2.5i to 2.5si

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As far as I'm aware the main differences on the face-lift N52 engine the 2.5i and 2.5si share is only the intake manifold, extra disa valve, and a map.

Has anyone successfully converted the 2.5i to a 2.5si? If so where did you get the map done?
 
The N52 and M54 engines have more differences than just those. Pretty sure the block and camshafts in the N52 use magnesium based aluminum versus just regular aluminum the M54 has. Also the water pump in the N52 is electronic versus belt driven in the M54. And the N52 has a different valve cover so the CCV system has to be different also?
 
Gregory_tolson said:
The N52 and M54 engines have more differences than just those. Pretty sure the block and camshafts in the N52 use magnesium based aluminum versus just regular aluminum the M54 has. Also the water pump in the N52 is electronic versus belt driven in the M54. And the N52 has a different valve cover so the CCV system has to be different also?
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OP means the facelift N52 2.5i (177) vs 2.5si (218) BHP.
 
I have been thinking about attempting this myself for a while, there doesn't seem to be anyone who has done so already but on paper it seems pretty straightforwards
 
I'm pretty sure there is a few N52 intake swap threads on either zpost/e90/1addicts albeit not on Z4s. You'd need to dig around a bit though.
 
The n52 si can be upgraded from 218 bhp to around 260 by the addition of a 3 stage intake ie 2 disa's + map .
I baught one for mi 125i ,only to find it got 1 already .
So i have a 3 stage intake for sale :D
 
AlienZed said:
The n52 si can be upgraded from 218 bhp to around 260 by the addition of a 3 stage intake ie 2 disa's + map .
I baught one for mi 125i ,only to find it got 1 already .
So i have a 3 stage intake for sale :D
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We’re talking about the 2.5si here, that can’t match the power of the 3.0si with a twin disa intake - it has one of those already.
Do you mean the lesser powered facelift 2.5 that’s not an si?
Rob
 
You got me wondering now ,
Mi 1,er is the n52 125i ,3.0ltr and was producing 218 bhp .
Thought that was the same as the same engine in the n52.2.5si Z .
To produce near the same as the 3.0 si Z the 3 stage intake + map ,i am led to believe is needed .
Just realised the z is an actual 2 5 ,not 3.0 :thumbsup:
 
The 125i is a bit different as it has a 3 litre N52 engine and can apparently be mapped to produce 130i power.

The 2.5i and 2.5Si in facelft Z4s have a 2.5 litre N52 and I'm sure when the topic has been raised before getting a 2.5i to 2.5Si power requires much more than just a remap - you should be able to find a thread on here.
 
Also i do have the disa valve on the right side of the manifold, but this doesnt neccesarily mean that i have the 3 stage? How do i check for the 2nd disa valve and if i have the 3 stage?
 
2nd
 

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Price is £100+ postage ,
I have included the part no so u can research it.to see if it fits yours ,Perhaps someone may be able to advise if it fits
I have put new bmw o rings on also .
As u can see both dis's and throttle body are incuded.
Here are some of ebay to compare .
 

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This is what RealOEM says - two slightly different part numbers - the 2.5i is described as lower compression other than that the rest of the associated manifold parts look the same - its probably worth a go for what the parts cost. You would need to find a mapper with a reasonable knowledge of the N52 I guess - there is also the question of the sport button which the 2.5 doesn't have but presumably this is just a throttle map anyway?

2.5i

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2.5si

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There are posts on here about this topic. From memory the conclusion was it wasn’t that easy as there were other differences.
 
FWIW i've had mine remapped to 200bhp (from 177) the other day. Its definatley more peppy now, they aren't fast cars regardless of 2.5/2.5si , ive owned 4 of each now, its just a bit more driveable, as the 177 is quite slow
 
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