M54. Let the foolishness begin.

[CorvallisBMW]

When did you convert to Megasquirt?

[hoveringuy]

227whp on Megasquirt!

I forgot to turn off fuel cut at 6000 or I'm sure it would have crossed 230whp at 6200. Oh well...

I have more details on the M54 megasquirt blog http://www.m54megasquirt3.blogspot.com

[rob_e30]

Just read the thread. Many have pointed out the great technical work (which was spot on), but you deserve plenty of credit for your writing too. Clear, to the point, funny. Thank you for the info.

[VinniE30]

Could not establish an 'off the shelf' purchase from ATI for the M54B30 engine. The 'rattler' mechanical damper is being prepared this week by a company called 'Vibration Free'.

http://e46fanatics.com/forum/showthread.php?t=765627

[Toni]

ATI makes a damper solution already.

Could not establish an 'off the shelf' purchase from ATI for the M54B30 engine. The 'rattler' mechanical damper is being prepared this week by a company called 'Vibration Free'.

[Toni]

why would you delete the cam sensors and COP? wasted spark and batch fire? I suppose it really doesn't matter for power output...

Cam sensors not required due to going wasted spark. The changes were done for engine reliability since this is a rally car and under a lot of stress. Coil on plug are a known failure mode and a GM coil pack running wasted spark looked a better option. After 3 rallies all good apart from the harmonics.
Yes I could keep the revs down and have timed the cams accordingly; however 6500rpm would be the optimum rev limit for my application, which them brings in the harmonic problem.

Welding/wiring the pump nut will not solve the destructive nature of engine harmonics above 6k rpm. I have engineered a solution for the oil pump and the sprocket will never come off but still intend solving harmonics to protect the cam chains and flywheel security.

Toni

[Elysian]

ATI makes a damper solution already.

[nando]

M54B30 harmonics are a known problem. try checking some E46 websites - custom dampers, wired/welded oil pump nuts, and keeping the revs down are some solutions.

why would you delete the cam sensors and COP? wasted spark and batch fire? I suppose it really doesn't matter for power output...

[Toni]

Running a M54B30 in a E30 rally car in UK forests. Vanos gone; std cams gone, MAF gone, coil on plug gone, cam sensors gone, Dual mass flywheel gone, power steering gone, viscous fan gone. Using DTA Engine Management and getting around 245BHP and similar torque.
My biggest problem is crank shaft harmonics unsetting the nut that holds the oil pump sprocket on; i.e. it keeps coming loose. Having a mechanical harmonic damper made in the UK (Rattler) with just the main water pump/alt pulley. Has anyone else had problems with harmonics and sorted out a positive solution?

Toni
www.tc-rallying.co.uk

[VinniE30]

So I don't see any reason a m54 can't be as reliable as an s50 revving over 6500 rpm if the oil pump problem is replaced with one of the solutions available for it and it has the ATI Super Damper.

[hoveringuy]

What's your opinion on US S50/S52 vs M54 reliability?

If you're not going to track the car the M54 is dead-nuts reliable. I'm talking the motor itself, not the crap radiator and expansion tank that comes with it on an e39/e46.

The reason the S50 makes more power is that the intake and the ports are better for high rpms flow. The M54 is optimized for torque. The numbers reflect that!

The problem with the aluminum block is that at high rpms (6500+) the oil pump suffers from harmonics and is prone to breaking the oil pump shaft from sustained exposure to the stress.

S50 will live happily at 6500 all day long!

[VinniE30]

What's your opinion on US S50/S52 vs M54 reliability?

IMO the biggest advantage of the M54 is the lighter weight.

Ignoring costs and swap difficulty I would rather have the M54 for that reason.

Seems we have established that with some bolt ons, power is very close, with M54 having slightly more lower rpm power, and S50 having slightly more higher rpm power.

Is the only advantage the S50 has over the M54, as far as output, the porting and cams? Intake and exhaust stuff can obviously be changed relatively easily and is not part of the engine.
I see the iron block as just potentially better reliability if it's going to be tracked hard.

[hoveringuy]

A fun result of running the Megasquirt is that EVERYTHING is on the table for me to examine, probe, measure and attempt to tune to perfection.

I recently discovered a possible cause of an issue that has been going back for years now, which is "why does the engine idle lean after a heat-soaked start?".

