CMI Air Actuated Mufflers
 

I'm adding CMI Aft Fire mufflers to my boat, and ditching the Corsa Silent Choice. So here is my question. I'm not giving CMI $750 for an air pump, when I can build the same thing for a fraction of the cost. For those of you with dual line air actuated mufflers, how do they work? Is it a momentary switch that pressurizes the cylinder, with another switch that opens a valve to release the pressure? Or are they pressurized to open and too close? Also, any idea what the PSI is to make these work?

https://cimg7.ibsrv.net/gimg/www.off...a29ea47c37.jpg

momentary switch that pressurizes the cylinder, with another switch that opens a valve

Just discussed the other day.

https://www.offshoreonly.com/forums/...i-exhaust.html

I built one with a Harbor freight air pump, check valve and a 12v NOS solenoid about 10yrs ago under $100. Use the pump for the trailer tires also. lol
I might actually have 2 CMI pumps laying around. Never changed out this system because it works so good.
https://www.harborfreight.com/air-to...sor-69284.html
https://www.ebay.com/itm/Normally-Cl...-/121090156302
https://cimg5.ibsrv.net/gimg/www.off...d3cdd57c54.jpg

Close up
https://cimg6.ibsrv.net/gimg/www.off...901257032f.jpg

Thanks Rookie! That is what I was looking for.

Here`s the actuators if you`re looking


https://gaffrigperformance.com/boat-...silencers.html

Sick Stinger has an air pump https://www.offshoreonly.com/forums/...ers-rings.html

Thanks Griff!

Another question for you guys running this type of muffler, how are you running the hoses through the hull? I've been trying to zoom in on some pictures, and it appears that some are just running the hose though small holes in the transom. I'm really not sure I want to do it that way. Is anyone using a thru-hull fitting of some sort?

https://cimg9.ibsrv.net/gimg/www.off...d5befc254f.jpg

The 2 lines coming out thru that square fitting.. no idea where you get it thou .

Thanks- I was thinking of making something exactly like that.

Mine use Shakespeare or equivalent through hull fitting for VHF antenna coax for the air lines to the mufflers. Chrome plated brass with rubber seal. Newer pneumatic actuators from Parker on Amazon for $30 each use only one air line. Makes for a cleaner look. I'll try to upload a pic.

I thought about using the VHF fittings, but 8 of them would have been too much. I just ordered 4 custom plates like ICDEDPPL has on his boat.

Where did you get the 4 custom plates from?

J'achète du kit en France, les volets doivent être verticaux ou horizontaux? , J’ai installé des vérins électriques à l’intérieur du compartiment moteur, des coques usinées pour laisser passer une tige reliant le cylindre au silencieux.

error translation

Metals Cut 4U, I had them make 4, 1"x 2.5" plates, with polished stainless, 1/8" thick. I have a drill press at my house, so I'll drill the holes here.

I buy kit in France, the shutters must be vertical or horizontal? , I installed electric cylinders inside the engine compartment, machined shells to pass a rod of the electric cylinder to the muffler.

Some other options:

https://www.defender.com/product.jsp?id=3411039

That's an indication of a leaking cylinder or leaking hose connection. Run some soapy water over each connection as you run the pump. You'll easily find the leak. They should remain closed overnight.

Originally mine would stay shut for days in storage.
I put a check valve inline so the air did not bleed back through the pump.

Mine will stay closed for about an hour.
FYI, the ends on the actuator cylinders will unscrew and there are O rings inside that can be replaced.

Part number? I'm to lazy to go measure my cylinders. I assume the cylinders were spring return.

https://cimg3.ibsrv.net/gimg/www.off...6c7ea24b66.jpg
You need to take the pin out of the end. (Tap out with hammer ) and these do not have a line from the vent. This did not matter to me as its a new install.