The good m52 gone savage!

There are few known cheap mods, allowing you to fire up some more horsepower / torque out of you m52. It’s all about little investment and effort, and you could achieve some sweet results no matter if it’s b20 or b28 (the bigger, the better). Improvement will be noticeable.

1. Replacing the stock m52 manifold with m50b25 one.

What’s all about.
First – all m52s are with exactly the same intake manifold. Like 800 cc between smallest and largest ain’t do any difference. Dumb huh ?
Second – m52 head intake ports are sligtly bigger than the manifold ones. This means your engine is factory restricted. Some people say this restriction actually helps.  You are gaining some low end torque, since the air is having higher velocity, because of the narrow runners, but you know … i would go with topping up few more real horsepowerZ, instead keeping it stock with some theoretical nms. m50b25 intake manifold is the thing you need . M50b20 is still good, but it allows only 10% more air compared with the m52 stock one . Go hard or go home . m50b25 runners are way larger, allowing around 37% extra more air (Yeah, probably fitting m3 itbs will be the best, but the m50b25 one is like 1/5 of their price ) . Manifold fits plug and play with few customizations – replacing the m50 air temp sensor with your stock one and some idle valve related stuff.

And here is the visual representation of the difference that im talking about.
(m52 manifold on the left, m50b25 manifold on the right.)

Just a tip. Replace the m52 fuel rail with m50 one.
Also replace the rubber gaskets – you need some extra air, but not some, sneaking and unmeasured  air.

 

2. Bring back the m52 throttle body while you are there.

The m52b28 throttle body is 1 mm wider than the m50b25. and that 1 mm makes difference.
The thing here is the TBs seal on m50 is mounted on the intake side.

And on the m52s seal is on the back of the TB. (Mine, just cleaned and polished inside)

Facing rubber to another rubber is not the brightest idea, because you will end up with LOT of unmeasured air and that will lead to bad throttle response and hp lost.

So the thing you need is just a simple thin flange between the two seals, just like this one.

 

 

3. The cone filter and the cold air intake.

As you may know the cold air is denser than the warm air. So what you need to do is basically separating the intake air from the rest of the engine bay. First of all  get yourself a decent cone air filter (K&N for the win) and alloy pipe extension.

Then get a large piece of cardboard, and form it arround the filter as a rough draft .

Sketch it on a paper or autocad it (if you can) and then get it to the nearest CNC machine and  fabricate it from 1.5mm thick alloy sheet.Bend it where is needed and install it.

Be advised, you’ll probably need to relocate your battery. ( I don’t have ABS, so i moved it on the right)

Allowing some fresh air into the shield, from the front of the car will do some extra work. In my case i had to combine oem look with performance, so i had to drill few holes on my headlight protective back cover.

4. Throttle body heater delete.

Cold air intake is completelly useless, if the air is heated again, in the throttle body.

The tb heating is actually more important with carburetted engines where atomized fuel will mix with warm air better than cold air rather than fuel injected engines. But the main reason why your m52 is having this is because BMW didn’t had a clue where their car will end up so :

Anyone who lives where it gets cold in the winter has heard of “wind chill”. It’ll be 30° with a wind chill of 10°. As the air moves through the throttle body, the same wind chill affects the inside if the throttle body. Under certain conditions, such as high humidity, condensation will form inside the throttle body and the moving air will freeze it. This ice will keep building up until it chokes off the air supply and the engine dies. By running hot coolant through passages in the throttle body, it keeps the throttle body warm and prevents this ice from building up.
 http://autorepair.about.com/library/a/1d/bl423d.htm

In case you are not living somewhere where -10 degrees is a normal temperature on an “hot” summer day – you don’t have to worry about this. Keep calm and move forward to procedure. It’s a 1 min job.

There are 2 nipples on the throttle body where the heated cooling fluid (oh the irony) circulates and heats the internals.
Basically unplug the hoses #14 and #12 and piece them together with a short tube (Ø8 mm) and couple of clamps. Done.

You can tap the nipples with a proper plugs and put everything back together if it gets too cold outside where you are.

5. Crankcase ventilation delete.

We’ve already explained why this is bad and how to do it, ( http://e28goodies.com/crankcase-ventilation/ )  but now we will give some head ups how to do it on m52, since it’s slightly more complicated.

So here how it looks the crankcase ventilation on m52.

The #3 above goes to #8 below.

In conclusion. All the bad stuff comes again from the valve cover (#1 on first schematic) into the valve (#2 on first schematic). The valve separates the vapours from the liquid oil. Liquid goes back to the oil pan (#6 on first schematic) and vapours are returning to the engine (#8 on the second schematic) which is causing this: (Yes, oil in the intake)

What you need to do:

Remove the valve with all the surrounding hoses. ( This is what it used to be, the previous owner got kinky)

If i have to draw the whole picture then here it is ( please notice my awesome presentation and drawing skills )

Tap the valve cover with a small motorcycle filter ( this is what i did, you can do it better with an oil catch can )

And then just connect the throttle body rubber boot with the intake manifold with a hose which is passing by the idle control valve.

Tap the unused dipstick vent.

6. Lightweight flywheel.

There is a lot of controversial opinions on the web about which is better option – light or heavy flywheel.
People say 1 kilo less from flywheel, rims, tires pulleys etc. equals to -10 kilos from the body.
I wouldn’t point exact pros and cons, but just some thoughts.

