Alternative Engines?

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sgilkey
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Re: Alternative Engines?

Post by sgilkey »

hmmmm, good find, Bob, that's basically the Mag 28XL engine, the description says "ASP" but the photo shows the Mag XL on the side of the engine! The site says "in stock" but the last update was 4/09 so who knows??? The price sure is right!!! less than $50 for an engine that works well for 2548, lim b, and can be made to work well for open too, in a pinch!
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lightning
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Re: Alternative Engines?

Post by lightning »

And this one sure looks like a Magnum 15XLS!!!
http://www.himodel.com/engines/ASP_S15A ... rsion.html
for a lot less than the regular XLS street price!
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Re: Alternative Engines?

Post by gsjames »

Thanks to the efforts of Jim Pope, NMPRA #85, AMA L-85, the Weatherford Aero Modeling Society (WAMS) has received 3 new Fox 25BB Schneurle engines for testing. I am receiving one of them and Jim is giving the other two to Gene Hodges and Gary Alphin for testing/evaluation. I will be breaking in the engine and running some prop/fuel/plug tests on it alongside my best OS 25FX as a control. I'll run it with PowerMaster 15% and on MAS 8-6, APC 8-6 and MAS 9-4 (combat) props to see if it is comparable with the OS products.

It sure would be nice to have an American-made option in Q-25 and in OpenB/2848 combat.

Here is the link to the Fox website. I understand that if you order direct from Fox that there is a discount available.

http://www.foxmanufacturing.com/index.p ... cts_id=281
Gary James
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Re: Alternative Engines?

Post by boiler »

The thing about the ASP 25 is it clearly shows a remote needle valve. The Magnum xls 15 has had some problems with the needle at the carb.
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sgilkey
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Re: Alternative Engines?

Post by sgilkey »

Gary, I'm anxious to hear your findings. I have a Fox 25BB Sch which I test ran for Open B a few years ago. Being iron piston, it vibrates at high rpm and does not respond well to a mcp. The results with 9x4MA on stock muffler were good, on mcp hardly better. I did not try it for LimB but got a notion to do so this year, unfortunately after the weather had gone cold. I think it has potential for that. Sadly the mounting pattern is unique as is the muffler spacing. The muffler mounting looks very prone to damage. I made an adapter plate to pick up the stock muff spacing and adapt to 25FX spacing, tried to make it weak so it would break before the tapped holes in the case. Anxious to see your findings!
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Re: Alternative Engines?

Post by gsjames »

I have completed my testing of the Fox 25 BB supplied to Jim Pope by Fox Motors. Attached is my results running the Fox against my second best OS 25FX. Same fuel, same plugs, same props, same day.

The Fox 25BB is a schneurle ported, steel piston/liner engine in contrast to the OS 25FX which is an "ABL" engine. The Fox is an attractive looking engine and has some unique features including a multi-piece main case which allows the user to rotate the upper case so as to allow the exhaust port to be to the rear if desired. Additionally the engine has a two-piece "button" head. The finned head acts as a clamp to the actual head. This is a fairly advanced feature usually only found in CL Combat/ Racing engines. It helps to insure an even clamping pressure on the head. One shortcoming, the engine does not have an indexing pin to assure that the sleeve is aligned properly with the case. Because of this, it is possible to assemble the engine such that the ports are partly or completely blocked off. As long as the owner pays attention during reassembly, this is not a big deal, but attention is necessary.

Fox Motors has a policy that I strongly disagree with. It is their policy to "test run" each engine at the factory to insure that it makes the stated rpm. In reality, the engines end up being "factory damaged" instead. Upon disassembling and cleaning the "as received" engine in lacquer thinner it was found that there was a moderate amount of debris in the engine including some very small metal flakes from the machining process. This policy of factory running each engine means that the engine was run while full of debris. This practice is virtually guaranteed to damage the piston/liner fit and possibly the bearings.

The engine disassembled in the usual way, although the case comes apart in several pieces. I found it very difficult to remove the front and rear bearings from the case. I had even more difficulty in reinstalling them after cleaning the engine. I have never had so much difficulty removing and installing bearings in any engine that I have ever had. The crankshaft to bearing fit is very tight and the crankshaft itself has several relief steps cut into the shaft making using it as a bearing installation tool somewhat problematic. It would no doubt be much easier to reinstall the bearings using a dedicated bearing installation tool. I was eventually able to reinstall the bearings and shaft and they went together without any binds.

Upon initial disassembly, the piston was found to have a small "impact" dent in it about half way between the top of the piston and the wrist pin. It appears to have occurred during the manufacturing handling process and was not the result of disassembly/reassembly. It was told to me that the automatic lathe that makes the pistons just drops them into a box when it finishes with one. The mark on the piston looks as if it was hit by the top edge of another piston.

I broke the engine in on my Tatone test stand using 15% PowerMaster fuel with 18% oil (12% synthetic, 6% castor) (Fox does not recommend using synthetic oil with their engines) and a balanced APC 7-6 prop. I ran several 6 oz tanks of fuel through the engine running very rich and over the next several tanks I slowly leaned the engine out cycling between running very rich and best rpm to allow the engine to go through several thermal cycles while maintaining adequate lubrication. I ran approximately 1/2 gallon of fuel through the engine prior to the rpm tests.

