air intake mods/kits?

[thorburn 121]

The intake is not the problem on the M52 and paticularly the 323-- The US 3 litre M3 sucks through the same manifold and air box to make 172kW.

I think you mean the s52b32 shares the same intake as the m52

[jom 98]

BBS, if you look at the dyno curves for both manifolds on the same graph you will note that at 3,000 RPM for example the M52 produces more power (it does this from idle right through to about 5,000 RPM) than the M50 manifold on the same engine.

So if we had two cars one stock and one with an M50 manifold condition and we accelerated from 3,000 RPM in 4th gear the M52 make more power so it will accelerate faster, when the M52 starts running out of power the M50 will catch up because it will continue to make power.

The M50 could keep up if it were 10% or so lower geared but then it would run out at the same time and just use MORE fuel so whats the point??

In short the M52 is an improvement on the M50 it makes more mid range useable power

Fitting and M50 manifold reintroduces the FAILINGS of the M50 - it was a soggy gutless engine that needed to be thrashed to give half decent performance.

My 1750 Alfa used to eat 325's for breakfast - more grunt more acceleration more top speed

So what happens if you fit an M52 manifold onto an M50 325i?

[thorburn 121]

It sucks 30% more air than my car (328) through this manifold which is supposedly undersized for a 325 / 323 which would suck 40% less than the US 3.2 litre M3

Do you have figures for how much air these engines pump at different rpms? genuinely interested

[Jacko 2158]

Exhaust - Standard are horrible , short and unequal

I concur, Ive seen better looking manifolds on tractors.

[thorburn 121]

I suppose i'll have to get a wideband and find out what my injectors are throwing out to really find exactly what air is being pumped.

Tractor what??

Do the euro m3 exhaust pipes have a larger internal diameter?

[Jacko 2158]

Tractor manifold = Cheap to mass produce

M50 Cast Manifold = Cheap to mass produce

Good exhaust manifold (M3?) = Not Cheap to mass produce

M50/M52 exhaust stock manifold might as well be off a massey ferguson. Most Japas have better designed cast manifolds!

Pod filter aint gonna do much but make noise, noise is cool though , and many stock intake manifolds have chambers built into them to give the same effect as a tuned length intake, making more power at X rpm. Some clever fellow has worked that all out, removing that may not help performance.

The whole idea is to get all the sucks and blows to help each other, so that as one cylinder sucks/blows it helps the next cylinder suck/blow. Getting all the pulses to work together at X rpm is done through the the length of the intake/exhaust. Its not just as simple as big hole in the front + big hole in the back to get the most air in/out.

Turbos make the whole intake/exhaust length tuning pointless, as the turbo/compressor wrecks all the waves, and the intake/exhaust charge is getting shoved through the engine anyway.

Edited September 7, 2010 by Jacko

[thorburn 121]

I was hoping you were going to show some Na tractor pull porn

I've found these. My knowledge of fluid dynamics and wave theories is quite limited. So really im just saying these are better because they look nice.

[thorburn 121]

Turbos make the whole intake/exhaust length tuning pointless, as the turbo/compressor wrecks all the waves, and the intake/exhaust charge is getting shoved through the engine anyway.

so you are saying on a turbo application a log manifold is as good as this

[Jacko 2158]

Looks like a friggin Pipe organ

[hybrid 1044]

The m3 pipe also runs an expansion chamber design for exhaust gas expansion, The collector is then strategically placed and then kind of ruined by the s-pipe just before the flanges. You can make some more top end gains by straightening (removing) this and running 2 inch runners as far up as possible.

You can also run 2 1/2 inch runners if you expect the car to live in the high rev band and want top end power.

[sweetm3 180]

As we are working our way along the exhaust how about this for scary

M3 muffler opened up

[Michael. 2313]

Rather interesting to see inside an M3 muffler. I assumed they would be like they are.

Are they made by 'Boysen' the German Exhaust company?

I have some Audi RS4 V8 rear mufflers, made by them in Germany, very nice design and top quality. What is particularly good is they have a vacuum actuated valve in one of the two exit pipes, with it open the muffler becomes straight through, but with it closed the exhaust gases have to travel through some perforated tube into a chamber and through some more perforated tube into the second exit pipe.

Means you can run the car quiet and louder with more flow at the push of a button.

[jom 98]

Going back to the (yawn) M50 manifold on M52 topic.....

Now I've actually tried it.

First of all, theoretically I can't get over the fact that the M50 manifold is perfectly matched to the M52 head. Has anyone considered the 40% step increase in area where a M52 manifold meets the head? Adiabatic expansion, fuel dropout, anyone?

Second - on an automatic 328 I think that the conversion is a no-brainer. The torque curve is embarrassing in NZ conditions on the standard car. At 100kph it's extremely difficult to keep the speed down - it's right at the start of that big torque hump - so in traffic driving gets very frustrating. Also the fact that the power drops off at 5500rpm - 500 revs before the gears change in sport mode - indicates a serious mismatch in the gearbox software.

Add the M50 manifold and both these problems go away. There is a steady power increase right up to the red line and the gears change up at maximum power. It also feels slower on the track (not so much drama!) but is actually quicker.

My vote is for the M50 conversion.

[thorburn 121]

The torque curve is embarrassing in NZ conditions on the standard car

Which part of the torque curve are you talking about?

