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which is better?

Old 11-20-2014, 05:54 PM
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An-2o
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Question which is better?

I'm considering a 70cc twin for my 1/3 cub and was wondering which engine is better, and has more power? The roto 70 or the da 70? I notice the carb location on the da would be easier installation, where as the roto is rotary valve which is a plus for me. Also could anyone posts rpm's and props used from each engine thanks.
Old 11-22-2014, 06:09 AM
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STUKA BARRY
 
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I've got a Proctor 1/3 Cub in a stolen German paint scheme, you may have seen it, anyway, its powered with a Zenoah GT-80 swinging a Xoar Sabre 24X10 scale prop. Its more than enough power.
Old 11-22-2014, 07:40 AM
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w8ye
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At my flying field everyone has at least one DA and no one has a Roto.

There have been some problems with the DA's at times but the factory has always taken care of them.
Old 11-22-2014, 07:59 AM
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speedracerntrixie
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I have only heard positive things about the DA. I have heard nor seen anything about any Roto, although they look pretty in the pictures. I have a DA 150 that is 13 years old and still runs like a champ. They are built for the long haul.
Old 11-22-2014, 11:12 AM
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This looks like a good option. I've not seen the 70 but the 60 single I have. Mile High's service is great.
http://www.milehighrc.com/EME70CC.html

Jim
Old 11-22-2014, 05:07 PM
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An-2o
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thanks for the reply's! Right now I haven't made up my mind as of yet, but now I'm looking at the roto 85 fs boxer. The plane had a dle85 which I gave away because of the clink and clank that engine made, so I'm going away from all the Chinese made engines. Don't get me wrong that engine ran beautifully, I'm just wanting a high quality engine for the long haul.
Old 11-22-2014, 06:16 PM
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STUKA BARRY
 
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Originally Posted by An-2o View Post
thanks for the reply's! Right now I haven't made up my mind as of yet, but now I'm looking at the roto 85 fs boxer. The plane had a dle85 which I gave away because of the clink and clank that engine made, so I'm going away from all the Chinese made engines. Don't get me wrong that engine ran beautifully, I'm just wanting a high quality engine for the long haul.
You just described the Zenoah GT-80 to a T and it fits in the Super cowl of a 1/3 scale Cub. I got mine for $400 off of RCU.
Old 11-22-2014, 06:35 PM
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speedracerntrixie
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May not be an issue but the GT 80 has a power band at a higher rpm then all the others mentioned. That's why they developed a race class around that engine. May naot be what you would want in a Cub.
Old 11-22-2014, 08:20 PM
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Truckracer
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I just sold a GT-80 that had very low time. Great engine but not one I would use on a CUB because it wouldn't effectively pull the sizes of props I would prefer. As speedracer says, these engines like to turn up and I don't think that would match the personality of a big CUB.

I'd be very interested to hear some reports about the Roto line of engines. I have never seen one in person.
Old 11-22-2014, 08:56 PM
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2walla
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You guys are nuts debating the power band charisteristics on the gt 80 for a cub. Same prop about the same rpm from both the the da 70 and the gt 80. If you put a little teeny race pitch prop the gt 80 will spin up reliably much faster. But this isnt a race it is a cub.. I would avoid the roto as i have never seen one. Phave you? What does that tell you? The gt80 is more than the da70????( *** come on horizon? What are you trying to do- get everybody to buy your china made evolutions?) the da 70 fits a little better on a cub, the top carb on the gt80 can cause issues if you arent careful with the cowling installation. Da is proven and has da service.. Hmmm. No brainer...
Old 11-22-2014, 10:37 PM
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speedracerntrixie
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DA 70 with a laminated wood 26x8 would look and fly great.
Old 11-23-2014, 06:03 AM
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It appears your mind is made up at to which engine you want, so get one and you can tell us all about the roto 85 who knows you may even get another one or two tried out with your report.
Old 11-23-2014, 08:02 AM
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Originally Posted by STUKA BARRY View Post
I've got a Proctor 1/3 Cub in a stolen German paint scheme, you may have seen it, anyway, its powered with a Zenoah GT-80 swinging a Xoar Sabre 24X10 scale prop. Its more than enough power.
Hi Barry, is that plane the one that our Balsa Eater tree reached up and grabbed at the warbirds event in Thornburg, Va a couple of years ago? Missed you last year. Sincerely, Richard
Old 11-23-2014, 10:10 AM
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Originally Posted by spaceworm View Post
Hi Barry, is that plane the one that our Balsa Eater tree reached up and grabbed at the warbirds event in Thornburg, Va a couple of years ago? Missed you last year. Sincerely, Richard
Nope, that was my Balsa USA 1/4 scale with the PTE36R engine. My 1/3 Scale 140" w/s is a Proctor with the Super cowl completely covering a Zenoah GT-80 swinging a Xoar 24X10 Sabre propeller painted in German markings. This plane was also at Warbirds Over Fredericksburg and flown by Rob and myself.
Old 11-23-2014, 11:04 AM
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The thing that sticks in my mind here is that the OP has told us that the airplane has flown with a DLE 85. This tells me that the airplanes CG was correct with that engine. Some of the suggestions here and including the OP thinking of going with the Roto 85 4s are much heavier then the DLE. Obviously this is going to lead to more work getting the CG back to where it was with the original engine.
Old 11-23-2014, 12:20 PM
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The Roto engines are an example of engines that if I were rich I would buy even if I didn't have a use for them, just because they are so beautiful and cool, especially that 170.

