rutanman

My Feedback: (10)

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.

opjose

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.

DavidAgar

My Feedback: (108)

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

MinnFlyer

My Feedback: (4)

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.

Razor-RCU

My Feedback: (50)

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-

opjose

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.