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Discussion Starter · #1 ·
Hey guys,

I'm in need of a replacement engine. I currently have a 3.3l SC engine but am wanting to know if it's possible to go BACK to NA. Everytime I try and look this up, it's always people trying to go from NA to SC, but not in reverse. If the "downgrade" is possible, would I really notice power differences between the two? Obviously these things aren't made to throw you back in your seat, but I don't want to be limping along on the highway either. Also, is there anything else to watch out for when doing the swap?

Thanks!
 

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2004 Xterra XE 4WD Auto 3.3L NA V6
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You'll also want to change the VIN so the rig doesn't think more of itself than it should. ;) Well, either that, or spray it with nitrous...!

The NA engine has a slightly higher compression ratio, around 8.9:1, where the SC has around 8.3:1. (Those numbers are likely a little off, but they're close enough for an estimate.)
 

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Discussion Starter · #5 ·
You'll also want to change the VIN so the rig doesn't think more of itself than it should. ;) Well, either that, or spray it with nitrous...!

The NA engine has a slightly higher compression ratio, around 8.9:1, where the SC has around 8.3:1. (Those numbers are likely a little off, but they're close enough for an estimate.)
Maybe just turbo it? 😅 what about internal components, like rings and pistons, anything different there?
 

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You can put a NA engine in your car but you’ll need the ECM to go with it and take the flywheel from the SC engine. Using the NA engine will cost you about 30 hp.
I dont think he would need the ECM if he slaps the Supercharger on the NA Would he?
 

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Hey guys,

I'm in need of a replacement engine. I currently have a 3.3l SC engine but am wanting to know if it's possible to go BACK to NA. Everytime I try and look this up, it's always people trying to go from NA to SC, but not in reverse. If the "downgrade" is possible, would I really notice power differences between the two? Obviously these things aren't made to throw you back in your seat, but I don't want to be limping along on the highway either. Also, is there anything else to watch out for when doing the swap?

Thanks!
I Was doing some research just for some quick checks. Looking on Rockauto for shits and giggles and It list's alot of the exact same parts except for some of the rotating componants like the Pistons. Might come up with a List of some of these major componants and take them to Nissan with a NA Engine and a S.C Engine and see what part numbers they give. I am also trying to locate a Machine shop that can take a look at your Block and see if its usable. I just realized That I have the Engine in my 2001 Xterra which should be the same 2000-2004 Internally for the 3.3V6 I think. If it is and the Block is in better shape it might be cheaper to use that. Pick up some S.C Pistons, S.C Rings, Get the Headwork done, and Rebuild yours depending on if the Block is cheap enough to Re-use.
 

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03 XE AT w/JDM VG + SC, AC UCA & BL
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I dont think he would need the ECM if he slaps the Supercharger on the NA Would he?
yes unless you have a method to tune your current ECM. This doesn’t exist as far as I know


Might come up with a List of some of these major componants and take them to Nissan with a NA Engine and a S.C Engine and see what part numbers they give.
OMG please don’t do this. They have different pistons. None of these parts probably exist anymore. Everything else inside should be the same. If you’re going to repair the engine you have, just get a quote from the machine shop and keep the supercharger.
 

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Discussion Starter · #9 ·
yes unless you have a method to tune your current ECM. This doesn’t exist as far as I know




OMG please don’t do this. They have different pistons. None of these parts probably exist anymore. Everything else inside should be the same. If you’re going to repair the engine you have, just get a quote from the machine shop and keep the supercharger.
I feel like a clean swap down to NA would be easier than trying to append a supercharger to an NA engine. I’m fine with losing 30hp if it means this truck can finally be up and running lol
 

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2004 Xterra XE 4WD Auto 3.3L NA V6
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Excellent, thank you! Looks like my supercharged dreams are still alive and well lol
Just in case you weren't aware previously, @Blackberry gathered all the parts and then modified his NA into SC, so that means he has the slightly higher compression ratio, making possibly a bit more HP and torque, but also with a bit more of a penchant to knock. That's why he says "make sure" rather than "you might wanna" regarding a knock sensor.

A lot of us on here, including myself, have learned a lot from him. He comes with the additional pedigree of being a dealer service tech. Those are rare on pages like these, and I always stop and listen when he speaks. (No, I don't worship him, but there's definitely a whole lotta respect.) He's even brave enough to correct wrong information or thoughts to be sure that we all learn the right way. You just can't get better than that!
 

