ORIGINAL: Marcio Senger
ORIGINAL: ATVAlliance
You know...I have an ASP 52 2s that doesnt run well on the low end/idle. And now that you bring this post up I may now know why. My other ASP engine runes and tunes just fine.
The stock ASP muffler has a baffle inside which creates about an inch or more of the overall length of the muffler. The plane I installed it in would not allow me to keep the baffle in without much modification of the firewall (as the muffler would actually be inside the fuse and exit from its side). So, I just removed the baffle and it fit better by being at least an inch shorter.
However, I have not been able to get a good tune on this engine either on the low end. So, now your post has me intriqued to say the least. I'll have to take the engine off and bench test it with and without the baffle to see the results. Doubt I'll do it any time soon as I have put this plane on the back burner for now...but just thought I would add this to the topic.
Removing the baffle substantially changes the backpressure (make it lower), and this is more noticeable in the idle tuning, because all the blablabla (fuel feeding in idle by pressurized fuel tank due to low
venturi effect in this condition).
The baffle may also have some fine tune effect related to the pressure waves trough the muffler, but I believe that, if ASP had tuned their mufflers, it was tuned for high revs. Thus, removing the baffle would not make difference in the idle due to the pressure waves bad tuning.
I have a Magnum GP .15 engine that runs the stock muffler without the baffle, and I added a 5" silicon tube to "guide" the castor oil out of my plane
AND try to keep the backpressure similar to the original...
Thanks for your insight. Maybe it does or doesnt have anything to do with the low end tuning.And I really dont have a comparison as I bought this engine new for the sole purpose of putting it in this plane. So when building, I knew that the baffle had to go...and never ran it with the baffle installed.
Ive had no problems with OS engines and thier conical/funnel shapped baffle insert (which at most reduces the length of the muffler by less than 2mm). I only noticed that the OS baffle made the engine a bit quieter. I may/may not have noticed a power difference.
I think Im gonna pull this engine, put the baffle back on it and shelf it until I can come across a 40 size ultra stick. On a stick I can muss around with tuning easier than the current plane which has an enclosed cowling (my issues are notwith the cowling as I was trying to tune/maiden the plane with it off, just FTR).