3W 90-degree intake manifold - experiences?
06-09-2004, 01:22 PM
#1
3W 90-degree intake manifold - experiences?
I've got a low-time (about a dozen runs) 3W 106 "AI" installed in a Carden 35% Extra 330. Wow, what a powerhouse! Top-end is pretty impressive. Idles great. Loads-up a bit in the mid range, but it's still new and I haven't really tweaked the needles yet.
However, when cruising along at around 1/2 throttle or so (throttle position doesn't really seem to matter), if I do a slow roll or sustained inverted flight, the RPM drops noticeably. Back upright and it will go back to 'normal'.
Wondering if I've got some sort of pressure issue going on and if the 90-degree intake manifold 3W offers would fix the problem. The manifold also has a fitting for a line to connect up to the carb's pump diaphragm cover to "equalize the pressure with that of the carb's intake", according to a write-up on Cactus Aviation's web site. I've got the manifold, purchased it with the engine, but it will take some additional cowl-cutting to fit it on, and if it's not going to help I'd just as soon leave the cowl alone.
Got cowl baffles above and below the cowl inlets, right up to the cylinders. Have a cooling exit in the bottom of the cowl probably about 4-times the area of the inlets. Also have some additional exit area through the "canister tunnel" and it's exit further back on the fuselage.
Anyway, anybody got any thoughts as to what's going on and if the 90-degree manifold will help?
Thanks in advance for any suggestions you may be able to provide.
BJH
However, when cruising along at around 1/2 throttle or so (throttle position doesn't really seem to matter), if I do a slow roll or sustained inverted flight, the RPM drops noticeably. Back upright and it will go back to 'normal'.
Wondering if I've got some sort of pressure issue going on and if the 90-degree intake manifold 3W offers would fix the problem. The manifold also has a fitting for a line to connect up to the carb's pump diaphragm cover to "equalize the pressure with that of the carb's intake", according to a write-up on Cactus Aviation's web site. I've got the manifold, purchased it with the engine, but it will take some additional cowl-cutting to fit it on, and if it's not going to help I'd just as soon leave the cowl alone.
Got cowl baffles above and below the cowl inlets, right up to the cylinders. Have a cooling exit in the bottom of the cowl probably about 4-times the area of the inlets. Also have some additional exit area through the "canister tunnel" and it's exit further back on the fuselage.
Anyway, anybody got any thoughts as to what's going on and if the 90-degree manifold will help?
Thanks in advance for any suggestions you may be able to provide.
BJH
06-09-2004, 04:35 PM
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RE: 3W 90-degree intake manifold - experiences?
bhall01,
I had the same problem with my 3W-150. I leaned the low end as much as I could and the problem you describe would not go away, I was very frustrated. Mine would even drop off on rpm on knife edge. Mid throttle was just horrible and when I added throttle after a Wall maneuver the engine would almost cut off.
I put off buying this $1 piece of plastic for $35 and thought that there was no way this would do anything. One of my friends also said the same thing and also said that I should just quit with this engine.
Gerhart at AI has always treated me very well and had done some work on the engine for me. So when I spoke with Gerhardt at the Joe Nall and told him of my troubles this is what he suggested. "Slightly lean the low end more and add the 90 degree intake."
Well I bought the $1 piece of plastic for $35 and was real sure that this would do nothing, as were my friends. Went home and bolted it on and soldered on the piece for the hose. I also leaned the low about 1/32 - 1/16 of a turn.
I went to the field for a test flight and was very surprised. No more burbling at any throttle setting in level flight. No more problem after a Wall maneuver. No more burbling on knife edge at any throttle setting. No more burbling while inverted at any throttle setting. By burbling I mean the engine would fall off a bunch in rpm and the plane would lose altitude, it was severe. I do still notice a tone change in the engine on knife edge and inverted at 1/2 throttle or less. However the engine does not loose rpm that I can notice and the plane does not loose speed and altitude. So I would say this is a 95% fix to my problem, and I am now very happy with an engine I was very frustrated with before.
I believe this worked for me for two reasons. First, my cowl has a large opening in the bottom and the carb is exposed to the air stream. Second, my low end needle is set so that the engine has to warm up 15-20 seconds before it will take throttle after the first start of the day. On the first start of the day it takes slightly longer before it will take throttle.
I would have payed more than $35 for this $1 piece of plastic if I knew in advance it would do what it has done!
Hope this helps.
I had the same problem with my 3W-150. I leaned the low end as much as I could and the problem you describe would not go away, I was very frustrated. Mine would even drop off on rpm on knife edge. Mid throttle was just horrible and when I added throttle after a Wall maneuver the engine would almost cut off.
I put off buying this $1 piece of plastic for $35 and thought that there was no way this would do anything. One of my friends also said the same thing and also said that I should just quit with this engine.
Gerhart at AI has always treated me very well and had done some work on the engine for me. So when I spoke with Gerhardt at the Joe Nall and told him of my troubles this is what he suggested. "Slightly lean the low end more and add the 90 degree intake."
Well I bought the $1 piece of plastic for $35 and was real sure that this would do nothing, as were my friends. Went home and bolted it on and soldered on the piece for the hose. I also leaned the low about 1/32 - 1/16 of a turn.