AV8TOR
Old 11-23-2014, 02:36 PM
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Originally Posted by speedracerntrixie View Post
The thing that sticks in my mind here is that the OP has told us that the airplane has flown with a DLE 85. This tells me that the airplanes CG was correct with that engine. Some of the suggestions here and including the OP thinking of going with the Roto 85 4s are much heavier then the DLE. Obviously this is going to lead to more work getting the CG back to where it was with the original engine.
The DLE require an ignition battery, the GT-80 does not, therefore moving the receiver battery back a few inches is really no work at all, plus Cubs actually fly better a little nose heavy. The GT-80 is really a great engine of choice for a 1/3 Scale Cub.
Old 11-23-2014, 03:04 PM
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and it will last long enough to hand down to your grand kids.
Old 11-23-2014, 04:14 PM
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Originally Posted by STUKA BARRY View Post
The DLE require an ignition battery, the GT-80 does not, therefore moving the receiver battery back a few inches is really no work at all, plus Cubs actually fly better a little nose heavy. The GT-80 is really a great engine of choice for a 1/3 Scale Cub.
Barry, I'm glad you are so happy with your GT80. I do agree it's a nice running engine. Just some food for thought, the GT weighs 2.5 lbs more then the DLE, I don't think relocating the RX battery is going to compensate. Personally I have not used a separate ignition battery for 4 years now so it really is not required however we do not know if the OP was running one or not..

Last edited by speedracerntrixie; 11-23-2014 at 04:23 PM.
Old 11-23-2014, 04:36 PM
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Originally Posted by av8tor1977 View Post
The Roto engines are an example of engines that if I were rich I would buy even if I didn't have a use for them, just because they are so beautiful and cool, especially that 170.

AV8TOR
I have one of the Valach 170's and it is truly sweet. Seriously heavy compared to a DLE 170 though, but well worth it.
Old 11-23-2014, 04:45 PM
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An-2o
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I agree with you 100% on the 170 it looks so sweet. I have a 1/4 hangar 9 with the os 320 ff pegusas which everyone said was too much for the airplane, and we all found out it was a match made in heaven, and it even looked scale. Problem with the 170 is the prop clearance on the 38.5 pd 1/3 cub. When I had a 26x10 on my dle85 and if you landed slightly hard it would hit the prop. I KNOW the 170 would be overkill since the dle85 was unlimited vertical but it would be cool to have the 170 on the 1/3 and the Pegasus on the 1/4...I'M real loyal to my four strokes!
Old 11-24-2014, 04:44 AM
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Personally I would only consider the DA for use in any of my airplanes because of weight, power, reliability, and by far, their service, but that is just me...

Bob
Old 11-24-2014, 01:03 PM
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I own a BUSA 1:3 scale Super Cub.

Itīs powered by a GT-80 which fits nicely in the cowl with the exeption of the plug caps. They extend about 5mm from the cowl.
The propeller I normally use is a Fiala 26x10 since the engine would rip the original Fiala 28x8, cut down to 27". Way too much noise.

The 26x10 spins about 6200 rpm and provides a good bit more than scale power for the 46 lbs Super Cub.

Donīt have direct experience with either the ROTO 70 or the DA-70, but from reading several reports on the net, I seems that the ROTO is not very powerful. About the same, or maybe even slightly less, than a G-62 on a non tuned exhaust.
The DA on the other hand is reported to be quite powerful. Not that itīs really needed for a Cub though. :-)

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