F32 Fuel specs- GPH

Stripermann2 · Post by **Stripermann2** » Thu Sep 10, 2009 3:56 pm

Hey all, just finished up installing my Floscans.

I'm using about 13.7 GPH on my Starboard engine and 16 GPH on my port engine at 3000 rpm.
I just overhauled my Quadrajet on my port engine- it was running rich so I haven't checked for new readings yet.
Granted my bottom is dirty and is getting hauled Saturday to be cleaned.
Will report on my findings after this weekend with carb reinstalled and specs double checked. Wasn't sure if my numbers on this were close...

What is everyone else getting for their specs? Seems high but really never paid much attention to the fuel numbers before. Thanks.

LSP · Post by **LSP** » Thu Sep 10, 2009 4:15 pm

Jamie .... what speed at 3000 rpms ?

Stripermann2 · Post by **Stripermann2** » Thu Sep 10, 2009 4:24 pm

Normally it would have been about 17-18 kts. Bottom and gear are fouled some...

ready123 · Post by **ready123** » Thu Sep 10, 2009 4:26 pm

Seems high to me also. What speed are you getting at those rpms?

Only comparison I can make is based on derived numbers from tank refills as I don't have flow gauges. This is from memory as the log book is on the boat.
I've got 318's and at 3200 rpm, 20.5 mph (GPS) I get around 22 gph total... I have got somewhat lower than that in ideal sea conditions. My numbers are in line with Trojan specs I have seen for the F32 efficiency of .91 mpg.... I'll check for better numbers on the weekend.

jav · Post by **jav** » Thu Sep 10, 2009 4:36 pm

Those are a little heavy compared to my Flow scan readings. When I had 318's- I would burn 11.5-13 gph per side (sea- state dependant) @ 17-18 knots with a clean bottom-fully loaded. I had no enclosure but I did have a hard top. Also- my bottom was very fair- 1.5 gears 16x15 3 blade props tuned but not prop- scanned.

I bet your more fouled than you think... makes a huge difference!

Stripermann2 · Post by **Stripermann2** » Thu Sep 10, 2009 4:59 pm

Thanks guys. I will check this weekend after she's back together.

Also, I have a set of 16X17 spare props. How will this equate to the boat's speed if I decide to swap them this weekend from my 16X16's? The 17's are slightly cupped, don't know the specs on them otherwise.

Or should I just keep them as a spare...

jav · Post by **jav** » Thu Sep 10, 2009 5:02 pm

You should prop to reach the engines full RPM- If you can do that with the 16x17's (which I imagine are correct for twin 270 hp engines)- I'd keep them. Better yet- while the boats out- see if you can have them scanned to see if there's a difference from port to starboard - that would explain a difference in consumption as well.

thelast322 · Post by **thelast322** » Fri Sep 11, 2009 10:25 pm

Hey Jamie, Its butch from the trojan rendevous . I can get up to 9gallon port 10 gph stbd around or slighty under 3000 rpm and be turning some pretty good speed. If sea condition is good, I can avg 19-20.5 kts . With a half full fuel tanks. On our boat trip we were loaded and I burned 225 gallons traveling 205 miles. That was open bay at 16-18 kts. As your getting the best speed for your rpm at cruise, just barely tap the throttle back a hair & you will see the floscan fall from 13 to 10-11. It only takes a smidget to get the same rpm w/ less fuel. Tweaking .....try it out . I have 16x16 on my boat and can turn 4200-4400 WOT. I believe that is the correct Size for our boats.