2.9 vs 4.0

jeffpinto · Apr 6, 2015

I am almost finished with my 4.0 install, I thought it would be interesting to see the difference between the 2.9 and 4.0. Has anyone tested the 0 to 60 time for the 2.9 and the 4.0? If not would some of you all be willing to post your times for your 2.9 and 4.0 broncos? I should have mine running this weekend but won’t be able to drive it until I change the tranny shifting over to the cable from the column.
Thanks

broncobuckinaround · Apr 16, 2015

lmao about 10 sec difference. 2.9 is garbage 4.0 is stronger and more reliable.

2.9 is good for a person that just wants a stock b2 or ranger. and for going on small trails.

swynx · Apr 17, 2015

In my experience a ranger with 3.73 and 31s with a 2.9. Is about as fast as a ranger on 35s with 3.73 and a 4.0...

AllanD · Apr 17, 2015

My vote goes to the 4.0 all other things being equal.

The 4.0 makes more torque by 1300 rpm that a 2.9 ever will make.

anyone who compares the two and thinks the 2,9 "wins" is not driving the 4.0 correctly

enjr44 · Apr 18, 2015

It all comes down to moving air. More air, more fuel, more power. A 4.0 has one additional liter of air going through it every time it goes around. Simple as that.

dirtcowboy · Apr 18, 2015

broncobuckinaround said:
lmao about 10 sec difference. 2.9 is garbage 4.0 is stronger and more reliable.

2.9 is good for a person that just wants a stock b2 or ranger. and for going on small trails.

So a BII 2.9 runs a 17 second quarter mile ( Motorcraft mag. ) and your supposition is that the same BII with a 4.0 that has 15 more horsepower and 20 lb. ft. of torque does the same quarter in 7 seconds?? Brilliant!!

fastpakr · Apr 18, 2015

dirtcowboy said:
So a BII 2.9 runs a 17 second quarter mile ( Motorcraft mag. ) and your supposition is that the same BII with a 4.0 that has 15 more horsepower and 20 lb. ft. of torque does the same quarter in 7 seconds?? Brilliant!!

There's a 50+ ft-lb torque difference, but yeah - his 10 second analogy doesn't work.

Dune Runner · Apr 18, 2015

I have owned both and there is a world of difference first time you pull a steep hill.

adsm08 · Apr 18, 2015

Dune Runner said:
I have owned both and there is a world of difference first time you pull a steep hill.

Or load it down. I run scrap with my truck, anywhere from 200 to 1300 lbs, one month. With the 2.9 I was always up and down between 3rd and 4th on the road to the scrap yard. With the 4.0 in the same truck, literally all else the same because I had a 4.0 trans in it before the engine, I just cruise in 4th the whole way.

4x4junkie · Apr 18, 2015

I currently own both and the difference is nothing close to what many make it out to be...

The 4.0L indeed has gobs more torque. But since it only has about 15-20 more HP (depending on which years are compared), it feels as if it's steam starts to run out after you've accelerated above about 3500 RPM, where the 2.9L continues to pull with all what might it has well beyond 5000 RPM.

I have not done any ¼-mile runs in either one of mine, but I'd be surprised if the difference in times was more than 1½ seconds or so (granted, my BII (2.9L) is also probably a good 500lbs lighter). The 2.9L with it's narrower powerband does require more shifting in everyday driving.

All that said, I will swap a 4.0L in place of the 2.9L when (if?) it's time finally comes to an end, since on my model year it's pretty much a bolt-in-plug-play swap. Until then, there's just not enough of a difference between them for me to yank out a perfectly-running engine.

trail B2 · Apr 21, 2015

There isn't much difference on the top end and a lot of difference on the bottom end.I drive on the bottom end.When I'm driving around my little town or in the forest there is a lot of 1000 to 1500 rpm time.If I'm really going some where it's duramax.

xcross · Apr 21, 2015

I do agree with trail B2, The power would be felt in the low and mid, but you will notice the top end is flat.

59bisquik · Apr 23, 2015

I went from a 2.9 with 200k miles to a low mileage 4.0 and then another 4.0 with unknown mileage. Both 4.0's have a bit more power than the 2.9, but after doing it, not enough to warrant the work. After I finish my current 54 project, I am yanking my 4.0 and going 5.0. I should of done that in the first place.

Sorry to be the negative guy, but I am just not happy with it!

94xlt4.0 · May 12, 2015

I have both a 2.9 in my 90 b2 and a 4.0 in my 94 ranger. The b2 is auto with 3.73s on 31's and is a little sluggish on take off but once your already moving pulls pretty good. The ranger is manual with 3.08s on 235/75r15 and pulls pretty hard like everyone has said up until about 3500-4000rpms. If you are replacing a motor its worth the swap on the plug and play models but i would probably swap a 5.0 on the models that arent plug and play since the wiring comes into play.

Kayakcrazy · May 12, 2015

94xlt4.0 said:
I have both a 2.9 in my 90 b2 and a 4.0 in my 94 ranger. The b2 is auto with 3.73s on 31's and is a little sluggish on take off but once your already moving pulls pretty good. The ranger is manual with 3.08s on 235/75r15 and pulls pretty hard like everyone has said up until about 3500-4000rpms. If you are replacing a motor its worth the swap on the plug and play models but i would probably swap a 5.0 on the models that arent plug and play since the wiring comes into play.

I agree, for all the work why not go with something that is a big difference. Nothing wrong with either engine. They both have limitations and do fine for what they were designed for. Lets be realistic, ford didn't really intend either to turn 35 inch tires. I have concluded that as long as the 2.9 is doing well I will probable keep it and when it goes ..... 5.0.

2.9 vs 4.0

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