Breaking in new os .25 fx's

Tell us what you do to get the best performance from your engines.

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wparmenter
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Breaking in new os .25 fx's

Post by wparmenter »

What is the latest technique for breaking in new os .25 fx's. I have the macs pipe and ky mousse cans for them. I was planning on running them for less than a minute at a time near peak rpm on an apc 7x4 to heat them up, and then letting them cool completely. repeat 3 times. Am I wrong?
BigCountry
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Post by BigCountry »

Sheep,

The last time I broke one in I used Mike Fuller's method (I believe it is essentially Dubb Jetts break in procedure) using an SSC MA 8x3 prop. It would easily turn the prop in the low 22's with plenty of oil still making it to the motor. Followed the procedure pretty much to the letter and it's a strong motor without question....Lou had it on his site maybe he could send it to you via email...
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boiler
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Post by boiler »

I recall you want a prop 2 inches smaller and one pitch less than you plan on using. An 8x3 fits that mold. You also want to run the highest projected nitro that you invision running in a heli fuel. You run it with the back half of the muffler off using a bladder to supply the fuel. This is done on the plane not a block. DON'T run it lean or near that point. Run it for 30 seconds and let her cool down so you can hold on to the head. Repeat 2 more times. Put the can on her and put the plane in the air. If I've screwed this up I hope CF gets on the forum and tells me so because I got 6 fx's ready to break in next week.[:D]
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Post by C/F »

Boiler,

You basically got it, the trick is to get as much heat into the liner for one time thermal expansion, and as much oil to seat the conrod bushings. My procedure for any ABC/ABN engine is to pick a prop that will let the (any size) engine run up "easily" in the 22K range "minimum". I run 7X4 on .25 and 6X3 on .15

This high rpm is the friction heat for piston/liner. I always use 30% heli fuel as nitro is additional heat and heli fuels IMHO have higher oil contents if not better oil packages given their limited cooling in heli hovering. Tweekin the needle in quickly to a clean 2 cycle note but hearing/seeing an easy 800rpm rise if fuel line where to be pinched is about right. This is the needed oil for conrod seating.

Removing rear portion of muffler is to reduce backpressure and spin higher rpm's more easily, I have ran/broke them in with mousse cans but if I have a stock muffler I opt for that with rear removed.

I do a 3 time 30-45 second runs with complete cooldown in between and then slap on the intended prop/muffler/fuel setup and run for a tank to see what it has. I generally do the break in, in the model, I do not use a bladder though not important, a standard tank is fine so long as it does not cause engine leaning or foaming.

This delicate balance of heat with plenty of oil, is how one obtains a strong box stock engine over the run it rich and fly instructions provided with the engines. The OEM's would risk warranty claims if put this in print for an extra 1K rpm's, simple economics for them, not worth it... K&B used to explain this procedure back in the 70's with 6.5 racing engines, Dubb Jett sells his motors factory broken in and also confirmed to me the engine is basically run for 2 minutes prior to ship with a minimum RPM guarantee, something he could not provide if initial breakin was done by the consumer.

IMHO breakin fuel and running fuel being the same is a myth yet to be proven. I run my Magnum .15 on 30% as well as 15% for SSC. IMHO its fuel brand selection that is key, I always use PowerMaster, I do not like Coolpower products. Magnum or Wildcat are other choices I have run, nothing else satisfies. Unles they bring back the ol'e, "DUKE Missile Mist 1000", aghhg now that was some HOT STUFF!!!!!
wparmenter
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Post by wparmenter »

Thanks folks. I will start breaking in tomorrow probably. I will use the os a3 plug and wildcat 15% with 16% synthetic oil with castor added to bring it to 18%. topflite powerpoint 7x4 wood prop. I think I will just start with the macs pipe and ky mousse can because I don't have a bladder setup, unless you think I can keep away from lean runs on suction alone with a full tank.
What length are most folks using on the macs pipe? what distance from the end of the can? total length from back of can to front of header? It appears the header is fairly long, but I also hear that is good.
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Post by wparmenter »

I have run into another problem. I have the macs pipe for the ky mousse can, but the blue aerotrend hose is too tight. The hose that came with the macs pipe does not have thick enough walls to hold the can, but fits the pipe nicely. How are you folks getting the rubber tube on the pipe? I have tried oil. It helps, but not much.
C/F
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Post by C/F »

Wes good ole saliva is the best ,,,,,,

The proper aerotrend tube for a Mac header and Ky mousse can is 1/2" ID and 3/4" OD if memory serves me correct........

