stunthanger.com
Engine basics => Engine set up tips => Topic started by: Robin_Holden on October 09, 2008, 12:56:10 AM
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Morning all.
Just acquired a Tower 40 off the infamous E-Bay ! It's brand spanking new and un-run.
So ...... Should I just install a venturi and one of Randy's terrific NVA's or , do I send it away to be modified ?
Any contributions would be appreciated.
Been told these were better constructed than the FP series ? Or am I preaching heresy ?
Much obliged ,
Robin [ Ex-pat BRIT in the Charente full of ex-pat Brits ]
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Send ito Brian Barker. He does good work.
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They are essentially the same engine. Parts can be swapped between them. If you have accustoimed yourself to the way that an FP 40 runs, do all the same things, and just enjoy what you have. All of my FP 40s are stock, and run about the same way. Feed them a high oil content fuel to keep them nicely cooled, and run them in a wet two stroke, or an unbreaking four stroke, whichever suits you, and just go fly . .
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I've flown them stock, with venturi and ST NVA, both with and without the boostport blocked. Couldn't tell much difference. A favorite engine.
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The Tower 40's do have a chrome sleeve rather than the nickel used in the FP 40's
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i currently have 3 of the tower 40 engines. two of them have had the port timing changed slightly and one of them is stock . i have found that a .281 venturi and st needle valve works well for stunt. the two modified ones stay in a 4 cycle run somewhat better than the stock one but they all make good stunt engines. I run mine on powermaster gma 10-22 fuel. I think you will be happy with this engine
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I've seen Mike fly his Tower 40s many times and they all run great. The modified ones have a very nice break. I liked the runs so much I've found 2 myself. Have not put either in a plane yet but I will. After watching Mike's fly I'd suggest you try it stock at first. You will probably be happy.
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The Tower,OS40FP and Thunder Tigre GP40 are all compatable with every part [TT40 venturi being the exception] being interchangeable. That said the Tower 40 is the best of the 3 with the TT40 next and then the OS. Heresy , not really. The Tower is a completely machined engine made from better materials, with a better balanced crankshaft, true ABC P/L. The TT40 also runs smoother and for some reason is the steadier runner then both the Tower and OS. I belive that the piston might be a few grams lighter.The OS is the most prone to runaway and also runs the hottest and vibrated the most.
Yes I realize that I'm stating my opinion on the subject but I have all three and have run them all and I based my results on that.
I've often wondered if OS didn't give Tower/Great Plains an ultimatum to discontinue the Tower 40 or else risk losing the OS franchise.
Dennis
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Remember that to use the ST style NVA, you need to drill out the crankcase.
The OS FP25 venturi and the OS NVA are a straight bolt in and give you very close to the right venturi size. If you don't like the way it runs then, you can get it modified.
Cheers
Geoff
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Much obliged everyone for all your contributions .
Kind regards ,
Robin.
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One of the easiest ways to use any of the three (.40FP & clones) is to bolt on a MACS Muffler. It's a rather long tuned pipe looking thing. Weighs about 2 oz. Then find the prop that your combination likes. It needs to peak to at least 11,000 rpm and have around 4" pitch or a bit less. Launch rpm needs to be 10,000 to 10,500, and you need to set it rich enough so it won't be lean in the overheads. Fuel economy is excellent, and except for needing a tacho to find the right prop, it's a dead simple setup. Once the muffler has cooled, it also makes an excellent carrying handle. It can interfere with the wing LE on upright/inverted engines, or the LG on side mounted engines and fuselage mounted LG legs. Sweet on a wing gear or trike. Fairly quiet, even. Works best on a box stock engine with a venturi. ~> Steve
http://www.macspro.com/onepiece.asp (http://www.macspro.com/onepiece.asp)
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I have a Tower 40 that was reworked by Tom Dixon about three
years back, lots of power, very smooth running. I have this
engine on a arf cardinal with an 11X5 zinger prop.
Very nice combination.