Fast OS .61 Warbird
02-24-2014, 08:01 AM
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Fast OS .61 Warbird
Guys, I have a World Models Silver P-51 .46 size Mustang. I also have a good running OS .61FX with stock E-4010s exhaust. We have no real (sanctioned) racing venue at our club as we have only 12 members. What we do have is a couple of the guys who just wanna go fast. It is not extreme at this point but, Ya gotta start someplace.
I am starting My testing this week on props and pipe. I will get an rpm baseline for the stock goodies. I will be starting with these props and 15% Omega. APC 11x7,11x8, 12x6 and a Master Airscrew 12x6 K series.
As I am more familiar with 4 stroke OS and Saito (with some .91 YS experience thrown in), I'm not really sure where to start on this two cycle thing. I will tach the stock muffler ,then tach it with the inner cone removed to see if there is a difference and if so, how much.
I have the OS tuned pipe,minus header, for the .61 but I can see no way to actually use it on the Stang, therefore I was wondering if the Macs one piece (black) muffler would be beneficial.
This plane/engine combo is the parameter I must work with ( I am already familiar with the OS 91fs and YS .91 on a 46 size plane) so any help getting this thing up and hauling the mail would be greatly appreciated.
Thanks in advance, TJ
I am starting My testing this week on props and pipe. I will get an rpm baseline for the stock goodies. I will be starting with these props and 15% Omega. APC 11x7,11x8, 12x6 and a Master Airscrew 12x6 K series.
As I am more familiar with 4 stroke OS and Saito (with some .91 YS experience thrown in), I'm not really sure where to start on this two cycle thing. I will tach the stock muffler ,then tach it with the inner cone removed to see if there is a difference and if so, how much.
I have the OS tuned pipe,minus header, for the .61 but I can see no way to actually use it on the Stang, therefore I was wondering if the Macs one piece (black) muffler would be beneficial.
This plane/engine combo is the parameter I must work with ( I am already familiar with the OS 91fs and YS .91 on a 46 size plane) so any help getting this thing up and hauling the mail would be greatly appreciated.
Thanks in advance, TJ
02-24-2014, 09:21 AM
#2
I run an FX61 in a daily flyer plane. Call Dub Jett and get a red Jett muffler for it. Prop it for mid 14,000 on the ground. Make sure your fuel has 19-20% oil with some of it caster. Use an OS8 plug when it is cold out and an OS10-A5 plug in the summer. I would probably start with and 11x7 or 11x8 depending on your altitude. This is a good running engine and should be pretty fast in your mustang. The engine is pretty heavy, so plan on moving weight to the back of the plane to balbnce it, you do not want to have to add lead...
Good Luck
Scott
Good Luck
Scott
02-24-2014, 07:24 PM
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Pylonracr, thanks for the quick reply. I found I only had 1/2 gal. of CP 15%. I tached the .61 with the APC 11x7 and stock muffler,and new OS #8 plug. Got 12,240 on the ground with 2,800 idle. Second run was with the baffle removed. Had to richen it up about 1/4 turn but got 12,600 on the ground and idle @23-2400 rpm. Sounded very healthy. As far as oil in the fuel I was using CP 15% and adding 3oz Klotz Benol to a gal.of fuel.Seems most fuel doesn't tell You what they use. Do You use higher ratio nitro? If so, what do You use? How do You determine if You need a head spacer/shim? We are at 42' above sea level here in this part of Fl.Will Dubs Red Jett Muffler make a bigger difference? Sorry for all the questions, but I want to get this right the first time. Thanks, TJ
02-24-2014, 09:29 PM
#4
No problem, glad to help.
I use 15% fuel. I either mix my own or add oil to store bought fuel. I have found that if you go to the website of the fuel manufacturer they will list the oil content. 3oz of castor per gallon should be plenty, since it is about 2 1/2%.
The red jett muffler should gain you about 1,000 to 1,200 rpm. It is basically a quarter wave pipe, so it is tuned for a particular rpm. You have to prop the engine to run in that rpm range. In flight you can hear the engine come up on the pipe. It is not the boost you get from a full length pipe, but it is pretty close and you do not have to tune it or find room for a full length pipe in the plane. I like them for a lot of applications, but I still run full length pipes when I am serious about speed. Call dub and talk to him, as he makes different color pipes tuned to different rpm ranges. The red muffler is the most popular and probably the best for your application.
