1999 BMW E46 328 - need advise on new headers???

[hough]

Hi can some one please help, as the thread states i have a 1999 E46 328, im looking at buying a new set of header for my car but am a little confussed, i noticed on a few different make that even tho the primary tube are all the same the outlet differ between either 2" or 2.25" i know it does not sound alot but im sure it would make a big difference, but which would be best suited to my car 2" or 2.25" i know my engine is pretty standard but am hoping to get her upto 250bhp later in the year
​

 

[Prince]

Are we talking exhaust manifold here? 250bhp is a high target for the M52.

 

[hough]

Yes the exhaust manifold and iv got the M52TUC28, iv been told i should be able to get car car to about 240 - 250 bhp with a few mods.

 

[Prince]

Then I would match it to the exhaust and sports cat/de-cat. On a 328 I would imagine the exhaust would be no bigger than 2 1.2 inches. Mods should be along the lines of intake manifold (as this is where the most restriction is), BBTB, exhaust, cams, remap.

 

[hough]

once iv done the headers, sport cat and the rest of the exhaust, i was going to put a M54B30 inlet manifold on and maybe a BBTB and a remap, and im currently building a alu air filter box for my itg maxogen filter...

 

[HDi fun]

One of the popular mods is to fit an M50 intake manifold which does not have the M52TUB/C 2.8 restrictors fitted. You'll lose the double VANOS which will cost you some loss of midrange flexibility and also your fuel usage will increase but this apparently yields quite a lot of top end power.

I've left my 528i E39 as it is because I feel the engine is not the 'torquiest' anyway.

The 2.8 litre M52TU series engine was a German eco/insurance 'special' whose intake system operates as two 3 cylinder units under light load and low RPM.

 

[hough]

i thought on the M52TUB28 it was the M54B30 inlet manifold you need to fit, as iv seen on a few forum this being done with good gains and no loss of power in the lower and mid ranges, i was trying to find out what headers people use on the 2.8 as when i replace my exhaust system some companies use twin 2" pipes and others use twin 2.25" pipes which allow a greater flow rate

 

[Prince]

I know it's the M50 on the E36s, don't honestly know if it's the same on the E46s. I would say 2.25" to allow more flow. I'm assuming you're going with an Alpina527 BBTB (if not have a look for him on BFukMW Owner).

 

[HDi fun]

Come to think of it, yes. I, too, have heard of the M54 2.5 manifold going onto the M52. Apparently this does again release a lot of top end power but still at the expense of midrange and economy.

 

[hough]

i have spoken to a few people about the M54 conversion and asked about if there is a change in midrange and economy and they have said that there is no loss in midrange power and the fuel economy is roughly the same if you stick to the original TB, but if i did go for the BBTB i will gain more midrange power but loss a little on economy? but this is only what people are telling me tho......

and on the subject of headers i only ask as some makes like super sprint make the output on the header 2" and other 2.25" and its the same with the exhaust system, so i want to get the headers to match the exhaust system, if that makes sense...

 

[HDi fun]

Surely this is going to make your car quite noisy though.

 

[hough]

i dont know to be honest? on my exhaust which im planning on building myself i am using 4 5" round boxes instead of 2 ovals, but was thinking of 3 silencers pre pipe as i want a proper twin pipe system i try and keep the noise down but the gases still free flowing

 

[Prince]

Surely it comes with a twin pipe system anyway? I would match the exhaust manifold to the exhaust and keep it constant. I wouldn't bother with 3 silencers either. At most 2 as this is what a fair few of exhausts use. Mine just has the one.

And yes, expect it to get loud.

 

[HDi fun]

The exhaust in my 528i is a single when it finally leaves the car. It works as a pair of 3 cyl units back to the pair of cats and then goes two into one on the way to the resonator and back box/tailpipe assembly.

It's a big pipe though, must be 3in diameter.

I suspect that running two pipes all the way back would release more power.

 

[hough]

on my e46 there are 2 headers (3 into 1) then a pair of cats then the pipes join into one then a silencer and all the way to the back box with twin tail pipes, so basically my system is a single pipe exhaust!

 

[hough]

thats the reason i want a twin pipe system, and the reason i want to change my headers, because as far as iv been told if i go for a proper twin pipe system with twin 50mm tubing then i will get an extra 9% flow or if i go for a twin 57mm tubing i will get an extra 29% flow over the standard exhaust system

 

[HDi fun]

on my e46 there are 2 headers (3 into 1) then a pair of cats then the pipes join into one then a silencer and all the way to the back box with twin tail pipes, so basically my system is a single pipe exhaust!

Disturbingly similar to my car then. Does yours have the pair of pre-cats in the 3-1 manifolds? I think you could probably dispense with these, they're 2 way unregulated cats.

 

[hough]

to be honest i dont know, but i will have a closer look later, i think the e46 in the US has the precat`s tho, but will still have a look as would be good to know....