DA-70 Exhaust

[mnfatboy]

I just recently got back into flying and started with electric but just bought a DA70 to take the leap to gas. I've been looking at a number of different forums to learn more about gas setups but I am still trying to figure out the exhaust options. I think I've narrowed it down to either Jtec mufflers or proflow canisters but I am still not sure what the best option is for me. I've done some googling and searching forums but never found clear info I was looking for...
Are canisters significantly quieter than the mufflers? Is it harder to tune the motor with canisters than mufflers? What header is needed to properly mount the canisters? I will most likely be putting this in a EF Extra 91 or the new AJ Aircraft Laser.

 

[Bunky.F.Knuckle]

I dont think that the 70 with stock muffler is much louder than one with one with canisters. I seen where DA come out with a 2 into 1 header for the 70.

 

[ryan_m]

Typically canisters are a bit quieter. They also add weight.
I don't know if they affect tuning much or not, a tuned pipe does. Tuned pipes are designed to add power in a particular range of the power band. Tuning gets more particular, and the pipe itself also needs to be tuned. (changing length usually)
As for header type needed, I couldn't help you there, sorry.

 

[49dimes]

I am hoping someone will chime in with some performance with a 2 in to 1 and a large smooth pipe. There are a few pics on Dave's site @Planebender . Very interested in getting the header and pipe.

 

[mnfatboy]

Thanks for the responses. I've dealt with tune pipes with glow engines years ago and I'd rather not start with those. I have limited time so I'd rather be flying than tuning. I did see DA released a Y-pipe which has me intrigued. Maybe that new DA pipe and a large proflow canister would be a good start?

 

[mnfatboy]

I dont think that the 70 with stock muffler is much louder than one with one with canisters. I seen where DA come out with a 2 into 1 header for the 70.

I've seen mixed info on this and was really trying to understand it more. I saw somewhere that the jtech mufflers were in the 106 db range @25ft but haven't been able to find out for sure.

 

[49dimes]

Thanks for the responses. I've dealt with tune pipes with glow engines years ago and I'd rather not start with those. I have limited time so I'd rather be flying than tuning. I did see DA released a Y-pipe which has me intrigued. Maybe that new DA pipe and a large proflow canister would be a good start?

Maybe so. My experience tells me you need an individual pipe for each cylinder to see a performance gain. But being that both cylinders on twins fire at the same time the combined resonance could be effectively tuned with a single pipe and Y header. I'm intrigued none the less.

 

[stangflyer]

I just recently got back into flying and started with electric but just bought a DA70 to take the leap to gas. I've been looking at a number of different forums to learn more about gas setups but I am still trying to figure out the exhaust options. I think I've narrowed it down to either Jtec mufflers or proflow canisters but I am still not sure what the best option is for me. I've done some googling and searching forums but never found clear info I was looking for...
Are canisters significantly quieter than the mufflers? Is it harder to tune the motor with canisters than mufflers? What header is needed to properly mount the canisters? I will most likely be putting this in a EF Extra 91 or the new AJ Aircraft Laser.

Balance and back pressure. It's all about how you get a motor to breath. There is absolutely no harm in using the stock exhaust that comes with many of the r/c engines of today. By all standards, they do exactly what they are designed to do. Direct the flow of the exhaust out and away from the engine and or airframe. They are however not the most efficient in getting a motor to reach its peak potential. A lot of people use them simply for the ease of installation and cost effectiveness. Most often than not, stock exhaust is louder at least to some degree over a tuned pipe or canister setup. A decent header and canister arrangement will often yield a quieter sound to most any motor. The benefit of a decent header and canister or tuned pipe arrangement is equalized pressure and balance for the engine. It is just as important to get the exhaust out efficiently as it is to get the fuel into the cylinder. An optimized fuel charge can only occur in the cylinder when the exhaust is also not just pushed out or released out of the cylinder by the piston, but more over "drawn" out by the exhaust system. Thus allowing the fuel charge to flow more evenly into the cylinder. A stock exhaust...(unless very high quality and designed in the proper manner) is basically a resonator with little to no baffling. Basically designed to "slow" the exhaust down on exist from the cylinder to help reduce noise. Many high performance race cars are utilizing "tuned" headers and exhaust. Primarily for the same purpose. To help draw the exhaust out of the engine efficiently. I have personally witnessed on three DLE 55cc motors the effect of a canister arrangement. I use these only as an example as it also is reflective of my larger displacement motors. DLE 55 with Bowman rings twisting Falcon carbon fiber 23x8 props. With stock exhaust, static rpm 6900'ish. Flight performance is really good, but quiet loud. Exact same three DLE 55's with various makes of headers and canisters. Static rpm 7250 plus. No other changes. Flight performance is insanely ballistic. Throttle response incredibly improved. As for the DA 70 twin and how it would perform on a single can verses two cans, the difference would probably be so minimal that it would not be too noticeable. The only draw back I have found is though it is proven the canister/tuned pipe arrangement is most times quieter and there is an absolute noticeable increase in performance, there is in fact a trade off for weight. Case in point: 30% Pilot Edge 540: DLE 55cc with stock exhaust, 15 pounds, 14 ounces. Same airframe and motor arrangement with header and canister, 16 pounds 8 ounces. A difference of 10 ounces. There was an upside to this arrangement also. No needed ballast weight added verses 2 ounces on the nose for the stock exhaust. So the trade off was not that great to even matter. With our higher performance motors and lighter airframes, it is just a no brainer to me to get the best tuning and performance available.

 

[Planebender]

Sorry I have been a sleep here. Very busy these days in the shop. The 2 into 1 set up works great on a Large Pro Flow Canister or our large Smooth Pipe. You will see a little larger gain running 2 pipes as opposed to only 1. Either way the new DA-70 is a good little engine and has sky high potential.

Dave

 

[49dimes]

Sorry I have been a sleep here. Very busy these days in the shop. The 2 into 1 set up works great on a Large Pro Flow Canister or our large Smooth Pipe. You will see a little larger gain running 2 pipes as opposed to only 1. Either way the new DA-70 is a good little engine and has sky high potential.

Dave

Bout time you showed your smiley pipes! lol And thanks as always brother!