N52 Swap Discussion

[hoveringuy]

I'm not too familiar with the S54, but the difference between an M54 and N52 is huge. LOTS of room for porting in the M54 because the exhaust port is small and everything is rough cast. Parting lines and all

N52 is completely CNC machined and is a jewel in comparison.

S54 has 7% more displacement so makes sense that the valves are bigger.

The N52 can flow plenty on a stock head without even MILV to make upwards of 280whp when intake and exhaust are optimized.

[nando]

the design is basically the same, but the S54 has bigger ports, bigger valves, and a bigger cam. Basically everything is 10-20% more on the S54. Part of the manifold is cast into the N52 head so it appears that the ports are really long in comparison, but if you measure from on the injector location to the back of the valve they aren't that different there either.

[MWC]

Has anyone here had the opportunity to compare an S54 and N52 head? I'm curious what the differences are as I'm interested in doing a mild port and polish on an N52 head when I build my next engine. I know bigger isn't necessarily better so I'm curious if there are any significant differences between the intake/exhaust ports, short radii, etc. that I can take something away from.

[HCMW Adam]

Unless you're body swapping the entire harness and all of the modules, there's not really any way to make it work properly without modifying the DME. For example, making the VSS input work properly without the DSC unit, adjusting the water pump speed to work without the radiator temp sensor input, etc. There were a lot of little things we tweaked on hoveringuy 's car to make everything work properly. Having the CAS might be fun for starting without a key (or retrofitting comfort access) but I don't see much point in doing that.

I'm picking up what you're putting down. I now know I must have the ECM modified and that will define some of my other considerations.

[nando]

Unless you're body swapping the entire harness and all of the modules, there's not really any way to make it work properly without modifying the DME. For example, making the VSS input work properly without the DSC unit, adjusting the water pump speed to work without the radiator temp sensor input, etc. There were a lot of little things we tweaked on hoveringuy 's car to make everything work properly. Having the CAS might be fun for starting without a key (or retrofitting comfort access) but I don't see much point in doing that.

[HCMW Adam]

You would disable the secondary sensors and leave them out entirely. they're not needed for anything unless you're trying to build an OBD2 compliant swap.

It will not work at all with an unmodified computer.

Thank you. That was very helpful.


I have an entire Z4 to pull parts from and am debating having the ECM tuned right now. My first goal is to get the engine in, running and enjoy it for a while. Change intake and exhaust and hopefully find some MILV's at a later date. There are several items that require ECM tuning and if I cross any one of them then I will likely have others done. Is this a correct list of things that would prevent the ECM from properly running the engine:

• Remove secondary 02 - might be able to cut and rotate and shoehorn OEM exhaust into my car. Custom exhaust manifolds if I have to.
• Change intake. Switching to N54 intake or fabricated intake requires tune for performance reasons, or is the ECM looking for DISA? Planning to use OEM intake to get car running. Change things later.
• Delete CAS - must use OEM key if not deleted. I have both keys. Bit of a pain to get the wiring out, but it is available.
• EKP controlling fuel pump.
• Variable speed Fan.

I have the engine and trans out of my E30. I have the engine and trans out of the Z4 with the complete wiring harness still attached. I have access to fabrication resources. I do not have time to make custom exhaust and things if I can get this to work without doing it.

[nando]

You would disable the secondary sensors and leave them out entirely. they're not needed for anything unless you're trying to build an OBD2 compliant swap.

It will not work at all with an unmodified computer.

[HCMW Adam]

I have a question about the N52 computer and the catalytic converters and the second set of O2 sensors. If the cats are removed and a smooth pipe installed in it's place will the second set of O2 sensors cause the engine to run poorly? Will this run properly with an un-modified ECM?

[moatilliatta]

I’d rather have balance over more power.

I could see some over braking happen, assuming.

What are you running for pads?

[hoveringuy]

Hows the car? Brakes balance? Putting down the power?

Who couldn't use an extra 50hp? That said, I'm happy with the reliability and drivability of the motor. I can mostly hang with a Cayman S or an E46 M3, but I get killed on the straight where aero and raw hp mean more.

I've got the Wilwood race kit front and rear and no hint of brake heat or fade after even 30 continuous minutes. Under hard braking, the car has tendency to develop a yaw in one direction or the other. Not sure what to make of it or how to correct it. Ironically, the brakes work so well that I need to learn to use them less...

The other cool thing is that I did 70 laps yesterday and this morning not a single drop of anything under the car, anywhere.

[moatilliatta]

Hows the car? Brakes balance? Putting down the power?

[hoveringuy]

I shaved another 1/2 second off my previous best. I thought I was going to do even better than that based on my Delta timer, but it just kept eroding as I drag-raced towards the Start-Finish line. You can see the delta timer lose multiple hundredths of a second as I can't keep up with my previous best from earlier in the morning. Even a 15 degree increase in temperature was impacting power.

https://www.youtube.com/watch?v=lnI-N3ZgLLQ

[hoveringuy]

Another "M3 won't let me pass" video... (plus I have a big-dude passenger!)

https://www.youtube.com/watch?v=bI7-jzxObkU

[D_Eclipse9916]

I struggled with getting VVT to work for the longest time and finally resolved it by extending the stop by a few mm. My issue was that it wasn't learning the stops and I had a persistent error. You should be able to manually turn the motor while tracking the position per the video.

https://youtube.com/shorts/pzpOTTT_IJ8

why the waterpump controller?

I have to look at the stops, I know one is adjustable but the other is not, so I hope max is adjustable to be slightly lower. It say 8 functions learned successfully so I didn't think there was an issue with learning the stops.

Waterpump controller was just reducing one more thing I couldnt "tune" myself. I wanted the ability to go 100% workload if need be and not be beholden to any tuning idiosyncrasies from a stock ECU. (such as F%&%ing 15% throttle and VVT issues).

[hoveringuy]

I struggled with getting VVT to work for the longest time and finally resolved it by extending the stop by a few mm. My issue was that it wasn't learning the stops and I had a persistent error. You should be able to manually turn the motor while tracking the position per the video.

https://youtube.com/shorts/pzpOTTT_IJ8

why the waterpump controller?