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  • hoveringuy
    replied
    AC isn't going to lubricate your engine. How's the oil pan??

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  • nando
    replied
    I bet you can swap pulleys. The only thing modern BMW loves more than cheap plastic parts, are cheap plastic parts that are interchangeable on multiple models.

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  • hubcapboy
    replied
    I said last AC post!

    Caperix almost ruined my surprise backup plan. The m54 compressor definitely looks like is a similar mount, but it’s driven off a secondary belt on that motor... so the pulley is narrower/fewer ribs.

    but the compressor from and m73 looks promising...

    http://www.bimmerboard.com/forums/posts/244196
    Last edited by hubcapboy; 07-28-2020, 06:58 PM.

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  • Caperix
    replied
    The mounts on a n52 & m54 compressor may be the same, they look to be. As long as the belt lines up that may be an option to just eliminate the swash plate. You would still want a way for the dme to see the compressor signal for idle speed changes.

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  • nando
    replied
    yeah, the E90 HVAC relies on other sensors, including a humidity sensor, to run it. You definitely don't want to try to swap all of that stuff over (although it does work really well on the E90).

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  • hubcapboy
    replied
    Oh that’s suspenseful... they’re showing up for me so I didn’t know what the issue was. Here’s where crank centerline hits... our conclusion was that we’re about 1/4” off chassis centerline at the rear axle, but the engine wiggles enough on the mounts to make that negligible. It’s a big ratio between the width of the engine and the distance to the rear axle... this misalignment is 32nds of an inch at the front. I could cut and re-weld the arms and be wrong in the other direction by twice as much.

    The diff is offset from centerline by about 5/8" to starboard, so as the engine sat in my fixture, we were slightly more offset than factory... but over the roughly 36" between the U joints it's the difference between 1 degree of joint angle (factory) and maybe 1.25 degrees (current fixture alignment).


    Click image for larger version  Name:	A6518979-DC12-4F7E-BDBB-F93F5E1B27DB.jpeg Views:	0 Size:	97.1 KB ID:	9941416

    Edit for clarity: At the rear subframe, the string is about 1/4" to port, that is the engine is pointed very slightly towards the left rear wheel. Over a 101.2" wheelbase this is a misalignment of less than a half degree.

    The diff is offset to starboard (left in this photo, but right in the car)
    Last edited by hubcapboy; 07-28-2020, 11:55 AM.

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  • LukeJ
    replied
    I care about it. I live in Az. Having A/C is only 2nd to being able to start the engine.

    But I have a different compressor, and I planned to pick up a Gpeterson CAN board. Hopefully one will be available. I was thinking having the hoses modified would be the biggest problem there.

    I wasn't able to see your alignment picture either. I have no idea 'where it ended up'. Was your block tilted, or did you already have it lined up?

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  • hubcapboy
    replied
    So. Last post about AC until the engines turning. I promise. I know no ones else cares about it ;)

    I’m just trying to determine if I can talk to the compressor without some serial connection I don’t understand. The alternator reports back to the DME in a language I don’t talk.

    If we assume that other reference is consistent with how PWM controlled variable rate compressors work (and other compressors on other manufacturera cars seem to work the same way) we can start figuring it out. As long as those wires connect to a coil and not some computerized controller, the resistance between them is meaningful.

    The info we have from the 7 series documentation above is 12v, 0.85A, 400 Hz. The frequency is almost meaningless. A coil doesn’t care if it’s driven by 400 or 600... but we can consider 400 a minimum (if it was 25 we’d be shaking the compressor to pieces, but at 400 it smooths out.)

    PWM is just a stand-in for variable voltage on a motor controller like this. If your supply is 12v and you turn it on and off 400 times a second with equal durations, a DC motor just thinks it’s being driven by 6v. If you turn it on and off 400 times a second with the duration 2/3 on 1/3 off, it sees the equivalent of 9v.

    If the coil was expecting to see 12v PWM with 99% on, 1% off and drew 0.85A, we’d expect its resistance to be around 14 Ohms. Well... it’s 11.2. By my monkey math that means we can certainly safely drive it with a constant 9.5V, or 66% duty cycle on the PWM driver. (I put 1.5v across it and didn’t hear it move).

    I’m going to pursue powering the compressor from the e30 chassis wiring, and controlling the demand with the PWM. I’m concerned that the DME control of the AC relies on other safeguards such as temperature sensors in the e90 dash HVAC (to prevent the evaporator icing up).

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  • nando
    replied
    yeah I am pretty sure it's not just an on/off 12v, but maybe it would work? if it's PWM could you overheat the coil by supplying a constant 12v?

    regarding the MAF, you can't disable all the pins. You still need the IAT (signal and ground).

