Randy..What are the MODS you are talking about???
Scott,
I've tried many mods on LA46's and a few on LA40's dating back to when they were first released as R/C only engines. I tried head mods to lower compression and change squish area etc...most of those either proved not worth the effort or actually less effective than stock.
The one mod that is worth the effort is reshaping the ports in the sleeve (not changing the timing) to direct the incoming charge to the back of the cylinder. The ports in the LA series are directly opposite each other and this results in slightly inefficient charging of the cylinder, in that a fair amount of the charge is lost out the exhaust port. The ports were obviously made this way as a cost saving measure (and they do function OK).
Redirecting the ports typically increases fuel economy and seems to broaden the midrange power some...though I've never had any on a dyno to prove this. I have had several back to back in an airframe, modified and unmodified and was convinced that the power loading in maneuvers was significantly better with the redirected ports.
It's a fairly easy mod but must be done carefully because the case must be machined inside to match the new port shape and the case is very thin in this area.
I wrote a lengthy post on this mod many years ago on Stuka Stunt. No secrets.
The increased fuel economy of course is not subjective and can be effectively measured. It does differ somewhat from engine to engine but typically uses about 1/2 to 3/4 oz less to do the pattern, using 10% nitro. There is a little less reduction on higher nitro content!
I've done a bunch of these for different folks over the years, but it usuall adds up to about 50 cents an hour for the work so it definitely became strictly a friendly thing and then I got much to busy at my job with Raytheon to continue doing any engine work. Now that I'm retired I have done a few recently.
That said I'd be the first one to say that the 46 runs very good stock and though these mods do apparently help they are not necessary for a good stunt run, and would likely only be appreciated (or even noticed) by and expert level flier.
Randy C.
PS: I also tried some port timing changes but all resulted in loss of power or no noticible change at all.
It would be interesting to make an AAC sleeve set-up with port timing more like the Aero-tiger but that's another story altogether.
This post is probably more suited to the Engine Set up tips section but I wanted to answer your question here.
Topic: OS LA.46 Blue engine or silver Whats the difference?? (Read 8647 times)
