Fuel Economy

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Fuel Economy

Post  1EFF100 on January 29th 2019, 11:27 am

I know this is pretty much an oxymoron but what is the best MPG one could expect from a 460--carbureted or EFI--in a 1987 F-250 4x4? I realize transmission selection, tire size, gear ratio etc. all have an effect. What is the absolute best mileage you're going to get? Is 15-16 even possible?
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Re: Fuel Economy

Post  jasonf on January 29th 2019, 1:47 pm

Between my dad and I we got 15-16 with all our F150's but they were all 2wd and had a C6 with 3.50 or higher gears. We had one F250 2wd and it got 10-12. They all had the standard advanced timing chain setup and recurved dizzy. Without overdrive it would be pretty tough in a 4x4. My brother had a 460 Bronco and it got a solid 8 mpg but I don't know about any engine mods as he bought it that way.
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Re: Fuel Economy

Post  somethingclever on January 29th 2019, 2:54 pm

15-16 not going to happen


You need to expect 11-12 driving it easy.

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Re: Fuel Economy

Post  Paul Kane on January 29th 2019, 4:26 pm

1EFF100 wrote:...what is the best MPG one could expect from a 460--carbureted or EFI--in a 1987 F-250 4x4?...Is 15-16 even possible?
For what it's worth, my 1985 F-250 2x4 4-speed truck did 14+ mpg with stock exhaust and stock carb. Would have gone 15+ mpg with freer-flowing exhaust and maybe 17+ mpg had I put that ZF -speed in.

My 1973 Mercury Marquis got 22 mpg highway. Cool
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Re: Fuel Economy

Post  1EFF100 on January 29th 2019, 10:05 pm

Thanks for the input, guys.

Those are actually some encouraging numbers, Paul.

Your Marquis had a 460? That is impressive!
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Re: Fuel Economy

Post  stanger68 on January 29th 2019, 11:48 pm

Yes 15 is possible. I had a 75 F-150 bone stock except holley carb that would get that if it was tuned just right. You have to baby it though. it would avg. 12-13

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Re: Fuel Economy

Post  cletus66 on January 30th 2019, 12:02 am

I got 16 mpg outta my 460, one time, on a trip that was all highway driving in a '79 Mustang coupe with 3.00 rear gears.  My F100 with a mild 460 got 9 unloaded and 7 towing.  

For reference, the 2011 F150 Crew Cab 4X4 with the 5.0 Coyote that I bought for snow, which my wife confiscated from me, gets around 16 mpg all the time.   Apparently trucks are heavy or something... Laughing

She can have the truck.  I prefer a Mustang anyway... Razz
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Re: Fuel Economy

Post  DaveMcLain on January 30th 2019, 11:10 am

1EFF100 wrote:I know this is pretty much an oxymoron but what is the best MPG one could expect from a 460--carbureted or EFI--in a 1987 F-250 4x4? I realize transmission selection, tire size, gear ratio etc. all have an effect. What is the absolute best mileage you're going to get? Is 15-16 even possible?

I think it is possible if you can keep the cruise RPM down, use a cam with very short duration on a lobe sep that isn't too wide. Raise the compression, use headers, use an intake with good mixture distribution at part throttle, use a carburetor with a small venturi and a down leg stepped booster. Work very carefully on the power valve opening point, channel restriction size and the idle feed restriction.

My '79 F350 can get 12mpg running 70mph on the highway with an E4OD transmission and a 4.10 gear ratio with a tire that's 33 inches tall by about 9.5 wide. With the C6 the truck would get 10mpg running at 62mph with the same setup so that's quite an improvement.

The engine is only 8.4:1 compression and will run fine on 87 octane. The cam is a Reed Torque master flat tappet hydraulic with 205 210 duration at .050 on 112 in on 108. I don't think that this cam is ideal for mileage or performance but the engine does run well and pulls a trailer nicely while running on the cheap stuff. The carburetor is a 650 Holley with down leg boosters and a BLP metering block on the front. I have a two stage power valve in the carburetor and that has allowed me to lower the jetting about 1 more size without making the engine surge at part throttle.

I wonder what mileage would be like if the compression was about one full point higher and I ran it on better gas? Would it break even?

