Guys,

Has anyone achieved the 20 MPG threshold with an E4OD? I have a 95 regular cab 2WD w/ the 4.9 and I am contemplating a V8 swap. It seems to me that with the V8 configuration the engine should be more efficient than the straight 6 even though you are adding two more cylinders. Any thoughts or comments are welcome.

Scott

 

Strictly highway cruising on flat ground at reasonable speeds it is possible with the right combination of truck, engine and gearing, but it is simply not possible in the city no matter what you do. Of all the motors available in these trucks the 4.9 generally delivers the best milage in stock form with lots of people reporting over 20mpg on the highway, but the 5.8 is capable of the same thing in my opinion, I got about 18mpg with the 5.8 I had in my truck which had a good TQ cam and longtube headers.

 

Conanski,

Thanks for the response. A couple of questions come to mind:

1) If you were to start from scratch and build a 5.0 or 5.8 (or other hybrid), what components would you include to achieve 20+ MPG on the highway? In other words, what headers? Which cam? What compression? What FI unit?

2) I did some research and pulled some old EPA charts and found that a 95 Mustang automatic 5.0 was rated at 22 highway and the 95 F150 2WD automatic 5.0 was rated at 17 highway. I realize that an F150 has a much greater frontal area than a Mustang but a 5 mpg difference?

Thanks, Scott

 

By far, the most important factor in the fuel mileage equation is VEHICLE WEIGHT! Another important factor for highway mileage is aerodynamics. In both of these categories, your full size pick up is working against you when trying to achieve maximum fuel mileage.

The factor that can trump the above is driving style and conditions (highway vs. city.)

If you are contemplating building and swapping a V8 for your fuel stingy six, it is possible that you could beat the fuel economy of the six, but at what up front cost?!? Even if you increased your fuel mileage by three MPG (not likely,) you would have to drive about 171,000 miles at todays fuel costs to get back your up front cost in the form of fuel savings, based on a $3,000 project cost.

If you are building this engine as a fun project and something you want to do, then money may be no object in which case, enjoy the project. I have done plenty of projects like this for the satisfaction of the project. If on the other hand you are trying to justify the expenditure in fuel costs, you're just fooling yourself.

If your goal is indeed fuel economy with minimal cash outlay, I would modify the six starting with full length, small tube headers.

My $0.02,

 

OK to start with it would be a 2wd reg cab truck that has been slammed on the ground and has either a tonneau cover or cab high cap over the bed, in other words the vehicle aerodynamics have to be improved as much as possible first. Don't even bother trying to achieve this with a jacked up 4x4. Then I'd build a 5.8 with a little more compression(9.5:1), GT40 heads, Comp 35-320-8 roller cam, stock truck intake with the lower port matched to the heads and longtube headers with a single 2.5" all mendrel bent exhaust with straight through Magnaflow cat and muffler. That combo makes over 400ft/lbs at 2000rpm and 300hp at 4500rpm according to DD, a 5.0 simply isn't capable of doing that. Ideally Id use a 5-speed manual with rear axle gearing that produces about 1800-2000rpm at 70mph, it could also be done with an AOD but the gearing would be slightly different and the auto consumes more TQ so it's not ideal. None of the electronic autos are ideal here because they downshift from OD too easily and you want to be able to avoid that and use more of the engine TQ to climb grades. Using a rear axle with a larger diameter ring gear will also put more TQ on the ground, a 9.75 from a newer truck or a 10.25 semifloater from an F250, though both are heavier than an 8.8 and will negatively affect ride quality(more unsprung weight), so the tradeoff may not be worth it or even necessary in lighter truck.

Yeah like the Doc said, that's because even the smallest pickup is 500-800lbs heavier than your average 5.0 mustang and also has much worse aerodynamics. The 5.0HO is also a better matched engine combo that produces more TQ.. 300ft/lbs vs 270ft/lbs for the truck motor.

 

Guys,

Thanks for the responses. I never thought about the weight factor, just the frontal area. I guess it's like pushing a brick through the wind huh?