For 15% you will not need a head shim. You can try more nitro, but near sea level you will need to lower the compression pretty soon. You may be able to get away with 20% with a cold plug, listen for detonation on the ground and check the plug every run. I would probably not push this engine that hard. They are pretty comfortable around 14K on 15% and will last a long time. Is it really worth a few hundred rpm to risk your engine? If it is, there is more in it. You can open up the crank, and raise the exhaust timing.
One more thing. Buy a good set of bearings from Bocca since the OS bearings do not seem to last very long. Keep an eye on the liner, since some OS engines like to peel the plating off the cylinder.
Scott
I use 15% fuel. I either mix my own or add oil to store bought fuel. I have found that if you go to the website of the fuel manufacturer they will list the oil content. 3oz of castor per gallon should be plenty, since it is about 2 1/2%.
The red jett muffler should gain you about 1,000 to 1,200 rpm. It is basically a quarter wave pipe, so it is tuned for a particular rpm. You have to prop the engine to run in that rpm range. In flight you can hear the engine come up on the pipe. It is not the boost you get from a full length pipe, but it is pretty close and you do not have to tune it or find room for a full length pipe in the plane. I like them for a lot of applications, but I still run full length pipes when I am serious about speed. Call dub and talk to him, as he makes different color pipes tuned to different rpm ranges. The red muffler is the most popular and probably the best for your application.
For 15% you will not need a head shim. You can try more nitro, but near sea level you will need to lower the compression pretty soon. You may be able to get away with 20% with a cold plug, listen for detonation on the ground and check the plug every run. I would probably not push this engine that hard. They are pretty comfortable around 14K on 15% and will last a long time. Is it really worth a few hundred rpm to risk your engine? If it is, there is more in it. You can open up the crank, and raise the exhaust timing.
One more thing. Buy a good set of bearings from Bocca since the OS bearings do not seem to last very long. Keep an eye on the liner, since some OS engines like to peel the plating off the cylinder.
Scott
02-25-2014, 04:48 PM
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http://morganfuel.com/coolpower_performance_detail
http://morganfuel.com/omega_gallon_detail
02-26-2014, 02:28 PM
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MJD, thanks. I am more familiar with 4 cycle engines and just like to use PM 20/20. I read that Omega has a mixed blend of Synthetic and castor and that the castor helped by coating the parts to resist metal to metal contact in case of a lean run as the synthetic had a lower flash point allowing it to burn off faster leaving little to no lubrication if You had a high speed lean out. I have tuned my buds Saitos with CP MVP. Don't like it. It says no need for after-run oil. We used it all summer long last year and the Saitos ran great,as long as they were a bit on the rich side . My bud is a scale flier and doesn't hot rod so it was ok fuel.. Then after 4 gallons I tore down both of the 100 Saitos and they were full of rust. Changed out the bearings and and added 3oz of Klotz castor oil and so far no problem. He fly's them quite a bit so it's not as if they got rusty sitting around. Me ,on the other hand ,I tend to run the snot out of them and although I am very careful of the tuning,like the idea of the castor being in there in case I screw up.
02-26-2014, 02:55 PM
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I don't run straight synthetic in anything except my bike. All you have to do is use Omega of the same nitro content as you are presently using CP and voila there's the castor you need. Omega is 17% total oil, 70/30 synthetic/castor. I run it straight on sport engines like my .46 FX etc., but for any higher performance stuff I add castor to bring it up to the target total oil content. Ducted fan engines on props for example, I bring total oil up to about 23%, same as for 1/2A stuff. I'd prefer 18-20% total oil for everything but Omega is the dominating brand around here, so for regular ol' sport engines I don't bother, it does well. The only SIG Champion I see up here is quarts, nobody stocks it as their standard fuel in gallons. Wish someone did, I think SIG makes every fuel I might ever need.
Last edited by MJD; 02-26-2014 at 02:58 PM.
