25+mpg 4.0l ohv build

[gaz]

I have avoided the 4.0l in my rigs up until now. I have worked on a few and been able to make improvements in mpg, however this was always for buddys who didn't want to spend enough to realise the full potential of the powerplant.

I desire 25+mpg while tooling around town but if I can not tow with 20 mpg+, I may scrap the 4.0l for a 302 or 5.0l.

Has anyone here built/rebuilt their 4.0l ohv for torque to maximise mpg and experienced positive results?

My plan is to do the following:

• 94 RANGER Federal 4.0L ohv
• Endrigo Flow benched port/polish intakes
• Endrigo Flow benched port/polished heads milled 0.03" (CORR; heads only had minimal resurface)
• Endrigo performance multi angle valve work
• High lift adjustable rockers
• Springless Al rocker arm spacers
• Improved oil passages on top end
• MSD DIS-4
• Set of balanced injectors
• Headers to 2.5" custom exhaust (2 into 1)
• Borla XR1 2.5" muffler
• Polish the crank
• Complete balanced bottom end
• Custom reground cam for maximum torque
• ECM chip
94 RANGER M50d r1 to B/W 1350 with man hubs (CORR; using 94 Exp A4LD)
94, d35/8.8LS 4.10' turning 32" tires, rear discs
Installed in a 3,200 lb 1987 BroncoII 4×4

I am uncertain who makes .020"-.030" over flat top pistons for this motor. I will use all of Sven's processes that are practical, since they worked so well for me rebuilding 2.9's.

I have a 94 donor so it has the original casting heads with big chamber and small dish pistons.

 

[alwaysFlOoReD]

I would be ecstatic if I could get over 20mpg. I'll follow along as you do your research.

One thing that will definitely hurt is the tires you chose. They will have more rolling resistance as well as inertia.

 

[gaz]

alwaysFlOoReD:

While more of a speculation, I do know this...

1) the 4x4 Bronco II weighs 700 lbs less than the 2 wheel drive Explorer
2) this combination of gears and tire size resulted in 28/25 mpg in my 2.9L powered 5sp Ranger??? Given, the 4x4 Ranger weighs 500 lbs less than it's BII little brother.
3) the maximum torque of the original 2.9L was 170 ft/lbs while 4.0l ohv delivers 225 ft/lbs

So, the stock equipt 87 BII had 26.5" tires and 4:10LS gears, I found that those gears performed better with 32's; it never saw north of 18.5 mpg until I installed the rebuilt for torque Endrigo 2.9l, then it was able to make 25 mpg towing 3,000 lbs at highway speeds? I didn't try to make sense out of it at that point, i just figured I had found the combo which made best use ofthe engines tq curve at US hibhway speeds .)

 

[alwaysFlOoReD]

I assume you changed the speedo gear to reflect the new tires? going from 25.6" tires to 32" tires and getting better mileage doesn't make sense.

 

[RonD]

Plan on getting rid of mechanical cooling fan and install electric cooling fan
Better MPG and Power, one of the few changes that does both.

Gasoline engines are about 25% efficient, newer gasoline engines can get to about 35%
75% of gasoline's released power is lost in heat.
So if you paid $4 for a gallon of gas $3 went to heat the coolant and air

One of the reasons is the throttle plate, most of the time the gasoline engines are inhibited by lower pressure, vacuum, in the intake.
And lower compression ratios

Diesel engines run higher compression ratios and have no "vacuum" to work against, so are 35-40% efficient

Good easy read here on this stuff: https://en.wikipedia.org/wiki/Engine_efficiency

It basically all in the numbers, and physics, of how internal combustion engines convert fuel into the energy that pushes vehicle down the road.

And no, 200mpg carb never existed, or could exist
And "pre-vaporization" is hooey, air/fuel is a WEIGHT ratio, doesn't matter how much you spread apart molecules, you still need 14.7 POUNDS of AIR to mix with 1 POUND of gasoline

Synthetic oil will help MPG, friction accounts for about 3% of efficiency, so less friction is always a good thing

 

[gaz]

RonD;

I am in complete agreement with the crank case driven fan delete; while i did see more of a power gain from headers then switching to a electric fan it is my number one with a bullet, go to mileage gain move.

alwaysFlOoRD;

You can call me lazy or good with math but I never correct my speedo after a tire size change. I know that it is about a 20% change, so i add 20% to the indicated speed and go the speed of traffic while on the highway (CORR; I have since recoged the mechanical speed cable).

I did verify my actual speed against the county roadside auto speed check device; it says I am going 29 when the speedo shows 25, says 41 when speedo shows 35...so i can work with that .)

