an engine test some will find interesting
#1
Thread Starter
My Feedback: (1)
an engine test some will find interesting
note that this test was performed last summer, and I have just not got around to testing more,, but I really didn't feel I had to do more testing any way, my wants were to achieve more speed from my plane, yet not have a short Power Band as a Cone pipe would produce, you must know that I knew my test would work out to some extant, so here it is,,
so I have this GP ShoeString with an OS 61FX in it, well it's a very fun plane, note that I have never had more fun flying than I have had with is plane,, but it's speed is nothing much with it's older, restricting Slimline Pitts muffler, note I usually burn 20% Nitro in it, well I wanted more speed, see Prop/Mufflers RPM numbers>>
(NOTE, that the stock OS muffler will not fit on this plane)
A) stock OS 61 FX Muffler, Baffle removed,, 15%/ APC 12X6...12,600 RPM,,
B) Slimline Pitts, 20%/ APC 12X6....10.200 "
C) Slimline Pitts, 20%/ APC 11X8....11.800 "
note that I ran the 11X8 98% of the time..
so at the time of the test the engine has 6+ gallons run threw it, and the liner and piston are in good shape, and it has good compression, and I replaced the bearings before the test,
well I made an exhaust adapter and I mounted an old Century 50 Heli muffler on the 61FX (Century's Silent Power #CN3038A), well it ant silent !!,, see mufflers sizes>>
A) OS 61FX Stock Muffler...OD, 40mm, down to 38mm,, 6 inches long,,
B) Century 50 Heli Pipe..... OD, 40mm,, 9&5/16 inches long,,
exhaust adapter) including the Century Flange, Pipe to Engine's Exhaust Flange length is 2&3/8,,
..
running on 15% with the Century Pipe the 61FX turned the APC 12X6 to a peak of "13.800" RPM (OS #8 plug),,
now, I have read that the 61FX will turn 16,000 with a Cone Racing Pipe,,,, but the thing that this is really all about, is, that the transaction from an idle to peak RPM was explosive, instantaneously , NO lag, the power band was from Idle to 13.800 instantaneously,,
I have been around, I have had RC boats with OPS 45s with Cone Pipes burning 55% and they did not perform instantly like this did,
I felt the engine really needed to be slightly loaded more, it's too bad I didn't have a larger prop to try, such as an APC 12x10, 12X13 or 13X8,
with this type of performance it surly would be a good 3D setup, it would strongly pull out of a hover.. see photo,, yes the plane has been beat up on a few times, it needs work..
Hummmm,, I do have a "never started" OS 70sz Heli engine just waiting around, and I do have than new Worlds Model Midget Mustang, mmmmm I don't think the Century pipe will fit it.
Jim
so I have this GP ShoeString with an OS 61FX in it, well it's a very fun plane, note that I have never had more fun flying than I have had with is plane,, but it's speed is nothing much with it's older, restricting Slimline Pitts muffler, note I usually burn 20% Nitro in it, well I wanted more speed, see Prop/Mufflers RPM numbers>>
(NOTE, that the stock OS muffler will not fit on this plane)
A) stock OS 61 FX Muffler, Baffle removed,, 15%/ APC 12X6...12,600 RPM,,
B) Slimline Pitts, 20%/ APC 12X6....10.200 "
C) Slimline Pitts, 20%/ APC 11X8....11.800 "
note that I ran the 11X8 98% of the time..
so at the time of the test the engine has 6+ gallons run threw it, and the liner and piston are in good shape, and it has good compression, and I replaced the bearings before the test,
well I made an exhaust adapter and I mounted an old Century 50 Heli muffler on the 61FX (Century's Silent Power #CN3038A), well it ant silent !!,, see mufflers sizes>>
A) OS 61FX Stock Muffler...OD, 40mm, down to 38mm,, 6 inches long,,
B) Century 50 Heli Pipe..... OD, 40mm,, 9&5/16 inches long,,
exhaust adapter) including the Century Flange, Pipe to Engine's Exhaust Flange length is 2&3/8,,
..
running on 15% with the Century Pipe the 61FX turned the APC 12X6 to a peak of "13.800" RPM (OS #8 plug),,
now, I have read that the 61FX will turn 16,000 with a Cone Racing Pipe,,,, but the thing that this is really all about, is, that the transaction from an idle to peak RPM was explosive, instantaneously , NO lag, the power band was from Idle to 13.800 instantaneously,,
I have been around, I have had RC boats with OPS 45s with Cone Pipes burning 55% and they did not perform instantly like this did,
I felt the engine really needed to be slightly loaded more, it's too bad I didn't have a larger prop to try, such as an APC 12x10, 12X13 or 13X8,
with this type of performance it surly would be a good 3D setup, it would strongly pull out of a hover.. see photo,, yes the plane has been beat up on a few times, it needs work..
Hummmm,, I do have a "never started" OS 70sz Heli engine just waiting around, and I do have than new Worlds Model Midget Mustang, mmmmm I don't think the Century pipe will fit it.
Jim
Last edited by the Wasp; 08-08-2018 at 10:49 AM.
#2
Sorry I didn't see this yesterday. I would have put an APC 13-8 in the box with your Saito 100! I have about a dozen of them sitting here!
Interesting report.
Interesting report.
#4
Muffler volume plays a huge role in the effective tuning of the engine and power output. I put a TT .46 muffler on an Enya SS30bb engine using an adapter I made. Turning a 9x5 APC prop, the engine gained over 1,500rpm over the stock muffler and open exhaust readings and throttle response was better. A modestly timed 5cc engine with a lapped piston turning nearly 16,000rpm blew my mind. All on just 5% Nitro fuel to boot!
#5
Thread Starter
My Feedback: (1)
Jessy Open) Sorry I didn't see this yesterday. I would have put an APC 13-8 in the box with your Saito 100! I have about a dozen of them sitting here! Interesting report.
blw) Nice looking Century muffler. Lot's of manifold hardware though. Too bad they don't have a side mount version as a stock item. Still a nice looking installation.
BTW, OS does make a 90 degree exhaust adapter for the 50 and 61 engines, this is so you can use a Heli muffler on your plane engine, but they are for engines that mount vertically on the plane..
1QwkSport2.5r )Muffler volume plays a huge role in the effective tuning of the engine and power output. I put a TT .46 muffler on an Enya SS30bb engine using an adapter I made. Turning a 9x5 APC prop, the engine gained over 1,500rpm over the stock muffler and open exhaust readings and throttle response was better. A modestly timed 5cc engine with a lapped piston turning nearly 16,000rpm blew my mind. All on just 5% Nitro fuel to boot!
my boats were the "3D" brand, I remember the owner/designer of 3D boats "Tom Daniels" was big into straight-line speed trials, he once told me (on the phone) that he had seen more than one engine step-up on the pipe double-times, and once he saw an engine step-up on the pipe triple-times
thanks for the replies
Jim