mylamo

My Feedback: (1)

My 2.5 diesels are running with the tuned mufflers and they don't
resonate but seem to restrict. Would it be helpful to cut the small
muffler exit off to allow a more free flowing exaust? Maybe weld
a 1/2 inch diameter extension to the rear of it.

pe reivers

What muffler do you mean?
We get excellent result with the 3241 muffler. Just take care to drain all oil from it and use after-run preservatives.

DarZeelon

Ralph,


I remember a discussion in Model Airplane News, some 20 years ago...

A tuned pipe was considered unusable with an R/C Diesel (which while running, essentially has a fixed C/R).

This, because the compression setting must be significantly lower when on-the-pipe, than when off-the-pipe.



Maybe this theory is not as it is and PĂ© can add some info.

A restrictive exhaust limits a Diesel, less than it would limit a glow engine.

As to a power boost; your engine must be capable of getting to about 15,000 RPM, on its own, before any 'productive' resonance can occur within the tuned silencer. This is true of a glow engine, but also of a Diesel.

Any change in the 'sting' would interfere with the design of the silencer. It will not resonate as designed.

pe reivers

we are getting nearer, Thanks Dar for not jumping to conclusions.

Mylamo, what prop and fuel do you run? be as specific as possible.

mylamo

My Feedback: (1)

Thanks for the replies. I was running a 9x4 MAS at 13800 on Davis BB fuel.
I Tried an 8X5 Zinger at 14400 on the same fuel.Both figures seem good but
mixture setting is really difficult. If I back off on the compression the engines
cool after about a half minute in the air and won't produce enough power to
fly very well at all. Otherwise the running temperature seems too high.
Maybe I need to add some ether?
Ralph

pe reivers

we run the MVVS mix with 40% ether, 25% oil and 2% IPN. Prop seems OK, but it would not hurt to try a 9x3 to see how the engine runs at higher rpm with your Davis fuel