A friend of mine, made a really good example few years ago.
Imagine if you are sitting with a twelve kilos backpack. You will find quite hard to stand up and run with it.
You would do better with six kilos backpack and also you will run way faster, but …If you happen to fall from a cliff, you will roll way more with the heavier backpack. The key here is the inertia moment.
With lighter flywheel your engine will rev faster and accelerate faster, but your speed will start to decrease in the exact moment when you let out the gas pedal. And i can confirm this, since i owned two b28s. One with the standart damper flywheel (12.8 kgs) and the current one with lightweight flywheel (6.3 kgs) and if i have to be honest, light one rox.

 

Aftermarket flywheels are expensive, but there is a cheap alternative available for m52s.

Basically all m20 engines which were made up to August 86′ and aren’t equipped with A/C are comming with single mass 6.3 kilos flywheels.

m20b27 on the left, m52b28 on the right

The only difference is the clutch diameter – m52b28 – 240 mms and the m20s is 228mm.
Not much of an issue if you are planing to keep the car under 300 hp.
I took from my old eta engine the flywheel and pressure plate and skimmed them.

Bought some new friction material made by LUK.

The only problem seems to be the starter drive. It was a bit different than the flywheel crown teeth.
So you need to find a BOSCH dealer and buy a starter drive with part number :
1 006 209 618 or 1 006 209 677 and just replace your current with it.
This drive is not for a BMW but WILL do the work.
Original m52 starter drive on the left and what you need on the right

Your other option is to find an e34 m20 starter. Fits plug and play.
Why not e28 m20 ? Because it’s HUGE and there is just no way to mount it on m52.
Also. For the conversion you will need new flywheel bolts.
8x M12X1.5X28  –  BMW part number :  #11227805885
And you better change your clutch release bearing while the tranny is taken off : #21517521471

7. Some fancy camshafts. 

The main camshafts characteristics are their lift and rotatation.
If I have to put this simple, “rotation” (measured in degrees – °) means how long the cam will keep the valve open and the “lift” (measured in milimeters) is how far the cam will push the valve into the chamber.

The stock cams for m52b28 are 228° and 9 mm lift for both intake and exhaust, so anything above that values will bring some improvement.Now just to be honest, there is nothing better than brand new performance cams like catcams or shricks but they usually cost a fortune, also going really hard with them will require some components arround valve lifting mechanism to be changed, but we are talking here about easy and cheap mods. The second best option is using cams from US m3 e36 ( intake 252°/10.2mm, exhaust 240°/9.7mm) if you have a pair by any chance – great ! If you are not, you  would probably figgure out bmw parts taken from M models are pricy.

And here is the last reasonable option – using m54b30 intake cam for the m52b28 intake side (240° / 9.7mm) and intake (yes, another intake one) from m50b20/5 NO VANOS  (240° / 9.7mm again) for the m52b28 exhaust side. How they both look before installing them on my car.

In the process

M54 cam fitted.

 

FAQ:
Q: Am I getting this right ? Do I really have to use another intake cam for the exhaust side and why ?
A: Yes, you are. There is nothing wrong with it.  The thing is m52 is operated by a single vanos, so you will need a cam without vanos gear for the exhaust side. And this is the only option here.

Q: Why not just use the m54b30 exhaust cam instead ?
A: The M54 is a dual vanos engine. It has vanos sprockets on both cams.

Q: Can i use the cam locking tool for this setup ?
A: Yes, you can. For the exhaust side. Adjusting the m54 intake cam on the m52 is tricky. Get someone who did this before.

Q: What’s next ?
A: DME remap.

8. Stepped headers.

Talking about M parts, the second thing i bought right after installing the new cams was the s50 exhaust manifold.
I was quite happy having one of these. Despite the fact they are rare arround here, their basic purpose is to keep all the runners with the same lenght which separates the gases for longer time, allowing them to keep their  temperature which increases their velocity. Again some exhaust science.
S50 headers compared with m50 headers (same as m52 headers, but made from cast iron)

But for my huuuuuge disapointment the s50 headers’ openings were about 40% larger than the ports on the m52 head. Also they didn’t have that threads allowing me to fit m52 lambda sensors. Not a biggie, but still ..

It’s not that bad, but the s50 is way more than casual ported m50 with M badges. That turned the table for me and I realised the ///M headers would do more harm than good to my project. So i went with that ebay “Basket of snakes” for m52 which were nothing more than stepped manifold, matching perfectly the m52 head ports. Also they fitted even better on my e28 compared with the s50 manifolds.

S50. Please notice the lack of clearance between the upper pipe and the gearbox.

And the new ones.

So long story short. In case you aren’t increasing your engine displacement (bore&stroke) and playing arround with your engine head, but still looking for something better than the stock manifolds – ebay headers are the right tool for the job.

9. Mechanical fan delete.

Have you noticed that instant power loss when you turn on your A/C ? Or the rpm drop on full steering lock ? That’s because of the additional load of your engine. In first case, engaging your A/C compressor, on the second overloading the power steering pump.The mechanical fan draw power from your engine on the same way, but you didn’t even notice, because it’s on all the time and you can tell the difference only when you remove the fan and drive the car a bit. It feels way more nimble.
Now don’t get me wrong, mechanical fan is basically most reliable way to cooldown your engine. It doesnt causе rapid temperature amplitude difference since the fan speed is synchronised with the engine speed. Even if the viscous clutch is completelly dead, it still spins the fan granting you some air flow. Something is always better than nothing.

There are A LOT of cars out there which rely only on an electrical fans, and they are just fine. And that includes e36 316 compact and 318is coupe. If it was me, i  would drive only with the electrical fan, keeping the mechanical one in the trunk for some unexpected circumstances when i need that extra cooling. (Mounting it on is a matter of couple of minutes and it doesnt require a wrench for the job since it is self tightening, reverse thread).