The popular theory is that it's from heat-soaked IAT sensor, but I'm finding that it has more to do with the fuel injector itself getting heat soaked. It's doing it even with IAT completely disconnected.

The temperature of my fuel injectors when the engine is running at operating temperature is about 110F and the resistance at that point is 12 Ohms. When the engine shuts down the temperature of the injector rises and settles at about 150F. The resistance is then closer to 12.7 Ohms. This matches the .4%/degree C coefficient for copper well.

My idea is that the higher resistance is increasing the latency of the injectors from 1.07ms to around 1.15ms. Megasquirt is still commanding a 2.2ms pulsewidth, but less of it is going to deliver fuel once latency is accounted for. I'm going from an actual 1.12ms pulse to 1.05ms which is about a 7% reduction.

You guys running huge injectors with tiny idle pulsewidths are probably effected even more!

On the 413 ecu the issue was being corrected after a few minutes from closed-loop O2 feedback and then corrected in short-term trim.

On my car it goes away, too, but is still annoying. I believe that the fuel itself has a huge role in cooling the injector during normal use.

Anyone have data on injector latency vs temperature in addition to the usual latency vs voltage??

[Leo_328i]

I believe that N52 engines either have DISA or don't have it at all depending on which car the engine is out of.

For the USA market:

The 325/328 engines are 3.0l but do not have DISA at all.

The 330 engines are also 3.0l but has the 3 stage DISA.


For Euro-spec cars

The 323/325 engines are actually 2.5l but have 3 stage DISA

The 330 engines are 3.0l and have 3 stage DISA

The 125i (not called 128i in Euro cars) actually has a 3.0l engine but without DISA.



Proof here, http://bmwfans.info/parts/catalog/11617522928/

Notice not all N52s have DISA, only the high spec 3.0l engines and Euro 2.5l engines have it. I believe its a cost-cutting measure.

[moatilliatta]

It's time for an update...

Cylinder head is back from the shop. It was heat straightened and decked .004. Good as new as far as I'm concerned and I'll even use the stock head gasket.

The block had pulled threads and I've installed 30mm Time Serts. Baum tools wants to sell you the 24.5mm ones for this but I've talked to some guys that had those pull out of the block, too. There's a reason no one says "tough as Aluminium". It's not a very tough metal and doesn't like getting hot. My block is fine now.

Anyway, I got the standard E34 oil pump and pickup tube and was messing around with that tonight when I realized the M54 oil pump is all different. Not even close. I will either need to switch in an e36 pump or fabricate a custom pickup tube. The M54 pump looks like it's got a larger capacity impeller. Anyone know for sure?

You be the judge... m50 vs m54 attached.

I would say the larger flow pump being there for the double vanos.

congrats also on the start up. Beware of the DISA valve pin falling out and getting sucked down the intake. Those have a nasty habit of backing out into the intake...lousy design.

Only falls out if you fuck with it.

Stuff like this shouldn't take me so long to figure out.

The motor has been running pretty good but there's been that constant *something* that I just couldn't put my finger on. I thought it was a tune issue but it just wasn't making sense.

The symptoms were that the car would run rich when the ECU was first adapting, but after it adapted it would tend to run lean before the O2 sensor went closed-loop. After it went closed-loop it ran fine. If I stopped at a store on the way home it wouldn't accelerate well when I first left the store, but a minute later it was back to normal.

Everything on the motor that relates to OBD1 has come from an M50 EXCEPT the IAT sensor. It snaps into a plastic fitting on the intake manifold and I figured it had similar values as the M50. It even has the same plug. I never bothered to check.

I finally got an M50 IAT and compared the two....they are substantially different. So far it has changed the driving characteristics quite a bit. I won't call the battle won but it's much, much closer.

The lesson is that the IAT has a huge influence on how the ECU programs fuel (and don't assume anything)

The IAT can effect timing a lot also.

I also logged my MAF signal with the DISA valve open vs closed. It shows that the DISA adds up to around 9% to the flow centered around 3500rpm. I switch the DISA valve at 3900 rpm to have good low speed and high speed flow. The DISA and the additional VANOS advance is what gives the M54 better low rpm torque.

The N52 has a 3 stage intake that has low, medium, and high speed configurations.

I believe they went back to the 2 stage like the m54 on later n52 because the gains wasn't as high as they though and it cost to much to manufacture.

What was interesting bmw doesn't design their newer intakes that has the multiple stages. I believe Porsche design does. Which i though was pretty interesting.