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Heater muff scat tube routing

dwranda

Well Known Member
I'm having an awful time routing the scat tube and came up with a possible solution. I'm wondering if anyone could tell me why I shouldn't route it this way. Someone may see something I don't see. I have 2 heat muffs connected in series and instead of going around the back of the engine I want to go under it. I will have to have the muffs welded differently but that shouldn't be a problem. In the pic you hopefully can make out the sharpie circles I drew where the new scat connectors will be. I have put the cowling on and looks like theres plenty of room to do it this way.
20220823-195505.jpg
 
Don't your heat muffs already have holes ???
Or are these just mufflers with a heat sheild??
And you will need 2 holes per muff.
1 for air entry, 1 for air exit...
Unless I missed something ??
 
Last edited:
Don't your heat muffs already have holes ???
Or are these just mufflers with a heat sheild??
And you will need 2 holes per muff.
1 for air entry, 1 for air exit...
Unless I missed something ??

Yes they each have 2 holes but I want to route the hose in a different direction therefore want to change the location of 1 hole on each muff. I've seen some heat muffs with 1 hole in about a 90 degree rotation to the other hole. My holes are aligned.
 
I’ve never lacked for heat with a single muff on one side, but I do live in california.
 
Only concern that I see is consuming a lot of surface area in cowl air exit path. Unsure if it is enough to reduce flow and therefore cooling capacity though. Several have shown that the A models have more turbulence here due to the gear leg support tubing and this has an impact on cooling air drag.

Larry
 
It is not a good idea to put them in series, no real advantage and in parallel you will have twice the heat.
 
It is not a good idea to put them in series, no real advantage and in parallel you will have twice the heat.

That is counter to the recommendation that I got directly from Robbins wings, the guy who makes the heat muffs for vetterman and others.

Larry
 
I spoke with Clint Vetterman. There are heat muffs and heat shrouds. The heat shrouds are not to be run in series. They need cool air to each one. He recommended only using 1 shroud and taking the outer piece off the other one so cooling air could at least hit the muffler somewhat. That's what I did. He says I should have enough heat using one but we'll see.
 
Only concern that I see is consuming a lot of surface area in cowl air exit path. Unsure if it is enough to reduce flow and therefore cooling capacity though. Several have shown that the A models have more turbulence here due to the gear leg support tubing and this has an impact on cooling air drag.

Larry

I would second Larry's concerns regarding hindering air flow.

But if you are set in your desire to do a crossover, I would approach Vetterman or similar supplier about fabricating a 90deg shroud. Would be awkward (not impossible but...) to modify an existing shroud-
 
Heat shrouds

Let me set the record straight here. There’s a big difference between heat muffs and muffler shrouds. As per Rick Robbins with whom we go back too many years to remember, he and I agree that you can plumb a cabin heat muff in series. Regarding shrouds on mufflers due to the increased size of heat transfer from the muffler can it is not good to plumb them in series. Hope this helps. Larry Vetterman
 
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