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HELP with Vetterman exhaust

MrNomad

Well Known Member
O-360 - RV9A - Vetterman exhaust with mufflers & heater shrouds on both sides.

The rite side muffler shroud routes air thru a scat tube to the heater located on the firewall.

The question is, where does the left muffler shroud get its air from and where does it vent? Carb heat will come from the standard source.

I thought about removing the muffler shroud on the left side but Clyde at Vetterman's nixed the idea. Vetterman's instructions tell you NOT to operate the engine w/o air going thru the muffler shroud.

How about building a scallop to capture the air passing thru the oil cooler and direct that warm air down to the shroud? It's better than nothing, but I don't want to restrict air passing thru the oil cooler.

I don't want to cut another hole in the baffle next to the oil cooler for a scat tube line cause that would decrease the amount of air forced over the cylinders and oil cooler.

Final thought: How about cutting a hole at the bottom of the left nostril alum shroud, attach a scat tube there allowing incoming air to travel down to the muffler / shroud? Will that reduce the amt of air rammed thru the left nostril and onto the left side of the engine?

I look forward to suggestions and ideas.

I plan to add a Dynon EMS with egt and cht so I can measure the difference between cylinders but that won't help determine if the muffler is being damaged.

I'd hate to plug up a muffler at 11.5

Barry
Tucson

PS: Thanks Jeff, for the great website.
 
Hi Barry:

One option to consider would be to connect the heat muffs in serial. Air comming out of the right gets plumbed to the left muff. Left muff gets plumbed to your heater box. Should be really HOT!

I too have the dual Vetterman mufflers but plan to cut a hole on each side to feed the muffs.

I was under the impression that it would not effect the cooling capacity of the oil cooler.

Mike
RV-8
Finish
 
Thanks Mike for your reply

drill_and_buck said:
Hi Barry:

One option to consider would be to connect the heat muffs in serial. Air coming out of the right gets plumbed to the left muff. Left muff gets plumbed to your heater box. Should be really HOT!

I too have the dual Vetterman mufflers but plan to cut a hole on each side to feed the muffs. I was under the impression that it would not effect the cooling capacity of the oil cooler.

Mike RV-8 Finish

Mike: I have no way of knowing how much air needs to pass over the heat muff to avoid damaging the muffler. Placing two lines in serial may increase back pressure & reduce flow. I plan to call the muffler mfg next week and will pass along whatever I find out.

Adding a hole in the baffle next to the oil cooler could reduce the volume of air headed thru the oil cooler and down around cyl #1. Of course, I am in the southwest where hi eng temps are the problem.

Logically, removal of the muff should allow the muffler to cool using the ambient air in the cowl but I must conclude that's not enough air if the muffler mfg specifically says NO.

Keep the ideas coming.
 
Up

Hello,
I will also install dual mufflers, what did you do in the end?
Any pictures appreciated.
 
O-360 - RV9A - Vetterman exhaust with mufflers & heater shrouds on both sides. The rite side muffler shroud routes air thru a scat tube to the heater located on the firewall..... The question is, where does the left muffler shroud get its air from and where does it vent?......
Barry,

Since Van's included an 8" muff with my FWF kit, I've been tempted to install it in series but based upon some of the postings here, I may revisit that notion.

My experience, though not directly transferable to your situation may be useful as a data point. Vetterman included a Superior/IO-360 9" heat muff with his exhaust system. The muff is installed on the #1 exhaust pipe and draws its air from a 2" flange mounted underneath the right intake ramp baffling.

Note: Because the instructions say limiting the airflow to the heat muff will improve performance, I drilled the hole through the ramp to only 1" diameter for now. I can always increase its diameter later if required, but my experience is a 1" diameter hole (located on the lower rear baffle behind #3 cylinder in my O-320) makes its 8" heat muff much more efficient and for me at least...provides plenty of hot air.

 
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2 muffs???

Hmmmm.. I'm confused. My FWF only came with 1 heat muff, mounted on the right side. Are we using 2 now?? Must have missed this upgrade..
Regards, Chris
 
Hello Chris,

I'm using a special ordered Vetterman exhaust with dual mufflers (noise attenuation in force in Europe), the mufflers MUST be ventilated at all times.
So I have to find a way to do this.
Here is a picture of the system as shown on Vetterman's website http://www.vansairforce.net/vetterman/VettermanExhaust.htm

H.jpg
 
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Rick - Is the picture yuol posted form your -8 or your -6A? I have a 180 hp IO-360 on my -8 and have had problems with the heat muff mounted on one of the cross over pipes. There's not enough room between the pipes and the heat muff burns through. I wasn't sure if there was room between the pipe and the cowling to put it where your picure shows.
 
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Rick - Is the picture yuol posted form your -8 or your -6A? I have a 180 hp IO-360 on my -8 and have had problems with the heat muff mounted on one of the cross over pipes. There's not enough room between the pipes and the heat muff burns through. I wasn't sure if there was room between the pipe and the cowling to put it where your picure shows.
Its on the -8. I too am concerned about the marginal clearance so I added an elbow to the muff to improve the scat's routing and placed a heat shield between the scat and exhaust pipe. I'm going to add another heat shield a bit more downstream for good measure but it is still on order.

 
Muff

Bubblehead:

I too have an 8 with the heat muff installed on a crossover. The aluminum shroud was showing signs of burn thru from the adjacent exhaust pipe. I took a piece of thin stainless and shaped it to the muff and glued it on with the 2000 degreee firewall plugging stuff from AC $pruce. It hasn't been on long enough to evaluate longevity yet, but it seems to be doing the job.

