JohnMcGowan

My Feedback: (15)

After my bearings in my magnum xl 15 went bad recently, Global Services sent me a new xls 15 blue head( thank you Global!!) which I mounted to my ripper tonight. Are there any hop ups I can do/need to do to this engine, or should I just go fly the thing? Ive heard that I DO NOT need to drill out the muffler exhaust hole?Right? It will be flying with a 8x3 combat prop. I am assuming I can break the engine in with this prop as well? Tell me if I am wrong please. I hope to try and fire the engine off for the 1st time tomorrow after work. What glowplugs are you using in this engine, maybe an A3? Ive taken the muffler apart, cleaned the joint, and rtv'd the joint with the red stuff. I also applied some red silicone carefully to the o-ring at the carb base, just for insurance.
Many thanks in advance,
John

Montague

I always break in my Mags with a MAS 7x4 prop. those engines like to rev up, and using a smaller prop with less load on the engine allows me to break in at high RPM to keep the piston-liner fit, while providing lots of lube to the conrod and bearings.

I personally use the K&B 7300 plug, but I'm probably the only person on the planet who perfers those plugs. I haven't tried an A3 in the XLS, but it might be useful to knock of RPM off the top, since the XLS tends to run well over 17.5K anyway.

Be sure to locktitle the stopnut on the muffler.

On mine, the high speed needle worked perfectly when the engine was new, but after it sat for a week or two after running, the O-ring shrank or hardened, and it started leaking air/fuel, so put a bit of fuel tubing over it.

Beyond that, I'm working on a set of mods to make the engine run around 17.5K with out having to close the carb. At the moment, I've actually put an insert in the muffler stinger to make the exhaust opening smaller, and I've added an extra head gasket (you can get them from global).

JohnMcGowan

My Feedback: (15)

Thanks for the comeback Kirk. Good to talk to you again. Whats your feeling on a moussecan muffler setup for one of these or just stay with the stock muffler? I want to boom and zoom with this thing if it will let me
So with the extra headshim, you are lowering the compression, right? What are you seeing that this is doing for performance so far? I actually have saved the old headshim that I took out of the first 15 in my toolbox-maybe a good thing huh? lol
I plan on running 30% heli fuel in it, btw.
John

rrh

The one I have turned an 8x3 in the high 18s on 25% coolpower right out of the box. See what it will do on your 30% but I see no need for a mousse can, especially if you are trying to get down to legal SSC rpm.

JohnMcGowan

My Feedback: (15)

Thank you Randy. WOW! Yours is really spinning that prop very well. We are having a 'in club' combat Saturday week so I just want to be sure Im not a 'slow target'. Know what I mean?
Thanks again, I will check it this evening if I get to do the break in run before dark .

Montague

Yeah, it depends on what you're trying to do. If you don't have RPM rules, I'd probably run the new XLS with just one head gasket. That's currently how I run my XL's to get them up to 17.5k. I'm trying to LOWER the out-of-box RPM on my XLS engines to make them legal for SSC with out using throttle endpoint to close the carb. However, if you don't have any RPM limits, then I'd break it in on the 7x4, remove a headgasket, and go. You should see 20k with a 7x4 or nearly that with the 8x3 easily. One of my XLS's hit 21k on the 8x3 out of the box, totally peaked out. You can't fly it that way, since it will lean in the air, but it sure has a lot of power.

Guys using pressure fuel systems will probably have a ball with this engine. I think it might have more power than the OS CV-A, at the very least, they are equal.

You could put a mousse can on if you wanted even more power, but I don't know why you'd bother. Unless someone is running one of those exotic FAI .15s usually found in control line and FF planes, you'll match up as well or better than anyone as the engine is.

For that matter, if you run 30% nitro, you might need to keep both gaskets in there to avoid detonation, and you might need a colder plug. I'm using 15% Omega.

JohnMcGowan

My Feedback: (15)

Sounds great. Your're DA MAN KIRK!! Thanks so very much , will try all of what you said and let you know the results. As of right now, we have no rpm limits. When you say colder plug, maybe a Fox miracle plug( I have a bunch of those new that I dont use on anything ) or maybe an OS A3 ? Isnt the 3 colder than the 8?
John

Montague

I'm fairly sure the Fox Miracle plug is rather hot, since it works in 4-strokes. The A3 and 8 are both medium-hot, I think.

Actually, I just checked OS's website, the A3 is a hot plug, the 8 is a medium-hot.

I honestly should do more plug testing. Since I tend to pull gaskets and we're running these engines at fairly high RPM, I go for a cold plug to avoid pre-detonation. For the .25 engines with mousse can and higher nitro, it makes sense. I'm not sure if the .15s might not run better with a hotter plug, but I have good luck with what I use so I'm keeping with it for now .

vertical grimmace

My Feedback: (1)

Rossi R5 plugs are a classic cold plug. Interesting you think this engine is comparable to the CV-A .15. That is good to hear. I have an older Magnum and a CV-A. I do not fly SSC though. I just like .15 size engines. Nice to know there is another quality engine available.