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  • hubcapboy
    replied
    This is a different model, but still a BMW PWM compressor. I expect this is going to be the same frequency and voltage.

    https://www.bimmerfest.com/forums/at...0&d=1353378307


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  • hubcapboy
    replied
    mmmmmkay. There's at least two types of compressor fitted to the N52. With and without magnetic clutch. BUT, I think they're both PWM controlled (at the compressor), not CAN.

    https://www.underhoodservice.com/bmw...c-compressors/

    Here are the models that got the clutchless:

    https://www.realoem.com/bmw/enUS/partxref?q=64526956716

    and here are the models that got the clutch:

    https://www.realoem.com/bmw/enUS/partxref?q=64526987862

    the e85 has it's own part number, so who knows what's going on there:

    https://www.realoem.com/bmw/enUS/par...&q=64509182800

    BUT the clutch doesn't stop it from being a variable rate pump. The clutchless pump is always turning, but can vary the pump geometry so it isn't actually compressing. I think the clutch just ALSO disengages so the bearings in the pump don't wear, and that was added on the later models??

    Here's the thing... if the control is PWM I *think* we just need to know the voltage. If it's "off" the modulation is 0, and "on" the modulation is 100. Am I crazy?

    https://www.motor.com/magazine-summa...nt-compressors
    Last edited by hubcapboy; 07-27-2020, 07:57 PM.

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  • hubcapboy
    replied
    The offset CSB could easily be an indication of the goofy underbody shape, and nothing to do with the driveline location.

    Factory I expect that the shaft is straight to the CSB (so that the flex disc is perfectly undisturbed in a resting state) and then the rear shaft does all of the offset.

    This is what I did with my lunch break:

    https://drive.google.com/file/d/1kZ8...H4RSWaKi1/view

    This spreadsheet compares the 330i DME pinout to the Z4 DME pinout. Differences that probably don't matter are in yellow. Differences that area big deal are in orange and get a little essay.

    nando : If you can get your arm down to the connection on your 330i to the AC and find out if the white wire pumps out 12V when you ask the dash for refrigerated air I think that'll be huge. If that wire is CAN, I don't understand how the compressor clutch works, because there's no other power supplied to the compressor that I can find. Dash control is CAN, and the DME may get a vote in whether the compressor is on or might get notified so it can raise idle, but none of those things matter if I can engage the clutch with the e30 chassis compressor wiring.

    How AC is handled is the biggest difference between the two cars. Everything else we pretty much knew. Once I know that the yellows don't matter for your tune, that the sport button doesn't matter, and that I can disconnect all signals for the MAF, I can apply this to the other spreadsheet and finish the harness design.

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  • hoveringuy
    replied
    With my M54 I've had to do all kinds of stuff to it, including ZHP cams, porting, M50 intake, etc. to get to ~245whp and I still have the looming issue of oil pump shaft harmonic failure. The N52 is a dime-a-dozen soccer motor that will do that off the shelf.

    Getting back to the motor alignment issue, it's clear that the motor is centered and the diff is offset to starboard. I've never really paid attention to this on my car, how is this resolved on stock cars? I know the CSB is offset, does that mean the shaft is straight from the transmission to the diff pinion (at an angle), or does it go straight to the CSB and then jog left?

    Leave a comment:


  • nando
    replied
    The off-the-shelf AA tune was garbage though. All they did was increase ignition advance by 3 degrees across the board. I think if you brought your car to them, they did actually do a decent tune, but it still had issues (limp mode and torque overflow errors).

    also the 330i does not put down those power figures stock - it's around 220whp, not 248whp. 268bhp was for the "3.0si" motors on the Z4, X3, and X5, the 330i was 255bhp. The differences there are basically all software. However it's kind of funny because the 335i was originally 275Bhp, barely any more than the N52 could do N/A (although it has more torque than the N52) - but BMW clearly couldn't have a 7hp difference between the high end and "low" end cars, so they de-tuned the N52 to 230hp.

    Obviously, tuned to an inch of it's life, an N54 can put down a lot more than 275bhp, but still. It illustrates that the difference really wasn't so big. It's too bad the M guys all left for Hyundai and BMW wouldn't let them make an M version of the N52..
    Last edited by nando; 07-27-2020, 02:13 PM.

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  • hubcapboy
    replied
    Oh. This write-up makes more sense:

    https://www.bimmerboost.com/showthre...ntake-manifold

    They recorded +40hp with their tune, headers, and the 3-stage intake manifold. That's suspiciously close to the difference between the BMW ratings for an e90 328i (228hp) and an e90 330i (268hp)... and the only difference between those engines is the 3-stage intake.

    Leave a comment:

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