N52 Swap Discussion

[nando]

the 330i 6mt came with a 3.15 stock. it's pretty perfect for that car, even though it's way heavier than any E30.

Some guys like to put in the 3.73 from the xi/auto, but I don't really see the point.

[DEV0 E30]

I'm running the 3.15 Torsen.

4th gear, 6000 rpm = 110mph.

6th gear, 2900 rpm = 80mph

Around town I'm in either 4th or 5th for 45mph. Which is between 2k and 2500 rpms.

EndTuning - Gear Speed Calculator

This sounds like my jam.

[LukeJ]

I'm running the 3.15 Torsen.

4th gear, 6000 rpm = 110mph.

6th gear, 2900 rpm = 80mph

Around town I'm in either 4th or 5th for 45mph. Which is between 2k and 2500 rpms.

EndTuning - Gear Speed Calculator

[DEV0 E30]

I'm curious too, but if a stock N52 can easily do 280whp as hoveringuy said, I think that is plenty for the street in a lightweight chassis - I'd be fine with 250whp+ honestly.

I thought S50s were pretty much perfect for daily needs like 15 years ago.

If the N52 + 6 speed can be had cheaper and with the help from hoveringuy, nando, and others in here to make it actually work... as soon as it cools down I really want to do this.

Questions:

What differential are you guys running?
Assuming you are running the 6 speed, anyone have a shorthand on what you get to in each gear?
What RPM are you at 65/80mph, etc?

I'd love for 6th to be the "activate better than any previous e30 mpg" gear.

[moatilliatta]

I wonder what the highest HP stock N52 is minus Milv mod.

[DEV0 E30]

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.

You're basically making me want to buy an N52 off of ebay today and throw caution to the wind.

[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?