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Discussion Starter · #15 ·
Just in case you weren't aware previously, @Blackberry gathered all the parts and then modified his NA into SC, so that means he has the slightly higher compression ratio, making possibly a bit more HP and torque, but also with a bit more of a penchant to knock. That's why he says "make sure" rather than "you might wanna" regarding a knock sensor.

A lot of us on here, including myself, have learned a lot from him. He comes with the additional pedigree of being a dealer service tech. Those are rare on pages like these, and I always stop and listen when he speaks. (No, I don't worship him, but there's definitely a whole lotta respect.) He's even brave enough to correct wrong information or thoughts to be sure that we all learn the right way. You just can't get better than that!
Oh for sure, I absolutely respect what he says. I’ve seen him aaallll over these forums so he knows his shit for sure. Always appreciated when he contributes!
 

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yes unless you have a method to tune your current ECM. This doesn’t exist as far as I know




OMG please don’t do this. They have different pistons. None of these parts probably exist anymore. Everything else inside should be the same. If you’re going to repair the engine you have, just get a quote from the machine shop and keep the supercharger.
What I am saying is XgonGIve it has a Supercharged Xterra Already with a Supercharger ECM. If he takes a NA ENgine, Changes the Injectors, Pistons, Rings etc.. and Uses the S.C Parts to Build the NA I dont see why he would have to program anything. Am I missing something? Why would he have to tune the Already Supercharger Tuned ECM. I have done alot of research and the reason the NA Compression ratio is different is not because of Cylinder size but The pistons. Am I Mistaken? If I am that would explain it but From what I can see the Heads, Valves, Cam, Block are all the same. The Passages and Combustion chamber appear to be the exact same. The Crankshaft is the exact same. So that leaves you with a few parts that are Not identicle which can be Installed.
 

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About the only thing you didn't mention is that the SC tune can handle manifold pressures greater than 1 atmosphere, aka "boost", whereas an NA tune expects manifold pressures to be at or below 1 atmosphere. That alone can cause issues all their own.

So, based on what I've read above, if you already have an SC vehicle with the SC ECM, and if the current engine is so shot that you just gotta wad it up and throw it away, then find an inexpensive NA engine and have a machine shop overhaul it. Or just overhaul the SC that you have.

Removing the SC to go back to NA will require you to change the ECM, and that is problematic at best.

If you don't want the SC, just pop the belt off. The ECM will see all the right parts and not sweat it, but you just won't have the extra boost that we'd all love to have.
 

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About the only thing you didn't mention is that the SC tune can handle manifold pressures greater than 1 atmosphere, aka "boost", whereas an NA tune expects manifold pressures to be at or below 1 atmosphere. That alone can cause issues all their own.

So, based on what I've read above, if you already have an SC vehicle with the SC ECM, and if the current engine is so shot that you just gotta wad it up and throw it away, then find an inexpensive NA engine and have a machine shop overhaul it. Or just overhaul the SC that you have.

Removing the SC to go back to NA will require you to change the ECM, and that is problematic at best.

If you don't want the SC, just pop the belt off. The ECM will see all the right parts and not sweat it, but you just won't have the extra boost that we'd all love to have.
The Piston rings Failed and polished the Cylinder walls. Currently trying to locate a Machine shop to look at the Block. If the Block is salvagable which it may be then we just Re-build it. If its not we were trying to Figure out if we bought an N/A tore it down and Rebuilt it Hoping the Cylinder walls are not polished and Scuffed. If not we rebuild that NA into a S/C Engine. Change Pistons, Rings, Fuel Injectors and w.e other componant we find that is not the same. Once we do that Bolt the S/C ECM and S/C back on and Bam.
 

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Discussion Starter · #19 ·
Sorry I just now saw all these extra replies. Maybe I'll just wait for an SC engine to pop up, that way we can avoid all the headache? Given how perfectly smooth the cylinder walls are, I'm not hopefull about a rebuild. Plus, the current engine already has 214k miles on it, so we would be doing all this work for an engine that has a questionable lifespan. What I would rather we do is find a lower mileage SC engine and plop it in. All I want is my truck to run and run for a long time lol o_O
 
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