328i with m52 manifold from 325i?
Discussion
The M52 range were designed with driving torque in mind, the inlet runners were thinner than previous types, and this gives a ram air effect.
The air moves faster through the thinner inlet tracts and builds up a momentum that can pack more air in, sometime called the "reverse supercharger"
This increases the Volumetric efficiency (VE, which is the % of air in the cyl, ie 50% is half full, and under lower than atmospheric pressure, 100% means the cylinder is completely full at ambient pressure, and 120% means it has been turbocharged, and it is under pressure. In most cases, Non turbo cars don't get 100% VE so that's why better filters, and bigger ports are used to try to get the max amount of air in)
For lower revs, this system works quite well, but at higher revs, it becomes too restrictive. The inlet systems are usually tuned for certain rpms, so only work effectively in certain bands.
The older M50 325 manifold was designed to be less restrictive, so fitting one of these to an M52 moves the inlet tuned band higher up, gaining 15+BHP but at a slight cost of losing the lower ram air effect torque.
Very rarely have i heard anyone complain about the change in driving feel though, the freer revving higher power is more intune with the people that want to make these sort of changes
The air moves faster through the thinner inlet tracts and builds up a momentum that can pack more air in, sometime called the "reverse supercharger"
This increases the Volumetric efficiency (VE, which is the % of air in the cyl, ie 50% is half full, and under lower than atmospheric pressure, 100% means the cylinder is completely full at ambient pressure, and 120% means it has been turbocharged, and it is under pressure. In most cases, Non turbo cars don't get 100% VE so that's why better filters, and bigger ports are used to try to get the max amount of air in)
For lower revs, this system works quite well, but at higher revs, it becomes too restrictive. The inlet systems are usually tuned for certain rpms, so only work effectively in certain bands.
The older M50 325 manifold was designed to be less restrictive, so fitting one of these to an M52 moves the inlet tuned band higher up, gaining 15+BHP but at a slight cost of losing the lower ram air effect torque.
Very rarely have i heard anyone complain about the change in driving feel though, the freer revving higher power is more intune with the people that want to make these sort of changes
the m52 uses the same manifold on the 320, 323 and 328s. On the M50s, the 325 manifold is bigger than the 320 one, so make sure you get a 325 manifold.
The 325 m50 one flows more than the expensive alloy Schrick manifold made specifically for the 328 as a tuning upgrade.
http://www.bmw-m.net/techdata/schrick.htm
The 325 m50 one flows more than the expensive alloy Schrick manifold made specifically for the 328 as a tuning upgrade.
http://www.bmw-m.net/techdata/schrick.htm
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