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Whos doing best fuel economy over power???

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Scuzzy_1250
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Whos doing best fuel economy over power???

Post #1 by Scuzzy_1250 » Sun Oct 07, 2018 4:23 pm

I've heard of dudes getting in the 20s mpg with their 300s



Quick specs

69 f100 240, got a Holley 1940 that I rebuilt and took FOREVER to find a working power piston but got a good one. Finally got this thing running well, timed good, elec ig, behind a c4.

I'm currently getting 11 mpg if I decide to keep the 240 and rebuild it what are the requirements to get the high teens maybe low 20s?

Who's done it or doing it now what's y'all's set up?

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Shorty
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Re: Whos doing best fuel economy over power???

Post #2 by Shorty » Sun Oct 07, 2018 5:57 pm

overdrive tranny and 3.08 or taller rear gear would go a long way for fuel economy. What rear ratio does your truck have now?
85 F150 on 78 bronco frame C6 np205 welded dana44 front, trussed posi nine inch rear. EFI exhaust manifolds into one 2 1/2" rolls on 35x12.5x15 Maxxis Trepador.

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THE FRENCHTOWN FLYER
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Re: Whos doing best fuel economy over power???

Post #3 by THE FRENCHTOWN FLYER » Sun Oct 07, 2018 10:14 pm

4 x 4
big tires
jacked up
aero hindrances like bug deflectors, sun visors, mud flaps

These things kill fuel economy.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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broncr
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Re: Whos doing best fuel economy over power???

Post #4 by broncr » Sun Oct 07, 2018 11:47 pm

I did a stock rebuild on my '82 Bronco in the late 90's. .060 over, otherwise bone stock.

After discovering FSP, I did the 4BBl/EFI exhaust conversion, and saw a leap in power, along with about +2 MPG ( from around 15, to around 17).

Then I did a "Cushman" (vacuum line) water injection, (and maybe the sbc rocker swap - not sure) and saw another 1-4 MPG. Yes - you read that right. I recorded my best MPG - 21, in a big old 4x4 1982 Bronco - zero aerodynamics, 31-10.50 15's, on 3.55 gears.

Overall it averaged 18 to 18.5 MPG. I checked virtually every time I filled up. The 21 MPG was inexplicable, and never repeated. I think I may have accidentally got a tank of racing fuel (seriously - it was just pump gas).

I'm in Colorado. All of the driving was at altitudes of 6,000 -10,000'. I often had to travel to the surrounding states for work.

Edit: A few more clarifications. Those numbers were somewhere around 80% highway driving. I did a lot of out of town work. I was in my mid 40's to early 50's, and drove rather conservatively. I didn't romp on it much - no point.

Also - to be fair, I had one hunting trip, hauling a utility trailer, heavily loaded with enough gear & supplies for a month of bow hunting, a couple of BIG boys, and battling 40-60 MPH head to cross winds for a good portion of the trip. I got a miserable 14 MPG - the worst I ever recorded.

I rarely had a full tank of all "around town" driving, but it usually dropped about 1-1.5 MPG on those few occasions where I did.

So how does 14 to 21 sound? :lol:
Last edited by broncr on Mon Oct 08, 2018 7:47 pm, edited 1 time in total.
'82 FSP Bronco. Just about every mod ever mentioned. ( Too much to list - or remember...)

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Shorty
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Re: Whos doing best fuel economy over power???

Post #5 by Shorty » Mon Oct 08, 2018 10:36 am

at least I don't have a bug deflector or visor on my truck to kill any fuel economy :rolflmao:
The truck in my avitoir is not designed for fuel economy although I have a zf5 speed I hope to put in it to help a bit.

I do have a stock 83 f 100 with 3.55 gears and an overdrive 4 spd standard that gets the same economy as my 2004 freestar mini van.
In Canada we use l/100km instead of mpg to rate fuel economy so my numbers will be hard to compare.
14-16 l/100km in town, don't really do much highway.
pretty comparable to the new trucks with bigger engines.
85 F150 on 78 bronco frame C6 np205 welded dana44 front, trussed posi nine inch rear. EFI exhaust manifolds into one 2 1/2" rolls on 35x12.5x15 Maxxis Trepador.

1986F150six
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Re: Whos doing best fuel economy over power???

