BSE 76L Pressurized System Help  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> BSE 76L Pressurized System Help
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BSE 76L Pressurized System Help - 11/18/2005 5:48:08 AM   
mikeygp



Posts: 187
Joined: 10/27/2004
From: Greenville, TX, USA
Status: offline 		I am running a BSE 76L with a Cline Regulator for a pressurized system. I taped the crankcase for pressure and plugged the muffler backpressure hole it is the in-cowl muffler. I have used the system before so I know the regulator is good. The engine runs great on a non-pressurized system. I have moved the regulator before and after the remote needle with no luck. The engine is starved for fuel on the top end. It is way to lean when I turn the needle past about four turns it does not do anything the engine stays lean. When I kill the engine the system stays pressurized I have waited up to 15 minutes and it has not leaked any pressure. Please help I love this engine but to work in the plane it needs to be pressurized.

_____________________________

Michael Yosten
       Post #: 1

RE: BSE 76L Pressurized System Help - 11/18/2005 6:58:42 PM   
bob27s



Posts: 4730
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hi,

Thanks for writing......

Jett does not typically recommend using any form of regulator on the engines. Pumps too are about a 50/50 proposition. We have done some testing with them, and have had some mixed results at best. I too have had some personal interest in making the regulators work, but Ive had very limited success.

Jett engines rely greatly on muffler/tank/fuel delivery pressure to run properly. Of note, the jett mufflers provide more tank pressure than most stock or aftermarket mufflers.

The cline and iron bay regulators are good devices. Both require a 'suction' at the carb, and thus suction on the fuel feed line, in order for the regulator to open and supply fuel.

The Jett engines do not have an agressive venturi, and tend to have too little suction to permit the regulator type valves to work properly.

The engine/carb creates some draw, as you saw in your tests, but they do not hold the regulator open "long enough" to permit enough fuel to be delivered at each intake stroke. The regulator becomes the limiting factor. Thus the needle valve does very little.

What aircraft do you have it installed in ??

Typically for installations where tanks are located a limited distance from the firewall, we suggest using a main tank mounted within 12 inches of the engine, and 2 oz hopper tank setup right at the firewall which the engine draws from.

Let me know more about your application, and I can try to assist.

Bob Brassell


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to mikeygp)
       Post #: 2

RE: BSE 76L Pressurized System Help - 11/18/2005 7:27:48 PM   
mikeygp



Posts: 187
Joined: 10/27/2004
From: Greenville, TX, USA
Status: offline 		Thanks for the reply I got an email saying that my post had been removed I see it is back. Anyway I called Dub and talked with him he suggested using an OS 45 carb so I am going to try that tonight. The plane is the powerline edge 540 the tank is on the CG. Dub said that the tank would work there from muffler pressure but not for extended amounts of hovering and I like to hover so that will not work. I would have thought that some else would have done this for a 3D application and got it figured out but I guess not.

_____________________________

Michael Yosten

(in reply to bob27s)
       Post #: 3

RE: BSE 76L Pressurized System Help - 11/18/2005 8:04:28 PM   
bob27s



Posts: 4730
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Im glad Dub got back to you..

Dubs carb suggestion is what I was illuding to with my own limit success. In my case, I installed an old ST magV carb with the round spray bar. Much smaller carb, lost about 800 rpm off of the top end, but it drew enough fuel to make the regulator work. I found with a reasonable tank placement (not over the CG, but back a small bit) I could simply richen up the engine an extra hundred rpm or so and got better performance using the stock 76L setup. The fuel draw at 1/3 to 1/2 power was great (carb partically open), hover was not a problem.

I rarely put the fuel tanks directly on the CG. Sure, a benefit to it, but sometimes its just not worth the hassle. I did with pattern for a while, and we do with qm40 racing. On one or two of the prop-jet planes I moved the tank back because of the long nose moment. But my Edge, Cap and Yak i just sport fly / 3D with, I have the tank up front. The 16oz of fuel at a full tank (center of mass of the full tank) are only located 4 or 5 inches forward of the CG at most. Thats not a significan moment arm to make that huge a trim difference.

Let me know how you make out with the carb if you try it.

images here are of my AW Edge 540 BSE-76L installation. I use a bubble-jett 8oz tank located pretty much in the stock location (just not the stopper suck through the firewall. Fuel draw is not an issue.



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_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to mikeygp)
       Post #: 4

RE: BSE 76L Pressurized System Help - 11/18/2005 11:45:42 PM   
mikeygp



Posts: 187
Joined: 10/27/2004
From: Greenville, TX, USA
Status: offline 		Ok I did some thinking about it and after I read your input on the carb results that you had I gave up on putting a new carb on it for the time being. A loss in 800 rpm would be performance like my YS 63 and it in my opinion is not enough power for the plane. I had some time this evening to mess with it what I came up with was to make the cline regulator more sensitive how I did this was by taking one loop out of the resistance spring in the regulator. Early results look very promising the whole engine needed to be readjusted because it was able to suck fuel much more easily I ran out of day light but from what I have seen so far I think it will work. Will continue testing tomorrow. Any additional input or thoughts would be greatly appreciated.

_____________________________

Michael Yosten

(in reply to bob27s)
       Post #: 5

RE: BSE 76L Pressurized System Help - 11/21/2005 3:17:27 AM   
mikeygp



Posts: 187
Joined: 10/27/2004
From: Greenville, TX, USA
Status: offline 		Ok I give up I messed with it this weekend with the adjustment to the cline regulator I could keep the engine from leaning out on the top in but mid range and low end were no good. If I planed on running wide open the hole time this would work ok but I don't. I am very hesitate to contune messing with it because even if I get it to work I am not sure how reliable the system truly will be and with the type flying I do engine failure is not an option. So for now I am going to use the Jett the way the fuel system was designed to be used muffler pressure only. The new item on my Christmas list is for Dub to come up with his own pressurized system. My two cents worth on this is with the 76L putting out close to the same power as the satio 82 with much less head ach and 2.5 oz lighter and a fuel delivery system as good as YS offers this would be no brainier for 3d pilots in 40 sized planes on what engine to buy.

By the way the help I got on this was bar none the best tech support I have ever received. Dub even offered for me to send the engine to him and he would make the modifications necessary to fit the 45 carb.

Thanks
Michael Yosten


_____________________________

Michael Yosten

(in reply to mikeygp)
       Post #: 6

RE: BSE 76L Pressurized System Help - 11/21/2005 9:12:29 PM   
bob27s



Posts: 4730
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Michael,

Thanks for giving the adjustments a try. Apperently there is a finer balance to get the entire throttle range to work.

Give it a try as is. You might be pleastantly surprised

Always here to help

Bob


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to mikeygp)
       Post #: 7

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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> BSE 76L Pressurized System Help
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