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Rossco · #2 04-05-2009, 06:41 PM

The closer you can get the injector to the inlet valve pocket the better.

The reason?
There is more turbulance behind the valve head than anywhere else in the inlet tract, this turbulance prevents the fuel from wetting the inlet port walls and ensures a more even fuel air mix inside the cylinder.

I had dramas when I added 4 extra 550 cc injectors to a 13b turbo (TO4E, large extend port) the bosses were welded in to the inlet runners (1 per runner) 6 inches higher than the stock injectors (that fired directly into the inlet ports).

The issue this caused for me was fuel condensing on the manifold walls at low to moderate boost levels - throwing the afr's all over the show. It was solid at full power on the dyno (440rwhp) but would foul (wet the plugs) cruising around on the streets, when on boost for short periods of time.

In the end the only cure was to fit 4 x 1000cc injectors & modified rails to the factory injector bosses and cap the whizz bang welded in bosses......