you want a max mpg bronco 2 with a gasoline cologne engine? running 32 in tires and a bit of lift?
i could not muster the will to spend the money to rebuild a 4.0 let alone try to make one for max fuel economy. so i admire your determination to polish one of these things to such an end.
i look forward to the education from your results. i just cant see getting more then 20 mpg as a normal matter of function from a 4.0 cologne in anything town. maybe a smart car.
i would likely change the stroke and run a custom cut crank....
and custom pistons from diamond and rods....
pushrods from trend.
custom injection and tuning.
the cost of that would be radically prohibitive for benefits gained to the mpg objectives.
once the flow numbers were known on the custom heads then cam selection for the now 3.x , if destroked indicated win, or 4.5 liter if bigger stroke indicated better bsfc could begin.. with some trial and error for sure.
a solid roller setup i dont know whether or not is workable for this situation.
this 25 mpg in town and pulling a 3 k trailer thing is firmly in tdi vw territory.
for what you have listed your doing to this engine i absolutely would have went with a gm ls 4.8 or 5.3 with the best tune i could manage for a gasoline application. that would be number 1 choice with a 3550 trans.
sticking with gasoline my second choice would be a 2.3 mazda engine from a later model ranger and a 2.3 m5od converted to 4x4 andcustom turbo setup..
then its tdi.
or wait to snag up one of the new ranger power trains. i suspect this will be the main swap for these older trucks fairly soon. LIGHT and powerful. and unfortunately.... complicated beyond ridiculous.
Isn't it a contradiction of terms to ask what has already been done to do higher mileage by burning more fuel. The engine is a factory modified 2.9 low rpm engine made into a 4.0 higher fuel consumption engine by volume. They did what you suggest by taking the block and adding higher efficiency overhead cam setup and more modern electronic fuel system it seems to me. I have in my garage an almost finished flat top 4.0 with a highly modified set of heads to keep the compression ration down. (BTW get a pair of the new casting heads, they will be worth it) I'm looking for horsepower which most of your other mods will accomplish. A later model 5.0 or 3.0 with intake and exhaust improvements will probably get you to your gas mileage numbers. And there is the kicker - it will be cheaper. I could have put a 500 hp 5.0 in this thing with a carb.
cheaper. The only reason I didn't is because of a engine size limit on the competition class I want to run. Good luck.
generally i would say yes it is a contradiction stock for stock...
not necessarily a contradiction in this view due to the stroke differential. the actual dynamics of the engine and what ranges you are working with vs actual load.
my truck with a medium/heavy load back when it was equipped with a healthy 302 and automatic overdrive was 10-12 mpg with 456 gears and 35 inch tires.
an old schoolbus with 8.1l detroit diesel can do 10 mpg pretty regular.
a fuggin bus!!!! those weigh a bit more then my ranger with a heavy load.
its embarrassing.
my 4.0 b2 gets about 15 cruising down the highway on 33 in tires and 370 or 410 gears with m5od transmission. i have both sets for the 9 inch.
it has a d44 and 9 in. about a 4 in lift.
so i am between a ecoboost 2.0 or 2.3 or vw tdi at this point as what will power it next....
if the op pulls off 25 mpg town with a sub 2k 4.0 build...my ugly ass will copy it. .