mwright

My Feedback: (5)

I figured you guys would know the answer to this question so here goes... How well would an OS 40 FP resond to a tuned pipe? This is a bushing engine and I can't remeber how these take to a pipe.

Marcus

kamlooper

My Feedback: (1)

I ran a FP 40 on my first Morris Knife a few years back. Of course with the stock muffler it was a real dog, just enough power to fly the plane around but without much authority. Then I found out about MCM pipes (mousse can muffler). I bought a macs header, found a site with a diagram for making a mcm and a few days later I was ready to try it out. %10 Omega (morgan fuels) 10-5 apc, os a-3 plug, cut about 1 inch off the lenght of the header. Fired it up, right away I noticed a different sound to the engine, quite pleasant really. Much more responsive throttle, and a noticeable gain in top rpm. I tached it, I had gained 1300 rpm over the stock muffler, with the same prop/fuel ect!! Needless to say the Knife was a real blast to fly after that. Plenty enough power to hover the plane, and it could climb out at a very good rate.
I ran this combo for a good year + 1/2 with no trouble. But I did notice the engine didnt run quite as nice as when it was new....of course. It still had the power and throttle responce but the idle wasnt as steady/smooth and it was not as user friendly to hand start, especially when hot.
So yes, the fp 40 does respond to a mcm pipe, and I would imagine it would gain good rpm on a tuned pipe as well. But be aware that all the extra rpm gained will wear the engine faster than running the stock muffler. I dont know what your running the engine on, but either a fun fly or a speedster, you might want to consider a mcm pipe, theyre cheap to build.

good luck

mwright

My Feedback: (5)

Thanks for the encouraging response. You just can't beat personal experience. I am not a fun flyer (but I have a kit of the Flying Machine next to build). I want to put the 40 FP in a 40 sized pattern type (New Era 40) plane.

I found a good site on making the MCM at:

http://webpages.charter.net/rcfu/ConstGuide/MCM.html

Would love to get the length of the pipe if you remember? How much different would it be from a 40 SF?

Marcus

kamlooper

My Feedback: (1)

I'm no pro at tuning, but what I did was shorten the header 1/4" at a time until peak rpm was reached then shortened in back again 1/4" to keep the engine from being "peaky" (broader powerband).
More info can be found here

PaulSwany

My Feedback: (45)

A few sites to check out for Mousse Can Mufflers:
http://webpages.charter.net/rcfu/ConstGuide/MCM.html

http://www.geocities.com/paducahrc/Article3b.html

http://fly.hiwaay.net/~dknight/rcpr/...se/mousse.html

http://webpages.charter.net/bobad/rapmcp.jpg

I'm about to build a few of these and try it out!! There are a few guys at our field running these with good results.

Foamguy

I've been using MCP's on my FF planes for a few years now. I've usually noticed a rather large gain on top end, plus a more linear throttle curve too. Some people say that they shorten engine life, but I havent noticed that as of yet.


Foamguy

PaulSwany

My Feedback: (45)

Hey Foamguy... Do you have any spec's on what works good for you?? Header length and mousse can size... stuff like that...

bugsiegel

My Feedback: (2)

I have made some.
one for a 32sx which worked out great.
the gain was about 1300 rpm's on the top and a much faster throttle responce. Here is a photo of it. I had painted it with primer to hide the design of the can but I have since removed the primer for a more natural look.
I mounted the exhaust with a full length header and then worked it down 1/2 inch at a time. each 1/2 inch i tested different props untill I found what I wanted/needed.
the best part about it is they are cheap.
when you get what you want out of a home made exhaust, it's just as rewarding as building a plane especially when not to many other guys at your field make them so they all come over to look..

kamlooper

My Feedback: (1)

Hey Bugsiege, you know macs makes different longer bends in the header pipes...... theyre listed on their site. http://www.macspro.com/
I used the medium extension on my Spinsation so the mcm would clear the wing.

mwright

My Feedback: (5)

I looks like making the MCM is fairly easy but what about the header? Has anybody come up with a good home built header (i.e. no leaks)? It would be nice if you could just unbolt the back of the existing muffler and attach to the MCM via a silicon coupler but tring to find a coupler of that size has been difficult (not to say expensive). The OD of my muffer is 32.5 mm or a little larger than 1 1/4 inch. Any thoughts?

One more question, anybody know the exhaust temps for these 40 sized engines?

Marcus

kamlooper

My Feedback: (1)

The macs headers are only $24-30 and I can tell you thats a great value. Sure you can try an fabricate your own but myself personally its not worth my time. (unless I worked at a machine shop) I've seen people make theyre own and the always crack in the welded area. I've used mac headers for 10 yrs and not one has broke....even through some big crashs.
Somehow I dont think a muffler would work well as a header. I dont know of any couple thats 1"+ that would work there.
RC Car engines run about 230F, and thats in an inclosed area. An airplane engine is behind a prop and generally out in the wind where it gets plenty of cooling. So I imagine a 2 stroke (fp 40) would run below 200, when mine was tuned properly you could put your finger on the head for several seconds before it would be "uncomfortably" hot.
Go buy a macs header (or other) and be done with it.
L8R