On my Nordic 28' Heat, open bow, I've calculated between 1.5 - 1.8 MPG running between 3500 - 4000 RPM.
Powerboat mag had an article a while back that had a 496 in a Sunsation and claimed between .8 mpg and 2.3 mpg. I made a run from Benton Harbor to Chicago 70 miles as the crow flies runnin 40-45 in 2-4's most likely put on about 80 miles fill up took 35 gallon. return trip 40-45 half way across then 55-65, second fill up 35 gallon again. 280 Velocity single 496 HO
Labbed 34 bravo I prop, 1.65 gears, single raylar 600 in 27' fountain single step with 3 people including driver
seeing 1.9 - 2.3mpg between 3200 & 3700 rpm's.
the reason i posted here is to make the reminder that the ho600 is based on the 496. It's working a lot less in my boat in terms of necessary output.
before with stock 496ho, had to run the boat 4000 plus cause it just wouldn't run much below without falling off or needing extreme trim which again, demanded heavy duty cycle. it was miserable much below 4000 r's.
sure if you open her up now, it'll burn more but cruise mpg has increased significantly with nearly 200 upgraded horsepower!!!!
Your number seems unbelievable to me but hey if you can get it that's way good.
The PCM555 is simply measuring open injector time so anybody using the SmartCraft fuel burn rate is getting there number from that.
I'd be curious to see what an actual flow meter would say in comparison but all claims are that the SmartCraft is very accurate.
Now my question is:
With that said, what if you have a malfunctioning injector but it's still responding to computer inquiries and pulse instructions? The computer knows what the open time is "supposed" to be so is it going by that very number or is it bi-directional to the point where the computer can actually monitor and compensate the measurement if the injector is dumping more fuel than necessary??
We have twin 496HO's in a 32 footer.
We average between 40 and 55 gallons to Avalon and back (depending on speed), which turns out to be roughly 1.1 - 1.5 MPG. I've seen higher other times when I cut the throttles back to 2800 or 3000. Throttle position makes a BIG difference :-)
I have twin 496/HOs in my Donzi 33ZX take in that the boat weighs 9200lbs at 3800 RPMs I burn 18 gallons and hour per engine running about 50MPH. at 5000 RPMs she burns 45 gallons per hour per engine running at 72mph. I have a Flo Scan.
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