Diff between round and square OS .91?
 

Is there a performance differnce either through engine life or reliabilty, etc.. between the round head version of the O.S. 91 and the square headed version

Regards,
Mike

Diff between round and square OS .91?
 

If I remember right one is for the ramtec or dynamax and the one with the bigger head is for the byron.

jason

Diff between round and square OS .91?
 

Yeah you're comparing the large and the small head. There are two different versions of the small head one.

Diff between round and square OS .91?
 

I don't know of two versions of the small head OS91. Can you elaborate?
JA

Diff between round and square OS .91?
 

There is the older one which is simply a round head. damn near a perfect circle. The newer design has a square-ish head.

Regards,
Mike

Diff between round and square OS .91?
 

I think the squarish head version is just a "sport" engine, not a Ducted Fan engine. I have a new OS 91vrdf and it has the round head.
I could be wrong.
JA

Diff between round and square OS .91?
 

I just looked at the Tower web site, and, indeed, they do show a small head version with what looks like a smaller "Byron" head.
But you can't buy one...
JA
Never mind...I think both pictures are of the Byron version.

OS 91
 

I just bought a new small head OS 91and a new replacement cylinder head and both are round.