Post #6 by 1986F150six » Mon Oct 08, 2018 2:54 pm

My 1986 F150 with 4.9L, 4 speed manual O.D. and 3.08 gears returns ~17.5 to 23.0 mpg.

https://www.ford-trucks.com/forums/1325 ... 300-a.html

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broncr
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Re: Whos doing best fuel economy over power???

Post #7 by broncr » Mon Oct 08, 2018 10:45 pm

Another clarification - I have a GV overdrive. Maybe another +1 MPG on the highway. Not very cost effective. (Work mileage allowance essentially paid for it, or I'd have likely never done it).

The GV solenoid has been problematic. I'm looking at a 2nd replacement in a fairly low amount of total miles, especially the second time around.

They didn't respond well to my request for a bulk discount. $150 a pop, so for now it's just dead weight. :roll:
'82 FSP Bronco. Just about every mod ever mentioned. ( Too much to list - or remember...)

Lazy JW
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Re: Whos doing best fuel economy over power???

Post #8 by Lazy JW » Tue Oct 09, 2018 12:57 pm

1986F150six wrote:My 1986 F150 with 4.9L, 4 speed manual O.D. and 3.08 gears returns ~17.5 to 23.0 mpg.

https://www.ford-trucks.com/forums/1325 ... 300-a.html


I just finished reading that long thread, great info!
Thanks for posting the link.

I ran my TorqueMotor in my old 81 F-150 for three years and 60,000 miles before installing the engine in my White Ox. It delivered just over 19 mpg for an overall average, winter, summer, any and all idling, stop and go driving (not much of that). This was mostly a 44 miles each way commute to work in northern Idaho.
Joe
"The White OX" 1974 F-350 300-6, Stock single exhaust, Carter YF, T-18A, Dana70 w/4.11, Flatbed dually w/dump bed. "Where no oxen are, the crib is clean, but much increase is by the strength of the ox" (Proverbs 14:4)
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1986F150six
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Re: Whos doing best fuel economy over power???

Post #9 by 1986F150six » Tue Oct 09, 2018 1:59 pm

Lazy JW wrote:
1986F150six wrote:My 1986 F150 with 4.9L, 4 speed manual O.D. and 3.08 gears returns ~17.5 to 23.0 mpg.

https://www.ford-trucks.com/forums/1325 ... 300-a.html


I just finished reading that long thread, great info!
Thanks for posting the link.

I ran my TorqueMotor in my old 81 F-150 for three years and 60,000 miles before installing the engine in my White Ox. It delivered just over 19 mpg for an overall average, winter, summer, any and all idling, stop and go driving (not much of that). This was mostly a 44 miles each way commute to work in northern Idaho.
Joe


Thank you! I have always enjoyed reading your posts regarding your mileage and engine build. I am the one who sent you a link to the "Oxx" valve cover [a long time ago].

I could not currently find just a valve cover, so will present this:

https://i.ebayimg.com/images/g/99YAAOSw ... -l1600.jpg
Last edited by 1986F150six on Wed Oct 10, 2018 8:49 am, edited 1 time in total.

jason832
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Re: Whos doing best fuel economy over power???

Post #10 by jason832 » Tue Oct 09, 2018 8:56 pm

Here's the best I've done.

Truck:
85f150 single cab
4 inch lift
4x4 np435
3.55 gears
35inch bfg mud terrains
Tons of extra weight (hitch, tools, push bar, rollbars, some cargo etc)

Engine
300 6
625 street demon tuned with wideband afr
Clifford intake
Clifford shorty headers, true dual magnaflow
Comp 268 can and kit
Head milled .060
4.000 h519p pistons
Stock DS 2 ignotion

Towing a 2200lb car hauler I made it from Chelsea QC to Quebec city on a tank, mostly level ground highway, cruising at 55-60mph. This returned about 16-16.5mpg US.

Not bad for a lifted 4x4 with big tires, a built 300 and car trailer. I think the very small, very tunable, ungodly responsive primaries of the street demon, tuned to cruise at 16/15.5:1 and drop to 12/13:1 under part acceleration has a lot to do with it. I'm sure more could be had with a recurved distributor.

old jupiter
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Re: Whos doing best fuel economy over power???

