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Discussion Starter · #1 · (Edited)
So I was looking around and thinking to myself. The versa has the MR18, but the Sentra has the MR20 and QR25. But the MR20 is compatible with the Versa and its ECU. Well I was looking and investigating, the computers between the 2.5 and 2.0/1.8 look exactly the same. So correct me if im wrong, but could you do a 2.5 engine swap and 2.5 ECU swap, and shouldnt the ECU just plug and play? As far as engine mounts, the MR20 and QR25 fit in the Sentra, arent they the same mounts? To me this sounds like a no brainer. Not that im saying it can or cant be done, or it isnt or it is worth time or money, but just for the thought of it? Or could the Versa ECU be reflashed with a 2.5 info? As far as trannys, if you have the 6spd, you shouldnt have to change that, right? Id only worry about a CVT. Just food for thought. :)
 
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I believe the spec v has a LSD. That's the only other difference I know of. I don't think the base level ser has it though.

Like it has been said before, with enough money, anything is possible. Perhaps there's a nissan employee who know the specs for the transmissions and can tell us if they are the same. The only way to really tell if it would work is to get a versa, base sentra, and an ser together and see what it looks like as far as engine placement and motor mounts.
 

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Also, older sentras used a 1.8 engine and the sers had the 2.5. If that was an mr18 they used, You might be able to find some more compatability there. Just thought id add that.
 

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Its a lot of work to do this. The list of parts is long. Just because the ECU looks the same means nothing. All nissan ECU look identical outside

engine
tranny
clutch
wiring harness
ecu
custom engine mounts, wiring job

at this point a 2.5 is a joke. Do an SR20DET. Much more reliable power
 

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Discussion Starter · #5 · (Edited)
So even though the computers and plugs look the same, and plug up to each other, Nissan didnt make the same wires go to the same thing in the engines? Like a base model altima 2.5, doesnt have all the bells and whistles of a motor thats in a Sentra SL, so there is a different computer for every car with different options? Or are the computers the same, they are just I guess "software" loaded differently? Im not trying to make things difficult, im just very, very, curious. Anybody got an Sentra SE-R/Altima and a Versa? I got the Sentra, so we can compare, lol To me, all the bells and whistles come from the BCM, the ECU controls whats in the engine compartment basically. So why wound an SR20 motor be any better as far as swap? The list is still long of things, right? Or are you saying if you go thru all that, you mine as well do an SR20 instead of the QR25. So then the tranny isnt isnt compatible from 1.8/2.0 to 2.5. See I thought it would be.
 

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Nope. ECU is tuned for transmission(which is different) different model, everything matters. I work for nissan in a dealership parts department for 4.5 years now. I am not guessing at this

The pin controls in the harness all likely are assigned different jobs in the 2.5 harness vs the 1.8/2.0. Also its a different engine series qr vs mr. The engines arent even built by the same company.

and in the end, the 2.5 is not worth all that money. You could do an SR20 for less and have way more bragging rights and power potential in the car
 

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Discussion Starter · #7 ·
Oh cool. I get it now. It makes sense to me now.
 

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You can get a SR16VVL (vvl is nissan's version of vtec) with tranny, harness and ecu for like $1600. I've been wanting to do a swap myself that would net more than a MR20
 

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Also, older sentras used a 1.8 engine and the sers had the 2.5. If that was an mr18 they used, You might be able to find some more compatability there. Just thought id add that.
in the B15 sentras (the previous generation, 2k-2006) the 1.8 was the QG18DE, a totally different engine from the MR series.

i generally agree with the thought that if one is gonna do a swap other than the MR18DE to MR20DE, then the SR20DE(+T) is a much better choice. again, more reliable engine (the QR25DE had some oil consumption issues in the B15, though seems to be okay in the D40 frontier pickup), more aftermarket support, and more easily able to handle boost via turbo.
 

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This is true. Mr20 was built for fuel economy and smoothness, not performance, so its hard to squeeze more hp out of it. The sr20 on the other hnad was built for performance and because its older it has a lot more aftermarket support. Although I did find some forged connecting rods for the mr20 the other day..
 

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Not quite sure the size difference either....that's another thing to think about. How small our engine bay is and how much bigger or smaller is the SR20/16? Would the QR25 really fit without cutting?
 

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If you look at the sentra engine bay, it appears to be a tight fit, and I'm assuming the block is a decent bit bigger. We'd probably be talking about battery relocation and whatnot to make it work.. it'd be cool, but I don't think it'd be practical. Too nose heavy.
 

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Also, if I were going the vvl route, id go all out and do an sr20vet. Stock they made 250+ whp. Idk if that would be too cramped though. The 1.6 might be easier to fit.
 

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I've already got my battery under my seat :) haha stock 1.6 nets 170-180hp which is still a good increase and it being n/a, it'll be more reliable and less weight up front, course I'm trying to just stay all motor
 

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Gotcha. They do make an NA version-the sr20ve. Makes a little over 200 hp. Only problem with these engines is they don't make a lot of torque in comparison to the hp, sorta like the rotary engines in the mazdas rx7 and rx8, although not as big of a difference.
 

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So I was looking around and thinking to myself. The versa has the MR18, but the Sentra has the MR20 and QR25. But the MR20 is compatible with the Versa and its ECU. Well I was looking and investigating, the computers between the 2.5 and 2.0/1.8 look exactly the same. So correct me if im wrong, but could you do a 2.5 engine swap and 2.5 ECU swap, and shouldnt the ECU just plug and play? As far as engine mounts, the MR20 and QR25 fit in the Sentra, arent they the same mounts? To me this sounds like a no brainer. Not that im saying it can or cant be done, or it isnt or it is worth time or money, but just for the thought of it? Or could the Versa ECU be reflashed with a 2.5 info? As far as trannys, if you have the 6spd, you shouldnt have to change that, right? Id only worry about a CVT. Just food for thought. :)
 
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