M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => General Topics => Topic started by: bmwman91 on June 21, 2013, 11:31:56 AM
-
Some of you probably saw these pics in my original engine build prep thread. I figured that I would condense them all down.
An M30 air box on an M42?
(http://www.e30tuner.com/other/uwotm8.jpg)
As everyone knows by now, the M42's air box and AFM are plenty big for this spunky, but small, engine. Well, the stock one anyway. A 2.1L version with hot cams, head porting, bigger valves, higher compression and a host of other stuff that is supposed to make ~205bHP might need to breathe a little more freely. Back in April 2012 when my original engine died of timing failure, I decided to go with a fully loaded Metric Mechanic Rally 2100 M42. FULLY, all the bells and whistles, and I ended up with a couple of things that they don't even advertise. I have wanted one since 2006 when I was a broke engineering intern that could barely imagine being free of student loans, let alone buying a crazy expensive engine for his E30.
Well, a lot can change in 6 years and since I had been earning decent money but still living like a mostly broke college kid all along, I had cash stashed and suddenly I had the motivation and means to call up Metric Mechanic. There was a laundry list of things I needed to do with the car in preparation for the new engine, but the air box retrofit was a lot of fun and I took lots of pictures to share. I won't stand for cone filter bullshit and other nonsense that both looks crappy and lets dirt into the intake. So here it goes!
Originally, I had looked into using the air box from a 325e since it uses the same filter panel as the E30 M3 but with the inlet tube behind the headlight instead of against my radiator. I can't recall exactly how much more surface area the M3 filter had than the M42's, but it was on the order of 175% or something. The down-side was that the internal flow path looked pretty restrictive, and it would be even more so after my mods to build-in a velocity stack for the MAF. I also picked up an E34 M30 air box and filter, which turned out to be a reasonably good fit since it was about the same width as the M42 box, and "just" 15cm longer. It had LOTS of room for a velocity stack (I have been tweaking a custom MAF conversion for the last 6 years and they definitely need a VS in front to work well).
All of this was done with the old engine in the car while the new engine was being built, hence pictures of a dirty engine.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw001.jpg)
Here are some measurements from the M42 and M30 stock air filters (I would NEVER run a K&N or similar one, they let all sorts of particulate shit through).
M42: 68 pleats x 46mm x 137mm
M30: 112 pleats x 46mm x 137mm
So, the M30 filter has 65% more surface area. Nice!
Hey, that PS reservoir bracket looks a little odd! I needed to mod the bracket to hold the reservoir about 25mm higher and 13mm further back. Some drilling, MIG welding and filing was all it took.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw013.jpg)
The throttle cable had to sit at a slightly steeper angle to clear the PS reservoir, and I later chopped off the part of the bracket that (obviously) interfered with it.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw014.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw002.jpg)
These sorts of tools are pretty useful for car projects. Actually, the most useful tool is not even visible; the 48" Clausing lathe.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw016.jpg)
I worked on the hoses' positioning a lot so that they would not touch anything, especially brake lines. In the end, I rotated the reservoir and rotated the banjo fitting on the pump to get everything cleared (not shown).
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw004.jpg)
It is very close to the radiator, but it makes it.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw003.jpg)
Clears the alternator just fine.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw007.jpg)
The box's original rubber feet actually sat on the hem in the chassis, but I did not like that and later came up with my own solution for the bottom mounting.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw005.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw006.jpg)
It was also a little close to the ABS unit. I carefully bent the top hard line by about 4mm to make some clearance without collapsing it where it exits the flare nut.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw008.jpg)
I also needed to move the charcoal canister back a good 10cm. That was SUPER easy. All you do is remove the bracket that holds it, flip it upside-down and reinstall everything. Voila!
