BEST M42 EXHAUST MANIFOLD???

[razler]

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TOP : M42 (original)
MID : M44 (other engine I have)
LOW : M42 (http://www.esatclear.ie/~bpurcell/318isengine.html)

My original manifold has a cracked weld inside connection between the top mounting flange and pipe, yeah yeah the obvious fix is to re-weld and maybe burr out todo abit of gas flowing..

question 1 : Would it not be better to weld the pipe to the flange on the outside and then heavily burr out the inside welds for even less restriction?
question 2 : Instead of doing the above to the original M42 manifold will the M44 manifold fit? looks to me that it will and that it is a better manifold for performance and design.
question 3 : The lowest photo was found after a google search, can anyone confirm that this is a M42 manifold and if so why dosnt my M42 manifold look like this?
The lowest M42 Manifold design looks like the best of the bunch to me, Correct?
question 4 : On the M42 manifolds, what are the pluged off ports for? a gas analiser tool jobby?

[rix313]

Doubt the M44 one would clear the steering linkage on the E30.

[jmc330i]

^^^ Or match up to the rest of the E30 exhaust.

[razler]

^^^ Or match up to the rest of the E30 exhaust.

The flange shape/size is the same the only difference is that the m44 has a cast flange and studs, my down pipe connects straight up to the m44 manifold...

Yes might be a clearence issue with the steering connection, wont no till I put the engine back in.. good point!

Whats the normal m42 exhaust manifold look like?

The guy thats done my machining work worked for Cosworth for 20yrs, showed him the m42 & m44 manifold, he said straight away the m44 manifold was a better design.. I'll be putting the m44 manifold on... if it fits?!

How come http://www.esatclear.ie/~bpurcell/index.html shows the best m42 manifold? And why dos'nt my m42 have it??

[rix313]

When you consider the other E30 engines came with cast sausage style manifolds and the M42 came with a fabricated one, I'd safely assume BMW made it with performance in mind. So I would say you're hardly doing your self over fitting the standard item.

Also consider the E36 inlet manifold is different to the E30 and not as good. The E30 one has nice equal length 'bananas' as opposed to to the E36 item. Perhaps in both cases it was there had to be a slight compromise with packaging and performance.

What do you mean by what does the standard one look like? You have it in your first thread?

[jmc330i]

^^^ Or match up to the rest of the E30 exhaust.

The flange shape/size is the same the only difference is that the m44 has a cast flange and studs, my down pipe connects straight up to the m44 manifold...

I wasn't talking about the flanges bolting together - Will the E30 exhaust line up with the M44 manifold once its all in the car? Don't forget the M44 manifold was designed to fit the E36.

People have used the M44 engine in E30s (using M42 intake and management), but they also use the M42 exhaust manifold.

[razler]

Thanks for the input, Think iv got it..

1st picture is of a M42 manifold right hand dive car (mine)
2nd is of a M44 manifold (may or may-not fit (probably the latter!)
3rd is of a M42 manifold of a left hand drive car

Wonder what the hp spec is from the right hand to left hand drive M42's with the different exhaust manifold??

[Jos]

iirc
4-2-1 produces more midrange torque at the expense of top end power.
4-1 (bottom manifold) produces better top end but not as much mid range.

The e36 M42 Manifold doesn't fit the e30 at all so I doubt the M44 one will fit easily.

If you are welding your manifold be aware they are stainless and will carbide out if you don't back purge it.

[appletree]

I've got three M42 manifolds all of which are cracked around runners four and one so I've gives them up using dissimilar wire on the outside and stainless on the inside and it's lasted well at twice the factory power and has stopped my ticking noise

[Dave_M3]

What you want is the fannymolds off the S42 :p

[DanThe]

What you want is the fannymolds off the S42 :p

Are they made by hottuning?

I answer to the original question -

BEST M42 EXHAUST MANIFOLD???

The one that clears an E46 steering rack

Welding the outside and burring out the internal welds is a worthwhile job

[saleTGW]

What for are there 4 bolts on the top? I see it on my IS too..