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Author Topic: OS40FP C/L boostport plug  (Read 1078 times)

Offline Kozmo77

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OS40FP C/L boostport plug
« on: April 18, 2014, 07:37:16 PM »
Ebay find - almost new but GUNKED UP- intend  to modify for the stunt birds. Know some guys block the boost port and modify the intake ports for some serious power at stunt specs. 1) is the boost port on the same side as exhaust? ( don't laugh, please) The liner has 4 ports and the exhaust side has a channel and port along with the exhaust. 2) Recently plugged the bypass on an old Fox35 laminated two craft sticks and shaped them to fit , put the J-B Weld in place and it worked fine. Don't knowhow it runs yet, but...Thought this might work on the 40FP. BTW, that wrist pin and rod was FROZEN  But when finally disassembled was CLEAN (after chemicals and heat). do know enough not to mess it up, but do need info to proceed. thanks WC  (and I did a search, nada)
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Offline Mark Scarborough

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Re: OS40FP C/L boostport plug
« Reply #1 on: April 18, 2014, 07:43:55 PM »
i did a search for "40 FP " and here are 4 of the threads I found,,
I ran these but never blocked the boost port,,
from what I gathered,, blocking the boost port will depower the engine,,

read these, then see if you can find a good solution to your situation,,
best of luck
http://stunthanger.com/smf/index.php?topic=27563.0

http://stunthanger.com/smf/index.php?topic=5796.0

http://stunthanger.com/smf/index.php?topic=33699.0

http://stunthanger.com/smf/index.php?topic=6225.0

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Offline Tim Wescott

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Re: OS40FP C/L boostport plug
« Reply #2 on: April 18, 2014, 07:45:46 PM »
The boost port is the one opposite the exhaust port.  If it's like the 20FP, the exhaust port points more or less back, and the passage in the crankcase sort of twists it around to the side.

I'd try flying it first without messing with the port, out of curiosity if nothing else.
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Offline Bill Little

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Re: OS40FP C/L boostport plug
« Reply #3 on: April 19, 2014, 03:57:42 AM »
The only major work I remember guys going to the .40FP was to raise the intake ports to lower the blowdown.  The hope was to produce a high rpm 4-2.  I have also heard that if you don't know what to do you can end up with a very weak engine.

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Offline Steve Helmick

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Re: OS40FP C/L boostport plug
« Reply #4 on: April 20, 2014, 08:01:43 PM »
Leonard Neuman plugs the boost port, and I think got that from Big Art. My recollection is that the .40 with plugged boost port doesn't work well when mounted in one orientation, but I can't recall if that is sideways or vertical.  n~

One of the deals here is that this modification pretty much requires running a big prop (12x5.5 is recommended for both .35FP and .40FP). Too many already whine about not having enough ground clearance for 11" props on Classic designs, and how heavy APC props are...and bigger props do weigh more than small props. Always have! D>K Steve
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Offline Kozmo77

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Re: OS40FP C/L boostport plug
« Reply #5 on: April 21, 2014, 10:38:04 AM »
Gentlemen, thanks tremendously for your masterful input.   I did read every thread I could find after I broadened my search parameters. Conclusion: 40FPs are powerful but temperamental when utilized in other modes than R/C. 46LAs are much more flexible and manageable.
       The absence of a boost port in the LAs must tame the tendency to "runaway" and minor mods can easily shape the LAs into real performers. I acquired one 46LA recently along with 2 40LAs NIB, so I will focus on getting the 46 modified. Bill, thanks for prompting the thread that generated so much info.  Mark, your references were terrific.  Tim, I appreciated your input as well. Steve good to hear from you. Len's ad on SSW gave me the idea to get a 40FP to begin with. He recommends and markets that engine and the 35 as Profile monsters. I'm sure they are. I am a very stubborn, financially challenged OLD guy and simply must do things cheaply and simply. I will make every effort to do things right- that's why I always call on you guys for help. I immensely enjoy this venue and told Admiral Bob personally. Stay well, safe, and happy. Best wishes and many thanks, WC H^^
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