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw015.jpg)
So here's the new, extra-spacious home for the air box.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw012.jpg)
To get the box level and where I wanted it, I needed to do a little washer-stacking. Note that the M30 box has its mounting holes on the other side in its stock application, and I made some new ones so it would bolt to the stock E30 bracket.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw009.jpg)
A little bit of cutting was required to get the stock chassis mounts into position. Because things were so tight with the radiator and PS reservoir, I had to put the mounts wherever they lined up with the stock bracket. I also needed to chop off a few ribs to clear the brake lines up by the ABS unit.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw017.jpg)
The front mount ended up in the perfect location. The box's stock clip got reused right next to a rib.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw018.jpg)
The rear one was almost on top of a rib. I really didn't want to chop it out since that would weaken things, so I ground-down a nut and got things together. I guess I was just being anal retentive since this box isn't exactly a structural piece and it really doesn't matter.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw019.jpg)
Original feet and stuff were later cut off with a hack saw and then cleaned up with a chisel.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw020.jpg)
A host of other plastic protrusions were cut off. There was no real reason, but I wanted it to look clean and deliberate in there.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw021.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw022.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw023.jpg)
Interestingly, the stock E30 intake snorkel fit the box. That wasn't going to fly in the car though since a) the radiator was in the way, and b) the tube's inlet would be jammed into a headlight.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw024.jpg)
Test-fitting the MAF, it was obvious that I would need to do some chopping of the air box's top.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw010.jpg)
Using a ruler and marker, I did my best eyeball-job for what the cut would need to be.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw011.jpg)
I did a rough cut with a hack saw, with the intent of cleaning it up on the mill.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw025.jpg)
I ended up moving the cut about 25mm further up than I had originally intended, for two reasons. First was that I would need more room for a silicone coupler to mate the MAF to the VS. Second, the 1" end mill that I was using caught the plastic and ripped a big chip out of it lol. I got impatient and tried to make too heavy of a pass on a work piece that was both flexible, and (clearly) not ideally clamped. Patience eventually got me a clean cut, though.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw026.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw027.jpg)
In order to have room for the planned velocity stack, I had to chisel out some of the internal ribs.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw028.jpg)
[COLOR="silver"]- - - Updated - - -[/COLOR]
Next was the business of filling the void, and cleanly too. My sheet metal fab skills are seriously limited, both by the tools that I have available and by my skills as a fabber. I needed to keep things simple, and a single bend was about all I had in the cards.
I took some measurements and got a concept going in CAD. It wasn't super duper accurate (missed the box's top curvature) but it was enough to get a feel for how much room I would have.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw034.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw035.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw036.jpg)
And of course, it would look a lot better with a satin black crinkle finish.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw037.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw038.jpg)
Naturally, the initial prototype was made from poster board!
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw029.jpg)
The actual article was made with a band saw and the mill. The nice circular hole was made on the mill with a rotary table and a 1/8" end mill. The material is 14ga mild steel. It needed a LOT of clamping.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw030.jpg)
To brake the sheet, I ran the 1/8" end mill across the sheet to make a groove. Then I clamped the flat piece between two big aluminum bars in a vise and used a third aluminum bar to bend the top over. The groove really helped things turn out well.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw031.jpg)
I did some rough test fitting to see how would all look.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw033.jpg)
The tubing is 2.75" OD (~70mm) and is the perfect size for connecting to the MAF.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw032.jpg)
To get the tube (poor-man's velocity stack; the right term is probably "air guide" or something in this case) and little mount tabs on, I did a lot of careful MIG'ing and even more grinding/filing/wire-brushing.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw039.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw040.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw041.jpg)
With that done, I just needed to make the final tweaks so that it all fit well.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw042.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw043.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw044.jpg)
Then it was off to the powder coating shop. They had the PERFECT satin black crinkle option that would make this thing match the air box, after I cleaned and painted the box of course. That sucker was NASTY when I got it off of eBay.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw045.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw046.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw047.jpg)
Everything was fully sealed with some Permatex Ultra Black RTV. Tube perimeter, panel perimeter, screw holes, all of it. Some of those fasteners are a real pain to get at too, lol. In the back where the panel sits low, I imagine that it is at least a little restrictive of the filter pleats under it. However, the stock filter has a section like that, and the totally-open area in this box is bigger than the entire M42 filter, so I assume that this still breathes a hell of a lot better.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw048.jpg)
[COLOR="silver"]- - - Updated - - -[/COLOR]
Alrighty, the last post'o'pics.
