e30 m42 intake manifold flow

[fumstoo]

What can you tell me about how our manifolds flow? Ive been reading a lot lately on designing custom plenums and it got me thinking about how good our stock one is.

[wazzu70]

The stock one could be a lot worse, but it could be a lot better too.

I would like to make one thats a side feed and uses an M50 throttle body. I would do something very similar to the AMS F1 intake for evo VIII/IX http://www.amsperformance.com/cart/AMS-Mitsubishi-Lancer-Evolution-VIII-IX-8-9-F1-I-Intake-Manifold.html

I have debated if its worth making a whole new manifold, or if just making a different plenum on the end of the factory lower intake would be sufficient. I know Rob at HQ autosport made one that was a new plenum adapted to the stock lower intake.

[fumstoo]

Thats what im trying to decide. Either building an adapter from the current manifold to an m50 tb or a completely new plenum using the lower intake to mount..

Ive also played with the idea of cheating and taking a manifold for a different car, s2000 for example, and modding it to fit.

[wazzu70]

I have seen people make adaptors for the stock mani to fit the M50tb. I think you would be better off with a new plenum and tb though.

[Slowered318]

I think the most effective modification to the m42 manifold would be to match the ports on the lower intake to the ports on the head.

[wazzu70]

That definitely helps a bit, but the manifolds design gets it the way of bigger power like the OP is going for. Port matching will optimise what is already there, but it wont do anything beyond that.