I'm working with a 95 regular cab SWB 2WD with a tonneau cover. I just did a Lightning conversion from a wrecked donor L so the body has already been dropped. My 4.9 has about 320K miles on it with no evidence of a rebuild. The E4OD has been rebuilt/replaced so it's good to go. I never got to drive a 4.9/E4OD when they were new but it seems to be really low on power. I had a 92 Flareside with a 5.0/E4OD that I bought new so I know what that feels like.

As far as gearing goes. The truck came new with a 3.08 and I replaced that with a 3.31 which helped a little.

I guess the ultimate goal here is to maximize the fuel economy without spending a tremendous amount of money. At some point in the near future the 4.9 will give up the ghost and will need to be replaced or rebuilt and I was weighing the cost of this as opposed to replacing it with a 5.0 or 5.8.

I forgot to mention that this truck will be handed over to my son when he turns 16 in December (if he can somehow get his grades up and manage to maintain them).

Scott

 

3.55 gears seem to be the happy medium for the 4.9 with stock sized tires. An E4OD truck will never get the best milage though because of the way it is programmed, it only takes a slight change in throttle position or engine load to force a downshift.

 

Wow, If thats the case. I may have something wrong with my transmission. It lug down untill I push the pedal enough to kick it down. Kinda like the older vehicles with the kick down inkage

 

Yeah that's not right, the E4OD is supposed to be real trigger happy.. dropping a gear at even the slightest indication of acceleration or increased load. Maybe check out your TPS and VSS and make sure the PSOM is accurately calibrated for the tires.

 

Jeff, i see you have oversized tires on that F250. has the speedo be calibrated for those tires?

 

I too would have to take exception to claims that the E4OD downshifts too quickly. Certainly, if you are using cruise control downshifts will be more frequent. But if the terrain is too rolling you would do well to not use C.C. anyway. Allowing your speed to fluctuate some; a bit faster descending then allowing a slight decrease while ascending will eliminate the "hunting" that can occur - plus also actually give you better MPG. Tire/wheel changes, lifts, added equipment, etc. can all have an impact on how your drivetrain behaves

This from the owner of a 95 F350 with a 351 & E4OD drivetrain that has logged 420,000+ miles with neither of these two items having yet needed a rebuild; just routine maintenance & oil/fluid & filter changes.

dn.

 

I'm gettin around 20mpg. as long as I keep my foot out of it. = ]

2wd 89 f150 supercab with tonneau cover
302 cid
3" stainless single exhaust with flowmaster muffler - no cat
4 spd auto trans
3.55 rear gear
15x10 cragar quick trick wheels
275-60-15 tires

smog removed
a/c removed
clutch fan removed

160 degree thermostat
k&n air filter
crankshaft underdrive pulley
1" throttle body spacer
1" plenum spacer

 

OOoooh.... a 160 degree thermostat. This is not good for long term durability. It allows acids and other problems in the oil because the water vapors do not get boiled off of the oil unless you always drive it 25 or 30 miles every time it's started. If this is not your driving situation, ALWAYS drain the oil when the engine is piping hot to get as much contamination out with the oil drain as possible.

 

also the SD efi must see the 195* temps to properly run. Your not saving anything by running that 160*tstat in there.

 

Also, since the EFI system is designed to run at 195º, putting in a 160º thermostat makes the ECU "think" the engine is always warming up which keeps the system in open loop, not using input from the o2 sensors. This causes it to run richer and can burn up the cats from the extra fuel being dumped in (but you've probably removed those from the look of it. That's a Federal crime, BTW)

Back to the original subject...if you swap out the tired 300 six in your truck for a V8, you'll get worse mileage for one simple reason: with the extra power on demand, you'll have your foot in it more, reveling in the sound and feel! It'll take a while to train yourself to drive it easier to get the MPG back up. And anyway, if you're planning on handing this truck over to a new 16-yr-old driver, I'd think about swapping in a 2.3 4-banger till he proves himself...

(Edit): I see Kem posted the above while I was typing this (and putting out the trash...)