Quick engine comparison.
 

Between the OS .46 fx and the OS 70 FS surpass. I have zero experience with 4 strokes. Would it be worth my time and money to get an OS 70FS surpass engine over using the 46 2 stroke? Any pros and cons of each? I'll be putting it in an extra 46 size.
Thanks,
Dan

RE: Quick engine comparison.
 

Most of my recent engine purchases have been 4 strokes. I view their pros as being quieter, smaller muffler, better fuel efficiency, and able to run larger props. I use 2 strokes when I need light weight, higher speed, or just because I already have the right size. Operation is essentially the same as a 2 stroke. The only differences I've seen are occasionally adjusting the valves and being more careful about using after run oil.

RE: Quick engine comparison.
 

How do the two engines I posted compare in performance? Does the 4 stroke have any more power than the 2?

RE: Quick engine comparison.
 

Hello; I guess it depends how you measure power, a 70 surpass will spin a 14 x 6 prop around 10,000, a 46 two stroke could never do that. A good 46 will spin a 10 x 6 prop pretty near 13,000, maybe even more. A lot depends on teh plane it's going into. My choice would always be teh four stroke. One of teh problems with four strokes in teh past has been the extra weight, Saito has done quite a bit to lower the weight to power ratio lately.

RE: Quick engine comparison.
 

Actually, a good .46 two-stroke will spin a 14-6 at ~ 10,000. However, it is a long way away from being happy about it & even farther away from its peak output.

A good .46 should spin a 10-6 at well over 14,000.

RE: Quick engine comparison.
 

I run a 12x7 prop on an OS 70

And given a choice between using a 70 /4 or a 46/2 on an Extra 300, I'll take the 4-stroke every time.

And while a 4-stroke MAY require an occasional valve adjustment, I have had about 12 of them over the past 15 years, and I have had to adjust valves once.

Also, I run them on Cool Power 15% and never use after run oil. Again, with 12 engines, over 15 years, I've had to replace bearings once.