JohnMcGowan

My Feedback: (15)

yes it is good to hear VG. There are a couple of guys who have the cv-a 15 on their rippers, and altho they scream, we may have something for them now with this new magnum !!!!!!
Im still stuck here at work,... hope I can beat dark tonite to fire the new engine up.
J

JohnMcGowan

My Feedback: (15)

I finally got to start the new magnum xls 15 this afternoon.I started out with a 7x4 prop and 10% omega.I also installed a new OS 8 plug.
It turned 18,600 after a 3 minute heat up run and was still a tad rich on the high speed needle.I ran about another 4 or 5, 4 minute runs with letting the engine cool down in between each run.I left the 7x4 prop on ,then hit it with 20% pro-pattern fuel and it got to about 19,700 (with it still not maxed out) .I then put a 8x3 combat prop on it and it ran 19,100. I wonder what it will do with 30% heli fuel?
I would think(and hope) that these numbers will only get better with more runtime. I plan to go fly the plane(a ripper) tomorrow and will shout back with how it does.
Thanks guys,
John

JohnMcGowan

My Feedback: (15)

Update; I went to the field today and one of my flying buddys had his ripper equipped with the high dollar OS CV-A matched with a tuned exhaust header/muffler (from a rc car setup).I have to admit that his plane was pretty fast compairing it to the old magnum xl15 that I previously had on my ripper. He would smoke me pretty good! Well.............. today was an eye opener for me( and altho he didnt say anything, I think he was a little surprised too, lol) My new magnum xls kept right up with that hi dollar OS!! Im still using 20% pro pattern blend fuel. I didnt tach it to see what it was turning today, but i will next time out. We are having a big combat meet next Saturday( King of the Hill) -our last shindig of the year, so wish me luck!! I am very proud of my new magnum xls!! She's honkin! . I will post how I do, or dont do next weekend.
Thanks for your help and advice again guys,
John

vertical grimmace

My Feedback: (1)

That is great news. Good luck next weekend and have fun!

JohnMcGowan

My Feedback: (15)

Thanks VG! I was very impressed with this engine, and its only on its (appx) 4th tank of fuel. I think it can only get better. There was a very big smile came on my face when I was able to hang with that CV-A [sm=lol.gif] . I didnt say anything to the other pilot, but we will put it all out on the table next Saturday and see. It will be my first real combat competition- I may not do worth a flip [sm=cry_smile.gif].
John

advanceandy

My Feedback: (116)

i too am trying to get down to 17500 i made a baffel and its running @17350 w ma 8x3 on 10% the db dropped from 103 to 95 thats the good heres the bad throttel responce from idle to 1/3 went into the dummper NFG the id hole currently is.242 dia

any help? any sugestions?

[img][/img]

rrh

I like your baffel idea although is that any different than mechanically limiting the opening of the throttle bore? If this is strictly a combat rig do you need good throttle responce from idle or do you start above 1/3 throttle? Just what pops into my mind immediately....

vertical grimmace

My Feedback: (1)

I think a better way would be to reduce the size of the venturi. Old Super tiger engines had a removable sleeve inside the barrel to reduce the size of the intake. The benefit here is you get better fuel draw.

Alex Treneff

Randy,

For safety's sake any combat plane should be able to be started at idle and then remain idling.

At the 2007 Nats I was judging for a pilot who was using a bladder tank and was unabe to make the engine idle correctly, so I had to pick the slippery (oily) plane up and walk up to the pilots' line with the plane screaming at full throttle. Not the safest situation.

JohnMcGowan

My Feedback: (15)

You guys wish me luck tomorrow at our family day/combat meet at our flying field!!
http://birminghamrcclub.org
John

Montague

I do think that a venturi insert would work better than limiting the exhaust, but right now it's beyond what I can make myself, so I've been doing the exhaust end.

If your engine is running poorly with the baffle, did you try resetting the idle mixture? I assume the engine is running rich on the low end? Maybe try opening up the baffle a little, or use a hotter plug to help the idle if it matters.

Some of my combat engines idle better than others. I normally don't worry about it, as long as I can get about half throttle, that's usually enough for me.

Clean

Makes me wonder if they make those little hose caps like the ones that come on Sullivan Nistarters that fit the Magnum venturi. If so, you could get some and bore different size holes so you could just slip a cap on for a quickly adjustable inlet restrictor.

Montague

Interesting idea, but would it improve fuel draw? I was under the impression that for good fuel draw, you wanted the smallest part of the venturi / air passage to be where the spray bar is located, since that creates the lowest pressure to suck in fuel. If you restrict up high, then you get low air flow, but you don't get lots of fuel draw, do you? Or do you?

The Internet Killer

I think the smallest part of the venturi should be just before
the spray bar (it creates a low pressure area for better fuel draw).

But restricting the venturi size will also limit how much the engine unloads in the air? I think !!

We may be in a low pressure area here. LOL

We are all use to trying to make the dang thing go faster, not slower. What is the world coming too ???

Montague

Well, if you aren't flying SSC by the rules, then you probably won't be worrying about getting the RPM down to 17.5K. If you do (and I do, a lot), then you will be worried about the RPM being too high.

Sure, you can use the throttle endpoint adjustment to reduce the RPM, but that does seem to limit unloading and can get into the range where the carb isn't working as well as it otherwise might. So, I'm looking to get the RPM down, the fuel draw up, but allow the engine to unload.

I'm beginning to think that the old Mag is going to end up being the better engine for SSC if you're willing to do the work to make it run right. It really does unload a lot in the air, more than the new mag or the LA. But if the new Mag can be set to run at or near the limit, and unload a little, it will be a great engine all around, and worth the hassle.

The Internet Killer

I understand SSC and 17.5. I just found it funny that for years people
have tried to get more out of their engines and now they are trying to get less
and most of our knowledge base is towards higher performance, which kinda
leaves tuning for lower performance in a grey area that people will have to
apply some grey matter to.

Again I just found it a little humourous.

Martin