cast exhaust manifold v tubular

[bmw2101]

I have a b230a non turbo engine, its never going to do more than 190 bhp imho. Its in a bmw e36. At the moment , the engine has a tubular exhaust manifold, not a kl racing one , but very similar.

At one point i had the cast manifold, 50mm down pipes, and the car made 167 bhp at the flywheel. I swapped for the tubular type and went back, it made 160 bhp!


Ive tuned the engine more now, but at <190 bhp, should i go back to the cast manifold which seems the wrong thing to do, or should i stay with the tubular one? Will the cast cope with 190 bhp? I had a friend who had a 2500 engine, that made 186 bhp with the cast.


thanks

[bmw2101]

well ive decided im going with the cast manifold. Im sure volvo has put some design into how it flows, and the tubular one i have is modded for the bmw, so maybe its not right some how. but the cast made 7 more bhp on exactly the same engine some years ago...

[Thunderbo1t]

You should have someone (maybe Erland can..?) calculate the length of the secondary pipes, cant hurt.

[bmw2101]

thanks that is a nice idea! ill measure what the exhaust measures in total, where the boxes are, and report back on tuesday hopefully. Its different to what anyone else would use as its in a bmw e36 compact.

thankyou!