nullarbor express wrote:
when I changed from the standard minifold to extractors and seperate inlet m'fold i was going to do the same thing... however i was told that the feul would not reach a high enough temperature to allow for effficient burn (especially in winter months) and therefore your engine will not run as well as it should. You can get a water heated inlet m'fold for about $160 new that solves this.
Vizard's book advices that you seperate the inlet and exhaust manifolds even if you are going to use both

The reason they were joined was as nullabor says to increase the temperature and atomise fuel better. But the joining of the exhaust and inlet manifold forms hotspots which means the fuel atomisation is not even and inlet temperatures can be too high. Sawing the manifolds appart solves this and in our climate there is not much use for a heated manifold I guess.
I can't remember whether this increased the performance straight away or if it increased because you could increase the CR or something similar
Up shot of it was you proably don't need a heated manifold and if you do heating it from the exhaust manifold (whilst simple and a kind of neat idea) is not a very good way to do it.
