warhawk demon

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Any of you guys having trouble getting RPM's with the j-tec muffler. On break in i was getting 7500 with the stock muffler. On the plane with the j-tec and the same prop and broke in im only getting 6700 RPM. Just curious if any of you is having the same issue. im runnig the DLE 55 with a exor 22x10.

n8622t

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Hey Warhawk the Wrap around mufflers will always choke you down a few rpm....its normal unfortunately

Jimmy

warhawk demon

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Yeah i figured that.. seems like they made it too shallow coming out of the engine. their is more room in the cowl.
wonder if the bisson would fit if the tubes were extended? I am finding it hard to get the tuneing right.

ROGER RUSSELL

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Anyone having their cowl keep coming loose and even wollering out the s screw holes
Going to try and reinforce mine with CA and fiberglass cloth

lomcevac540T

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Hasn't happened yet, but I could see it being a problem once it ever starts to wear.

masteromodels

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I have found if you drill the holes to hold the large inner nyrod and screw into them they will hold and not come loose. Just drill the ca the inner rod into the hole and your done.

thanks Bob

dasintex

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I use rubber rivets (see picture) you have to carefully drill a 5/16" hole in the mounting blocks, I used a 3 point brad drill, you set the rubber rivet inside the holes, no need to glue them in place, make your holes in the cowl, the cowlmounting screws pass through the cowl and threads into the nut that is embedded in the rubber rivet, as you tighten the screws draws the rubber into the hole you drilled in the blocks and expands, holding the rivet, screw and cowl in place, the rubber shoulder which is larger in diameter than the rivet shaft, cushions the cowl against the blocks and acts as a vibration cushion/dampener; you can get them from keleo creations http://keleo-creations.com/index.php under 'Assesories' and are called 'Cowl Mounting System' http://www.keleo-creations.com/index...roducts_id=228

The only other thing you have to do, is shave down the blocks about 1/16" to 1/8" to allow for the thickness of the rivet shoulders

warhawk demon

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sounds like the new rear exaust DLE 55 would be the ticket then.

warhawk demon

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Hey lomcevac. i think im having the same issue you were with the air pressure. i just cant get the popping out of it.
mine hasent died yet but it sounds just like yours did on your video

lomcevac540T

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I posted some pics earlier of how I closed the intake down and baffled the air to the engine, then I added some more exit holes in the bottom of the cowling. Mine runs great now and id staying way cooler. Last time I temped it, the engine was around 195 degrees after a flight.

warhawk demon

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I think i am going to try The tube in side the fuse trick first and see what happens.

n8622t

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You have two choices, restrict the inflow by baffling the intake or use the diaphragm snorkel into the fuselage...they both will work.

Jimmy

n8622t

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Roger if you will epoxy some 1"x 1" thin ply squares to the inside of the cowl the holes will have a lot more integrity and withstand the vibration much better.

Jimmy

ROGER RUSSELL

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Jimmy
Pretty much what I have done
Have not flown it yet
Will attach it tonight and fly this weekend
Thanks guys

jblloyd

My Feedback: (17)

[/quote]
You have two choices, restrict the inflow by baffling the intake or use the diaphragm snorkel into the fuselage...they both will work.
[/quote]

Has anyone tried a velocity stack to help with the air flow? http://www.troybuiltmodels.com/items/TBMVS-S.html

lomcevac540T

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It's not an airflow problem, it's a pressure inside the cowling problem. That might help if the carb was outside the cowling, like with a G62 or similar side carb engine.

jblloyd

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On a rear mounted carb, you would have to cut a hole in the firewall which would extend the velosity stack out of the cowl area. Would that not help?

Maxclimb

My Feedback: (61)

You are both right. I used to fly UAVs that were powered by modified 3W-28cc engines. Our engines were rear mounted in a pusher config. We used a velocity stack and the intake was concealed inside the fuse where there wasn't any airflow to pressurize the carb. Walbro carbs use a diaphragm that uses automatically makes adjustments for altitude changes for mixture. We flew at altitudes up to several thousand feet without problems. I am going to make a hole in my firewall on the P-40 and extend it into the fuse. I also plan to baffle the cylinder and open up the "scale like" cowl flaps to aid in cooling and reducing pressure.

Thunderbolt47

My Feedback: (8)

Putting a volosity stack inside the fuse will not stop the pressure differances. The little hole on the side carb plate at the is the culprit. You can soilder a tube onto the cover and run some tubing off of it into the fuse.

Volosity stacks are to help smooth the air out before entering into the carb. They will help an engine run better. however, I believe they have the most to gian when the carb is sticking out the side of the fuse in "open air"

Also some engines when ran at high RPMs will blow fuel back out the carb while running. If it is pointing into your fuse you will be soaking your insides. My ZDZ 80 does this in my corsair and my G-62 with velosity stack blows fuel down the side of the fuse. It's not much, but in the corsair it made a mess inside before I noticed it.

I believe that most all engines need to be baffled in some way. That way you move the air over the fins of the cylinder as efficiently as possible. Also this will help stop the over pressuazation on the cowl causing erratic running and high engine temps.

Kelly

n8622t

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you are correct Thunderbolt and the Walbro carb on these engines will not automatically do anything

Jimmy

357magnum

Check this out .....

http://www.thunderboltrc.com/tutoria...ial_seven.html

Lifer

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What is the advantage of the film cannister over simply running the tubing into the fuselage cavity?

Thunderbolt47

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I don't know exatly what you are refering to with the Film Cannister. Are you talking about useing it as a sheild to the fuse?

crashproof

I have this plane with DLE 55 with no problems, maybe I just got lucky but I thought one of the rear carbs advantages was that it was not in the wind flow out the side ie G62 which I have had many of (good engines ). I have often found folks try way to hard to not cut the bottom of the Cowl for asthetic purposes. This will cause heating issues and it can cause pressure issues because the hot air cannot escape and the heat and pressure builds. I know I am just stating the obvious but I have always allowed enough opening in the bottom for air flow out and have never had any of these issues. Just something to ponder. Good Luck, Kevin.

n8622t

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Lifer they do the same thing...I would be surprised if you could find a film can in todays digital world

Jimmy