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bse 90 - 9/28/2005 6:51:39 AM   
MFLOOD3800


 

Posts: 253
Joined: 4/7/2004
From: beaver, UT, USA
Status: offline 		hey, i just finished install and cowl cutting of my new bse 90, wow what a beauty.
im putting this in a world models dago red (45 size). the muffler wont clear the bttm of the fuse and the leading edge of the wing ( my eng is installed sideways with exh header pointing down). ive emailed dubb asking for the neccesary 2" ext, do they all come in only 1/4 or 1/2 " sizes only?
also i had to remove the needle, straighten it out and install a wheel collar on top and then cut a thin slot in that for a screw driver to be used for the adj after cowl is installed.
it was 3 turns out when i took it off, i read here in another post that it should start at 4 out and then lock down the nut, what is the nut?
mine just backed right out, is there a locking nut on it, did i mess it up??
thx
marty
       Post #: 1

RE: bse 90 - 9/30/2005 4:07:35 PM   
bob27s



Posts: 4740
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hi Marty,

sorry for the delay...

First, a suggestion ---- If you wish, remove the entire needle valve assembly from the engine - install it on the firewall where you can easily extend the needle outside of the cowl, and adjust it without any extension or modification. That is one of the best parts of this needle assembly. Mount it where it is most convenient. Also, Dub has longer needles available if you need one.

4 turns out is fine to start with. The packing nut must be fairly tight. It provides needle tension and also serves as a seal. You should have to use a little effort with your fingers to turn the needle.

You require a 2" extension ?? Bear in mind, any extension will mess with the tuning length. The longer the total length, the lower the rpm tune point is. The trick here, is you trade for torque - so you would utilize larger props (go up in pitch/dia). You want to keep the extensions to a minimum.

If you require a LONG extension, you may want to contact Dub about getting the Little Toni extension set. That is the longest set offered by Jett. Take a look on here in the support forum, there are some photos of the installation. For the 90L engines, Dub offers an alternate muffler combined with the extensions - the muffler is re-tuned to make up for the longer extensions.

Most folks I know of that have used the Jett engines in the World Models (and clones) have mounted the engines inverted, with the muffler exiting the side of the cowl. My VQ mustang has a side mounted engine, but I use a turbo-jett inside of the cowl.

photos here are P-51 installations other folks have done with the inverted engine and the jett-stream muffler out of the side. these do require an extension, but not more than two 1/4" pieces.

Can you provide me with a photo of your installation ??? That might help.

Bob

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_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to MFLOOD3800)
       Post #: 2

RE: bse 90 - 9/30/2005 9:54:41 PM   
MFLOOD3800


 

Posts: 253
Joined: 4/7/2004
From: beaver, UT, USA
Status: offline 		hey bob
thx for the response
i did talk to dubb and he sent me a lil toni ext and three 1/4" spacers as well
it did the trick just fine and let me keep the pipe on the bttm and not on the side
what size prop will i now use i have a 12x7 apc maybe a 13x7 ?? here are some pics of it done, i had to add a ton of lead under the airscoop to balance this out w/ this oversized beast up front. i was gonna go to the tail area but with the rx wire and tail surface control wires it was already packed, it should still about 120 i hope. hey if i get more torque and less rpm maybe i can use this as my new 3d plane ???
just kiddin

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(in reply to bob27s)
       Post #: 3

RE: bse 90 - 10/1/2005 4:16:34 PM   
bob27s



Posts: 4740
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		well......... Im glad the toni kit worked with just one more spacer That is a bit less than 2", and well within reason.

You now basically have a 90T (torque) setup. You are good for between 12K and 14K rpm. Prop accordingly, try to keep it above 12,500-13000 ground peak.

The photos are very helpful. Thanks.

Id suggest starting with the 12x7 for the first handful of flights. The engine will run well with that. Figure on 13,000+ rpm. After that you can try an 11x9, 11x10, 12x8 and a 12x9. The 13x7 will work too, but on this plane I'd stay at 12" or smaller. If you goal is top end speed, keep the diameter down, and pitch up. If you have a tach, keep track of the rpm. Always set the engine 500-600 rpm down from peak rpm... it will unload in the air and require the extra fuel.

One thing - dub includes instructions about double checkign the head bolts after the first few runs, or if the engine experiences a hot/lean run for some reason. Do not forget to do this. Make sure they are snug.