Post #11 by old jupiter » Thu Oct 11, 2018 10:09 pm

My answer to the O.P. on how to get there, after you have got and installed your choice of the parts suggested above:

tachometer
stopwatch
vacuum guage
air/fuel meter
dial-back timing light
a good stretch of road for testing, hopefully with a fairly constant up-grade and some part of the day when traffic is minimal,
and, Christopher Jacobs (PhD, Elec. Engr.) old book on ignition systems and tuning for getting your mechanical and vacuum advance dialed-in, since the factory's carefully-arrived-at ignition advance curves will no longer be suitable with all of your other non-factory alterations.

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THE FRENCHTOWN FLYER
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Re: Whos doing best fuel economy over power???

Post #12 by THE FRENCHTOWN FLYER » Fri Oct 12, 2018 9:12 am

All good suggestions jupiter.

Also, many modern cars can read out both average fuel economy and instantaneous fuel economy based on the measurements of fuel flow in the EFI system. I find them helpful for studying the effects of grade, towing weight, wind direction, etc. so why not use the instantaneous fuel economy read out on a given stretch of highway to evaluate changes.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

Phase3
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Re: Whos doing best fuel economy over power???

Post #13 by Phase3 » Fri Oct 12, 2018 4:11 pm

1996 f150
stock 4.9
M5od
3.31 gears
31x10.50s
Averaged 15 mpg with a good bit of hills and red lights in western pa.

Once turboed it gets about 16. Running front and rear tanks down to 1/4 tank i get about 350 miles between fillups which seems reasonable.
Heard these newer ford 6.2 gassers really suck it down
1996 f150 turbo 4.9 OBD2 M5OD 4x4 12 lbs on 93
1997 f350 351w cclb

moroza
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Re: Whos doing best fuel economy over power???

Post #14 by moroza » Sat Oct 13, 2018 5:25 am

I've been reading this thread with a lot of interest. Thank you! My 73 P-400 gets ~10mpg in mostly-highway use. For how often that happens, it's not a big problem in the bigger picture, but improvement's welcome. I know it needs more gears - currently 4.56 with a non-OD NP435. Are there 5-speeds (or better yet, 6) that will bolt in place? I have one forward center motormount and two at the (rather large) bellhousing, not like an F-150. And I have a driveline parkingbrake to complicate the matter further.

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Shorty
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Re: Whos doing best fuel economy over power???

Post #15 by Shorty » Sat Oct 13, 2018 5:59 pm

zf 5speed is O.D. and in the sf47 version used in the super-duties had a parking brake on the output that bolted on the rear of the 4x4 style transmission instead of a transfer case
85 F150 on 78 bronco frame C6 np205 welded dana44 front, trussed posi nine inch rear. EFI exhaust manifolds into one 2 1/2" rolls on 35x12.5x15 Maxxis Trepador.

Scuzzy_1250
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Re: Whos doing best fuel economy over power???

Post #16 by Scuzzy_1250 » Sat Oct 13, 2018 6:00 pm

So I popped my head under the truck and there was no axle tag and no data tag on the truck so I'm not sure what the gearing is. It's a 240 so I'd imagen it's 3.5s but who's to say cause the past owners did some work on the truck. I'd like to get a 4 or 5 speed under it. But we shall see what's up if I can find one cheap enough.

Old Jupiter damn dude that's some good stuff. I wasn't expecting to get that deep. This is all good info.

Also I know we have bricks with wheels so I know 30mpg is out of line but it is cool to see how far it can be pushed with old tech.

Thanks to all that have replied

Scuzzy_1250
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Re: Whos doing best fuel economy over power???

Post #17 by Scuzzy_1250 » Sat Oct 13, 2018 6:02 pm

What do y'all think of the notion of a new carb being able to give an up on mpg with everything being in spec.?

jason832
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Re: Whos doing best fuel economy over power???

Post #18 by jason832 » Sat Oct 13, 2018 10:54 pm

If you have a tachometer it only takes a minute to figure out what rear gears you have. See what youre rpm is at an exact highway speed (say 2100 rpm at 62 mph). Punch in the numbers at this link and see what you have.

https://www.summitracing.com/newsandeve ... calculator

You can also mess around and see what gear ratios will do to highway rpm.

A stock carb on a 240 should work decent for milage. I'd say throw good plugs wires cap and rotor at it, then concentrate on the distributor curve and make sure the vacuum advance is set good. Timing males or breaks how everything performs...

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