|Displacement:||1.98 cu in (32.4 cc)|
|Stroke:||1.13 in (28.6 mm)|
|Practical RPM:||1,800 Ė 10,000|
|Power Output:||2.9ps/9000 RPM|
|Weight of engine:||30.68oz. (116g)|
|Propeller:||15x12 thru 20x8|
|Crankshaft Thread Size:||5/16-24|
|Available From:||Tower Hobbies|
The newest and largest in the Surpass line is a perfect power plant for any 1.50-1.80 size plane!
O.S Engine's latest addition to their FS series engines!
OSís new FS-200S came in the OS blue box with their usual quality packaging. As I unpacked the box, I was impressed with the finish and size of the new engine. There was no damage and the finish was perfect.
At first, I thought this couldn't be a 2.0 displacement engine. It was way too compact and light. Amazing!
Here's a photo overview of this innovative engine:
|Crankshaft Thread Size:||5/16-24|
|Distance from Carburetor to end of Crankshaft:||6.8" (172mm)|
|Distance from Crankcase Center to Prop Hub:||3.03" (77mm)|
|Distance from Prop Hub to End of Crankshaft:||1.45" (37mm)|
|Distance from Carburetor to Crankcase Center:||2.3" (58.5mm)|
|Distance from Carburetor to Prop Hub:||5.3" (135.5mm)|
|Distance from Center of Engine to End of Crankshaft:||4.48" (114mm)|
|Height from Crankshaft Center to Rocker Cover:||4.68" (119mm)|
|Height from Crankshaft Center to Muffler Center:||3.2" (82mm)|
|Height from Crankcase Bottom to Rocker Cover:||5.7" (144mm)|
|Width at Mounting Tabs:||2.6" (67mm)|
|Width of Crankcase Below Mounting Tabs:||1.9" (48mm)|
|Width of Cylinder Head:||2.2" (58mm)|
|Distance Between Mounting Holes Same Side:||0.98" (25mm)|
|Distance Between Mounting Holes Opposite Side:||2.3" (58mm)|
|Engine||1.83 lb (830 g)||1.9 lb (862g)|
|Muffler||NA||4.1 oz (116g)|
|Total:||NA||34.49 oz (978g)|
I set my OS 1.20 FS on the bench next to the OS 2.00 to compare the size difference. Considering the 2.0 is almost twice the displacement, its compact size and similarity to the 1.20 footprint is amazing!
|Displacement:||1.98 cu in (32.4cc)||1.218 cu in (19.96cc)|
|Horse Power:||2.9ps /9000 RPM||1.9 /11,000 RPM|
|Crankshaft thread size:||5/16-24||5/16-24|
|Bore:||1.50" (38.0mm)||1.22" (30.4mm)|
|Stroke:||1.13" (28.6mm)||1.08" (27.5mm)|
|Distance Between Mounting Holes Same Side:||0.98" (25mm)||0.98" (25mm)|
|Distance Between Mounting Holes Opposite Side:||2.28" (58mm)||2.28"(58mm)|
|Distance Center of Crankcase to Drive Hub:||3.03" (77mm)||2.99" (76mm)|
|Width Between Mounting Tabs:||2.6" (67mm)||2.6" (67mm)|
|Width of Crankcase Below Mounting Tabs:||1.9" (48mm)||1.77"(45mm)|
|Length of back of carb to drive hub:||5.33" (135.5mm)||5.03"(128mm)|
|Height/Bottom of Crankcase to Top of Cylinder Head:||5.7" (144mm)||5.45"(138.5mm)|
|Weight:||30.68oz (116g)w\header pipe||30.5oz (864g)|
It was around 75 degrees when I arrived at my test stand. I bolted the engine to the stand, and mounted the Top Flite 18X8 I planned to use for break-in. I filled the tank with Byron 15% fuel and was ready to fire it up!
