Magnum XL.15 vs. OS .15LA
10-03-2007, 10:05 PM
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Magnum XL.15 vs. OS .15LA
Guys,
A friend and I are just now getting into SSC combat and we're trying to decide which engine to use. I've read that the old Magnum .15 had air leaks and such. How are the new ones? Are the problems fixed? I realize OS engines are good but I've never cared for bushed engines, that's why I'm leaning away from the OS and to the Magnum since it has bearings. What would you choose and why, if you have experience with either engine, I'd like to hear it. Thanks.
A friend and I are just now getting into SSC combat and we're trying to decide which engine to use. I've read that the old Magnum .15 had air leaks and such. How are the new ones? Are the problems fixed? I realize OS engines are good but I've never cared for bushed engines, that's why I'm leaning away from the OS and to the Magnum since it has bearings. What would you choose and why, if you have experience with either engine, I'd like to hear it. Thanks.
10-04-2007, 06:32 AM
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RE: Magnum XL.15 vs. OS .15LA
The OS engine is very dependable, will turn 17,500 without modification (do not modify!), has very tough and hard to break crankcase, has a remote needle valve (safety!) and includes the OS A3 glow plug. The fact that it's bushed in this case shouldn't be much of a problem becuase you can't tell it other than reading the specs. The little engine runs great.
For reliable engine runs, check out the [link=http://www.treneffrc.com/LA-15%20Clunk%20Tank%20Secrets.pdf]TreneffRC Clunk Tank Secrets[/link].
All in all, the OS is a much better deal to me. The remote needle valve is also important to me because I can have my fingers further from the prop.
Some food for thought.
For reliable engine runs, check out the [link=http://www.treneffrc.com/LA-15%20Clunk%20Tank%20Secrets.pdf]TreneffRC Clunk Tank Secrets[/link].
All in all, the OS is a much better deal to me. The remote needle valve is also important to me because I can have my fingers further from the prop.
Some food for thought.
10-04-2007, 07:25 AM
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RE: Magnum XL.15 vs. OS .15LA
I would agree with Alex. The Magnum 15 can run well but takes a little work on the carb as the fits are poor and it wil tend to leak and vibrate apart if not cared for. the magnum does have ball bearings but the OS still seems at least as smooth if not smoother. On the LA, I would ream out the muffler baffle, making the center hole as big as you like. Also, the plastic backplate will creep and the backplate screws will get loose, making for an airleak. At a minimum, put some blue loctite on the backplate screws. Also, the fuel nozzle on the OS carb is a press-fit and sometimes will get loose and create an airleak so I put a bead of JBWeld around the base where it joins the aluminum carb body, just to seal it and be sure it won't loosen. these are fairly minor steps and once taken the LA is a very reliable engine, IF you get your fuel tank set up properly, see Alex's tips. these little engines vibrate and cause fuel foaming which will give you fits if you don't take precautions.
10-04-2007, 07:59 AM
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RE: Magnum XL.15 vs. OS .15LA
Personally, I think the old Magnum XL is more powerful in the air than the OS LA. On the ground, the old Mag has trouble with the 8x3 prop, it's just too big for that engine design. But that's not a bad thing in SSC, where RPM is measured on the ground.
In the air, the Magnum unloads more than the LA and results in more power when it matters.
As for engine reliability, it's not hard to get the old Mags to run well. The highspeed needle is touchy, and the O-rings leak, but there are easy fixes to all of that. I have my Magnum engine mods posted on www.MidAtlanticCombat.com.
The new Magnum XLS is a better all around engine than the old Magnum XL, but I don't think it unloads as much in the air. It has a longer stroke and a smaller bore, and seems to develop more torque, so it's not as over-loaded with the 8x3 as the XL was. But it does produce plenty of power in the air. The biggest problem I have with the XLS is getting it under the RPM limit. They fixed most of the problems with the carb. The XLS needle is a much finer pitch, so it's not as touchy as the XL, and they used a more reasonable low-speed screw design that seems to be working great. I haven't had any problems with parts vibrating off the carb either. I did have to put some fuel tubing around the high speed needle, as the O-ring in there seems to have the same old problems. It sealed perfectly at first but after about a week sitting between runs, it started leaking. But the fuel tubing fixes that right up.
I'm currently working on a set of engine mods to make the XLS run around 17.5k consistanly, at full throttle (I hate using EPA to slow an engine down). And the XLS has a HUGE carb opening and exhaust opening, so the tank position is more critical than with either the XL or the OS LA.
So far, I seem to be having some real progress by JB welding a bit of tubing in to the exhaust outlet to make it a little smaller and increase backpressure to the tank. I'm also running an extra head gasket, for a total of 3. (I've run as many as 6, but that many actually makes the fuel draw problems worse). Once I get a set of mods nailed down, I'll get them up on the web.
It also pays to take the XLS muffler apart and re-assemble it using RTV on the joints and around the screw head at the front of the muffler, and locktite on the stop nut at the back of the muffer. The muffler tail cone will work loose otherwise.
Anyway, when deciding on engines, the bushing vs bearing thing really doesn't matter. I do think the LA, the XL, and the XLS all can work well, but they all have their quirks, and none will run for years with out issue out of the box, you'll have to fix something at some point.
In the air, the Magnum unloads more than the LA and results in more power when it matters.
As for engine reliability, it's not hard to get the old Mags to run well. The highspeed needle is touchy, and the O-rings leak, but there are easy fixes to all of that. I have my Magnum engine mods posted on www.MidAtlanticCombat.com.
The new Magnum XLS is a better all around engine than the old Magnum XL, but I don't think it unloads as much in the air. It has a longer stroke and a smaller bore, and seems to develop more torque, so it's not as over-loaded with the 8x3 as the XL was. But it does produce plenty of power in the air. The biggest problem I have with the XLS is getting it under the RPM limit. They fixed most of the problems with the carb. The XLS needle is a much finer pitch, so it's not as touchy as the XL, and they used a more reasonable low-speed screw design that seems to be working great. I haven't had any problems with parts vibrating off the carb either. I did have to put some fuel tubing around the high speed needle, as the O-ring in there seems to have the same old problems. It sealed perfectly at first but after about a week sitting between runs, it started leaking. But the fuel tubing fixes that right up.
I'm currently working on a set of engine mods to make the XLS run around 17.5k consistanly, at full throttle (I hate using EPA to slow an engine down). And the XLS has a HUGE carb opening and exhaust opening, so the tank position is more critical than with either the XL or the OS LA.
So far, I seem to be having some real progress by JB welding a bit of tubing in to the exhaust outlet to make it a little smaller and increase backpressure to the tank. I'm also running an extra head gasket, for a total of 3. (I've run as many as 6, but that many actually makes the fuel draw problems worse). Once I get a set of mods nailed down, I'll get them up on the web.
It also pays to take the XLS muffler apart and re-assemble it using RTV on the joints and around the screw head at the front of the muffler, and locktite on the stop nut at the back of the muffer. The muffler tail cone will work loose otherwise.
Anyway, when deciding on engines, the bushing vs bearing thing really doesn't matter. I do think the LA, the XL, and the XLS all can work well, but they all have their quirks, and none will run for years with out issue out of the box, you'll have to fix something at some point.
