I have a Diablotin Super FG coming and am planning on hanging a .91 MVVS on the front of it. My question is, what muffler would you recommend for this engine in this 3D application? I plan on mounting the engine inverted. I need to strike a good balance between blistering 3D performance using a large diameter (15" or 16" ) low pitch prop, without too much noise or added weight. Any suggestions? Thanks for your input.

Dave,


MVVS offers several muffler options for this engine.

The simplest is the #3298/10 'dustbin', then there are the #3255 normal muffler and its 'A' quiet sibling.
There are also the Pitts style #3267 and the tuned silencer #3253 and the highest power is made by the #3250 tuned pipe.

The tuned pipe is the only one I would clearly not recommend for 3D applications, from a response standpoint.

With the tuned #3253 silencer, you may have to extend the header a good deal for the ~9,000 projected RPM, with a 16x4/5, or 15x6 prop.

Either of the #3267 and #3255 will make good power, but not as much as the tuned silencer.

The #3255/A is the quietest and will give you several hundred RPM less than the previous two.

Dar,

Thanks for the help! If I decide to go with the tuned silencer (not the pipe), does MVVS manufacture a series of header extensions, or am I going to find that I have to have several fabricated and then have to test each one for performance? I am pretty new to this (only an Irvine .53 in the hangar right now), so I think it might be a little more challenging for me than a seasoned vet. What do you think?

No, Dave.


You will just have to get some aluminium tubing; about the same inner and outer diameters (20 mm O/d, 17 mm i/d) as the original side header and to try different lengths.

Thanks for your help, Dar!

You're welcome, Dave.


You will find this exhaust is pretty forgiving, compared to a full length pipe, in this respect.