The Tower .40 is a "clone" of the OS FP-40, but is probably made a bit better. It is a true ABC I believe, really needs nothing in the way of rework, just needs proper venturi, needle valve assembly, and the proper prop, usually an 11-4. They take a bit more breaking in, but last a whole lot longer. Lots of information on this and the other .40's used for stunt with a lot of them pinned at the top of the section.
   Type at you later,
    Dan McEntee

I'm having the timing changed a bit. Blocking off the boost ports and possibly adding a head gasket. Won't know till it's measured. Getting rid of the stock muffler to shed weight. I'm looking at a 12.25x3.75 for a prop.

I'm having the timing changed a bit. Blocking off the boost ports and possibly adding a head gasket. Won't know till it's measured. Getting rid of the stock muffler to shed weight. I'm looking at a 12.25x3.75 for a prop.

    That is too much prop for a .40. The APC 12.25 -3.75 is more for the .51 and larger engines. The Thunder tiger 11-4.5, APC 11-4 and 11.5-4, Master Airscrew 11-5 and 5, and  what ever you can find in Top Flite , Falcon , and Xoar props also. If the model is small enough and light enough 10 inch props in the same pitch range may work better in controlling speed. Play with mufflers some, depending on what your balance is on the airplane. I would see no reason to block off any ports. Just break it in properly with a flat 10 inch props. This engine wasn't designed to run in a 4-2 break mode like a Fox and will make more power in stock form. Don't get carried away with the castor oil as these engines seem to fit closer than the OS engines and will varnish up and get sticky. No more than 50% would be needed and less might be better. I run a fair amount of Morgan Fuels Omega in 5% and 10% nitro content and add just a bit of castor to each gallon in my OS engines and they seem to like it a lot. What fuel you use may well depend on what you can get in your area easily.
  Type at you later,
   Dan McEntee

Let us know how that works out so I can buy one of those magic engines.

I'm getting a Tower Hobbies 40 reworked with a tongue muffler and custom venture. Can't wait to see how it runs. Name your favorite engine and mods and why it works the best for you...

   Did you fly it stock, fist, as a baseline? What was wrong with it?

    Brett

I have 3 of these engines. I've ran all of them and all pretty much the same. I put 38 flights on 1 of them. There isn't anything wrong with any of them.

   The reason I ask is that the sort of modifications you are talking about tend to greatly reduce the power. If you want to run the sort of props you are talking about, you need as much power at relatively high RPM as you can possibly get. The "blocked boost port"  has the effect of causing the torque to drop at high revs, allowing the engine to run stably at low revs more suited for 6" or more pitch. The problem with that is that the performance in terms of speed stability will be greatly reduced. That's why it is rarely used in competition any more, and then in only specialized situations.

     Brett

Brett, I'm just going by what Leonard at Stuka Stunt Works told me. He has a website with all this on there. It's his profile special engine that he does. I talked to him and he he has made 40 size engines turn a 60 size prop all day long over 12000 rpm on only 5% nitro. So I said what the heck, I'm going to have him work over one of my Tower Hobbies 40s and see what happens. He explains on his website what all he does to them so I'll see what happens when I get it back.

   OK. The good reverend and I go back a very long time, we will see. His are more likely to work the way you want than many of the other practitioners.

     Brett

   

I completely understand what your saying Dan but the guy doing the machine work says he can make it run a 12" prop over 12000rpm on only 5% nitro and has been doing this for years so I figured I'm going to put it to the test a d see what happens.

   I was suspecting you have been talking with Leonard Neuman when you mentioned the 12 inch prop at 12,000 RPM. I have known Leonard and his son Matt for a long time, and used to see them all around the midwest. Matt pops up here on Stunthanger every once in a while. Matt is one of the top level flyers at the NATS each year.
  I have read of his work on FP type engines, but have never seen one in action. It's goodo that you have some experience with them in stock form for comparison. As good as that type of performance sounds, I have never experienced or seen a situation where I would want or need to use a 12 inch prop on a .40 size airplane. Turning a prop that big at that RPM was most likely based on a wood prop. I like Leonard and respect him, but I have serious doubts about it swinging an APC 12.25-3.75, but I will keep an open mind. Tell us more about the whole project you have in mind. What is the extent of your flying experience? What type of airplanes have you been flying? What model do you intend to put the engine on?
    If you have talked with Leonard, you probably know that he had an on line forum also as part of Stuka Stunt, and that he had a bot attack that shut it down. Many of us have been wondering if he has had any progress in trying to get it back up and running, or if he intends to. Stuka Stunt had been around a long time before Stunthanger was launched, and a whole different group of people frequented the site> there was a great wealth of information in it's archives from people who are no linger with us. I looked at it as kind of a bridge between what things were before the internet and what we have now on this and other sights. I for one and there are many others that would like to see Leonard bring it back, or some how make it's archive accessible if he does not want to have it as an active forum any longer. If you happen to hear anything from him in this area, please share it with us.
   Good luck and have fun,
    Dan McEntee