In all cases, the Fox 25BB engine did not perform as well as my 2nd best OS 25FX. Typically, it was 800-1000 rpm lower than the OS. It is possible that the engine will improve a bit more with additional running, but at this point, I would say that the engine is only capable of performing as well as a slightly below average OS 25FX. It is certainly not a "magic engine" but is a very reasonable powerplant for someone that wants a US made engine as opposed to an import. The cost of the engine, if purchased directly from Fox is less than an OS 25AX but more than the retail price of the FX if you can still find one.

Based on my tests I conclude that the Fox 25BB engine would not provide any advantage to a Q-25 racer or Open B pilot and may in fact be a slight disadvantage (all other things being equal).

Respectfully submitted,
Gary James

Engine Comparison Test
Date: 22 Jan 2010

Fuel: Powermaster 15% Temperature: 75 F
Relative Humidity 25% Baropressure ____


Plug/Prop OS 25FX Fox 25BB

OS 8
MAS 8-6 17,000 15,900
APC 8-6 16,500 15,500
APC 9-4 16,100 15,100

McCoy 8
MAS 8-6 16,900 16,000
APC 8-6 16,300 15,500
APC 9-4 16,000 15,300

K&B 1L
MAS 8-6 17,300 16,000
APC 8-6 16,800 15,600
APC 9-4 16,300 15,100

Weight of engines, ready to mount, including applicable backplate mount for Q-25:

OS 25 FX 370gm Includes aftermarket standoff backplate mount
Fox 25BB 320gm Includes standard Viper kit backplate mount

Gary James
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Ed Kettler
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Re: Alternative Engines?

Post by Ed Kettler »

Great write up Gary!

Thanks
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Re: Alternative Engines?

Post by sgilkey »

Thanks for the info, Gary. My Fox 25 turned about equal, a little lower, than an FX on a MA 9x4 with stock muffler, but that's not terribly useful since I'd never use it that way. On a MCP the FX was much stronger, the Fox barely improved on the MCP. I never tried it on a 10x4MA, have you? I got it set up to try that but then the weather turned cold which would have given me useless tach readings. Plan to try it in the spring!
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Re: Alternative Engines?

Post by gsjames »

I just got off the phone with Charles Thacker, plant manager for Fox Manufacturing, letting him know the results of my test. I mentioned to him that the compression seems low and he replied that they originally had made the engine as a higher performance engine but that the powers in charge at that time made them "down tune it". He is going to send me a higher compression button insert for the head and I'll test again. The engine doesn't have head shims so I can't remove them. BTW, my OS 25 FX used in the test has the shim removed, so perhaps it wasn't a completely fair test. I suspect that the high compression button will make a BIG difference. They are also working on advanced ceramics for piston/liners and have one released for the 35Stunt engine. It is possible that with these factory improvements, the Fox 25BB will be a very competitive engine.

I'll let you know the results.
Gary James
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Re: Alternative Engines?

Post by Yankee Samurai »

Any new rumors on the New Magnum .25 that is supposed to come out this year?
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Re: Alternative Engines?

Post by sgilkey »

We finally got a break in the weather and I test ran my Fox .25BB Schneurle on a MA 10x4 and 15% PowerMaster, got 13,500. Engine runs fine, just doesn't have the power attributes we need for either limited or open classes. It has a large combustion chamber and no head shims, I suspect a "high compression" head would help it but would not invest the money to buy one, it would at best help maybe 3-400 rpm???
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Re: Alternative Engines?

Post by Blue Note »

Yankee Samurai wrote:Any new rumors on the New Magnum .25 that is supposed to come out this year?

Testing is underway, but no word on official release date that I know of. It was received by Global mid February, but some bugs may need to be worked out. I too am curious about how it's coming.

BNC
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Re: Alternative Engines?

Post by The End »

Terry Yates has some inside connections with the Mag 25 crew, and looks like he has just done some testing. Here is a quote:

"OK Guys,

I have some new information. The Macs headers arrived yesterday and the combat cans came for Andy today. THANKS ANDY!

Here's what I got.

Power Master 15% fuel
Master Airscrew 9x4 prop
72 degrees F
3000 Ft above sea level

stock muffler w/o baffel = 17,600rpm
Combat can = 19,200rpm

I'm not sure how this compares to an OS 25 FX but I did get a reading on a used Magnum .28XL with Combat can, same prop and fuel. = 18,300 rpm.

Blessings, Terry"
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Re: Alternative Engines?

Post by EK »

If that's the 'NEW' MAS 9X4 G3 then that's better than I'm getting. With the old 9X4 it's in the range, depending on the day.
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Re: Alternative Engines?

Post by boiler »

I saw the new Magnum 25 at the Toledo show but they kept it under glass except for some pictures that Don Veres took. Looks good with the remote needle valve. Don and I as well as Keith Jones gave the Great Planes, Futaba, OS guys at the show an ear full. We told them how much we appreciated Magnum listening to our concerns and suggestions. I bought 3 Magnum 15's and two sets of the carb inserts. We had a SSC plane on display with a Magnum 15 mounted on it. Near the end of the show one of them came by to apologize and said he would try to resurrect the FX but didn't know if it could be done.
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