After opening the high speed needle four turns, I spun the engine a couple times by hand to prime it and hooked up the glow driver. I thought I'd try my usual method of starting big four stroke singles of spinning the prop backwards against compression with a chicken stick. It immediately fired and kicked the prop nut loose enough to freewheel the prop! And believe me the prop was tight! I thought, "Ok, we won't be doing that again!Ē
After re-tightening the prop, I hooked up my Sullivan Dynatron Starter. A quick bump of the Sullivan starter and the motor was purring. I followed OS's recommended break-in procedure of leaning the engine for five seconds, then richening it to let it cool. After four 10 oz. tanks, I leaned it out and checked RPM and transition. It was spinning the 18x8 prop at 7620 and idling smoothly at 2160. Transition was excellent! I never did have to adjust the low speed needle through all the test runs.
I've owned and flown quite a few large displacement four-stroke engines., and all of them tended to vibrate and were rather noisy. Through all the OS 2.0's test runs, I was really impressed at how smooth and quiet the engine was for such a powerful large displacement single.
My test stand is on the edge of a small patch of wood, and my son ďassistedĒ me with the testing. He made the comment that the prop wash was moving the leaves on the trees 30 feet behind us!
I always figure around two gallons of fuel for break-in for a four stroke engine before trying to achieve top RPM, and I usually assume performance will increase with each tankful of fuel. But the following figures were pretty impressive!
|PROP||WOT RPM||IDLE RPM|
|Top Flite Power Point 16X8||8,620||2160|
|Top Flite Power Point 18X8||7620||2160|
|Top Flite Power Point 18X10||6,890||2040|
|Top Flite Power Point 18X12||6270||2040|
|Top Flite Power Point 20X6-10||5660||2010|
|Top Flite Power Point 20X8||6300||1920|
|I'm sure RPM readings will increase as the engine continues to break-in.|
|PROP||Static Thrust at WOT|
|Top Flite Power Point 16X8||13.68 lbs.|
|Top Flite Power Point 18X8||17.13 lbs.|
|Top Flite Power Point 18X10||14.0 lbs.|
|Top Flite Power Point 18X12||11.6 lbs.|
|Top Flite Power Point 20X8||17.85 lbs.|
|Top Flite Power Point 20X6-10||14.1 lbs.|
|Computed using the ThrustHP static thrust program|
|Readings taken at app. 6 feet with a Top Flite Power Point 18x8 prop installed.|
The OS 2.00 is a powerhouse, on a small footprint with an impressively quiet muffler for its size! It's size and power makes it a good fit for a broad range of sport and scale models, and it should be another big seller for the already famous OS lineup.
I believe OS has just set the bar a little higher for large bore single cylinder engines. I sure can't wait to get her flying!!Last edited by Angela H; Jun 25, 2007 at 02:20 PM..
I don't know where that guy has been but a Saito 1.80 on its worst day will slaughter that thing.
Saito 1.80 & APC 16x8==9,500 rpm
Saito 1.80 & Graupner 16x8=9,400 rpm
APC 18x6W==8,900 rpm
Menx 18x6 on 10% nitro==8,600
My own lowly Saito 1.50 turns an 16x8 Graupner at 9,000 on 15% PM
Last edited by I TOBOR; Jun 30, 2007 at 06:25 AM.
Where are the comparisons?
What good is an engine review without comparisons to competing products. How does it compare to the Saito 1.80 and 2.20? It's nice to know that it runs smoothly and doesn't make too much noise, but if I'm going to spend $500 for it, I want to know whether it is in the same league as the competition powerwise.
And if it isn't, you owe it to your readers to say so.
All reviews should include the following information:
1. was the engine purchased by the reviewer or supplied by the manufacturer or publisher?
2. if the engine was supplied by the manufacturer/tester, was it returned after the testing was completed or was the reviewer allowed to keep it?
3. What frames of reference does the reviewer have when drawing conclusions and rating the various aspects of the product?
4. Does the publisher accept advertising from the manufacturer or distributor of the product being reviewed?
These, and many other factors can sometimes influence the outcome of a review and unless we know the facts we can't judge just how objective the review might be -- hence it is worthless.
I like what they've done with the muffler. Still, this engine is a little on the expensive side. A comparable gasoline engine such as the Evo 35GT2 is $50 cheaper and is also more economical to run. Even the Evo 26GT2 would work for models in that range and it's a full $100 cheaper. Once models get over 1.20 size, glow starts getting impractical simply because of the cost of fuel.
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