The reason why the injectors are located a little upstream compared with the original configuration is to favor the mixture formation at medium/high engine speed.
In any case the injectors are pointing directly to the valve, and the barrel throttle opening is just under the injector tip (from top to down in the outlet side) helping to direct the fuel to the cylinder.
The injector cutouts in the cylinder head have been weld filled to avoid disturbance in the flow and waves propagation.
The barrel throttles have an internal diameter of 40mm, then the diameter is reduced progressively till 38mm at the manifold flange in the head, after, the internal diameter is approximately constant till the guide/seat area, where the diameter is 40mm approx. With these diameters the oil gallery bump simply could be eliminated, as will be seen in future pictures.
I suppose the absence of the angle in the inlet manifold flange is the reason of the better flow/performance of the 155 head, but when installing these engines in 105 chassis (and specially in spiders) is necessary to give some angle to the intake. In the 155 head the port is straight with an angle of 26º approx, further, the engine is tilt 4º to the exhaust side, all together means that if you want to maintain the throttles/trumpets in horizontal position, the ducts have to bend 30º, but in the fabricated manifold this is done with an ample bend.
- SNO Director, Spain branch, Barcelona
- '90 2.0 Spider -- '93 164 QV -- '93 155 2.0 TS -- '02 156 2.5 V6 -- '?? FMG 3.8 Project