Lower in the rev range (where the majority of automatic traffic driving is done) the m52 intake makes more torque.

At 100kph it's extremely difficult to keep the speed down - it's right at the start of that big torque hump - so in traffic driving gets very frustrating.

So are you saying giving your car less torque where you use it is better? did you consider a 318?

If your up high in the revs for a lot of your driving then the m50 intake could be a good change. But for your average daily 328 that spends most of it's life travelling low in the revs you aren't helping it.

[thorburn 121]

3pedals did you ever start making a new intake manifold?

[*Glenn* 855]

How many times has this been debated and argued over now ???

[jom 98]

So you have sucessfully retuned your car so it is a slug at low speed and sucks more fuel at 100kmh - well done. I think I will leave mine as it is.

You missed my point - it is a much better match for the characterisics of the AUTO gearbox. I'm leaving mine as it is, too, with the M50 manifold.

[thorburn 121]

which characteristics are these? I have no clue about autos

m50 manifold is better in the higher rpms. Is this where you use your auto?

If your happy that's all that matters. I'm not trying to bag on you. Just don't want someone taking your word as gospel then being disappointed at the results.

[jom 98]

which characteristics are these? I have no clue about autos

m50 manifold is better in the higher rpms. Is this where you use your auto?

If your happy that's all that matters. I'm not trying to bag on you. Just don't want someone taking your word as gospel then being disappointed at the results.

No, serious. The throttle response at 100kph is too harsh with the standard manifold and the auto - the natural cruising speed is about 120 and a small throttle movement at 100 means that you "hunt" to keep it at 100 and it's tiring. The lack of excessive torque at 100kph with the M50 makes for a more relaxed traffic drive.

In (auto) sport mode the change point is about 6200rpm. With the M50 manifold the power is linear right up to the change point. The original setup has an embarassing power dropoff at about 5500rpm, which is OK with a manual (you'd change gear) but crap in an auto.

The fact that the M50 conversion makes the car missile -like on 'sport' full throttle more than makes up for the torque loss. Yes it does feel more sluggish at low revs, but that's cruising territory. Sport mode puts the box up into vanos territory and it makes a big difference. It revs with consistent power right up to the red line. Overtaking speeds on full throttle get embarrassing!

My own observations - no difference in fuel consumption, 1/2 second a lap (better) at Manfield, more civilised on the road.

I know what the theory says, I tried it anyway!

Come and try it if you're in Wellington....

[No name user 379]

If anyone is interested i have a m50b25 intake manifold thats no longer needed and a couple of oversized m50b20 throttle bodies, i put a 2ltr manifold on my 2.5 and cut 3" out of the runner lengths mainly to fit as ive stood the engine up and it works pretty good but will be binned once ive finished the custom intake.

[jom 98]

I Have not missed your point. You are simply talking total crap, an auto gearbox is more suited to constant torque delivery and incremental RPM increase for the most effecient energy transfer. guess what thats how BMW engineered the M52 my original comment stands:

"You have sucessfully retuned your car so it is a slug at low speed and sucks more fuel at 100kmh - well done."

Yes, and by using the M50 manifold I get CONSTANT torque - it's a dead flat line rather than a hump.

As I've tried this, and you haven't, I suggest that you at least consider my opinion rather than tell me it's crap. You can read as many books as you like, but there is absolutely no better way to find something out than to try it.

Fuel consumption, by the way, is totally unaffected.

[No name user 379]

The way i see it is do whatever you like and if it works awesume and if not yourve learnt something either way, nz is the land of diy and im a big fan of that with thanks to people like Burt Munro we have left our mark on the world, my business started over 25yrs ago cause some said to me " you cant do that" and ive yet to be proved other wise.

"Dont just do things to make others happy, do what they will remember"

[jom 98]

Which part of the torque curve are you talking about?

Lower in the rev range (where the majority of automatic traffic driving is done) the m52 intake makes more torque.

So are you saying giving your car less torque where you use it is better? did you consider a 318?

If your up high in the revs for a lot of your driving then the m50 intake could be a good change. But for your average daily 328 that spends most of it's life travelling low in the revs you aren't helping it.

I may have missed the point of this post. The majority of my automatic driving is just that -in traffic. I don't need torque in Wellington traffic because I can't overtake. Out of heavy traffic I use sport mode on the auto and floor it as soon as I'm committed. Overtaking is faster with the M50 manifold. I don't have as much control as with a manual so I want the seamless power to get me past as fast as possible. What it lacks at the low end (8bhp?) is more than made up for at the top end (20 bhp). So it works with the auto box and my driving style. FYI, a manual 318iS with lightened flywheel, a cam job and Toyo stickies is still slower round Manfield.

So - when it matters I am up in the top of the rev range, that's pretty much all you can do with an auto.

Edited January 8, 2011 by Jo M

[summerscheifer 0]

guys, i have recently bought a K&N cold air intake kit. I installed the cold air intake and now at wide open throttle it hesitates for a second then it takes off but it only does it when its cold? Where should i start. i heard it could be the spark plug gap. could this be it? thanks for the help.

[smiddy 76]

Mate, never wide open when cold! Pressure drop from full throttle cold is fooling ecu. If all is well when warm..... all is good.