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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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