High Compression N/A full build

[Hendersoncj]

Hey guys, I have a couple questions regarding a full build on my m42. Im hungry for more power but I refuse to do an engine swap and I like the idea of keeping things N/A. Aside from the expected parts (gaskets, arp studs, bearings, etc.) what would you guys recomend. I am planning on running forged eagle rods, cp high compression pistons, and a light weight flywheel. The compression ratio should be somewhere around 11.1 and I think with a proper tune and some flow work on the intake and exhaust I could get some decent power gains. I have seen a lot of talk about solid lifters on here and was wondering if someone could explain that a little more. Also what have you guys found to work best for a MAP/MAF conversion. Ive been looking around but I havent been to impressed. Also what do you recommend for tuning. I was thinking of an aem piggy back kit or a miller war chip. Let me know your thoughts. Thanks!

[selespeed]

please tell me too because i want to do a MAF conversion. I am tired of this lousy AFM that i don't get steady idling

[Hendersoncj]

please tell me too because i want to do a MAF conversion. I am tired of this lousy AFM that i don't get steady idling

I totally agree. Not only is it inconsistent but when it goes bad it costs like $500 to replace. I got in contact with Miller performance a couple of weeks ago because they make kits for all of the other engine options that go into the e30 except the m42. They offer the miller war chip which allows you to go in and tune the timing and what not but they dont offer a MAF conversion with it. So I am leaning more towards a MAP sensor but if I go that route I might have to run a standalone.

[bmwman91]

Save your money and just use the stock AFM. I am running a 2.1L M42 that is rated at 205bhp, and after some fairly extensive datalogging, I can report as a hard FACT that you lose zero power to the stock air box and AFM (versus an M30 air box which is 60% larger and a VW MAF).
http://www.m42club.com/forum/index.php?topic=18727.0

An unsteady idle can be a number of things, and it is almost always a vacuum leak or bad O2 sensor.

[selespeed]

Save your money and just use the stock AFM. I am running a 2.1L M42 that is rated at 205bhp, and after some fairly extensive datalogging, I can report as a hard FACT that you lose zero power to the stock air box and AFM (versus an M30 air box which is 60% larger and a VW MAF).
http://www.m42club.com/forum/index.php?topic=18727.0

An unsteady idle can be a number of things, and it is almost always a vacuum leak or bad O2 sensor.

This i have to diagree! unsteady idle is NOT due to bad o2 sensor and vacuum leaks. It is due to a bad air flow meter. i have gone through this thoroughly and i can confirm this. the flap door of the air flow meter is just a lousy shit. stuck and not smooth

[selespeed]

please tell me too because i want to do a MAF conversion. I am tired of this lousy AFM that i don't get steady idling

I totally agree. Not only is it inconsistent but when it goes bad it costs like $500 to replace. I got in contact with Miller performance a couple of weeks ago because they make kits for all of the other engine options that go into the e30 except the m42. They offer the miller war chip which allows you to go in and tune the timing and what not but they dont offer a MAF conversion with it. So I am leaning more towards a MAP sensor but if I go that route I might have to run a standalone.

are you abel to get Miller to do this conversion for M42? i am sure many of us here would want to do this

[Hendersoncj]

please tell me too because i want to do a MAF conversion. I am tired of this lousy AFM that i don't get steady idling

I totally agree. Not only is it inconsistent but when it goes bad it costs like $500 to replace. I got in contact with Miller performance a couple of weeks ago because they make kits for all of the other engine options that go into the e30 except the m42. They offer the miller war chip which allows you to go in and tune the timing and what not but they dont offer a MAF conversion with it. So I am leaning more towards a MAP sensor but if I go that route I might have to run a standalone.

are you abel to get Miller to do this conversion for M42? i am sure many of us here would want to do this

When I talked with them I told them the same thing, just that there are a lot of us that would buy it if they figured it out and all they kept telling me was that they couldnt get good results. I have no idea what that means. Basically they are too lazy or something. I will try and get back in contact with them and see if they have anything new.

[bmwman91]

Miller probably ran into many of the same issues I did when developing a MAF conversion. It requires a great deal of signal processing because a 4 cylinder has no valve overlap which means huge voltage swings on the MAF output, and chances are that Miller would have to charge an extra $100 on top of their kit price for an M42 version because of the additional electronics that would need to be integrated into the MAF unit. Since there are not that many M42's out there, and even fewer M42 owners that wold want to buy the MAF kit, they probably don't see a very good potential for return on the investment. I spent 10 years coming up with a good MAF conversion, even some graduate level courses on signal processing, only to find that it has no benefit at all to power or throttle response when using the stock ECU. Keep in mind that there was no performance gain on a >200bhp 2.1L M42.