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Re: Fuel Economy

Post  1EFF100 on January 30th 2019, 11:34 am

Thanks again for the replies. You guys are awesome.

I posed this question over at the other site as well. Here is one of my posts explaining why I'm interested in fuel mileage.

Hi Scott. Either or.

Here's what's on my mind. I have kind of been on the lookout for a 2wd truck that gets decent fuel economy for highway travels to pick up motorcycles, engine parts etc. but the truck must have a V-8. I'm a V-8 guy and will always be. Anyway, I don't have a lot of capital to spend on another truck and the ones I have been looking at in my price range--even though they are considerably newer--have a bazillion miles on them and would probably need engine or transmission work soon anyway. So, I was pondering the following.
The stroker build for the Cougar is on temporary hiatus for now and I got to thinking the 466 in the F-250 runs like a bat outta heck with your big valve D0VEs, custom cam and recurved distributor, why not kill 2 birds with one stone and install the hot rod 466 into the cougar for now and try and build a fuel efficient 460 for the F-250?
The truck is old and needs paint but it drives and handles fantastic. The suspension and all still feels tight and there are no rattles. I am not sold on this idea by any means but it's definitely on the table--if a fuel efficient 460 is possible.

Thanks.
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Re: Fuel Economy

Post  Paul Kane on January 30th 2019, 2:34 pm

1EFF100 wrote:Those are actually some encouraging numbers, Paul.

Your Marquis had a 460? That is impressive!
Yes I built the 460 for the Marquis (it came with a 429) and I had fuel economy in mind with the 460 recipe.

If you want torque and fuel economy for a 4x4 build, then I have a set of specially prepared 370 castings and a specially machined iron 460 intake package that will work excellently in a lot of build combos.
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Re: Fuel Economy

Post  1EFF100 on January 30th 2019, 9:52 pm

Paul Kane wrote:
1EFF100 wrote:Those are actually some encouraging numbers, Paul.

Your Marquis had a 460? That is impressive!
Yes I built the 460 for the Marquis (it came with a 429) and I had fuel economy in mind with the 460 recipe.

If you want torque and fuel economy for a 4x4 build, then I have a set of specially prepared 370 castings and a specially machined iron 460 intake package that will work excellently in a lot of build combos.

Paul, what's the difference between the 370 heads and the 429/460 heads? Chamber size? Do they have the air injection ports?

I may be interested.

Thanks.
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Re: Fuel Economy

Post  Paul Kane on January 31st 2019, 9:46 pm

1EFF100 wrote:
Paul Kane wrote:
1EFF100 wrote:Those are actually some encouraging numbers, Paul.

Your Marquis had a 460? That is impressive!
Yes I built the 460 for the Marquis (it came with a 429) and I had fuel economy in mind with the 460 recipe.

If you want torque and fuel economy for a 4x4 build, then I have a set of specially prepared 370 castings and a specially machined iron 460 intake package that will work excellently in a lot of build combos.

Paul, what's the difference between the 370 heads and the 429/460 heads? Chamber size? Do they have the air injection ports?

I may be interested.

Thanks.
The D8TE head is for the small bore 370 and is unique due to its intended application:  Their 90cc chamber has a smaller cross section which stays inside the 4.050” bore of the 370, and therefore results in a “360* quench pad” when they are bolted to the larger bore 429/460 block.  These are the heads and intake manifold that were on my F-250 economy/tow engine (described above) and they worked exactly as I had hoped.  They are ported, stainless oversize valves, hard seats, fire slots, etc. Call for details and I’ll tell you all the changes from stock to fully modified and prepped.
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Re: Fuel Economy

Post  1EFF100 on February 1st 2019, 8:30 am

Okay, a little different direction here but would a '91 351W with an AOD be any more fuel efficient in this application? How difficult would it be to mate the 2WD AOD up to the transfer case in the truck?

Thanks again.

*EDIT* Never mind. I spoke with a buddy who had a '91 version of my truck with the 5.8 and he was very disappointed. He said it didn't have power and it got crappy mileage.
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Re: Fuel Economy

Post  1EFF100 on February 1st 2019, 10:15 pm

I guess you guys are bored of my asinine thread. lol.

