzzingb

My Feedback: (2)

It seems to me in a taper boared engine that the piston would not really be contacting the side of the cilinder much at the port. The piston only is in close contact with the cylinder wall at the top of the stroke thus peeling would not likely happen. I am only guessing. What do others think.

MyWay

Buzzingb, I have modified many engines and only had problems with the nickel plating on one engine. That was an os 28. The plating was so thin you could almost see thu it.

bob27s

My Feedback: (19)

What he built here with the agressive timing, reporting a bit, and larger carb is essentially what the Jett .40 started out as long ago. The SS muffler will draw it up into that 18K range. If done right, with a good piston/sleeve seal, and the right combustion chamber, no reason he would not get that sort of performance.

If there is any weak link in the setup, id imagine it would be the crankshaft. I seem to recall the GS-40 crankshaft was made somewhat 'light' to help keep the engine weight down. The rod might be next, but most ST rods are pretty stout.

MyWay

bob27s; Looks to me that the wrist pin to piston fit might be the weak link. I might of over compressed it at some point. Time will tell.

DarZeelon

Buzz,


That would only be true with a cold tapared-bore engine.

When the engine is at operating temperature, the differential heating makes the sleeve nearly cylindrical and the piston expands too.
Piston-sleeve contact is possible all over the working area of the piston, including the exhaust port.

Besides, piston friction is not the only thing that would contribute to peeling.
Combustion, exhaust and rapid heating/cooling cycles would also make this area pretty hostile, for a scratched surface.

Sport_Pilot

IMO most peeling is started by FOD cutting through ito the brass, on a nickle surface that is poorly adhering to the brass. Just as Monokote will peal away if you cut it at a bubble, but remain stuck to the balsa if you cut it where it is adhering to the balsa.

downunder

Hay Dar, if yor going to corect eveyones typos and hilite them, youd better make sure yours are rite

Diamond filing or machining ABC liners is done all the time with no apparent ill affects. Some have got away with doing it to ABN as well but I think there's a bit more luck involved there.

Duane-RCU

My Feedback: (5)

I know this thread has been a while, but how did the engine hold up? I compared my new chinese 45 to my old 45 S, and the sleeves are quite different. The ST forum said they were the same, but I also asked if there was porting/performance differences, and all I got was they will interchange. The port did not line up on the exhaust, so I don't think they will change. I'm no guru, really almost stupid, but looks like the old one I have will be much stronger than the new style. Ports are bigger, ect... What muffler do you recommend to just bolt up? This is on a Viper, so higher rpm is needed. 9X8 Apc prop? My old 45S wore out, would get 16,300 with the 9x7, about 1,000 lest on a 9x8, the new one is in the break-in stages now, using the old style muffler.

MyWay

Duane- Rcu. Engine is fine but has not been installed in a plane yet. For a good bolt on muffler get a Jett or ultra thrust tuned muffler. I know they cost more than you probably paid for the engine but they will add about 400 rpm more than your engine will run with open exhaust. I would say just put a tower muffler on it but the bolt spacing is different. It can be modified to fit with a little effort however.

Stoneweapon

I also have some experience with the Jett SS muffler.

I think it is the best muffler you can get if you want to use it in a user friendly 40-50 engine.

I used it first in with a G500 Super Tigre engine for pylon racing. The best tuned rpm seems to be 18500 because the engine reached it with different pitch props like 8,75x7N 8,75x7,5W and 8,75x7,75W but it did not unload much in the air. Fuel was FAI 20% castor 0% nitro mix.

Another very nice way to use the Jett SS muffler is to convert ordinary sport engines into real power houses.

In the german Q500 sport series we have to use 10 inch props.
The normal Jett stream muffler seems to be the best muffler for that purpose but with a 10x6 APC it is still possible to tune a Super Tigre G40 (made in Italy) at 14800 rpm using the SS muffler.

If the q500 model is airborne it unloads incredibly with the 10x6 APC.
As the speed and the rpm increases, the engine gets even stronger and screams like it wants to destroy itself.
The setup is al little bit tricky. If you start at a healthy rich setting on the ground the engine becomes extreamely rich in the air if it starts to reach the real tuned rpm range.
I lean the engine until it is really peaked and add one click to the lean side extra just before the start. This setting is right if it is airborne. I recommend to run in the engine with smaller props before doing this procedure. My G40 has done some training flights and one racing weekend with this setup. It has not suffered from it and I will continue to use it that way.
What I want to say is, that the SS muffler has a very broad range of usable props from pylon to sport and gives real good extra performance without the extra trouble of a tuned pipe.