The final order of business was dealing with the bottom mount situation. The stock setup uses a little black rubber nub that mates to a cup in the stock M42 box. I wanted to use it with this too.
During the project I had to go to China for work. The last few days were spent in Hong Kong before I caught my flight home. It happened to be Dragon Boat Festival week, and my room had a great view of HK Harbor. Normally my employer sort of has a limit of ~$150/night for hotels, but since everything was totally booked for the festival I scored a Harbor-view executive suite at the Intercontinental Grand Stanford.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw049.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw050.jpg)
HK is a hell of a place. The night life is great and it is a killer international city. Think NYC, but way cleaner and way safer. Even a white English-speaker like me has NO trouble getting around and finding good food. There is a strong legacy there from when the Brits ruled it (they returned it to Beijing's control in 1997 but with the requirement that it could operate independently until 2047).
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw050b.jpg)
OK, back to car stuff. I wanted the box to use the rubber mounting nub. I had some 2" nylon rod stock left from something else, which was perfect. Stepping through drill bits and finishing up with the compound cross-slide on the lathe got me an identical cup to the M42 box's. The angle on the other end was eyeballed on the band saw.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw059.jpg)
I sort of hand-fitted stuff in the car, drilled holes in the box when I was sure things were aligned and then marked corresponding spots on the nylon part. I then drilled them and installed M6x1 helicoils since plastic threads are shit.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw060.jpg)
With the cup installed, it fit perfectly under the hood.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw061.jpg)
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw058.jpg)
Being mega anal retentive, I wanted the cup to FIT the contour of the box. So, I wrapped the box with plastic food wrap ans slathered a bunch of plasti-weld epoxy between the nylon part and the box/plastic wrap. Here it is after curing and removing the wrap.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw052.jpg)
Looks like ass and I won't stand for it!
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw051.jpg)
The lathe, my favorite tool!
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw053.jpg)
All cleaned up.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw054.jpg)
Now it looks like it fits well on there. After this, I scrubbed the hell out of the bottom and painted it to match the top. The nylon/epoxy part was painted too. When I did final assembly, I used more Permatex Ultra Black RTV to make a nice fillet where the nylon part meets the box. I also drilled a second drain hole in the read of the box bottom since it sits with a slight rear-ward tilt and I want water to be able to escape. For some stupid reason, I am missing a TON of pictures of all these little details. Bummer!
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw055.jpg)
With it in there, it is darn close to where it needs to be. The MAF is still 5mm off from a perfect fit, but the intake boot can very easily accommodate that.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw056.jpg)
I had some old coupler scraps laying around and got it all fitted. Later I ordered a nicer looking silicone coupler for this.
(http://bmw.e30tuner.com/images/my318is/pic/rally2100/bmw057.jpg)
-----------------------------------
So there it is. How does it run? I have NO idea lol. There were some complications with valve springs, not MM's fault at all (let's just say that MM dropped a supplier as a result) and they paid an insane amount of money shipping this engine back and forth to deal with it and make it right for me, never asking me to pay a penny. The folks at MM are really awesome. I JUST got the head back on the engine a week ago actually. Yup, a 14 month engine project!
Before slapping my silly air box project on, I want to do a little final tweaking on a dyno to get things dialed in 100% with stock stuff. The car pulls like hell with the custom chip that MM sent me for it, but all engines are different and I want to get things fully dialed. From there, I will install the air box and do some final tweaks to the MAF conversion. The intent is to eventually make plug-n-play MAF conversions that are direct replacements for stock AFMs with NO need for a new chip, so a big part of that is making sure that I can get it to work perfectly with a car that was known to be working perfectly with stock sensors. I am 90% of the way there already, but the whole "engine blowing up in 2012" and then some other stuff sort of delayed my progress lol.
-
Really nice work here! I like how it looks factory.
You know, you might be able to swedge the end of the metal tube to give it a slight bell mouth if you wanted.
-
This is an awesome guide. I have the same idea to fit an original BMW air box in my E30 with an E36 m42. :D