I went to the field for a test flight and was very surprised. No more burbling at any throttle setting in level flight. No more problem after a Wall maneuver. No more burbling on knife edge at any throttle setting. No more burbling while inverted at any throttle setting. By burbling I mean the engine would fall off a bunch in rpm and the plane would lose altitude, it was severe. I do still notice a tone change in the engine on knife edge and inverted at 1/2 throttle or less. However the engine does not loose rpm that I can notice and the plane does not loose speed and altitude. So I would say this is a 95% fix to my problem, and I am now very happy with an engine I was very frustrated with before.
I believe this worked for me for two reasons. First, my cowl has a large opening in the bottom and the carb is exposed to the air stream. Second, my low end needle is set so that the engine has to warm up 15-20 seconds before it will take throttle after the first start of the day. On the first start of the day it takes slightly longer before it will take throttle.
I would have payed more than $35 for this $1 piece of plastic if I knew in advance it would do what it has done!
Hope this helps.
06-09-2004, 07:26 PM
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RE: 3W 90-degree intake manifold - experiences?
Yes, the 90 degree horn does work. On my 3W-100 / Edge, I get no mixture change in slow rolling maneuvers and knife edge. Before the horn, it was like someone threw out the anchor on knife edge.
I liked the way it worked on the 3W-100 so I made the same setup for my ZDZ-80 using a velocity stack. It also helped the ZDZ-80 / H9 Cap which used to go rich on knife edge.
I liked the way it worked on the 3W-100 so I made the same setup for my ZDZ-80 using a velocity stack. It also helped the ZDZ-80 / H9 Cap which used to go rich on knife edge.
06-10-2004, 06:48 AM
#6
RE: 3W 90-degree intake manifold - experiences?
Thanks for the replies, it's encouraging to hear that the 90-degree unit should largely take care of my problem.
If it works that well on the 3W I might buy another one and try it on my DA-100.... it does a similar thing in my 35% Carden CAP, although not nearly as "dramatic". Similar installation, baffleing, and cooling opening.
Thanks again, I'll start on the install tonight since it's looking like Thursday night flying is going to be a rain-out.
BJH
If it works that well on the 3W I might buy another one and try it on my DA-100.... it does a similar thing in my 35% Carden CAP, although not nearly as "dramatic". Similar installation, baffleing, and cooling opening.
Thanks again, I'll start on the install tonight since it's looking like Thursday night flying is going to be a rain-out.
BJH
06-14-2004, 10:03 PM
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RE: 3W 90-degree intake manifold - experiences?
Guys,
I just bought one of these manifolds for my DA100.
Although I don't have ANY problems with my DA100 whatsoever, I originally purchased it, on a friends recommendation.
He has two DA150's and a ZDZ210.
He told me he purchased the 3W manifolds for two reasons.
1 First reason he spoke of, was to prevent the carb spit within the cowl.
Keeps things a lot cleaner, according to him.
2. Second reason, is fuel economy.
He SWEARS that he went down to a 40oz tank, and (I guess) still gets the same run time, (or close) to his previously larger tank size.
Now, I am going over to his house to discuss this matter tomorrow night, so I have not discussed this matter in great detail yet, but my friend has always seemed to be intelligent, and have a great knowledge of engines.
I however, am still skeptical, and cannot see how this little plastic piece can save enough fuel to justify changing tank size in a 40% sized aircraft.
Any thoughts guys?
I STILL would like to know JUST WHAT exactly this item is designed for, OTHER than stabilizing the air around the carb.
What is the fuel nipple/fuel tubing setup for? What is it's specific purpose?
Who out there, in FACT, is using this manifold on their engine, and WHAT advantages have you seen, OTHER than better transition, or mid-range, etc?
I would like all the info I can get on this product.
THanks.
I just bought one of these manifolds for my DA100.
Although I don't have ANY problems with my DA100 whatsoever, I originally purchased it, on a friends recommendation.
He has two DA150's and a ZDZ210.
He told me he purchased the 3W manifolds for two reasons.
1 First reason he spoke of, was to prevent the carb spit within the cowl.
Keeps things a lot cleaner, according to him.
2. Second reason, is fuel economy.
He SWEARS that he went down to a 40oz tank, and (I guess) still gets the same run time, (or close) to his previously larger tank size.
Now, I am going over to his house to discuss this matter tomorrow night, so I have not discussed this matter in great detail yet, but my friend has always seemed to be intelligent, and have a great knowledge of engines.
I however, am still skeptical, and cannot see how this little plastic piece can save enough fuel to justify changing tank size in a 40% sized aircraft.
Any thoughts guys?
I STILL would like to know JUST WHAT exactly this item is designed for, OTHER than stabilizing the air around the carb.
What is the fuel nipple/fuel tubing setup for? What is it's specific purpose?
Who out there, in FACT, is using this manifold on their engine, and WHAT advantages have you seen, OTHER than better transition, or mid-range, etc?
I would like all the info I can get on this product.
THanks.
02-26-2020, 08:36 PM
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I have 3W150 with 90 deg intake manifold,
on ground the idle is very good but after 10 minutes flight the rpm of idle increase
i can not get lower can some body give me some help thanks
on ground the idle is very good but after 10 minutes flight the rpm of idle increase
i can not get lower can some body give me some help thanks
02-29-2020, 11:13 AM
#10
sounds DS like you have an air leak that gets worse as the engine gets hotter. Open the low needle 1/16 turn and see if it gets better or stays the same. If it gets better then the low was too lean, if it stays the same you have an air leak. Many guys lean the low too much while trying to get rid of the midrange burble. Fix for that is to gap the plugs at .026-.028.
