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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> Custom made Stream Muffler
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Custom made Stream Muffler - 2/17/2005 7:56:44 PM   
Stoneweapon



Posts: 60
Joined: 11/28/2004
From: M'gladbach_NRW, GERMANY
Status: offline 		I purchased an 60-90 Stream Muffler which I tested on an OS Max 70SZ and the engine showed awesome performance.

Now I think about using an Stream Muffler on my Irvine .39 which is an small block engine with the exhaust bolt-spacing of the small OS Engines 25FX, 32SX) which is 35mm.

The Stream Muffler offered for this bolt spacing is tuned to about 18-20k. The Irvine .39 likes to rev like an normal 40 engine at about 15-17 on the ground. I got 17000 rpm after initial break in on an 8x7 APC with the Stock Muffler using FAI fuel containing 0% Nitro and 20% castor. With 10% Nitro and 17% synthoil I got 18000+ with the 8x7 APC. After a few flights the engine became better and has more Power now. I have yet to test the RPM's with different props. The engine has no Problem to turn bigger Props like 10x6 or 10x7.

Is it possible to get an Stream Muffler for the 40-50 sized engines combined with the small front end of the .25-.30 Muffler which has an bolt spacing of 35mm so that it would fit my smallblock Irvine .39 ?

If you have any experiance about Stream Mufflers on this Engine please let me know. May be the smaller one works good with it. The Manual says that the mecanical RPM-limit of the engine is 25000 rpm but I think the timing will not support higher RPM's than 19000.
I will use the engine into an small speed model. I will test some 9xx APC to set the Engine to 15000 on the ground.


Thanks
       Post #: 1

RE: Custom made Stream Muffler - 2/17/2005 9:54:36 PM   
bob27s



Posts: 4833
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hey there Stoneweapon ...

Someone else told me about the OS70 heli engine. From what I can tell, the OS70 is pretty high timed......was meant to really turn up in the helicopter. Seems to really enjoy a pipe or tuned exhaust. If you have time, perhaps send me an email with any performance data you might have, and maybe a photo showing jett-stream installation. Much appreciated!

As for the Irvine .39 engine..... the regular Jett-Stream .30 size muffler should work just fine for you, unless you wish to slow the engine down much below 14K rpm.

The JS-30 muffler is essentially the same RPM range as the 40-50 muffler. Anything from 14K to 19K is fair game. Just select the prop accordingly. Works best between 15,000 and 18,000.

From what you described, that would work out pretty well for you. If you are getting 17K now with the stock set-up, adding the jett-stream muffler would allow you to stay at 17K, and increase the prop pitch a bit... or drive the rpm up more.

Jett's BSE-40L is similar in displacement and size as your irvine (OS 32 size), and is intended for lower RPM that our normal BSE-.30-.35 engines. Typically turns a 10x6 around 15,500 to 16,000 peak rpm. (all most as good as the SJ-46 actually!) We use the same JS-30 muffler on this varient.

If there is a specific rpm (lower or higher) you are shooting for, let me know what that might be, and I will see if Dub would be able to accomdate that within the muffler.

Bob


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to Stoneweapon)
       Post #: 2

RE: Custom made Stream Muffler - 2/17/2005 11:58:01 PM   
Stoneweapon



Posts: 60
Joined: 11/28/2004
From: M'gladbach_NRW, GERMANY
Status: offline 		Thank you again Bob for the useful informations. I'll test-fly the Model with the stock Muffler and change to the Stream Muffler if it is set up and still alive after some flights. The red Irvine should look nice with the Stream Muffler.

I dont want to hide the information about the 70SZ with the the Stream Muffler so I post it here (my emails are filtered out too often).

The 70SZ has only about 1/4 Gall fuel burned. I did the initial break in with the stock muffler and tested the engine for a few flights in my Krick Blue Max. The pilot has seen many different engines in front of his gun so far.

After this I ordered the Stream Muffler and ran the engine with it on a test stand.
I used only the 20/80 FAI Mix and the setting was still a bit rich.
It was an good flying day so I did not make a long session.

The Temperature was about 2-4°C (aboute to freeze...sorry that I cant tell you in °F)
I started with the stock muffler to be able to compare the effect of the Stream muffler.

On an 12x6 APC it was at about 12100. Very well for an almost new Engine of this size.

Then I changed to the Stream Muffler and got 13300 with an rich 2-stroking setting.
The engine ran very well and responded agressively to the throttle. The needle settings was very uncritical.

I also tested the 12x8 APC with the Stream Muffler.
It turned 12300 rpm. Still rich and no problems with the needle setting. This might be a little heavy prop since the 60 class heli engines work around 14000 into an helicopter.

Remember: Everything without nitro! 14000 should not be a problem with the 12x6 on 15% nitro.

The Engine is going to be used as an powerplant for an conventional Trainer Airplane, which has an relatively thin Airfoil but a bit much weight for ordinary 60 engines. It should have a lot of Power for this job. The model can be flown at higher speeds around 100 mph or more.


I've heared about broken pistons in some OS 70SZ-H Engines. If this happens to my one, I think I will upgrade to an Jett 76 or 90.
Can these Engines (Sport Jett or BSE) be purchased without a Muffler at a special price?
In the case of "sudden OS piston death" I would already have an Stream Muffler that fits the Jetts.

I have only one Picture of the 70SZ-H with the Stream Muffler fitted. It looks nice anyway... Yes it was cold that day.


EDIT:Tried to fix my english.

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< Message edited by Stoneweapon -- 2/18/2005 8:40:12 AM >

(in reply to bob27s)
       Post #: 3

RE: Custom made Stream Muffler - 2/18/2005 2:15:08 PM   
bob27s



Posts: 4833
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Thanks a great deal for the info and photos. Always good to have that information at hand. I am most pleased that you have obtained good performance.

Your information supports another post in the Extream Speed forum. One person there noted the performance of the OS70 with a full Hatori pipe on it, where that OS70 was indeed turning over 14,000 rpm on a 12x6.

I was unaware of the piston issue on the OS70 you noted.

As for the engine/muffler .....

MOST of the OS compatable Jett mufflers are drilled for both the OS bolt pattern and the ST 47mm spacing. If you have the one with two sets of bolt holes, it will work on the Jett 76/90 engine. Jett uses the 47mm ST spacing. In which case, you could not that you have a muffler at the time of order, and Dub may make some adjustment. Or, you might want to order the engine with a Turbo-Jett, and then you would have one of each muffler


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to Stoneweapon)
       Post #: 4

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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> Custom made Stream Muffler
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