Thanks sport that was rather helpful.

The only direct comparison test I ever read was in SpeedBoat magazine. A 39 Outerlimits was tested with twin Illmore 625s vs twin Merc 600SCIs. The Mercs were 25+% more fuel efficient at similar cruise speeds, and then both engines burned about the same at WOT with similar top speeds. I believe that is because the twin screw supercharger is going to be more efficient at moderate loads.

Data I've got from ilmor showed the following fuel burn for 710's in a 41 ft fountain p1 boat.
18.6 gph @ 4k

26.3@5k

47@ 6k
These are of course, per side
These were similar to what my 525's were at wot, and the ilmors are turning more rpm's. 6350 vs 5300

At 4200 rpm's in my 32 skater I'm going rt around 90 mph, which works out to about 2.25 mpg @ a 90 mph cruise. pretty good , I think!

I just found another test that listed 525's at 60.15 gph Per side @ 5000 rpm's
Tested in a baja 40
(just google fuel consumption for mercury 525s @wot)

For the ilmor, that's 43.7% of the 525 consumption @5000 rpm's .
I know it's apples vs oranges comparing a 41' fountain p1 boat vs baja 40 pleasure, but you get the idea at least.

i have yet to fuel scan my ls7 small blocks remember when i say small blocks there 450 cubic in but so far they are super fuel effeicent im mean i almost thought my fuel gauge was not working its that awsome i knew it was going to be good but i didnt think it was this awsome its unbelevable

If you say the next issue there was a correction. The illmor was more fuel efficient than the Mercury. If memeory serves me correct it was 40 percent better.
Allen

You have an outstanding engine package and boat. I remember the discussion about your motors. Do you think you are getting close to 2 mpg or more at cruise speed? How many rpms and at what speed do you cruise?

I never saw that--did I miss an issue? (and does anyone have an extra one to sell?!)

60 mph is about 3000 rpm

Another entertaining thread... :D :drink::evilb: :D :drink::evilb:

Below is something that I posted last September in another thread:

I just filled up last night.....and did calculations that I probably shouldn't have.

I went 136 miles (95% of this was 3600-4000rpm's) in a 38 Cigarette with 800's
I burned 171 gallons

That is .8 mpg...or 1.25 gallons per mile

70 gallons of AvGas @ $4.70 per=$330
101 gallons of 93 octane @ $3.279 per= $330

So, that's $660 to go 136 miles for a grand total per mile of .....................$4.85 per mile.

Like everyone else has said, the gas isn't the expensive part.....breaking chit is and everything breaks eventually.........if you use it :D