The G40 performance can be compared to the hand selected Webra Q40 Engine with 9,5mm carb which some pilots use in the german Q500 sport series.


Another good thing is, that the 38mm bolt spacing is used by ST, Jett, Nelson and the newer Webra engines.
I would like to know what a [link=http://www.webra-austria.at/motor.php?search=1026GT&folder=AERO&lang=EN]WEBRA 55 GT AERO PM 9,5[/link] can do with this muffler.

MyWay

Stoneweapon, The Super Tiger 40 sport engine is a good engine. I ran mine with a Jett SS tuned muffler and a 9 1/2 x 8 apc. Like you said they unload a lot when they get in the air. Good bang for the buck!

Ernie Misner

How many of these performance mufflers are we talking about? There's the:

Performance Specialties muffler

Jett muffler (almost identical to the PS muffler, these might come in long and short versions for different rpm tuning)

Jett "SS" muffler?

Jett In Cowl Muffler (that is compact but actually gives performace boost)

Thanks,

Ernie

MyWay

Ernie, The Jett SS tuned muffler seems to work the best for me.

Stoneweapon

I was talking about the Jett Super Sport (SS) muffler.
This muffler is normally used for the Jett super sport Q500 engine which is legal for some race series in the U.S.

It is tuned for a higher rpm range (16000 to 19000) than the normal stream muffler which is normally sold as a after market magic muffler for sport engines and has a tuned range from 12000 to 17000 (from my experience).

I use them both and found that the SS muffler gives a better boost if you want to run your engine in the area above 15000. Even if the ground rpm is the same with both mufflers, the super sport muffler gives extra rpm in the air if you choose the right prop. This characteristic is very interesting if you want to fly your model fast like in Q500 racing.

The super sport muffler can be purchased as a spare part for the super sport Jett engine and is a little more expensive than the longer stream muffler.

Performance specialties may also offer mufflers which are tuned to different rpm ranges.

Here are some pictures from the Jett page:


( OS Max with the Jett Stream muffler)


(Jett SS 40 pylon engine with the shorter SS muffler)

As you can see, the SS muffler is a little bit shorter and has a different shape. The Bolt spacing is the Jett 38mm. I am sure they will also make one custom for people who want to use it on OS (37mm or 35mm). I think a OS 32FX will also run very well with a muffler which is tuned for 18000 rpm.

Ernie Misner

It looks like they put a Jett needle valve and carb on that OS Max engine also.

Ernie

propjets4me

very interesting, I've just bought a Supertigre GS 40 ringed .. I might have a look at doing similar mods... not sure what airframe it will end up in..probably a viper.. dont know how far I can take the timing up but I wouldnt take it to far just want to add a little bit , looks like it time to get out that degree wheel!!!.. might be a fun project..

if anyone has any advise or tips or suggestions ..please feel free


thanks Frank.H

bob27s

My Feedback: (19)

That is the photo we call "dressed to kill" Just showing all of the available aftermarket parts on one engine. Not required to make the muffler function as designed.

As for the ST45 muffler, it will depend on if you want speed, or just some real good sport performance power. The standard Jett-Stream is probably the best match for it, for about 80% of applications. Effective boost anywhere between 13,500 and 18,500 rpm. Perfect for your average 10x6, 9x7, 9x8, 11x5 type props.

For sport pylon and speed, the SS muffler is a good choice, but you have to select the prop to match the muffler's needs. Get the engine up above 16,500 rpm on the ground, and have the ability to unload in the air - i.e. a quick airframe. Effective boost range is from about 16,000 up to 20,000.

The turbo-jett is a unique animal. Gives you an rpm boost, but is quite broad banded, and tends to increase torque a bit. Allows using a larger prop. On my P-51 shown here, the SJ-46 is turning a 12x4 around 14,000 rpm. Unloads nicely in the air as well. With that engine's timing and the jett-stream, it will not turn that big of a prop - but it can and does very well with the turbo-jett. Engines like the ST45, ST50, Webra 50, OS46, OS91 love this muffler.