I'm flying a 4.4 lb Gee Bee profile. It currently has a reallllly old K&B .40 Torpedo on it. Now this little .40 is o.k. on the Gee Bee. My buddy just gave me a Thunder Tiger .54 4 stroke. I looked at the hp on the TT 4 stroke and it was listed as .8. I looked at the hp on an OS .40 LA to get an idea of what I might be getting out of the K&B. The OS .40 supposedly puts out 1.0 hp. The question is what benefit am I getting out of the 4 stroke? Am I going to get better bottom end? Better transition? Better thrust? I've never owned a 4 stroke so I have no idea.

a lot less rpms' alot more TORQUE..(can swing a lil bigger prop) alot more effecient... a lil more maintenance,
the transition will be a lil slower (not much)....but is only nature of the beast ( 2 strokes vs 4 strokes for 1 combustion cycle)

and probable the coolest...is the sound....they purr like kittens...

If your TT runs ANYTHING like my OS, you'll love it! In addition to what jetfreak stated, it should use much less fuel than the two stroke and won't get near as much oil on your plane. But I'd run one just for that wonderful sound!

While I'm sure I don't qualify as an experienced pilot I do fly between slow and half throttle. I rarely open her up unless I need it. This 4 stroke might be just the thing to help me learn my first 3d moves and maybe hover.

I just flew a new plane with the TT91 4 stroke, and it is one great running engine. Could you ask your buddy to give me a TT54 too.Go with the TT, you wont be disappointed, a K&B 40 does not compare!! Daz...

This 4 stroke will mount right to the frame of the profile. Do I need some sort of dampening grommets or something like that to cushion the vibrations? My friend that gave it to me said I would need something like that.

It depends greatly on the application wheather to use a 2 or 4 stroke. Ladyflyer, think you are stroking me, as the best engine recomended by those in the know for a Han 9 73" cap 232 is the Moki 1.80 2 stroke. The weight of the Moki ballences out the plane perfectly, & the power is grate for 3D. Balsa USA recomemds and built ther Phaeton 90 around a 120 size 4 stroke for power. I love the sound of a screaming 2 stroke on the pipe mounted to a sleek 40 size screamer. To me a war bird just does not sound right with out a 4 stroke out front. You can throw numbers, and terms, such as better transition, don't load up as much, around all day, but some ariframes beg for a certain stroke engine.

would a 12x8 prop be too big for that size 4 stroke?

The destruction manual that came with my engine suggests the following props:
Break-in - 11X5
Stunt - 10X9,10X10,11X5,11X6,11X7,11X8

The main needle setting should be around 2 1/4 turns out.

Hope this helps some.

Good luck

Jeff

I have deleted all off-topic posts to clean up this thread. If you have any questions, please feel free to PM me.

Elwood

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