Least restrictive exhaust manifold(s)?

[lloyd]

02' conventional wisdom says that the best exhaust manifold for a stock or mildly tweaked 02 is the cast iron tii manifold.

I have the opportunity to install a stahl setup on a stock 73 CSI and wonder if there is any advantage(s).

Would I be correct in assuming that the stock iron manifolds were the least restrictive mass-produced pipes offered by the factory?

 

[Malc]

In terms of horsepower the gains are miniscule, but if its in good condition then go for it, it won't do any harm
For us "RHDers" there is no choice in the matter :?
BMW did and still do a pretty good job on inlet and exhaust manifold design for mass production so the you are correct regarding your last question.
HTH
Malc

 

[x_atlas0]

The Stahls should give some boost in power. I would imagine the M535 headers are a bit better flowing, if you want to stay OEM.

 

[30csl]

Malc, the rhd manifold is a disgrace, i reckon there would be some nice free ehorsepower there.

I have heard people mention getting a six branch made which goes over and around the steering box. WHen i get my manual box in i will look into this.

Regards

Rohan

 

[blumax]

exhaust manifolding--my take

According to Hans Herman--the engine design engineer who in early 1967 headed the small design team that layed out the original "big six" cylinder head design--I quote his statement--"the stock exhaust manifolds provide minimal restriction to exhaust gas flow"--I trust his professional knowledge on this frequently raised question--I had asked him this same question several years ago--as to what might be gained by a change--his answer "very little"--"only the change in appearance and sound it makes and the extra "jingle" in the pocket of manufacturers and fabricators".

Other owners who have spent money on exhaust manifolds may disagree with the preceding.

 

[CookeD]

I spent no money on my setup, as the header came along as an added bonus with the non-running, diamond-in-the-rough that I dragged home. So, I have no investment to substantiate.

Murray, I have to disagree. A header on an otherwise stock engine, and my car goes better than I think it should. Without question in the mid-range and higher up the tach.

And, you're right-- It looks way cool, and sounds like it has a header.

 

[30csl]

The difference is between rhd and lhd, the position of the steering box means that Hans must have been referring to the left hand drive car!

 

[andrey]

The headers help a little. On the up side, the car revvs a little more freely (really). Nothing major though, but definitely they make a slight difference. My problems with them have been: heat (several destroyed washer bottles), noise (not really a problem ), and fit (a bit of rubbing here and there, fixed with some adjustments to the pipes). If I was to do it again, I probably wouldn't bother.