Well, another question anyway. Very Happy Would doing up a 429 be at all beneficial toward the efficiency goal? Or is 30 cubic inches not enough to matter at that point?
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Re: Fuel Economy

Post  cletus66 on February 2nd 2019, 3:29 pm

1EFF100 wrote:I guess you guys are bored of my asinine thread. lol.

Well, another question anyway. Very Happy  Would doing up a 429 be at all beneficial toward the efficiency goal? Or is 30 cubic inches not enough to matter at that point?

For a truck, I would prefer the extra torque from those 30 cubes over mpg any day.
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Re: Fuel Economy

Post  1EFF100 on February 2nd 2019, 3:50 pm

cletus66 wrote:
1EFF100 wrote:I guess you guys are bored of my asinine thread. lol.

Well, another question anyway. Very Happy  Would doing up a 429 be at all beneficial toward the efficiency goal? Or is 30 cubic inches not enough to matter at that point?

For a truck, I would prefer the extra torque from those 30 cubes over mpg any day.  

Under normal circumstances I would completely agree. However, this is a MPG build. I never use this truck for anything other than dump runs, hauling motorcycles or car parts etc. It's never used for towing or anything heavy duty.
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Re: Fuel Economy

Post  Paul Kane on February 2nd 2019, 4:33 pm

1EFF100 wrote:...Would doing up a 429 be at all beneficial toward the efficiency goal? Or is 30 cubic inches not enough to matter at that point?
It really depends on the actual engine combo, actual vehicle, final gear ratio, etc, but for an F-250 4x4 it's more likely that the vehicle's cruise speed will be at an rpm better suited for the peak torque efficency generated by a typical 460 than a typical 429, and therein the 460 could get the better fuel economy.

Additionally the 460 will have more overall usable power for such a truck than would the 429, let alone the fuel economy.
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Re: Fuel Economy

Post  rmcomprandy on February 2nd 2019, 6:20 pm

Years ago, probably 20 years or so, someone I know pretty well tried doing the mileage thing with his F250 truck. It was a 98 460 F.I. California vehicle.  I built the engine to exactly what HE wanted.

He used it for transporting vehicles all over the country in a tag type trailer so, it was almost constantly in a towing type atmosphere.  He got it up to about 10 miles per gallon, regular 87 octane gas, towing a load of about 10,000 lbs. plus the truck.
Without towing a heavy load like that, I am almost sure it would have gotten better mileage.

A long story shortened he used a "stroker" 370 base engine.  
4.090" bore x 4.300" stroke which is a 452 cubic inch engine.
The long block was almost entirely 370 parts; except the 4.300" crank, 6.700" rods and custom pistons for the 9.2/1 compression ratio.
(Those 370 heads have merely a 1.785" diameter intake valve and 1.560" exhaust valve)
The hydraulic flat tappet cam was a "Street Rod" cam from Bill Metzger at LAZER.  
250/255@.006" - 200/205@.050" - 106 separation - .481"/.499" valve lift.
I am sure you can get the same type custom cam from other people today.

Welding and porting the lower intake with the head ports to almost match with a good exhaust system using the Ford air flow meter & ECM computer did the rest.


Last edited by rmcomprandy on February 2nd 2019, 6:31 pm; edited 1 time in total

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Re: Fuel Economy

Post  1EFF100 on February 2nd 2019, 6:28 pm

Cool. Thanks for chiming in, Randy. Cool
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Re: Fuel Economy

Post  rmcomprandy on February 2nd 2019, 6:35 pm

He put almost half a million miles on this truck.
I am not sure it would be worth the investment for a regular drive around vehicle unless you could do it all yourself.

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Re: Fuel Economy

Post  1EFF100 on February 12th 2019, 10:24 am

Okay, here's the plan as of this time.
Remove the heads, intake and cam from the engine currently in the truck and install Paul Kanes reworked 370 heads and factory iron intake. Not set in stone yet but probably go back to stock exhaust manifolds. i'm sick of headers on the street; they went to crap visually almost immediately and I'm constantly chasing leaks at the collector. Manifolds are quiet under the hood and virtually maintenance free.
I haven't done any compression calculations but it will be significantly lower than it is now with the D0VE-C heads.
I rebuilt this engine in the early 2000s using off the shelf forged TRW pistons with the large dish, truck rods with ARP bolts, high volume oil pump and the moving parts balanced. It's a D9TE block and has had the deck cut but I don't remember how much.
Been looking at off the shelf camshaft options and am looking at a couple Crane grinds. I like Crane. Want to keep the valve train quiet and last a long time.

