[zydeco]

dd 450's .... what fuel consumption should I expect at 85% power

[whadley]

As a general rule, you can calculate fuel burn on a Detroit 2 cycle with the following formula.
8ozs per hour per HP
twin 450's = 900hp X 8ozs or 7200 ozs/hour at 100%. Divide by 128ozs. to change to gallons = 56.25 GPH at 100%.
I believe you will find your "normal" RPM and cruise speed will be closer to 65 or 70% not 85% so your fuel burn should be about 36 1/2 GPH.
No matter what a lot of Detroit people tell you, these motors should not be run close to max. RPM. Typically, a 2300-2350 RPM motor is happiest and will live a lot longer running at 1900-2000 RPM than it will at 2050+. Also, make sure your motors will turn up close to the reccommended maximum RPM with a full load. If they don't, find out why. Without going into a lengthy rant, if the engines are running properly, with 100% no load RPM, and the bottom is clean, your props will be the first place to look for more or fewer RPM.

Capt. Bill Hadley
United Yacht Sales

[YachtForums]

Hi Bill,

Welcome aboard. Thanks for posting an informative answer. I might be filling-up in your neck of the woods soon. I've been cave hunting in Jupiter/Tequesta for a few weeks. I've always considered myself a fortunate person, but man... I feel like I'm on welfare with the prices of these homes!

Look forward to seeing you online (or around town!)