E36 328i/325i exhaust manifold difference?

[BMRBOI 8]

Was thinking, is there any difference in flows etc between a 328i header exhaust manifold and a 325i cast-iron manifold?

If the 328i inlet manifold is "strangled" is the exhaust too?

[BM WORLD 1265]

328i flows a bit better .

325i rear muffler sounds better than 328i type though .

328i has cats , cut them out .

[BMRBOI 8]

Hmm, if i am pulling my engine out i wonder if i should look into changing the manifold while im doing everything else. do you know if the manifold would mount straight to the 325i exhaust system?

328i flows a bit better .

325i rear muffler sounds better than 328i type though .

328i has cats , cut them out .

[KwS 2378]

323i intake is restricted so that there is a bigger difference in power between 323i & 328i

[smiddy 76]

Talk about strangled- M52tu twin vanos E46 320, 325, 328 all share same inlet manifold and throttle body, 37mm runner diameter.

Hence poor top end power. Lastest mod in US is to fit M54 manifold [50mm runner dia] with adapter from Turners to allow cable throttle body to fit to manifold. Torque is retained with top end gains of 10- 15 RWKW.

Will be doing this modd myself in two weeks.

Edited June 2, 2011 by wayney

[smiddy 76]

Hi Ron, check my vanos seal replacment post from last week. Gained a load of torque and a few ponies.

Will need to adjust AFR so will run it up for sure.

[smiddy 76]

Yes, for sure. Manifold matches head ports as it should. The throttle body adapter for 60$ and m54 m30 manifold $150 makes this swap very attractive. Remap is recommended and headers. I have both so here we come!

[KwS 2378]

i assume the M54 manifold would also work on a single vanos M52?

[smiddy 76]

This manifold is designed for twin vanos engines, you would need to mod a lot to fit and maybe lose power.