Question about drive rotation and friction
 

I have noticed that my engine that is driving a LH TRS drive won't pull as many rpm as the one driving the TRS with RH rotation. Both have BW 72C transmissions.

Does the TRS drive that has reverse rotation soak up more horsepower in friction than the one with standard rotation?

I doubt it. I think somebody posted a couple weeks ago that the only difference between the LH/RH rotation drives was that one gear in the lower was moved from one side of the vertical shaft to the other.

Depending on how much rpm your talking about...if were talking just a bit its probley more like a difference in the tachs or one eng is just making a little bit more power than the other, or props, could be anything,

That makes sense that the rotation would be accomplished with the same number of gears.

It's about 5400 vs. 5100 rpm difference at WOT. The weaker one has the power steering pump and maybe 8 fewer cubic inches due to a 0.030 smaller bore size. Also, compression is a bit higher on the stronger engine too because the combustion chamber is the same size but more displacement packed in.

Does this sound like enough to account for the difference?

Yep, it sure does. But Merc did use some reverse rotation engines at times and I have seen boats with two RH TRS units running counter-rotating props with the lefty being on the reversed engine. Your prop shafts will have a small "RH" or "LH" stamped on the very tail end where the prop nut threads on to confirm what's inside your lowers. The rolling friction or RH and LH units should be identical. --- Jer

Why not put the PS pump on the engine that is built a bit stronger in order to even things out a bit?? --- Jer

Yup, that's what I'm thinking now. Longer hoses might be the only expense in giving that a try.

Thanks for all the input!