Large .90 thru .120 motors not ringed  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> Large .90 thru .120 motors not ringed
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Large .90 thru .120 motors not ringed - 2/10/2005 6:59:40 PM   
STG



Posts: 3498
Joined: 7/3/2003
From: New Richmond, WI, USA
Status: offline 		I have herd nothing but good things about your motors but have always been reluctant to try a larger 120L because it was not a ringed piston design. Could you elaborate why Jett does not use a ring when going to the larger piston sizes? Don't get me wrong, I am sure you know more about motors than I do and that is why I would like to hear a reply about this. Thanks

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RE: Large .90 thru .120 motors not ringed - 2/10/2005 8:08:33 PM   
bob27s



Posts: 4834
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hi,

Thanks for writing... I'm always happy to answer questions (when I can).

Good question too. I belive Dub is one one of the few out there using AAC (ringless) on his larger engines. Some of the better big engines use AAR and toss a ring in (webra for example). Its a good approach.

The ABC and ACC type designs Dub uses in his engines are pretty tried and true. If you use the proper metals, design it properly, and exercise extreme care with tolerances during manufacture, the "ringless" design provides an engine capable of higher performance. Plus, if taken care of properly, it will last a long time.

Ring engines have been around for a long time as well. They are like 'comfortable shoes'. That is one reason people like to stay with the design And yes, there are some valid design concerns as the engines get bigger and bigger.

Keep in mind that the Jett 1.20 is basically a "60" size engine. Its development was a real achievement. I thought Dub had streched a "60" as far as possible when he made the BSE-100. He pushed it a little more, and came up with a gem of an engine. Its only real limitation is phycial strength. That is why it is designed, timed and intended for bigger props, and operation below 12K rpm. Much more than that, and something might give out. Runs best right around 9500-10000 rpm.

The materials used for fabrication are fairly easy to come by. The entire Jett "big block" line from the SJ-76 to the BSE-1.20L are decended from Dubs FanJETT.95 ducted fan engine. That engine is gone, but its legacy survives. Components are just a bit larger, or a bit smaller.

If you would be comfortable running a .61, .77 or .90 size AAC/ABC engine, you would be right at home with the BSE-1.20L

In the future, you may see a "120" sized 1.60 or 1.80 from Dub. Design is in work... a totally new design on this one. No hardware running yet. As far as I know, this will be an AAC engine as well. Lets see what happens.

Bob


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Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to STG)
       Post #: 2

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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> Large .90 thru .120 motors not ringed
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