what gas consumption reading per engine could be logical?
 

15 gal/hour per engine for example at 5000 rpm... does that make sense to you?

That is what my floscan tells me but I feel it must be more than that...

Any idea on that?

Which engine and h.p.?
Type boat?

check the other thread.

454-485 hp in F35-7 1989

A good rule of thumb is 10% of Hp @ Wot = GPH.

From past experience I would say it is burning 46-54 gph.
The above would be correct if near max rpm.
My 502/465s burned right at 47 gph wide open throttle.
They were carb motors..efi should be a tad more effecient.

46-54 per engine or for both?

true, but most often under that real world. I've seen it and verified it more than once.

my 350 HP 454 mags would burn ~ 28 GPH WOT (accurately calibrated (<2%) Floscan)

no, that's why I told you in the other thread YOU'RE READING 1/2!

your real GPH is about 30 GPH WOT on those 385's

been there done this! I just can't tell you off the top of my head after a few years and on my 5th 12 hour night shift which switch to change!

call tech! they are fantastic and will give you the answer!

If you are making 450 HP at 5000 RPM. My math says at .5 lbs of gas per HP you will use 225 lbs divided by approx 7 lbs per gallon = 32 gal per hr per engine. The FloScan should be reading in range of 29-35 gal per hour per engine