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E83 2.5si engine


jss33
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We have an X3 M Sport 2.5si with a cooked engine.  We sent the head to be skimmed and were told it was too distorted. Can we fit any n52 head, or is the M Sport fitted with different valves? Code is N52K B25a

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Morning jss33

Welcome to the Forum

These are pretty tough engines so unusual damage

Take a look at www.realoem.com it's a BMW online parts list put the last 7 digits of your Vin into the search box it will call up your model. Then in the engine section open the Cylinder Head section double click the part number and it will bring up a list of alternate part numbers and the Models they were used in.

These engines were used in several models from the E46 to the Z4 

Good luck with the rebuild

Dave

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Or upgrade to a 3.0i engine basically the same block 255hp just make sure you get the ECU with the engine. If you get a copy of PA Soft BMW 1.4.0 you can register it to the chassis and the other units 

Dave

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Hi Jim

I believe the valves in your head are Inlet 33mm Exhaust 30.5mm a quick look at the TIS and it seems to indicate all the heads up to the 3.0 use the same Cylinder Head /Valve combination The models it was used on are as follows

It isn't until you get to the M3 that the intake changes to 35mm exhaust stays the same obviously cams are very different.

Just talked to a pal who runs a tuning company he informs me that your 2.5 motor in standard trim will give around 190 bhp and ecu tune on its own would lift it to 210 ish bhp with cams some intake work and a better exhaust around 250 is easy to achieve. If the motor were changed to the 3.0i 250bhp  is your starting point.

Hope this helps you

Dave

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18 hours ago, Greydog said:

Hi Jim

I believe the valves in your head are Inlet 33mm Exhaust 30.5mm a quick look at the TIS and it seems to indicate all the heads up to the 3.0 use the same Cylinder Head /Valve combination The models it was used on are as follows

It isn't until you get to the M3 that the intake changes to 35mm exhaust stays the same obviously cams are very different.

Just talked to a pal who runs a tuning company he informs me that your 2.5 motor in standard trim will give around 190 bhp and ecu tune on its own would lift it to 210 ish bhp with cams some intake work and a better exhaust around 250 is easy to achieve. If the motor were changed to the 3.0i 250bhp  is your starting point.

Hope this helps you

Dave

Might be easier to buy a complete  lump ? How is the extra m Sport bhp (218)produced? Is it the head  , or ecu software? 

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I assume ECU, Throttle Body and cams, As all the heads appear to be the same the only things variable are (a) Capacity (b) ECU program (c) Throttle Body (d) Camshaft duration/lift

I thought you were just rebuilding the motor in the X3 and looking for a head that would fit. Remember if you change the engine you will have to change the sump as it also mounts the front diff and has to have a Drive Shaft pass through it there are probably a few other differences I have not thought of. Best option would be the 3.0i engine from either the X3 or X5 both would need the corresponding ECU and the ECU would need matching to your existing chassis and other key control units 

Dave

 

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1 hour ago, Greydog said:

I assume ECU, Throttle Body and cams, As all the heads appear to be the same the only things variable are (a) Capacity (b) ECU program (c) Throttle Body (d) Camshaft duration/lift

I thought you were just rebuilding the motor in the X3 and looking for a head that would fit. Remember if you change the engine you will have to change the sump as it also mounts the front diff and has to have a Drive Shaft pass through it there are probably a few other differences I have not thought of. Best option would be the 3.0i engine from either the X3 or X5 both would need the corresponding ECU and the ECU would need matching to your existing chassis and other key control units 

Dave

 

I am torn between a head or engine replacement. I bought as is expecting it to be a simple head  skim and rebuild. The engineering company said it was too distorted, which I was surprised at, as these units are pretty bombproof. I am sick of breakers yards  advertising engines (at silly prices) with either no mileage, or false mileages quoted. If it was genuine, why not quote the VRM of the donor car so mileage can be checked via the VOSA website. TBH I struggle to find a helpful  and courteous breaker (apart from Quarry) at all. I found a lovely low mileage 130 head on eBay, but different bores obviously. I may try a second opinion on the head, or perhaps sell as a project. The car is a great spec in impeccable condition apart from the obvious, and too  good to break.

Thank you once again for your help!

Jim   

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If the engine is stripped already my personal route would be another head assembly. Checked for flatness with a good straightedge and a torch. If OK I would fit new valves and springs and rebuild the engine. 

Always worth more as a running car than a project

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5 hours ago, Greydog said:

If the engine is stripped already my personal route would be another head assembly. Checked for flatness with a good straightedge and a torch. If OK I would fit new valves and springs and rebuild the engine. 

Always worth more as a running car than a project

I owe you a beer... or two! Thank you.

 

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  • 3 weeks later...
On 9/25/2021 at 7:16 AM, Greydog said:

Don't post them, our Postie keeps telling they were leaking 🤣🤣

If I buy a complete head,  as the cams on mine look poor, are the cams different on this model i.e 218 bhp standard ?

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realoem will be the place to check. Logic dictates that cams are probably standard 2.5 and 2.8 engines as the valve sizes are the same, with Vanos timing being the difference. The 3.0 engines may have longer duration cams (it still has the same valve sizes) but if you are fitting a complete assembly the ECU should be able to adjust and cope.

Dave

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