The two in question:

H-260-2: 204/216 .487/.518 112
H-272-2A: 216/228 .518/.513 112

Of course the duration figures are at .050.
I want this engine to pass smog if need be.
I'm pretty sure since fuel economy is the ultimate goal, the H-260-2 would probably be the one to go with but thought I'd consult the pros on here.

I built a 400 for my uncle years ago for his 2wd '79 F-150 using the H-272-2A and that thing was a torque monster.

So, would either of those cams be an acceptable choice for my goals? Would the 112 lobe separation be an issue?

Thanks again for any input.

Bruce
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Re: Fuel Economy

Post  rmcomprandy on February 12th 2019, 10:43 am

CRANE used to have a 260/266@.006" - 204/210@.050" - .487"/.487" - 110 separation; 105 intake. Worked real well for good mileage, race car trailer towing.

If it is not in their present listings, I am sure they can grind it "special". All it usually takes is a phone call.

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Re: Fuel Economy

Post  1EFF100 on February 14th 2019, 10:37 am

rmcomprandy wrote:CRANE used to have a 260/266@.006" - 204/210@.050" - .487"/.487" - 110 separation; 105 intake. Worked real well for good mileage, race car trailer towing.

If it is not in their present listings, I am sure they can grind it "special".  All it usually takes is a phone call.

I emailed Crane about this grind and the gentleman on the other end said he did a search but found no such cam in their file but did say they could grind it for me for $192.00. That's approaching custom cam territory.

So Randy, neither of those cams I posted look viable to you for my application? Crane lists one of their attributes in the description economy and fuel efficient.

I value your opinion tremendously. Thank you for taking the time to answer my posts.
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Re: Fuel Economy

Post  rmcomprandy on February 14th 2019, 10:48 am

1EFF100 wrote:
rmcomprandy wrote:CRANE used to have a 260/266@.006" - 204/210@.050" - .487"/.487" - 110 separation; 105 intake. Worked real well for good mileage, race car trailer towing.

If it is not in their present listings, I am sure they can grind it "special".  All it usually takes is a phone call.

I emailed Crane about this grind and the gentleman on the other end said he did a search but found no such cam in their file but did say they could grind it for me for $192.00. That's approaching custom cam territory.

So Randy, neither of those cams I posted look viable to you for my application? Crane lists one of their attributes in the description economy and fuel efficient.

I value your opinion tremendously. Thank you for taking the time to answer my posts.

I have the cam specs for that Crane Cam in my build files for a customer engine but, maybe it was a custom grind from Crane at that time; 2004.

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Re: Fuel Economy

Post  Paul Kane on February 14th 2019, 6:13 pm

1EFF100 wrote:Okay, here's the plan..install Paul Kanes reworked 370 heads and factory iron intake...probably go back to stock exhaust manifolds...
I have some D5TE truck manifolds that will work great with your combo. The D5TEs take a bigger exhaust head-pipe diameter than the passenger car engine manifolds...I think a 1/4-inch more.

1EFF100 wrote:I haven't done any compression calculations but...using off the shelf forged TRW pistons with the large dish...It's a D9TE block and has had the deck cut but I don't remember how much.
You might be at about 8.75:1 or so.

1EFF100 wrote:Been looking at off the shelf camshaft options ...The two in question:

H-260-2: 204/216 .487/.518 112
H-272-2A: 216/228 .518/.513 112
Given you compression ratio and intentions of good fuel economy, I think the bigger cam is too much.  I also think the smaller came doesn't necessarily need +12* of exhaust duration. Randy's suggestion is super close to what my 22 mpg Marquis used; the Marquis cam was 207*/213*/110* in at 106* And the compression ratio was 8.6:1 which is close to what your engine will have.  Frankly 207* is as big as I would go based on your goals.  If the engine must pass tailpipe emmisions, then I might consider my grind on a 112* LSA or use Randy's profile..........but California emissions-wise it all really depends on the year of vehicle, etc.
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