Godzilla Engine?

I wonder what experience the owners of the 7.3L Godzilla engine report.   There is some controversy related to MPG's using 87 octane regular fuel vs 91/93 octane premium fuel with that engine

FORD fine print states the 7.3L  Max. 430 horsepower and 485 lb.-ft. of torque based on PREMIUM fuel.  All this time I assumed the 430 HP 7.3L HP/torque ratings were with regular 87 octane. Wonder how much is given up using 87 LL

The question is……will using regular 87 LL save you more than any noticeable difference paying for premium?

I have found owners who claim they get slightly better mileage running premium. According to the fine print, this is the fuel the engine was designed to run on. While it will run fine on regular, the ECU will be retarding spark to run on that fuel.

Due to the high cost of premium, as others have mentioned, you won't get your money back with the mileage increase.

87 octane fuel actually has more BTU/gallon (better mileage) than premium fuel. You will notice a slight acceleration loss using 87 octane because of retarding the spark slightly.

https://www.eia.gov/energyexplained/gasoline/octane-in-depth.php

The price difference here is 60 cents per gallon more for premium over regular.  That's 1.2 times higher or a 20% increase.

You'd have to get 20% better gas mileage for the cost per mile to be equal.

We get about 9.5 mpg with a 2552 pulling a little Mini Cooper toad running on regular gas.  Without the toad, we could get closer to 10 mpg.  I cruise at 65 mph.

I really like the engine and the transmission combo (6-speed).  Good power across all rpms with a nice range of gears.  The extra sound insulation that comes with the Ford chassis that Phoenix uses combined with the V-8, you can carry on a normal conversation even when you are working the engine hard.  I do control the shifting for steep grades up and down.  I don't see any reason to run premium gas.  As mentioned above, the cost increase of the premium fuel won't lead to that much of an increase in mileage. 

We get about 9.5 mpg with a 2552 pulling a little Mini Cooper toad running on regular gas.  Without the toad, we could get closer to 10 mpg.  I cruise at 65 mph.

I really like the engine and the transmission combo (6-speed).  Good power across all rpms with a nice range of gears.  The extra sound insulation that comes with the Ford chassis that Phoenix uses combined with the V-8, you can carry on a normal conversation even when you are working the engine hard.  I do control the shifting for steep grades up and down.  I don't see any reason to run premium gas.  As mentioned above, the cost increase of the premium fuel won't lead to that much of an increase in mileage. 

Same here with my v-10 powered 2551.  Except I cruise at 70mph.  No TOAD but fully loaded so 12,000+ lbs. Driving at 55 to 65 on state highways yields 10.8 mpg.

That's using "regular" gas, not midgrade or premium.

I've settled on mid-grade Top Tier gas.  My ScanGauge indicates 9 MPG on a one hour + drive.   The 7.3 RIPS compared to our previous 2013 Ford/Winnebago with the V-10.   I was cruising on the local Interstates at 65 mph+ and passing cars as needed.   I also changed out the Autolite plugs for NGK Ruthenium.... maybe a tiny bit smoother idle.

For reference, our 2007 E350 PC-2350 with 6.8L-V10 engine, easily gets 11 mpg on the open road (not towing) as long as we limit our cruising speed to 62-63 mph, and we don't have a significant head wind.  Increasing our speed an additional 5 mph and we loose 1/2 mpg or worse.

I recently invested in the 5 STAR TUNE which seems to increase our fuel economy an extra 1/2 mpg over what I just stated above.  I invested in the 5 Star Tune primarily for improved behavior when using cruise control of which it seemed to do the trick, but I have yet to go on a cross country trip to verify my satisfaction while towing our Jeep Liberty.

I have a Scan Gauge on my 2013 3100. I get an average of 10 MPG towing a Ford Fiesta. But speed and road grade makes a huge difference. On flat terrain if I hold 65 MPH i'll get that 10 MPG. If I go to 70 MPH my MPG gove down to 8.6. And if I hold a 55 i'll get as good as 11.5 MPG. But on hills that mileage widely varies.

We have been using the 5 Star for 4 years; not much change in mpg, but the drivability is greatly improved.  (6.8 Triton). Average 9.2 mpg pulling a CRV @ 62 mph.  I’m hoping our old buggy takes us to the end of the road.