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Agreed Mark. Was just looking for some feedback on
that aspect since your first email focused on the durability side. Thanks for
the info and keep us posted. If it holds up I'll give it a try.
Mike
----- Original Message -----
Sent: Tuesday, March 10, 2009 5:57
AM
Subject: [Norton AntiSpam] [FlyRotary]
Re: DNA Muffler
That's true Mike, but the opposite is also true. If it muffles but
doesn't last, it still fails the test. That was the case with the
HushPower II. It muffled great for about 30 minutes, then the
guts oozed out into a puddle on the hangar floor. As
for muffling, well, let's just say that you won't be the stealthiest a/c
of the group. But then my 20B Lancair isn't any louder than an
IO-540 powered Lancair, or so I'm told.
When I first installed the DNA "Full Throttle Collector" (DNA p/n
1040) muffler I was disappointed in its poor muffling
qualities. It was about as loud as the gutted HP II, but at a lower
tone and with a very high-pitched aspect that my Lightspeed ANR
headset couldn't cancel out. Then I remembered what Tracy said
about large diameter exhaust pipes (the DNA muffler that I chose has
a 3" inlet & 3" outlet). So, I purchased a 3" to
2" tapered reducer from Burns Stainless and welded it onto the
outlet. It is surprising how much difference that one small change
made in reducing the noise level. The high-pitched aspect was now
gone and the lower frequencies were noticably reduced. If
there was any loss of power I couldn't tell it. So, out of the box
the DNA is too loud, but with a slight modification, it is very
acceptable.
My main guage for acceptable exhaust noise is the comments I
get from my hangar neighbors. Early on I used to get lots of "friendly"
comments about how they could hear me coming long before they could see
me. Now, those comments have stopped. They still ask about that
"strange sounding" engine, but only because it sounds different, not because
it is loud enough to break windows for miles around. I'll try to
remember to take some sound level measurements next time I'm out at the
airport.
Mark S.
On Mon, Mar 9, 2009 at 10:50 PM, Mike Wills <rv-4mike@cox.net>
wrote:
Well, the other big question is does it
actually muffle? If the best thing that can be said about it is that
it's surviving I'd be a little disappointed. I know its hard to judge but
how about your opinion regarding the volume?
Thanks,
Mike Wills
----- Original Message -----
Sent: Monday, March 09, 2009 8:38
AM
Subject: [FlyRotary] Re: DNA
Muffler
"sounds good" Mark. My guess is that the 2"
restrictor is in the correct place now. Don't think it would be as
effective before the muffler. But the big question is, did the 3 to
2 " reducer cause any noticeable power loss? I plan to do the
same thing on my plane when time allows. Tracy
On Mon, Mar 9, 2009 at 8:08 AM, Mark Steitle <msteitle@gmail.com> wrote:
Mike,
It may be a little premature to declare it a winner, but with ~10
hrs on it now, it is holding up better than anything I've tried so
far. Keep in mind that this is DNA's best muffler, rated for
1000hp. It is made of fairly thick SS, .030 if I recall, much
thicker material than most mufflers. I had to add a 3" to
2" taper to the outlet in order for it to be acceptable in the
noise category, but that was surprisingly effective in
reducing the exhaust noise to an acceptable level. (Maybe I should
have just put the reducer on the 3" downpipe and saved some
weight.) Anyway, when it passes 25 hours, I'll post another
update. At this time it is looking very promising.
Mark S.
On Sun, Mar 8, 2009 at 9:20 PM, Mike Wills <rv-4mike@cox.net> wrote:
Mark,
Any update on the DNA
muffler?
Mike Wills
RV-4 N144MW
-----
Original Message -----
Sent:
Friday, January 16, 2009 7:05 AM
Subject:
[FlyRotary] DNA Muffler
Does anyone on the list have any real-life rotary
experience with the DNA Gen II muffler ( http://www.dnamufflers.com/DNA/main_DNA.html)? It is
an interesting design in that it has no packing material to burn
out. Instead, it utilizes ladder-rungs, which they call
"internal sound diffusers", which resemble a chain of DNA down
through the center of the muffler body, which is made of 304
SS. Their web site claims that the racers use them with great
success. From speaking with a sales rep, they claim there the
rotary crowd uses them too. I'm considering purchasing one of
their FULL THROTTLE COLLECTOR mufflers (P/N 1040), but thought I
would check to see if anyone else has used this style
muffler. This muffler has a 3" inlet/outlet with a 4"
body. So it is compact enough to fit inside my
cowl. My exhaust header has a 3" swivel joint, so it should be
a good fit.
Mark
S.
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