hello, just a quick question on size comparison of 2 stroke and 4 stroke engines.

i just bought my first 4 stroke and was wondering what it compaired to in 2 strokes

example: 4 stroke .52 = about a .40 2 stroke ? for power or am i off base on this ? please let me know and thanks in advance.

bassmanh

that sounds roughly right, i usually take off .10 from a 4-stroke to give me the size for a 2-stroke, not exact but it works fine for me

I've got an OS48FS and it's about the same as my OS40FP, the FP likes a 9x7 and the 48 swings an 10.5x6

It depends on the four stroke AND the 2 stroke you're comparing. I'd say a 52 four stroke might even be comparable to a 46, if it's a 46 LA.

Four strokes used to be considerably less powerful than 2's. But over the past few years, four strokes have gained and gotten relatively close to 2 strokes. (Hence, Woodsy statement comparing his 48 to his 40.)

It will also depend on the aircraft it's going into and the performance you're looking for. ie. I'd rather have an OS 48 four stroke than a good 46 two stroke in a Cub or a Taylorcraft, but not in an Extra.
Dennis-

Four strokes generally give you more torque at lower rpms and will pull harder. If you look into the hp on four strokes YS has the most. Their web site is www.ysperformance.com.

But the main question is what type of flying do you want to do.

If you plan on doing acrobatic flying then a four stroke is the way to go.

thanks for the help. the engine is a magnum lx fs .52 and its either going on my AT6 or my arobat speed air .40 should work well on both i would think.

now the question is what props to use
and can i use the same fuel i am using in my 2 strokes now ? thanks again

For a 52fs i'd start with about an 10.5x7 or 11x7, one problem with 4s is they typicaly like to swing a larger which can be a problem with ground clearance on some models.

as for fuel 4s typicaly run about 2% less oil than 2s you don't HAVE to youcan run it on 2s fuel but 4s dont need as much oil.