91 ranger,4.10's,33's-what would get better mileage?4.0l or 2.9l?

[rickcdewitt]

o.k. guys, besides putting the 4.56's back in which engine will net less $$$ at the pump whith sensible driving-my factory 2.9l or a 91 4.0l?any opinions on the explorer tune(i have a complete 91 X donor truck) or the ranger computer? or are computers even interchangable?

 

[MAKG]

You don't actually expect higher mileage from a 4.0L, do you? That only happens if you don't know how to drive a 2.9L properly (it happens all too often -- stay over 2000 RPM all the time).

If you never accelerate any faster in the 4.0L, the mileage will be the same. If you do (and you can...), it will be lower. Look up "brake specific fuel consumption" (BSFC) to see why.

Cruise mileage should be nearly identical, if done correctly. It's all what you do when you accelerate.

 

[ArcticRaiders]

Well it will really depend on your driving conditions and style. I know I drive in the mountains and have a 2.9l which if I had a 4.0l i would get better miles. If you stop and accelerate more the 4.0l will be better. If you stay at a constant speed around 55mph or 65mph the 2.9l is better. Often times once you get over 65mph the 2.9l has to work harder. And since you have bigger tires the engine does have to work more generally too. In my opinion I would go with the 4.0l

 

[MAKG]

Well it will really depend on your driving conditions and style. I know I drive in the mountains and have a 2.9l which if I had a 4.0l i would get better miles. If you stop and accelerate more the 4.0l will be better. If you stay at a constant speed around 55mph or 65mph the 2.9l is better. Often times once you get over 65mph the 2.9l has to work harder. And since you have bigger tires the engine does have to work more generally too. In my opinion I would go with the 4.0l

Please look up BSFC.

This makes no sense.

If you generate more horsepower, you burn more fuel, in direct proportion. Unless you don't know how to drive and you lug the engine.

 

[cr_the_machinist]

In theory, the 2.9L should get better millage. Less displacement = less air/fuel mixture to properly run the engine. The conditions for the engines (which is an exception to this theory) would also affect millage. The list could go on and on. Also, even if the computer where interchangeable, they would do the exact same thing, monitor the amount of air coming into the engine, the amount of O2 in the exhaust and adjust the injectors to the desired air/fuel ratio. I'd say keep the 2.9L.

 

[rickcdewitt]

i was just wondering because the 94 explorer with a a4ld i drive now doesn't get that much worse mileage and i figured the 91 m5od donor trucks motor in my ranger might equal or exceed my current mileage(especially on I-5 to oregon at 65)my 2.9l is history so i'm pretty much looking at a rebuilt 2.9l or the donor 4.0l in my yard.i could spin third on the cement with the explorer and the 2.9l only dreams of it.i think i'de be happy with 40% more power at the expense of a little mileage when i use it.i already drive about as fast as i can on these mountain roads i just think the 4.0l wouldn't be working as hard.although the smaller motor would probably make the tank of gas last longer when on trail runs and in 4-low.

so i guess what you're saying MAKG is that if i drive with my truck with my foot down (like i do normally) the 2.9l truck is the mpg winner?i want my truck as utilitarian as possible an i wheel, get firewood and go hunting with it.if the 4.0l uses more on the trail i'll put a camcraft cam(RV one) in the 2.9l and go with the 4.56's.i'll just treat it more like a 4 banger on the freeway.at least when the shitzu fm-146 burns up 5th i have a m5od that worked when pulled.the thing that made me leery about it was a mangled thrust washer of some kind on the magnetic drain plug when i checked the atf in the
m5od
i had a 71 datsun pickup with 4.375 gears and little 14" rims and tires with a 4 speed once and it got at least 25 mpg no matter what i did to the old girl.

 

[rickcdewitt]

Please look up BSFC.

This makes no sense.

If you generate more horsepower, you burn more fuel, in direct proportion. Unless you don't know how to drive and you lug the engine.

i don't lug my truck i try to keep the rpm's where you have to use less pedal to maintain momentum(2000-3500).its probably doubly so with the jet chip i have that goes pig rich a few degrees of turn in the tps faster than stock(it worked to stop cold start issues after the headers,etc were installed).maybe i should scrap the chip and maybe clean the injectors or upgrade/replace to get the cold start enrichment it needed?it would be cheaper to build a new long block myself than swap motors also.

 

[rickcdewitt]

In theory, the 2.9L should get better millage. Less displacement = less air/fuel mixture to properly run the engine. The conditions for the engines (which is an exception to this theory) would also affect millage. The list could go on and on. Also, even if the computer where interchangeable, they would do the exact same thing, monitor the amount of air coming into the engine, the amount of O2 in the exhaust and adjust the injectors to the desired air/fuel ratio. I'd say keep the 2.9L.

thats probably why the 2.3 and 2.5 trucks break 20 mpg's all the time

 

[Evan]

From a Physics standpoint, a 2.9L will get slightly better mileage than a 4.0L if both are driven under the same conditions.

 

[cr_the_machinist]

What did you get (miles per gallon) with the 2.9L. I'm running a 4.0L in my ranger and I get about 16 mpg in the winter (Michigan). 16 mpg driving it like a normal person (at $3.15 a gallon, I know its probably more in other places, I'm gonna take it easy) If your really gonna dig into it all the time its not going to be forgiving on your wallet.

 

[Evan]

To put things practically; running a 2.9L or a 4.0L are not going to make a huge difference in your yearly gasoline expense if you're an average driver.

If you're truely concerned about gas mileage, neither is a good engine.

 

[rickcdewitt]

To put things practically; running a 2.9L or a 4.0L are not going to make a huge difference in your yearly gasoline expense if you're an average driver.

If you're truely concerned about gas mileage, neither is a good engine.

that was kind of along my train of thought.i've been kicking around an "other engine conversion" category idea for a while.the faggot yuppies are thicker than soup around here and none of them know how to work on cars so i was thinking about getting a mercedes deisel and tranny cheap and throwing it in my truck with a nissan cast iron divorced transfer case with calmini gears so i could get 20-25 mpg and a reliable crawling setup.

 

[Evan]

that was kind of along my train of thought.i've been kicking around an "other engine conversion" category idea for a while.the faggot yuppies are thicker than soup around here and none of them know how to work on cars so i was thinking about getting a mercedes deisel and tranny cheap and throwing it in my truck with a nissan cast iron divorced transfer case with calmini gears so i could get 20-25 mpg and a reliable crawling setup.

With the time and money you'd spend on such a conversion I'd recommend buying a cheap, small car as a daily driver. Something like a generation 2 Nissan Sentra or Toyota Corolla.

 

[rickcdewitt]

With the time and money you'd spend on such a conversion I'd recommend buying a cheap, small car as a daily driver. Something like a generation 2 Nissan Sentra or Toyota Corolla.

yeah i hear ya but since the engine is toast i'm throwing it all out there for inspection.sides the smell of bio deisel would get you a lot of nooky in this neck of the woods

 

[Original_Ranger84]

Please look up BSFC.

This makes no sense.

If you generate more horsepower, you burn more fuel, in direct proportion. Unless you don't know how to drive and you lug the engine.

Yeah but the engine has to work harder with less torque and horsepower. and EFI engines adjust the amount of fuel that is injected depending on how much you push down on the gas and how hard the engine is working on turning the tires. But with 4.56 gearing ether way would work. 2.9L would probably be easier.