E30 Zone

I've got a m52b28 which I'm going to be turbocharging with an aim of 350-400bhp.

I've ran one of these N/A with the original and then the m50 inlet manifold which I thought was a good upgrade but I did notice the drop in mid range torque.

I would like to keep as much torque as I can down low while running a larger turbocharger for the top end, will sticking to the original inlet manifold cause a significant restriction >5k rpm and thus lead to increased exhaust back pressure?

Does anyone have data/examples of this?

What exhaust will you be running? That's the main thing that'll effect your back pressure.

A few millimetres in intake runner size isn't going to make a lot of difference when you have compressed air coming through it

Thats my thinking too DanThe. I'm not chasing silly power so why not have my cake and eat it too
(even though I think > 300bhp in a light rwd is bordering silly)

I was just wondering if anyone had actually experienced the difference. If you're not going for peak bhp numbers then why not keep the midrange boosting inlet manifold, run a slightly larger hot side and pick up the 5-6.5k rpm with the forced induction?

Acjj619, the exhaust system (turbo to tailpipe) back pressure is not the issue here. If I try to overcome too much intake resistance by increasing boost pressure the turbine back pressure multiplies by > 2 times the intake resistance. This leads to reversion/charge dilution then things take a swift downwards spiral to pre-ignition and unhappy engine components.