Does the LA 40 and 46 use the same crankcase? It says the 46 is .1 oz. heavier so, was wondering why not go for the extra power if it fits the same mount and muffler.
Giffy
OS LA 40/46
Stuka Stunt Main Forum · 5 of 5 known posts recovered
LeagueCityRalph · Oct 16, 2004 12:32 AM
#1 sourceOnly considerations are the larger line-size requirement and slightly greater fuel consumption, as far as I know . . .
Ralph Wenzel
Steve Helmick · Oct 16, 2004 02:45 AM
#2 sourceLAST EDITED ON Oct-16-04 AT 02:49 AM (CDT)
Actually, I think you have it reversed, and the .46 is .1 oz lighter than the .40. Bigger hole, more hollow space, same stroke. The original .40LA may have been lighter than the .46, due to having a boost port (less aluminum, less brass), while the .46 had no pocket in the case, and no port in the sleeve. But as I recall, the spec sheets always said the .46 was lighter of the two. This is very typical of engines made in two or more displacements on the same case. On a profile, I'd probably go with the .40, so it would be legal in P.40, should I get the urge to enter an event. With a full fuselage, I'd go with the .46, just 'cause Mo'Power is awful cool.
Steve
Actually, I think you have it reversed, and the .46 is .1 oz lighter than the .40. Bigger hole, more hollow space, same stroke. The original .40LA may have been lighter than the .46, due to having a boost port (less aluminum, less brass), while the .46 had no pocket in the case, and no port in the sleeve. But as I recall, the spec sheets always said the .46 was lighter of the two. This is very typical of engines made in two or more displacements on the same case. On a profile, I'd probably go with the .40, so it would be legal in P.40, should I get the urge to enter an event. With a full fuselage, I'd go with the .46, just 'cause Mo'Power is awful cool.
Steve ty marcucci · Oct 16, 2004 12:00 PM
#3 sourceLAST EDITED ON Oct-16-04 AT 10:32 PM (CDT)
Giffy, whichever one you use, be sure to replace that stupid plastic back plate with an aluminum plate from an OS .40 or .35 FP. They are the same size. It took me six flight before I, or rather, my pit man discovered why my flights were always so short. Once the engine gets up to operating temps, the plastic back plate will warp just enough for fuel to pour out the back. Also the Towers .40 back plate will fit it. In fact I have just returned from the LHS with three back plates from the OS .35/.40 FP series for my three .46 LA engines.
Giffy, whichever one you use, be sure to replace that stupid plastic back plate with an aluminum plate from an OS .40 or .35 FP. They are the same size. It took me six flight before I, or rather, my pit man discovered why my flights were always so short. Once the engine gets up to operating temps, the plastic back plate will warp just enough for fuel to pour out the back. Also the Towers .40 back plate will fit it. In fact I have just returned from the LHS with three back plates from the OS .35/.40 FP series for my three .46 LA engines.
For those of you wanting a metal backplate for your OS .40/.46 LA engines, part # 23307000 for the OS .35/.40 FP is the part. Also, I heard it on here, the OS .35/40 backplate gasket fits the ST .G21 .46 like it was made for it. Nice to know that, especially as I used one today on a ST .46.
Gasket set is part #23364000. The local hobby shop owner looked at me like I was looking for parts for the Titanic!! But they came in Thursday and I ordered them Tuesday, so they are out there.
Gary Weaver · Oct 16, 2004 11:06 PM
#4 sourceThe 40 and 46 are identical the only difference is the 40 block is bored out larger for a larger piston to make a 46.
My 40LA weighs 273 grams = 9.555 oz.
My 46LA weighs 266 grans = 9.310 oz.
Both mufflers are the same and weight is 87 grams = 3.045 oz.
Gary Weaver