Anyway, there are a couple of things you can do with the AFM to try to clean up its behavior. If you can feel it sticking, then there is dirt or crud in there somewhere and you can use rubbing alcohol to get it out. You won't hurt it by wiping out the inside with alcohol. If it is physically damaged, then you can probably find a working replacement on here or r3v for $50 or less. If the output voltage skips and is not smooth, you can adjust the wiper to contact at a smaller or larger radius where the track is not worn out. These are fairly simple sensors, really.

There is no point in spending $500 on a MAF for the M42 because it will get you nothing, other than the fact that it does not have a physical wear mechanism. A clean used AFM will resolve your problems for less than 10% of the cost of a MAF conversion (and no commercial one exists). The only benefit you might get from a MAF is improved throttle response, but you would need to run an aftermarket ECU that could actually take advantage of the MAF's faster response. Actually, since we are on the topic of expensive modifications...why not look into Megasquirt or some other aftermarket ECU? Then you would not even need to use a MAF at all, and could use MAP or Alpha-N if you prefer!

[benz-tech]

Miller probably ran into many of the same issues I did when developing a MAF conversion. It requires a great deal of signal processing because a 4 cylinder has no valve overlap which means huge voltage swings on the MAF output...

I think the added sensitivity of the maf is not condusive to running bigger cams combined with a LTW as well. That said, who doesn't like a little lumpy idle.

If you are still having issues with your Afm, I have one for sale.

[Darky]

Hi

Miller tried to do a maf conversion but failed.
Even had a dozen or so pre sales that they had to refund.

Bmwman is right! Due to the m42 having no valve overlap. Sends pulses that just suck. I've looked throughly at his comparison graphs.
You see the m20, m5*, s5* and s14 has inlet valve overlap which means that there is always a bit of air flow. Therefore no pulses. But I have to wonder now that bmwman has 270 deg cams whether that issue would be solved, possibly.

But there are ways that would work
1. Go m44 engine ecu and everything that involves, obd2, cam timing wheel on inlet camshaft. To name a couple of headaches.
2. Splitsecond
3. Maybe even pilot. (Ping pong)

My 2c and good luck
Rohan

[Warsteiner]

I can offer my personal experience with this.  I went the 2.0+L route with lots of modifications which led me in the direction of a standalone unit. I run Alpha N with MAP on MSII. It's working flawlessly. I had a professional tuner dial it in and it was worth every penny. My motor is 2045cc with 10.9:1 compression with lots of goodies and 212HP at the crank. Torque peak is 172ft/lbs. The torque band is flat from 4,100rpm to 6,800rpm. Rev limit set at 7,500rpm and my crank pulley is still intact. All my power is made before 7K so I can shift earlier to get back in the torque band

The stock ECU/DME is plenty capable of handling many changes. MAF is not one of them. Many have tried and came to the same conclusion as bmwman91. The airbox is definitely not a problem either as bmwman91 has also stated. If you guys could have seen the Super Touring Car intake that I tested on my car on the dyno to prove that, you would have died laughing. My phone was dead and I didn't snap a picture, but it was ridiculously cool and eye opener as to how well the stock box really works!! Not only for airflow but you have to remember that it draws cooler air that stays insulated where as a cone filter that draws much warmer air.

That being said.....you need to plan out your entire build. It's not a change it as you go. That will cost you money and lots of it. I've gone the piggyback route and don't like it. A standalone gives you every advantage and you only buy it once. Unless your motor is going to be extreme, you should then keep the AFM which will save money and get a tune from Barrie or Mark.

I knew from the beginning that I was going standalone. My whole build was planned out. It was using mostly M3 parts and at least 2 Honda parts. There are so many variables to build the M42. 212HP is only a limiting factor due to choice of cam. IF I moved up in duration and lift then I would see an increase in power but my torque band would shift as well, to the right. I built mine for a solid street motor, not a race motor. I have a 330+HP S14 for that.

So far everything sounds great for your build. I am anxious to read about it some more. Good Luck!!

Cheers,
~Ralph

[benz-tech]

I will let you all know how the piggyback route goes, my safc2 will be here in a few days. I'm hoping it's all I need to fatten everything past 3,500 rpm at above 40% throttle. No need for that on AFM cars since a few clicks can accomplish something similar.