Just to be clear, I do know how little I know...what I do not know, is what the Ford 4.0L ohv is actually capable of. I know the 2.9L can be massaged to very respectable torque and mileage numbers. Who has built one of these 4 liters for mpg performance?

 

[truckerdawg]

Town driving and 25+mpg is tough in any 4 wheel drive. Towing something like a bass boat and 20 mpg with the BII 4X4 on the highway I think is dreaming again. I have Pacesetter coated headers in a salt environment and they are doing well-just needed to have them planed/shaved flat to mate up to the heads. High lift rockers(roller) are a waste of money and no one I have seen recommends trying to outfit them. I think flat tops can only be found in the 4.0 inch bore which can be done with other modifications-not necessary in my thinking but if you have the money then do it. Run Bosch 4 hole injectors. A cam grind like the 410 Comp cam is pretty stout while not requiring double springs and a lot of duration which will kill some mpg. Just another opinion is that 2.5 inches is too much pipe for a 4.0-these heads do not have the valve sizes and exhaust port angle to run that much exhaust through them until you force air into them. I pull my bass boat with ease but do not get 20 mpg when I do.

 

[Andy D]

I got 21 mpg once with the Rat. Kept the speed at 60-65. Stock '94 4.0/5 spd, 3.27 gears,235 r75 15s . Keep your tires hard,bed empty and engine tuned. Itsa effen 4x4. I didn't buy it for its mpg.

 

[gaz]

tuckerdawg:

Thank you for your resopnse. I used hi lift rockers and spring delete rocker arms in my 2.9L builds with awesome results. That is why I am asking those who have used these products in the 4.0L, how it likes them. I am quickly reconsidering yet another 2.9L rebuild as there doesn't seem to be anyone who even considered it worth trying to see north of 30+ mpg from this powerplant???

I am miffed, I am begining to think that the ohv 4.0 was just the big boys making something that sucks more fuel, on purpose?

Andy D:
Thank you for yohr response .)

 

[truckerdawg]

I have built the 2.9 with flat tops, big cam, and 86-87 throttle body with the 5 speed on my other BII 4x4 and can tell you it was worth it. But, I do get better than 20mpg with my built 4.0 on the highway and it is much stronger and to me worth it. The 2.9 if rebuilt, I would go with the solid lifter fix. You never know when that dreaded lifter tick will start and when it does power is diminished.

 

[BlackBII]

I average about 18mpg with my 4.0

All that has been discussed should net you some efficiency, but at the end of the day, you are still driving around a giant brick, and bricks are not aerodynamic, especially when not close to the ground.

I average 25mpg in my 2006 Taurus with the 3.0 Vulcan, but that car is much more aerodynamic.

I bet you could get 25mpg from a 4.0 -- if it was in a more aerodynamic vehicle, and at about 50mph with the cruise control set.

 

[gaz]

BlackBII;

Thank you for your responses. That seems to be respectable mpg #'s for the 4.0 ohv from what I have gathered.

truckerdawg:

I too have experienced OUTSTANDING results using late era 2.8L pistons in 2.9 rebuilds, so much so that I am spoiled by the economy of it.

I have learned a couple things about the 4.0, 1st hand and some other things from reading other's posts.

I shall be installing new lifters and pushrods when I install the 4.0 in the Bronco. I will be correcting the air path through the intakes to the head; seems Ford did not care enough to let it draw in nice and smooth. The ports and gaskets line up horrible! The next thing that shocked me is the way Ford laid out the exhaust from the heads to the exhaust manifold.

I will be re-using the 2.9L headers to correct most of this problem. Strangely, the 2.9L exhaust manifold gasket matches up real sweet to the 4.0 head, even the correct size ports (CORR; as it turns out, this 94 Ranger donor engine had been rebuilt at least once, the heads were replaced with 98 spec heads, hence the smaller exhaust ports line up perfect to the 2.9l headers)??? I can only speculate at this point but I hypothesis that the matched port sized will result in a smoother air flow and at substantially higher velocities! I expect these results to yield me some power back from Ford's reverse engineering. The 2.9's "H" pipe also affords me a simple start to true dual exhaust, though my plan remains a custom 2.5" single system (in accordance with my machinist's recommendations, it will be a true dual, retaining the cats, 2.25" exhaust and I have decided to use Borla Turbo mufflers [now designated ProXS])

I am going to try this setup with a set of balanced rockers and springless rocker arms with the Bronco's A4LD to establish a baseline prior to the rebuild on my turnkey 4.0 ohv donor.

 

[Craig0320]

Before I converted my stock 98 4.0 4x4 3.73 ls automatic to 5.0 I was getting 18 around town and 20 on the interstate.

 

[gaz]

Craig0320:

Thank you for the info .)

 

[Craig0320]

No problem. The truck was bone stock also besides 2 sizes over stock all terrains.