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I should have said “Hush Power II weight is significant”
can’t remember what it weighed … was hoping the DNA weighed
considerably less … guess not.
I’m interested in the tapered outlet as well.
Jeff
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Tracy Crook
Sent: Wednesday, March 11, 2009 11:26 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: DNA Muffler
Hmm... I weighed my HushPower
II at 8 lbs (with guts :-)
I assume at this point (300+ hrs) that mine has lost the fiber
packing but the internal baffles are still there. Anxious now to try the
outlet neck down to see if it has as much effect on the HP II as Mark's did on
the DNA.
Tracy
On Wed, Mar 11, 2009 at 8:22 AM, Jeff Whaley <jwhaley@datacast.com> wrote:
Hi Mark, I was just at the DNA
website … they don’t specify weight for any of their products.
The Hush Power II is about 20
lbs.
What is the weight of your
DNA-1040, Full Throttle Collector?
Jeff
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Mike Wills
Sent: Tuesday, March 10, 2009 10:36 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: DNA Muffler
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.
----- 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.
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?
----- 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:
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.
On Sun, Mar 8, 2009 at 9:20 PM, Mike Wills <rv-4mike@cox.net> wrote:
Any update on the DNA muffler?
----- 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.
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