Hi Guys, Just wanted to get some thoughts on what engine in the .40-.46 size that OS made that you feel marked their pinnacle of manufacture and performance for the average flyer ??? I just bought a like new OS 40 FSR from the '70's I believe. I had to have one of these because I remember an old friend that owned two of them and they were quite powerful and hauled his planes around with ease. I also have a like new OS 46 FX that seems like a real screamer on my engine test stand, it hasn't been in a plane yet. And then there's the used OS 46 SF I have. This is more like the FSR with the carb mounted needle valve, and I believe it may have been the replacement engine for the FSR. So, back to the original question, is the OS 40 FSR a better engine than the ones that replaced it ? And, why would OS stop making an engine that flat out worked so well and seemed to stomp on most of the competition ??? I also have a second request on your ideas as to which of these engines would be a nice combo for the vintage Sig Kougar I purchased ? The Kougar is about 25-30 years old but is almost ready to hit the skies once again ! Your responses are greatly appreciated, thanks in advance, Shoo

I think the OS 40 FSR was made at the peak of OS quality, so yes - its a hard engine to beat ! The bean counters have ensured that we will not see engines of that ilk again. BOB

Actually, being a Super Tigre and HB proponent in those days I hated the OS 40FSR .
Yes, it was that good ! Those engines are pure classics. Build quality was excellent and they ran so perfectly . If there was one very small negative it was that the OEM bearings seemed to develop play fairly early on. Replace them with US made or Euro bearings and the package was near bullet proof. (Yes, they used to make excellent bearings in the US and not long ago ) All of the OS engines of the pre Great Planes debacle were splendid. Sorry to see what became of them ..after.

Originally Posted by Gary Cee

Actually, being a Super Tigre and HB proponent in those days I hated the OS 40FSR .
Yes, it was that good ! Those engines are pure classics. Build quality was excellent and they ran so perfectly . If there was one very small negative it was that the OEM bearings seemed to develop play fairly early on. Replace them with US made or Euro bearings and the package was near bullet proof. (Yes, they used to make excellent bearings in the US and not long ago ) All of the OS engines of the pre Great Planes debacle were splendid. Sorry to see what became of them ..after.

As I'm just getting back into the hobby after about 28 years, can you enlighten me on what Great Planes did to OS ? Is it like what AMF did to Harley-Davidson ? Did they increase production so much while quality suffered as a result ? Thanks, Shoo

The only other negative I see with the 40 FSR is the muffler mounting. The crank case gets broken when in a crash......

Jason

My favourite OS is the rear exhaust 40/46 VF's which came out during the FSR series. Far from being a screamer they were very mildly timed and dead easy to set up with a tuned pipe. When tuned pipes started to be used in CL stunt they were the engine of choice and even today they're still the benchmark against which other piped engines are compared to.

My 40 FSR was about the most powerful 40 I have ever tested. I think the two piece crankcase probably made the intake ports easier to machine "properly".
Unfortunately a one piece crankcase has less steps to the machining process and is thus cheaper.
The FSR also seems to have a lot more beef in the crankshaft to keep it smooth and strong.
Of course they were made in the screamer days before they cracked down on noise.
Have to agree, the muffler bolt holes break easy in a crash and should have been redesigned.

I have 2 40 FSR's, one ringed and one ABC, and they are great engines.

Also a handlful of Irvine 40 MkII's, which I like just as much, and seem to be very similar in conception and execution.

I loved the 45FSR. It was just a bored version of the 40. It came both as a ringed engine or an ABN version. I preferred the ABN's and still have 4 or five of them. Also have a couple 40's. I fly mostly 4 cycle now so they sit in boxes with all their friends.

The FSR's were made from the little 10 all the way up to the 108. Only the 40, 45, 60 and 61 had the bolt to the case mufflers. I bought several of each knowing the problem. I think the old 90FSR had a bolt to case too as it used the same muffler the 61 used.

Still, were some of OS better engines. Take care of them and they last forever. One of my 45ABN's has been on a flying airplane since 1980 and it still has great compression and runs excellently.

Thanks guys ! Great info. Now my dilema is do I put it in my vintage Sig Kougar, a new Kaos, or just not use it because it is in near new condition ? Decisions, decisions....... Oh, I do have other choices for those 2 planes, I have an OS 46SF and an OS 46FX, so maybe the FSR should get a nice spot on a shelf..... Shoo

As pretty as they are ; They are a lot more fun to run than look at.

Run it .

Run it, I have 3 or 4 of the ringed 45fsr engines, they are awesome engines + they last forever.
I run mine on 10% or 15% nitro 18% syn/castor oil mix fuel.

Jeff

I have both the .40 and .45 FSR and they are still in great shape since I got them in the early 80s. I also have the .60 ringed and the .61 ABC FSR which are also great engines.

Bruce

I liked the .40 and .45 FSR's but the ABN versions peeled like an over ripe banana . The ringed versions to me were a better motor in the fact that they ran hard and lasted longer . Sold all of my ABN's and picked up some Rossi's . Rossi's still running strong on original piston /liners , over 2.0 hp. Best .40/.45.... try a Rossi and you will know.

Mike1484