Want more power

let me start off by saying i have read the tech write ups, as well as several of the topics in the 2.9l section before coming to the conclusion that a new thread was warranted. i feel that there is contradicting information that has been given, making my decision on how to gain more power difficult. i also feel that my situation is different than the other guys who asked "How do i get more power."
Ok, my situation. My 88 B2 is the rig i am looking to make more powerful. the only thing i use the rig for is mud racing, so i relay don't care what will happen to my MPG's, as a result of adding power. i dont care if it idles ruff, or how "smooth" the power is, or if it is road friendly. i am currently running the 2.9l, all stock except a K&N cone. the FM146 5 speed trans, and 4.56 gears in my axles. so i am looking at adding some power. in the "Kunz Korner" in the tech library's it seems to suggest that there are things that can be done to the 2.9l to see significant power gains. (yes i understand significant, is a relative term.) mainly by working with the intake, throttle body, and using low temp thermostat. in my case i would, if i go this rout use the 160. Then i go into the 2.9l topics hear in the forums, and any time a guy asks about adding power everyone says "you cant get more power out of a 2.9, do a 4.0 swap." iv seen guys ask about the Tom Morana stuff, and get the same answer, but then other guys will say that anything Tom Morana makes is top notch, and that he is a reputable builder. So if he is a reputable builder, and he says that one of his parts adds 20hp, shouldn't one assume it will. i realize a lot of company's will claim there $200 computer chip will add 20 hp, and i know that is BS. but again when a reputable builder makes that claim about there $800 part, it seems a lot more believable. Now as for doing a 4.0 swap as an option, please excuse my ignorance to the subject. it seems to be relatively easy, except the wiring, and the need for the dash out of the donor vehicle. i see that Morana also offers a conversion intake manifold, to switch the 4.0 from fuel injected to a carb'd engine. would this eliminate the need for all this wiring and new dash? Ok i think that about covers my question, sorry i did not know which topic to put this thread in sense it deals with more than one type of 6 cyl motor.

If this is for mud crap only......Put in V8 and you won't have to worry about anything until you break something.

i dont think a V-8 is a good option for me. the classes i currently run require 6cyls. Most the guys in my class are younger guys, who dont have heaping piles of $$$ to throw into there rigs. i kinda fit into that category. (im 30, have a wife and kids on just my income) and i do very well for myself in the 6 cyl classes. but once you get into the V-8 classes your racing guys who are much older and have much more $$$ to put into there rigs. there must be at least 10 to 15 guys in the next class up who are running custom built V-8's costing over $10,000, and pushing close to the 8 ton 900 hp mark. even if i could afford one of them motors, all that power would rip up everything between the motor and the tires. all im relay looking to do is gain 25 to 30 hp. if Morana's claims are true and the boss 2.9 intake will gain me 20hp, and the low temp thermostat will get me another 5-10 hp, i would be happy with that. also if dropping a 4.0l in could be done using his carb kit, to gain ruffly the same hp gains i would be happy with that to. but jumping classes, spending 10k on a custom big block, just to have to turn around and rip my axles out and replace them with Tons, is not something i am interested in doing.

Don't bother carbing anything. That is not the way to gain any power in any circumstance.

Honestly, wiring the 4.0 to the 1st gen dash is not all that hard. It will snap your tranny in half and eat it for breakfast though.

I have a performance built 2.9 in my truck, and even with 3.45 gears 4th gear pulls from 35 to 65 are impressive, and all it really has in it is a high-lift long-duration cam. My standards may be low though since I've never really owned anything but worn out 2.9s.

adsm_.......how bout if he just puts some new injectors in that squirt a bit more fuel---low dollar items like 1 to 6 ratio steel stamped rocker arms...etc.?

Bigger injectors are great, but you have to make sure you can get all the air and fuel into the cylinder. A longer/higher cam will help with that.

sorry, i am still very much in the learning stage when it comes to motors. but what i am getting out of this thread is that, yes in fact i can get the extra 25-30hp out of the 2.9.
Now as for the tranny. in the tech library, i see that is says that the FM145 may hold up to a 4.0l but no telling for how long it will. i was told once that the FM146 was stronger than the FM145. is this true? if i managed to get the +20hp out of the Morana intake box, and the roughly 7 hp out of dropping the thermostat from 192-196 degree to the 160 degree. that would put my total Hp at around 167. though i know the torque would not quite be that of the stock 4.0ohv, the hp would be around the same. would my FM146 hold up to the 2.9 if i was pushing that kind of power?

mud junky said:

sorry, i am still very much in the learning stage when it comes to motors. but what i am getting out of this thread is that, yes in fact i can get the extra 25-30hp out of the 2.9.

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And spend $$$ doing it.

The 2.9 already makes a lot of HP for it's size and era, squeezing more out will be pretty futile.

Hahnsb2 said:

And spend $$$ doing it.

The 2.9 already makes a lot of HP for it's size and era, squeezing more out will be pretty futile.

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i dont care if i have to spend $$$ doing it. this is a race truck. the roughly $850 it would cost me to do this, is less than one weekends earnings at the races. if it will get me the extera power i am looking for than it is well worth it to me

Hahnsb2 said:

squeezing more out will be pretty futile.

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I disagree.

I bought my engine for $900 with about 3000 miles on it. I am quite happy with the way it performs. Compared to what I had going on before, I'd say this is quite worth it.


The 146 is not significantly stronger than the 145. The both share the same fatal flaw, namely that they use roller bearing instead of ball bearings for the mains. That makes them less able to withstand the side-loading that comes with high torque applications, which is why the 4.0 kills them so fast. But make no mistake, a stock 2.9 is more than capable of killing any FM transmission.

Run her 'til she blows, but I'd look for an M5OD and have her ready to throw in at a moment's notice.

Not to mention it requires either a MAF setup (good luck finding one) or some other form of tuning.

I did a 4.0 swap for less than $850.

I am sure you can figure out a 4.0 swap

i am am mechanic my no stretch of the imagination. i learned the suspension and axle work by helping install them on mine when i first got the B2. i am now confident with working with my suspension and axles. but a motor and transmission swap is way above anything i have ever done. if it comes to the point were i need a 4.0l, i would be much more likely to buy a ranger with the 4.0, and swap my suspension and axles from my B2 into it. but seeing as how i already win races more often than not with the stock 2.9l, im gona bet that if i do the thermostat, the cam, and injectors. that should be enough.

you can wire it to the stock dash... trust me. i did it.
i don't, however, have a diagram. i just looked at both haynes manuals and connected the wires to make it work. it wasn't difficult at all. i did it at like 15 mostly by myself. at the time i never knew TRS exsisted or if anyone had ever done a 4.0 swap in a b2 before... lol. i didn't know it was easier to use the newer dash... i like my dash tho.

i spent to much money on the 2.9 and was NOT happy w/ the results.. the stock 4.0 in my b2 impresses me more than the 2.9 i spend several hundred on w/ tb spacer, filter set up, injectors, cam, headers, all new exhaust, polishing stuff, so on... so forth. it was a waste IMO. glad i found a buyer that wanted a "supped up" 2.9.. lol.

did the stuff help the 2.9, yeah. no questions asked... was it enough to cover the cost of it in my eyes? heck no... i don't say 4.0 swap it because i did. i say 4.0 swap it b/c i wasted money on a 2.9 and i try to keep others from doing it also. i'm not saying 4.0 swap it b/c its the "cool" thing to do.

i did a 4.0 swap in an 87 ranger and kept my stock dash too. if you start out with the right donor harness for your engine controls, there should only be about 8 wires you have to splice.