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View Full Version : Difference in 49 and 56 c.i. Omc



PIP
06-08-2010, 04:44 AM
Okay, i have an old 75hp (non-nitro case) and was told that the newer 56 c.i. Has a lot more "spank" to it down low, in the middle, and on top. Is this true?

If so, could someone tell me the changes the occurred from the 49 to the 56 inch motor?

In short, i would like to know a little history on the omc 3 banger from the stinger, and on. Anybody feel like that?

I am assuming the sst60 is to today, what the nitro- cased stinger was to the 1970's. Are these pricey motors because i don't see many of them being run on the old 13 and 14allisons and vampires, and the host of other ally splashes that came out? How much faster on a light hull is the 56 over the 49 (race model and standard)? Thanks

ima75man
06-08-2010, 06:26 AM
on a 200 lb. race boat, the 56" stock 70 h/p is almost 7 mph faster than a stock 49"..bottom end night and day difference. mid range at least 10 boats lengths instantly. my modify 49" is faster on top end but take 800 foot to catch the 56" 70h/p

PIP
06-08-2010, 06:34 AM
Bang for the buck, would a stock 70 hp fishing motor (56 inch) whip a 75 nitro case stinger out of shear grunt? I know the lower is not as good, but it sounds like it would win.

ima75man
06-08-2010, 08:28 AM
the 56" from a dead stop will outrun the stock 49 in" stinger, until the 70 tops out,, the 70 gear ratio 2.42, strong bottom, 49" 1.85 gear ratio good for top end. but if you put a 27 or 28 pitch on the 70, it will outrun the 49" with a 23 pitch. i have both set ups. for 700 foot drag i use the 2.42 gears with a 27 pitch cleaver,stop watch says the big gear is quicker in 700 foot, it wont tear up. same 70 powerhead with small nitro is quick but the stop watch goes with big gear set up. hope this helps. i've run the 49" omc's since 1974..