You must have a proppy Johny can???

A standard tank for break in is fine, in my post, where have I mislead you into believing a bladder?? I've never used a bladder for breakin and beyond. I preffer JETT Bubbleless, what you need to worry about is that high of rpm's will cause most tanks in a plane to foam, If nothing else mount an external tank with allot of vibration dampening foam.

Maybe some o-rings or hightemp glass tape can tighten up the can fit????
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Post by wparmenter »

Its a mousse can from flying z hobbies, and the pipe is from flying z. I just got the pipe, and the can is about a year old. It appears it will fit well once i get the whole thing on there. Thats going to be a chore. I will give saliva a try. Thanks
wparmenter
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Post by wparmenter »

After 24 years of marriage, I forgot what a good lubricant saliva is![:0]
I have one I have run through about 4 ounces of fuel. I think this is five times for 30-45 seconds. 20% nitro with 14%oil castor/synthetic with two additional oz of castor added to the quart. This should be around 20% oil. Powerpoint wood 7x4 prop. rpm around 21k-21.5k static with a good jump in rpm with a pinch. The piston is still extremely tight at TDC. It squeaks still. Starter has a hard time turning it over.
I couldn't take it any longer and tried the ma 9x4. 18300 static with a fair rise in rpm with a pinch. Not what I hoped, but not bad. The oil coming out was a nice yellow/brown color, so there isn't anything grinding off. The can fits fairly loose on the pipe, so I dorked with it a little. It was set very short to start, and as I put the can further out down the pipe, the rpm dropped noticably. So static, the shorter the better. Does anyone know in general if maybe I should lengthen it a little with a slight power drop static for a gain once things unload, or should I try for even shorter? Thanks for all the good advice so far.
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Post by sgilkey »

Sheepy, you should have read my article on setting up a MCP in RCReport. A few hints:
1) use the blue Aerotrend tubing, the gray stuff you get with the header is too thin
2)saliva will work but I use water spritzed on with a mister bottle.
3) with a sharp #11 blade, slightly bevel the INSIDE of one end of the silicone tubing, and the OUTSIDE of the opposite end, with a sharp blade it's real easy to make the slight bevel
4) mist the inside of the tubing, and the outside of the header
5) clamp a wood block with a 5/8 inch hole bored in it in a vise
6) start the tubing on the end of the header, leading with the end that is beveled on the INSIDE, work it on so it's fully on the end of the header
7) stick the header on the wood block and push on the flange of the header, this will push the header thru the tubing, thru the hole in the block. the block will cram the tubing up on the header pipe, this is better than working it on with a twisting motion which will thin the tubing- cramming it will tend to increase its diameter slightly, improving the fit to the can
8) flare the open end of the can, the sharp edge will dig into the tubing when you try to install it. I put a large xacto handle in the opening of the can and roll it around the edge while holding it at an angle, the aluminum is very soft and it will flare easily.
9)mist the outside of the tubing and inside of the can, then thread the can onto the tubing
10) thru bench testing I found the best rpm on an FX and 9x4 was to have the end of the header pipe be 17mm forward of the end of the STRAIGHT portion of the can side (not counting the flared end that tapers down to the stinger). Your results may vary.
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Post by wparmenter »

I forgot that article was in RCR, but now that you mention it, I knew I saw something somewhere on the mcp. Thanks everyone for the help.
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Post by C/F »

Sheep you actualy have no room to experiment with KYMC can on stock MAC header.

The pipe will be within a 1/2" of the can bottom and a short stinger you are barely legal within the rules on a 8" max limit allowed.
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