2.9 to 4.0 swap

[ProjectMiniBeast]

I plan on swapping the 2.9 in my 1991 Ranger STX to a 4.0. Has anyone else on here done this swap?
I also plan on supercharging said 4.0 when I do it and was just curious to see how much boost a rebuilt stock 4.0 OHV can handle before things need to be beefed up. Not going to be a drag truck, just something to get out of its own way. 230 HP is my goal and yes, I have thought about a 5.0 swap but decided against it.

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[chewy012]

I read a thread on here about a guy who pull't a supercharger out of a junk yard... (I can't remember what it was off, something with a 4.6L?) that just needed some grinding to mount to the 4.0 lower plenum... Short story long, it's possible. Good luck and def start a build thread cause I'm love to supercharge my 4.0

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[chewy012]

Also, keep in mind 230 HP is almost 50% over stock which MIGHT be kind've pushing it. I'd say if that's what you're going for, at least do a full engine rebuild. Maybe look at boring out or thicker head gaskets so lower your compression ratio? Just ideas, have not done any major mods like that myself, but I look forward to seeing your progress.

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[JoshT]

Since you are swapping anyway, maybe consider a 4.0L SOHC? Not sure how it would fit in the engine bay of the older trucks, but if it would I think it would make a better starting point for a supercharged motor. Thanks to it's run in the Mustang there are probably a lot more off the shelf components for supercharging the SOHC.

 

[fordwheelinman]

Have you tried searching? Or even looking in the tech library? Been done many times.

If I remember right, the 4.0 has high strength internals good for up to about 5psi boost. I'd much rather do full rebuild with oversized SOHC pistons to boost compression, put in a performance cam, and get it tuned for 93 octane.

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[BlackBII]

There are many topics covering the 4.0 swap. The gist of it is that it's nearly a bolt in and plug and play swap, depending on which 4.0 you choose, what year, and what you want to swap. Both the OHV and SOHC are options, the OHV will be an 'easier' swap. You will need to swap the engine and harnesses.

As far as boost goes, you could safely run 5-7psi on stock internals, provided you have adequate cooling. Heat and boost together will be a problem. A charge air cooler and/or a water/meth injection along with a larger radiator or oil cooler will help with this. Will you be running larger valves and a different cam? How are you going to tune it? If you are sticking with OBD-I then you'll have to find someone to tune it on a dyno. Switching to OBD-II will make this easier as you can log more parameters and tune it remotely.

How are you going to mount the supercharger and what type will you be using? There are no kits for the OHV, so you'll be making your own intake manifold if you want to run a roots style compressor. You could also do a side mount, which would make things easier and allow you to place a charge air cooler somehwere. There is/was a kit available for the SOHC for a roots style compressor(Eaton M90), though I am unsure if you can still get it.

At the end of the day though, you'll have to go a very long way to make the 4.0 a high HP engine. You can however make plenty of torque which will be nice in a truck. 5-7psi of boost will get you at most 50-70hp.

 

[ProjectMiniBeast]

I am new to this fourm. I searched 4.0 swap posts right after I made my first post on here and was shocked to see just how many people have done it. I see now that the wiring harness, gauge cluster, computer, and cooling system all have to to be swapped. To answer some of the questions that have been asked, I plan on rebuilding the engine completely. I am sticking to an OHV engine and I think anywhere from 3-7 PSI would be pleny for what I need for more off the line power. Like I mentioned before this isn't going to be a top speed truck. I also suppose 230 HP is just a bit of a high goal for a stock OHV now that I see they only make around 160 HP stock from what I have found. I found an adapter plate for an Eaton M112 supercharger on the Morana v6 performance website so I hopefully shouldn't have to do to much milling. I also plan on sticking to OBD-I, and for keeping the engine cool an oil cooler wouldnt be a terrible idea either. The truck is getting lifted 6" and its also getting 33s with either 4.10 or 4.56 gears and eaton true tracs front and rear.

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[ProjectMiniBeast]

Also, keep in mind 230 HP is almost 50% over stock which MIGHT be kind've pushing it. I'd say if that's what you're going for, at least do a full engine rebuild. Maybe look at boring out or thicker head gaskets so lower your compression ratio? Just ideas, have not done any major mods like that myself, but I look forward to seeing your progress.

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Will for sure make a build thread. YouTube videos will be in the works in the near future. Starting a new job as a fulltime firefighter in about a week so I should have a bit more time and extra cash soon.

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[BlackBII]

Ah I see. I wasn't aware Morana made an adapter plate. That makes this much easier.

With that out of the way, I think your biggest hurdle will be tuning it with OBD-I. Not that it's difficult, but it would definitely be easier with OBD-II.

 

[ProjectMiniBeast]

Ah I see. I wasn't aware Morana made an adapter plate. That makes this much easier.

With that out of the way, I think your biggest hurdle will be tuning it with OBD-I. Not that it's difficult, but it would definitely be easier with OBD-II.

Yeah it would for sure be easier to run OBD-II. But more cool factor when its done

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