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Old 02-26-2018, 10:08 AM
oviedoed is offline
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Joe,
you pretty much hit the nail on the head with that setup. I was thinking more of a stock setup (see attachment) but yours incorporates the muffler which is a win-win. Great job. Shame the exhaust guys don't have this setup on their shelves. Call it "Pitts for Twins"
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Old 02-26-2018, 11:31 AM
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Originally Posted by oviedoed View Post
Joe,
you pretty much hit the nail on the head with that setup. I was thinking more of a stock setup (see attachment) but yours incorporates the muffler which is a win-win. Great job. Shame the exhaust guys don't have this setup on their shelves. Call it "Pitts for Twins"
I sent a message to Jtec/radiowave to see if they are interested, I'm happy to send them my mockups for free, just the price of shipping.
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Old 02-26-2018, 12:00 PM
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Originally Posted by JoeT View Post
I sent a message to Jtec/radiowave to see if they are interested, I'm happy to send them my mockups for free, just the price of shipping.
Joe,

Thank you for the PM and information. We would love to look at what you have designed. We have done a fair amount of that style over the years.

Most any style like that has to be custom fit for the application, meaning the engine, header drop and space for mounting is needed which is not a problem given the correct information from the customer. Doing a mockup like you have is GREAT!!

I have included a couple other pictures of mufflers we have done for twin engines. basically a wraparound style pitts but this design needs to have room behind the cylinder head or room in the cowl to be offset.

We have done some real crazy stuff but it all has to work. If we think it will affect performance we will raise a red flag and let the customer know.

When we build mufflers we build to order so if the customer has a special application we can design or modify a muffler to what the customers need.

Again thank,

Al
www.jtecrc.com
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Old 02-26-2018, 12:33 PM
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I wonder how that affects cooling to have the muffler chambers right behind the cooling fins?
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Old 02-26-2018, 01:11 PM
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Question for Joe and/or Al at JTec: would the design Joe had for a single muffler be quieter than stock mufflers? And, same or more/less power than stock-type mufflers?




If it was quieter with no or little power loss, that would be sweet!
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Old 02-26-2018, 01:47 PM
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Quote:
Originally Posted by wyo69cowboy View Post
Question for Joe and/or Al at JTec: would the design Joe had for a single muffler be quieter than stock mufflers? And, same or more/less power than stock-type mufflers?




If it was quieter with no or little power loss, that would be sweet!
We have strict sound restrictions up here in Toronto Canada for some of the RC Airfields. When I designed the Big Can pitts muffler, it was to keep things quiet without loss of power.

This passes @ 91db at 21 Feet of measurement, using a bambula (heavy load) 28x10.

The key to keeping things quiet is volume. The stock mufflers, I would not call a muffler, since it's basically an exhaust redirector with very little volume.

The Big Can Pits, is 5" in diameter with 9.5" of length. That's HUGE volume, for a pitts, but not large in volume as a canister. The inlet size is 25mm aka 1 Inch, and the outlet sizes are 20mm each, approx.
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Old 02-26-2018, 02:46 PM
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Quote:
Originally Posted by JoeT View Post
We have strict sound restrictions up here in Toronto Canada for some of the RC Airfields. When I designed the Big Can pitts muffler, it was to keep things quiet without loss of power.

This passes @ 91db at 21 Feet of measurement, using a bambula (heavy load) 28x10.

The key to keeping things quiet is volume. The stock mufflers, I would not call a muffler, since it's basically an exhaust redirector with very little volume.

The Big Can Pits, is 5" in diameter with 9.5" of length. That's HUGE volume, for a pitts, but not large in volume as a canister. The inlet size is 25mm aka 1 Inch, and the outlet sizes are 20mm each, approx.
Yes, volume is a big requirement. As Joe said he also loaded up the engine. In turn less RPM ( but performance maybe close to the same for flying) Less RPM means less Exhaust Noise. A lot can be accomplished by just changing props or going to 3 blades.

Stock type mufflers and in-cowl box type are basically exhaust diverters'.

Al
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Old 03-01-2018, 08:13 AM
decuzar is offline
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We like DIVERTERS
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Old 03-30-2018, 01:38 PM
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Question for Denney47

It was mentioned that RCGF is planning a new Head/Barrel for the 70 twin for more power. Has this been implemented yet or is it there going to be a v.2 motor coming out? If so what is the time frame?
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Old 03-31-2018, 09:23 PM
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Originally Posted by cmouse42 View Post
Question for Denney47

It was mentioned that RCGF is planning a new Head/Barrel for the 70 twin for more power. Has this been implemented yet or is it there going to be a v.2 motor coming out? If so what is the time frame?
Sorry but I have not heard anything about this? When I originally ask them to manufacture this engine for me I wanted the smaller spark plugs but they refused to do that for me. The engine has enough power now so I don't see any reason to change it. Can you let me know where you received this information?
Thank you
Tom
Valley View RC
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Old 04-01-2018, 05:31 AM
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To Quote post #27

"
Howdy,

This is Joe from RCGF. The 70T does Kick Booty but I have not had a chance to compare it to a DA 70 yet… We are in the process of developing a new and improved cylinder for the RCGF 70T to get even more power out of the platform. We have a bunch of new engines entering the market place as well we have some in the E&D stages. If you all have any questions get it from the horse… Call me at 520-732-2200 9 to 5 MST I will be glad to share.. Joe

"

or have I misinterpreted it?
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Old 04-01-2018, 05:35 AM
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Quote:
Originally Posted by cmouse42 View Post
To Quote post #27

"
Howdy,

This is Joe from RCGF. The 70T does Kick Booty but I have not had a chance to compare it to a DA 70 yet… We are in the process of developing a new and improved cylinder for the RCGF 70T to get even more power out of the platform. We have a bunch of new engines entering the market place as well we have some in the E&D stages. If you all have any questions get it from the horse… Call me at 520-732-2200 9 to 5 MST I will be glad to share.. Joe

"

or have I misinterpreted it?
You do find some differences between what RCGF says and other things stated about the engines and some times you find them extremely different.
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Old 04-01-2018, 09:33 AM
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I'm going to be getting one of these 70 Twins for my new Extreme Flight 91" Laser.
Curious as to if anyone has tried this?
I know lots have used a DA70, and with Jtec Slim line mufflers, fits under the cowl.
I would like to do the same.
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Old 04-02-2018, 12:32 PM
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Quote:
Originally Posted by cmouse42 View Post
To Quote post #27

"
Howdy,

This is Joe from RCGF. The 70T does Kick Booty but I have not had a chance to compare it to a DA 70 yet… We are in the process of developing a new and improved cylinder for the RCGF 70T to get even more power out of the platform. We have a bunch of new engines entering the market place as well we have some in the E&D stages. If you all have any questions get it from the horse… Call me at 520-732-2200 9 to 5 MST I will be glad to share.. Joe

"

or have I misinterpreted it?
That post is almost a year old and I don't think there is a new cylinder on the way. This engine was copied from an engine Valley View RC (Jody Hack) and Tomy Chen developed. RCGF agreed to manufacture it for me. They sent me a prototype for testing and I approved it as it was.
Thanks
Tom
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Old 04-02-2018, 02:31 PM
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Was that the MT70?
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