4.0L OHV to SOHC conversion

ZNathan130 · August 5, 2009

I have a 1996 XLT 4.0L ohv EFI engine, and I was wondering what all would be involved in converting to an 4.0L SOHC engine?

I searched the forums, and there are a few SOHC to OHV swaps, but not the other way around.

So, what electrical components would need to be changed?
Any fabrication or modifications to the engine compartment?
Does the fuel system stay the same?

Thanks in advance.

IZwack · August 5, 2009

You pretty much need the wiring harness and the ECU because the SOHC has different sensors (like the camshaft position sensor) and no metal fabrication is needed.

Stic-o · August 5, 2009

I remember someone telling me it's just a drop in. the computer dosn't care if it's a SOHC or OHV. 4.0 is 4.0 to it. IZ does have a point though, I think there are some different sensors. Hopefully some one can confirm this.

I've thought about this for awhile, If I could just drop a SOHC in mine and pick up 50 ponies I do it. :thumbsup:

I think you typed it wrong...why would any one go from SOHC back to OHV

ZNathan130 · August 5, 2009

Stic-o said:
I think you typed it wrong...why would any one go from SOHC back to OHV

99ex22 said:
I don't have an answer to your question but I thought I would let you know I have 163,000 trouble free miles on my sohc. I with you on that one though....I would much rather have a OHV.

My dad bought me my X, and I was very disappointed to see an OHV...

IZwack · August 5, 2009

Camshaft sensor

Here is the one for the OHV:

Here is the one for the SOHC:

The position of these two devices are diffrent too - the OHV's sensor sits at the back while the SOHC's is on the driver's side valve cover.

Stic-o · August 6, 2009

So IZ...you think you just wired pluged in the OHV wires to the SOHC plug, it would work?

I understand how the OHV one works, but not sure how the SOHC one works or what it reads off of.

I see in your pic here on the valve cover

Does it read off the lifters or something?

you don't want to change the computer if you don't have too, due to PATS

jlsparky7 · August 6, 2009

If your gunna go through the trouble go with the 5.0 or a diesel motor.... Make it worth the trouble.

IZwack · August 6, 2009

I have yet to take the valve covers off of my SOHC engine but looking at CDW6212R's image below, I can only guess that you're probably right Stic-O. -- its probably reading the driver's side camshaft front lobe or something within that small area (since the SOHC has an "overhead" camshaft on each head).

Stic-o · August 6, 2009

jlsparky7 said:
If your gunna go through the trouble go with the 5.0 or a diesel motor.... Make it worth the trouble.

A. Because if I can swap the motor, the SMOG police will not know the differance

B. SOHC puts out same power with less weight then V8

C. If I were to go through the trouble of diesel, I'd just go electric

IZwack · August 6, 2009

jlsparky7 said:
If your gunna go through the trouble go with the 5.0 or a diesel motor.... Make it worth the trouble.

Not sure how thats going to fly with emission laws (if it applies). And then the rest of the drivetrain has to be swapped out because I'm not aware of a diesel engine that will mate up. This includes driveshafts because the transfer case's rear output flange is quite unique and chances are, the driveshaft lengths probably wont match. Adapters and such could be made but that takes time and money since thats going to be a special input gear grind for the transmission, CNC cutting for the bellhousing adapter plate, and so on.

ZNathan130 · August 6, 2009

I'm with Stic-O and IZ.
Emissions aren't a concern here in Indy, but I don't want to go through the trouble of a V8 or diesel conversion. I want the increased power from the SOHC, and also the increased economy of it. Mine is a street machine most of the time, so I don't have to worry too much about off-road capabilities.

Okay, so I'm pretty positive I don't have PATS on my X. I don't have a chip on the key, and I had some spares cut and I didn't have to get a PATS for the keys. I may just be too dumb for words, but I don't think my 96 has a PATS system.

If I were going to want to switch to a different tranny (not sure auto/manual yet, but going for a 5-speed. I've got the 4r55e), what would you guys recommend for the swap, and would I be best off doing it while I've got the engine pulled? What all would be involved?

To please the powers at be, if I do end up doing this, I'll definitely be doing a full write-up. Pics and all.

Cobraguy · August 6, 2009

Get in touch with Jamie (410Fortune...or Fortune410...I can't remember now!) He knows what needs to be done to use the OHV ECM with the SOHC. I guess it is very simple to do and is being done quite a bit. You could also just wire up the SOHC harness and ECM. Both vehicles are OBDII.

Neil1750825 · August 6, 2009

I'm fairly certain that will be more of a ***** than you think... The SOHC didn't come out til '97 and you should know that it only came with one tranny, the 5R55E. If you don't have a tranny to go with you might as well not even start. There are far more differences than you think. It might as well be a V12 because they are very different. Good luck.

Cobraguy · August 6, 2009

Neil1750825 said:
I'm fairly certain that will be more of a ***** than you think... The SOHC didn't come out til '97 and you should know that it only came with one tranny, the 5R55E. If you don't have a tranny to go with you might as well not even start. There are far more differences than you think. It might as well be a V12 because they are very different. Good luck.

This is not a virgin swap...it's been done fairly often. I don't believe you will find it that difficult to do. But I do agree with one thing...most of the swaps I've heard about have been with manual transmissions.

ZNathan130 · August 6, 2009

Are there any threads on this? I shot 410Fortune a pm, so we'll see what he says.

I wouldn't mind having a manual tranny, but, of course, that would require learning to operate one (don't kill me. I have really tried to learn, but no one around here has a manual anymore!). Like I said, I would prefer a 5-speed, so if anyone has any suggestions, I'm listening!

Edit: Checked out the pricings for engines and transmissions at the local pic-a-part. All engines and transmissions are sold at flat rates. Total cost for a combo: $400 ($50 of which are core charges)

Neil1750825 · August 6, 2009

Cobraguy said:
This is not a virgin swap...it's been done fairly often. I don't believe you will find it that difficult to do. But I do agree with one thing...most of the swaps I've heard about have been with manual transmissions.

I realize its not a virgin swap. How many SOHCs do you know of that came with the five speed manual? I know of none. If I'm not mistaken, they all came with the five speed auto, the 5R55E. It will be a pain in your ass no doubt. For fifty horse I would suggest a bottle.

ZNathan130 · August 6, 2009

Some '09 Mustangs have a 5-Speed with their 4.6" V8 SOHC's, if I'm not mistaken.

Doubt if I'll grab one of those transmissions though. lol

Neil1750825 · August 6, 2009

And the 4.6 is completely different so that was a pointless comment....

ZNathan130 · August 6, 2009

This is what I've gathered so far:

1) Retain my computer to avoid messing with PATS. I don't have it, and don't want it.

2) If I want an auto tranny, I should probably just grab a motor/tranny combo. I'd still like to try to find a 5-speed, and if anyone has a lead let me know. The new mustangs have them, and I think Troopers had them at one point too. Could be mistaken though.

3)A few sensors are going to be off.

4) I might have a problem with the heater box.

Neil1750825 · August 6, 2009

Don't look to new mustangs. Totally different. You should also specify when you say five speed whether you're referring to the 5-speed auto (5R55E) or the 5-speed manual. Trust me, you'll want the auto.

4.0L OHV to SOHC conversion

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