As for 3D ..... one day for goofs, try a 14x6 or 15x4W on there (if only as a test run on the ground). You may be amazed

Let me know how things go and how the aircraft performs

Bob


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to MFLOOD3800)
       Post #: 4

RE: bse 90 - 10/1/2005 6:19:53 PM   
MFLOOD3800


 

Posts: 253
Joined: 4/7/2004
From: beaver, UT, USA
Status: offline 		hey bob
i actually have the lil toni set up and 3 shims to clear the wing and fuse area
im running a 12x7
i broke it in w/o the ext at 13000-13200 on the stand this was right near a 1000 less than peak with the 12x7, running pretty rich.
with 4 tanks(8 oz each) at break in i think ill have to run this 12x7 or maybe a 13x7 with all these shims. i havent fired it up with the new muffler set up yet but will try to keep it above 12000 rpm
after the first 5 minutes of break in i had a head bolt back all the way out, i shut it down and checked all of them and all were loose, a little tightening and then they stayed tight for the next 3 tanks or so
marty

(in reply to bob27s)
       Post #: 5

RE: bse 90 - 10/1/2005 10:12:17 PM   
bob27s



Posts: 4740
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		gottcha marty....

Of note, please review the break-in instructions for the engine. Breakin for this engine is typically done with an 11x7 or 11x6 prop, getting the engine up to 14,500 with the engine still just slightly rich. You want the engine at rpm, and at operating rpm at the same time, or the piston and cylinder will not fit up properly. Its important to get it up to rpm. The engine timing plays a part here. Even when moving on to the longer muffler setup, this is important.

Id stay away from the 13x7 for a while. You really want to keep the engine well above 13,000, even with the longer muffler. The closer to 14,000 it runs the better it is going to perform. Only try draggin it down toward 12,500 once you have some time on the engine, and are sure the engine will easily unload up over 13K+ in the air.

Good job on the head bolts. Keep an eye on them too.

Bob


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to MFLOOD3800)
       Post #: 6

RE: bse 90 - 10/2/2005 12:42:41 AM   
MFLOOD3800


 

Posts: 253
Joined: 4/7/2004
From: beaver, UT, USA
Status: offline 		hey bob
i appreciate all the help and info
when i broke in the motor w/o the ext and the 12x7 prop all i could get was about 14400 rpm, as i leaned it out it changed very little maybe bouncing at 14600-14800 and so i backed it down to the recommended 1000 less than peak rpm for 15 minutes. my instructions say that a 12x6 prop should turn 13500-15000 and that the motor was tuned to run at least 13000 and still a little rich
then with the needle at 4.5 out run about 13000, then lean it out to peak and then open needle to decrease rpm by a 1000 and run it there for 15 minutes the most i could get was about 14800 actual holding rpm was closer to14400 so i broke it in at 13200 - 13500
my instructions said nothing about me running it at 14500 all i saw was that when it hit 14500 on a 12x6 thats when you ship it to me. could be that when i peaked it and the head bolts loosened i lost some of my compression and then got a lower than optimum rpm. i think im still ok although i will reprop it w/ 11x6 or 7 and see if i can get 1000 or so, hopefully itl be ok ya think
marty

(in reply to bob27s)
       Post #: 7

RE: bse 90 - 10/2/2005 1:13:50 PM   
bob27s



Posts: 4740
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hey there.....

All you could get was 14,600-14,800 ?? If you were getting 14,600 with the 12x7 at peak, there is definately nothing wrong

Although, yeah, that is probably when it got a tiny bit hot.

The engine is just fine. Run it the way you have it set up in the plane. Fly it with the 12x7 the first handful of flights before trying anything else. Find peak, back down 500-600 rpm.

The concept of using a prop 1" less diameter than the flight prop is addressed here.
http://www.jettengineering.com/tech/breakin.html
and the mention of using 11x7 or 11x8 for the 90 breakin is here
http://www.jettengineering.com/tech/techsj90.html

Worry not. Its hard to hurt these things. However if you have the opportunity to run it on the test stand, no spacers, with an 11x7, for a tank or two -- it will do it some good.


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to MFLOOD3800)
       Post #: 8

RE: bse 90 - 10/2/2005 4:51:40 PM   
MFLOOD3800


 

Posts: 253
Joined: 4/7/2004
From: beaver, UT, USA
Status: offline 		hey bob
thanks again you guys are great and respond superbly
i will definately recommend jett eng to anyone looking for performance as well as customer satisfaction as their priorities.
this is my 2nd jett engine, the first i got off rcu, this one i bought directly from jett eng.
i will be buying again, and ordering hats shirts etc..
you have my permission to show this to dubb personally and let him know how much you, bob, have helped and made this an enjoyable purchase.
you guys are the greatest.
im a small business owner and really appreciate the personal touch your business displays, and that we both live in the same country - go usa !!!!!
if youd like you can also post my plane in your web site
its a dago red from world models, modified covering by yours truely(thats what my business is : decal applications), all futaba digital high torque servos,i reside in ehrenberg, az and my engine of choice is the 90 bse. my flying buddies are gonna get into local, backwoods type fun racing. one has a lil toni and was gonna put his rossi in it, but hes really eyeing the jetts at this point. i also have a offbrand voodo 60 size w/ a ys 120 in it, what would be the right jett for it speed and more speed desired
again thanks for your time and help
marty

(in reply to bob27s)
       Post #: 9

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