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OS 60 FP vs. OS FS 70 II Surpass

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OS 60 FP vs. OS FS 70 II Surpass

Old 08-13-2007, 01:46 PM
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Default OS 60 FP vs. OS FS 70 II Surpass

Hi All,

A while back I was looking at buying a new engine for my Great Planes Matt Chapman 580 (.40 -.70 Paintball paint scheme plane). After reading many of the links in the forums, it sounded like the way to go was the OS FS-70 Surpass II four stroke. After thinking about it a little more, I have a little bit older OS 60 FP that seems to run pretty good. Here are the specs on the engines from RC Universe's engine data:

O.S. Engines
O.S. .60 FP
Rating: 4 / 5
Type: 2-Stroke
Displacement: 0.600 cu. in.
Cylinders: 1

General Specs:
- Bore: 0.945 (in.)
- Stroke: 0.906 (in.)
- Shaft: 5/16 x 24 Thread
- Low RPM: 2000
- High RPM: 16000
- HP: 1.600 bhp@15000 RPM
- Weight: 18.00 oz.


Applications:
- Sport

and the

O.S. Engines
O.S. FS-70 II Surpass

Rating: 4 / 5
Type: 4-Stroke
Displacement: 0.700 cu. in.
Cylinders: 1

General Specs:
- Bore: 1.020 (in.)
- Stroke: 0.870 (in.)
- Shaft: 5/16 x 24 Thread
- Low RPM: 2000
- High RPM: 12000
- HP: 1.100 bhp@11000 RPM
- Weight: 20.10 oz.


Applications:
- Competition Airplanes
- Sport
- Standard Airplane


Sound is not a consideration, performance would be more important. The 60 FP looks like it has it over the 4 stroke on weight and power. Should I stick with the 60 FP or am I missing something?

Thanks,
Paul D.
Old 08-13-2007, 04:34 PM
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Default RE: OS 60 FP vs. OS FS 70 II Surpass

There is no reason you could not use that engine.

It will produce about or more power than the FS-70 II if it is properly propped so you would be happier with it's performance from that standpoint.

As you move towards larger planes the four strokers have a big edge in fuel consumption, but in this range I'd just go ahead and use the 2 stroke engine, especially if I had it on hand.



Old 08-13-2007, 10:24 PM
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Default RE: OS 60 FP vs. OS FS 70 II Surpass

The OS 60 FP is a good choice. They are very dependable engines and have good pulling power. I am as we speak installing one on an Ugly Stick that I am building. Good Luck, Dave
Old 08-14-2007, 07:31 AM
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Default RE: OS 60 FP vs. OS FS 70 II Surpass

The 60 FP *would* work well, but those numbers are misleading.

The 60 claims: " - HP: 1.600 bhp@15000 RPM" But you'll never hit anything close to 15000 RPM with a sport prop.

It will also consume a lot more fuel than a 70 4-stroke - the oil from which, it will promptly spit all over the plane.
Old 08-15-2007, 12:29 AM
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Default RE: OS 60 FP vs. OS FS 70 II Surpass

Ignore all manufacturers HP #'s. They are all bunk anyhow---

If I had both on hand I would run the FS-70 because I like the torque but Since you have the 60FP and it is a good engine, use it! As far as practical power the 60FP will have more power than the 70 4 stroker

If I were to recommend a 4 cy engine to ANYONE it would be:

YS-63
Saito-82
Saito-72
Then the OS, Magnum, ASP clones. Nothing wrong with them but power vs weight they are under-dogs to the above anyhow.


Cheers-
Old 08-15-2007, 11:12 AM
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Default RE: OS 60 FP vs. OS FS 70 II Surpass


ORIGINAL: MinnFlyer

It will also consume a lot more fuel than a 70 4-stroke - the oil from which, it will promptly spit all over the plane.
On the smaller engines the difference is not very dramatic. As you move up things change.

His .60 will consume about .6-.8 oz/min at WOT.

His .70 4 stroker will come in at about .5-.7 at WOT. Not a huge diff.

Compare that to say an OS 1.60 FX ( close to 2.2 oz/min ) versus say a Magnum XL FS-180 ( 1.3-1.6 oz/min ) and the difference in fuel comsumption really starts hitting home hard.

A properly tuned 2 stroker shouldn't really produce that much more "spit" than a four stroker in this size range.

The 4 stroker has the advantage of a hotter exhaust which may burn up more of the residue though.


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