I am curious which gets better fuel mileage for the more recent, fuel injected versions.

 

My 96 SuperCab Longbed HevyDuty F250 460 EFI w/ 4.10's gets around 11 MPG on average, using only 85 octane in Colorado.... Only mod is a drop in K&N filter.

I don't know what the newer ones get, but I demo'd an '89 454 with TBI for a couple of days and it was only getting around 9 MPG...

Comparing Apples to Oranges here... Take it for what it's worth.

 

My brother claims his 97 F350 reg cab long box 4X4 gets about 9.

Disclaimer, I'm not responsible for what he claims, nor can I be held accountable if another truck gets different mileage. Finally you don't buy one of these pigs for gas mileage.

 

Tough question........It's gonna be hard to find IDENTICAL combos.

I actually owned an '85 Ford F-250 460, regular cab, 2WD AND an '87 GMC 454 reg cab, 2WD at the same time.

Prior to those trucks I had an '89 F-350 CC, 4WD, 460EFI 5 speed.

The '85 Ford was a 4 barrel with a few mods, GMC was a stock TBI.

IF there was a noticable difference in MPG between ALL these trucks, I really couldn't tell you.

Seemed 10 MPG was the norm and down to 6ish pulling a 26' daycruiser with a 11' camper for all the trucks.


For comparison sake, my current V10 Crew Cab got a decent 13.5 MPG on a recent road trip and I don't think I've been below 9MPG pulling up to 10K. 11MPG seems to be the average for the V10.

 

I'm thinking of motorhomes. My 9500 pound, 27' 1990 E350 (Class C) motorhome with 460 V8 got barely 8 mpg. Then I bought a 13000 pound '97 Class A 32' on a Ford F53 chassis and the 460 V8 got only 7 mpg. Now I am back to a Class C, a 2000 28' with the 454. I think it weighs around 11000 pounds. Just picked it up Monday, so haven't had a run to see what the fuel mileage is, but a couple guys on a motorhome site claimed 10-11 mpg with 30+ foot motorhomes in the mountains. Kind of hard to believe.

 

I have my doubts about the 454 MPG claims.

 

we have had a 1986 22 foot Chev RV with a 350 GM engine 3 speed automatic transmission fuel mileage averaged 9-11 MPG in hills and flat country

we now have a 26 foot Flair RV with a 454 G.m.Gas engine and overdrive automatic transmission Fuel injected unit in alberta flat lands we can get 11.7 to 12 MPG and in hill areas 9- 10 MPG But the 454 engine drives like a dream lots of power and cruise like a bus watch out on downhills as the unit will run away unless you select lower gears

 

My 2wd 1996 460 f250hd with SEFI/MAF with 4.10s gets about 14.5 on the highway. Of course I drive 60 mph on the highway in the slow lane . When i'm towing the 7k concrete pump and have 2.5k of hose/equipment in the bed I get about 12 on the highway.

Now if were talkin about driving in the city its pretty much always 8-9 no matter what I do in the city. If i'm lugging the pump around in the city it drops to 7.

 

My 97 f350 4x4 cclwb gets 11mpg on cruise control hwy and 9mpg city

 

No difference. Fuel injected/TBI was a little better than the 4bbl., but a 460 and a 454 get the same.

 

Big block gas engines in motorhomes, bad or worse? We seem to be talking about 1990's vintage rigs and not new, since both engines are long out of production. In the real world, Ive actually found the GM TBI system (coupled with Vortec heads) slightly more efficient than Ford's bank-fired port injection. Also, the 4L80E tranny is a bit better than the E4OD.

The problem with comparisons are variables like final drive ratios, frontal area, etc.

 

Best mileage I've ever seen was 3 tanks @ 16 mpg but that was in overdrive going 35 mph for the entire tank. with the 4.10's 35 mph seems to be the sweet spot gas mileage wise. The motor is just slightly above an idle and easily cruises at 35.

Quite unrealistic to actually drive like that on most highways, I just drove like that during my trip through Canada when I was going from california to alaska.

I could have gone much faster than the 37 mph speed limit (I believe it was 60 kph) because there was only about 1 cop every 500 miles.

The main reason I stayed 35 was to maximize my gas mileage because it was around $3 per liter at the time. (which is something like $11 per gallon.)

 

WTF?

Unless you REALLY clearify yourself on this post I would think you were driving thru the WRONG country to Alaska.....

Where exactly in Canada was gas 3 bucks a litre and you saw a cop every 500 miles?

Nevermind driving thru a country at exactly 37 miles an hour to get optimal fuel mileage.... last time I checked the speed limit on any highway to get thru Canada was 100 kph....around 62 - 65 mph.

 

$ 3 a liter ? Never....maybe in the far north where gas had to be flown in. I filled up yesterday...gas was $ 1.04 a liter.

60 kph is around 42 mph, not 37 mph. That's the speed usually in town.

On the highways it ranges from 90 kph (56 mph) to 100 kph (62.5 mph) to 110 kph (about 69-70 mph.)

As to the OP's question... neither a 460 or a 454 is going to wring out impressive gas mileage...either with a carb or FI. They're big blocks and suck a lot of gas, although they produce a lot of power.

I drove a 460 4 bbl truck engine in a E 350, DRW, cab and chassis with a 16 foot box in the '70's for many 1000's of miles.

The truck was usually loaded to about 12,000 GVW and the 460 was a magnificent engine in terms of torque, passing ability, totin' that load...but gas mileage was in the single digits.

 

Well I will admit there were some zones that were 80 kph (50 mph) but at least 1000 miles was 60 kph (37 mph). This was in the winter of 09 I believe? Might have been 08 but I'm fairly sure it was 09. Gas in California was almost $5 a gallon at the time and I distinctly remember $2.96 a liter at most of the Canadian stations along the highway. Although the 2.96 was Canadian dollars but I believe Canadian and american dollars were pretty close at the time.

The reduced speed might have been temporary as a large majority of the trans alaskan highway was under construction/road repairs. We had to drive behind pilot cars on gravel/ frozen mud roads

Edit: Please forgive me if my speeds were off. I am terrible at changing english to metric. I was taught the most illogical method of measurement ever conceived in school. 12 inches in a foot? 5280 feet in a mile? There is no consistency to it and it appears the numbers were made up at random.