Can't remember the $pruce part no. but if you want it, email me, I'll get it for you.
 
Dual mufflers in a 9A

I installed Aircraft Exhaust muffler system (Vetterman did not have mufflers at the time) in my 9A with O-320. The air is routed from the front ramps (left and right) back to the muffler shroud and then to two heat valves through the firewall.

The amount of cabin heat available is outstanding. So far I have only had to partially open one valve to get all the heat I needed with 15F OAT. I doubt if I'll ever need both valves open for cabin heat. That said I think it makes sense to plumb one muffler with a scat tube to the cowl exit rather than go to the expense and effort of fitting two heat valves.

At one time I covered up both ramp intakes to see if that would help with CHT temps and noticed no change so I don't believe the ramp openings are robbing cooling air from the engine.

Paul Eckenroth
N509RV
 
Thanks Paul,
would you have any picture of your install, I'm interested in the position of the two heat boxes
 
Pascal

I do not have pictures of that area. The boxes were installed side by side with the two sharing the center attachment bolt. The fit was very tight but worked well with some minor trimming of the flanges. I used the SS boxes so adding the second box was $$$. I really like the mufflers as they reduce the noise significantly. They also lessen the vibration through the floor from the exhaust pulses. However if doing again, I would use only one heat valve and route the hot air from the other muffler to the cowl exhaust.

Paul Eckenroth
N509RV
 
Any updates on dual muffler installations?

I'm planning on dual Vetterman mufflers for my 9A. I'd like to put the firewall heat box on now, and wondering if I need 1 or 2 box4es

I talked to Larry today and he told me that you cannot plumb twomufflers in series, but in parallel might be OK... 2 mufflers feeding 1 heat box. Has anyone done this?

Another option might be to remove the shroud around one of them. Is anyone operating that way?

I'd love to see some pictures of a 7A or 9A with dual mufflers.

thanks for any info,
 
I have the Vetterman mufflers on my IO-320 9A. I "Y"ed off the duct from the right baffle to both mufflers, then "Y"ed back together just prior to the cabin heat valve. Spruce sells the "Y" parts for the duct.
 
Mufflers give more heat than ordinary shrouds!

According to Larry, the heat from the mufflers is superior to the heat from a normal shroud. So there should be no need for using the heat from both mufflers for cabin heat. The mufflers need cooling though, unless you take the "shroud" off. I use the RH muffler for cabin heat (like the original setup).

Since the shroud is a good heat shield, so close to the throtle body and fuel lines, I left the LH one on as well and have a 2" tube from the baffles just underneath the oil cooler on it, for cooling it. No need for an "exit" hose, it just blows inside the cowl (without the shroud on, that heat would be there anyway). There will be not much air going through it (and maybe even already a bit warm from the cylinder), but it should be enough to keep the muffler from getting red-hot.

I may have some puctures, If I find them, I will post them later.

Regards, Tonny.
 
Time to revive this thread, now that I'm trying to get the hoses connected up to my dual muffler system.

So what is the current concensus?
Two intakes - one from the rear baffle to the right muffler and then to the cabin heater, the other from another inlet on the inlet ramp to the left muffler and no hose on the outlet of the muffler?

One intake - Y'ed or Tee'd to both mufflers. One side to the cabin heat, or both coming back together for cabin heat?

I sent email to vetterman but haven't heard back anything in over a week.
 
I have the Vetterman exhaust with mufflers as well, and based on the fact that my area is pretty mild all winter long and i dont plan to fly north during the winter, I have decided just to use one intake and one heat muff to the cabin heat. I have removed the left side outer sleeve and can always put it on later if I decide to fly in colder weather more often. I'm told that one side should be enough to keep me warm most of the time.
 
Bruce,

If you only have one heater valve on the firewall then just use one heat muff and remove the other. I have two heater valves and tapped the airflow from #4 and #3 rear baffles.

It's a pretty crowded area behind the engine and I thought my scat tubing may be inhibiting low preeure airflow so I removed one heat muff. When I did I saw no difference in oil temp or chats.

With two heater valves I can fly through the New England winter with just wearing a sweater in the cockpit.

Note, if you do remove a heat muff you do have to fabricate a heat shield that is placed around the bottom half of the muffler. Pretty straight forward, lake a piece of .040 and two screw clamps, curve and install.
 
Dual Heat Muffs

Bruce,

I contacted Vetterman about this back in Februrary. I planned to use only one heat muff so the question was what to do with the unused side. Clint responded as follows:

"The unused heat shroud needs to be vented or taken off. If you take it off, you will probably want to wrap a short piece of aluminum around the muffler to act as a heat shield where it is near the cowling. I hope this helps. Clint"

Here is how I did it. I wrapped a pieces of .025 Alclad around the bottom half to form a heat shield and clamped it on with the clamps that came with the heat muff.

dsc_3200c.jpg
 
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Thanks! Looks like taking the shroud off and using a simple heat shield is the simplest solution.
 
I have the Vetterman mufflers on my IO-320 9A. I "Y"ed off the duct from the right baffle to both mufflers, then "Y"ed back together just prior to the cabin heat valve. Spruce sells the "Y" parts for the duct.

My Vetterman mufflers have been operating for two and a half years like this. Works great.
 
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